69 results on '"MINERAL ADDITIONS"'
Search Results
2. Activity Enhancement Study of Xinjiang Silica-Alumina Volcanic Rock Powder through Different Activation Processes.
- Author
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Yang, Shuhong, Wu, Yingjie, Wang, Huaiyi, Yang, Guiquan, Ding, Xiangyi, and Xia, Zhaoxuan
- Subjects
VOLCANIC ash, tuff, etc. ,CHEMICAL processes ,ACTIVATION (Chemistry) ,PARTICLE size distribution ,SURFACE area - Abstract
In response to the dilemma of the scarcity of mineral additions and the high cost of long-distance transport in Hotan, Xinjiang, China, this paper presented an activation process study on the feasibility of volcanic rock powders unique to this region as mineral additions. This study explored the activity-enhancing effects of volcanic rock powder via three methods: physical activation process, chemical activation process, and thermal activation process. The results showed that physical grinding improved the particle size distribution and enhanced the 'microaggregate' effect. For every 80 m
2 /kg increase in specific surface area, the particle size decreased by approximately 0.7 μm, and the 28-day activity index increased by up to 4%. In the chemical activation process, the optimal combination scheme of 6% CaO, 2% CaCO3 , and 2% CaSO4 ·2H2 O increased the 28-day strength of volcanic rock powder mortar specimens by approximately 20%, achieving an activity index of 82%. Thermal activation studies showed that the low-temperature heat treatment interval of 300 °C to 700 °C increased the 28 d activity index of volcanic rock powders by 12 to 22 percent. However, when the temperature reached the high-temperature interval of 800 °C to 1400 °C, it, rather, inhibited the activity enhancement. A combination of the three activation methods (physical milling with a specific surface area of 560 m2 /kg after heat treatment at 600 °C, chemical activation with 6% CaO, 2% CaCO3 , and 2% CaSO4 ·2H2 O) resulted in an activity of up to 86% for the volcanic rock powder. The activity enhancement by different activation methods provided a theoretical basis and practical reference for the application of volcanic rock powder as a mineral additions in Hotan, Xinjiang. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Self-Leveling Mortars Produced with Different Types of Cement: Physical–Mechanical Properties and Carbon Emissions.
- Author
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Alves, Brenda Maiara Oliveira, Teixeira, Misley da Cruz, Bernardo, Karen Suely Martins, Cordeiro, Luciana de Nazaré Pinheiro, and Possan, Edna
- Abstract
Self-leveling mortars are a product that stands out in the market for optimizing production. Greater speed of application is achieved due to its high fluidity, and the ability to level without segregation. This paper approaches self-leveling mortars formulated with different types of cement and additions and evaluates these material's effect on the rheological behavior, physical–mechanical characteristics, and environmental aspects of this type of mortar. The results indicate that rheological aspects can be achieved regardless of the type of cement and addition. With proper proportioning, the normative requirements in terms of mechanical properties are met. When using lower-fineness cement, the risk of cracking and the demand for water and chemicals increases. Mineral additions contributed to the mortars' cohesion and reduced shrinkage in mixtures with contents of up to 25% metakaolin and 15% silica fume. Regarding the decarbonization process, opting for cement with pozzolanic additions becomes a favorable solution as it presents a reduction in CO
2 emissions of around 170 kg per m3 of mortar produced. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
4. Effect of the fineness of mineral additions on the behavior of low impact environment self-compacting mortars.
- Author
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Ouazir, Amine, Boukendakdji, Otmane, Kadri, El Hadj, and Debieb, Farid
- Subjects
MORTAR ,MINERALS ,FIXED interest rates ,COMPRESSIVE strength ,SLAG ,CEMENT - Abstract
The aim of this experimental work is to analyze the effect of mineral additions fineness on the hydration of self-compacting mortars, as well as their behavior in the fresh and hardened states. To do this, cement was partially replaced with a fixed rate of 20% for natural pozzolan and 30% for slag. The additions were ground to three different fineness. The results showed that the use of slag is favourable to the formulation of self-compacting mortars, the workability has been considerably improved, the increase in its fineness, meanwhile, reduces the dosage of superplasticizer up to 46%. For the pozzolan, on the other hand, not only was the workability reduced, but the increase in fineness implies an additional demand for superplasticizer up to 16%. Mortars based on additions release less heat, nevertheless, this reduction is accompanied by a drop in compressive strength at a young age. However, the increase in fineness lets to accelerate the initial hydration, inducing additional strength, and to generate heat comparable to that of the reference mortar. Nonetheless, in the case of excessive grinding, the heat release must be taken into account in order to avoid the thermal cracking. [ABSTRACT FROM AUTHOR]
- Published
- 2024
5. Enhancing Concrete Performance with Crumb Rubber and Waste Materials: A Study on Mechanical and Durability Properties.
- Author
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Moolchandani, Karan, Sharma, Abhay, and Kishan, Dharavath
- Subjects
FLY ash ,RUBBER waste ,WASTE products ,CRUMB rubber ,WASTE tires ,ENVIRONMENTAL protection ,CONCRETE mixing ,PORTLAND cement - Abstract
In addressing the dual challenges of sustainable waste management and environmental conservation in the construction industry, particularly the disposal of waste tire crumb rubber (CR) and the demand for eco-friendly building materials, this study explores a novel solution. It examines the sustainable incorporation of waste tire crumb rubber and mineral additions—namely silica fume (SF), marble slurry powder (MSP), and fly ash (FA)—as partial substitutes for natural fine aggregates and cement in concrete. Through comprehensive testing of seventeen concrete samples, the study reveals that the specific mix of R10S5M10F15 that contained 10% crumb rubber as replacement of fine aggregates, and 5% silica fume, 10% marble slurry powder and 15% fly ash as replacements of cement, not only achieves compressive and split tensile strength comparable to the control mix, while the 90 days flexural strength was improved by 4.48%; credited to SF's pozzolanic action and the filler effects of MSP and FA, but also that the inclusion of CR, while reducing compressive strength due to material variations, enhances ductility and improves resistance to sulfate and acid attacks, despite increasing water absorption. The primary goal of this research is to investigate the feasibility and effectiveness of using waste materials in concrete to foster more sustainable construction practices. The objectives include a detailed assessment of the mechanical properties and durability of concrete incorporating these waste materials, aiming to determine the optimal mix proportions for their effective utilization. This study's novelty lies in its detailed analysis of the synergistic effects of combining CR, SF, MSP, and FA in concrete, contributing to the field by offering a sustainable alternative approach to traditional concrete formulations and highlighting the delicate balance required for optimized concrete performance. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Biosorption of Sodium Dipyrone by Industrial Ash and Its Potential in Portland Cement Matrix
- Author
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Luiza Lascosk, Eduardo Pereira, Rodrigo Brackmann, and Juliana Martins Teixeira de Abreu Pietrobelli
- Subjects
biosorption ,emerging pollutant ,filler ,mineral additions ,Portland cement ,Biotechnology ,TP248.13-248.65 - Abstract
Abstract This research evaluated the use of industrial ash from eucalyptus chips in the biosorption of sodium dipyrone with the subsequent, study of its potential in Portland cement matrix. The biosorbent was characterized by the point of zero charge and the surface area. For comparison, before and after the biosorption process, scanning electron microscopy, energy dispersive x-ray spectroscopy, and Fourier transform infrared spectrometry were performed. Regarding the study of the potential of industrial ash after biosorption (AAB), it was characterized by analyzing specific mass, moisture, loss on fire, and X-ray fluorescence, as well as by X-ray diffraction, modified Chapelle, pozzolanic activity index with lime, and performance index with cement, compressive strength, and tensile strength by diametral compression. The biosorption tests were carried out in batch, it being possible to observe that at 298.15 K, 130 rpm, without pH adjustment approximately 93% of commercial dipyrone was removed. The pseudo-second-order kinetic model fitted better with the experimental data and the process was characterized as exothermic and spontaneous. The chemical composition of ash and AAB showed a predominance of CaO followed by MgO, without the presence of an amorphous halo. In the study of the filer effect, using cement pastes, both materials showed favorable results. Thus, it is concluded that the industrial ash studied has the potential to be applied as an alternative material in the removal of sodium dipyrone and for the replacement of cement in the composition of cement matrices, due to the filer effect they presented.
- Published
- 2024
- Full Text
- View/download PDF
7. Modelling of fresh properties and strength activity index with microstructure characterisation of ternary cement incorporating waste glass and granulated blast furnace slag
- Author
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Salah Eddine Daguiani, Oussama Kessal, Abdelouahed Kriker, and Abdessamed Mokhtari
- Subjects
mineral additions ,mixture design approach ,ternary binder ,fresh properties ,microstructure ,strength-activity index ,Mechanical engineering and machinery ,TJ1-1570 ,Structural engineering (General) ,TA630-695 - Abstract
Research in innovative construction materials has focused on utilising supplementary materials in cementitious composites to promote sustainable development and reduce CO2 emissions. Within this context, this study aims to investigate the fresh properties and assess the pozzolanic activity of ternary blended cement by incorporating two industrial waste materials, namely waste glass (WG) and granulated blast furnace slag (GBS), as cement replacements up to 30%. A mixture design approach was employed for composition optimisation, and mathematical models were implemented to achieve this. XRD and SEM/EDS analyses were conducted to examine the structure and composition of the cementitious matrix. The results indicate that the setting time was prolonged compared to the reference mixture. Furthermore, based on the results of the SAI (Strength Activity Index) test, an acceptable level of strength development was demonstrated, confirming that WG and GBS possess the potential to replace cement while meeting the minimum strength requirements outlined in the specifications. Microstructure analyses revealed good adhesion between WGP, GGBS, and the cementitious binder. This research contributes to the development of eco-efficient binders that exhibit increased cement replacement ratios and qualities comparable to, or even superior to, traditional cement systems.
- Published
- 2023
- Full Text
- View/download PDF
8. Activity Enhancement Study of Xinjiang Silica-Alumina Volcanic Rock Powder through Different Activation Processes
- Author
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Shuhong Yang, Yingjie Wu, Huaiyi Wang, Guiquan Yang, Xiangyi Ding, and Zhaoxuan Xia
- Subjects
volcanic rock powder ,mineral additions ,physical activation process ,chemical activation process ,thermal activation process ,Technology ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Biology (General) ,QH301-705.5 ,Physics ,QC1-999 ,Chemistry ,QD1-999 - Abstract
In response to the dilemma of the scarcity of mineral additions and the high cost of long-distance transport in Hotan, Xinjiang, China, this paper presented an activation process study on the feasibility of volcanic rock powders unique to this region as mineral additions. This study explored the activity-enhancing effects of volcanic rock powder via three methods: physical activation process, chemical activation process, and thermal activation process. The results showed that physical grinding improved the particle size distribution and enhanced the ‘microaggregate’ effect. For every 80 m2/kg increase in specific surface area, the particle size decreased by approximately 0.7 μm, and the 28-day activity index increased by up to 4%. In the chemical activation process, the optimal combination scheme of 6% CaO, 2% CaCO3, and 2% CaSO4·2H2O increased the 28-day strength of volcanic rock powder mortar specimens by approximately 20%, achieving an activity index of 82%. Thermal activation studies showed that the low-temperature heat treatment interval of 300 °C to 700 °C increased the 28 d activity index of volcanic rock powders by 12 to 22 percent. However, when the temperature reached the high-temperature interval of 800 °C to 1400 °C, it, rather, inhibited the activity enhancement. A combination of the three activation methods (physical milling with a specific surface area of 560 m2/kg after heat treatment at 600 °C, chemical activation with 6% CaO, 2% CaCO3, and 2% CaSO4·2H2O) resulted in an activity of up to 86% for the volcanic rock powder. The activity enhancement by different activation methods provided a theoretical basis and practical reference for the application of volcanic rock powder as a mineral additions in Hotan, Xinjiang.
- Published
- 2024
- Full Text
- View/download PDF
9. Physicomechanical Properties of Gypsum with Mineral Additions at Elevated Temperatures.
- Author
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Wang, Junjie and Liu, Engui
- Subjects
MINERAL properties ,HIGH temperatures ,HOUSING ,THERMAL resistance ,PHYSICAL mobility ,PORTLAND cement ,THERMAL insulation - Abstract
Gypsum, from either nature or industrial by-products, can be a lower-cost and cleaner alternative binder to Portland cement used in construction projects, such as affordable housing in developing countries. Although various building products have successfully used gypsum as the binder, some drawbacks of this material have still been claimed, for example, in the aspects of mechanical strength and some other physical properties. Using mineral additions to gypsum seems to be a possible solution to create composite gypsum with improved properties. This work has investigated the possibility of two common minerals (silica flour and talc powder) in modifying composite gypsum's physical and mechanical performance at elevated temperatures (100–1100 °C), including hydration, strength, thermal conduction and stability, and microstructure. The results suggest that 10% gypsum replacement by silica flour or talc powder modifies gypsum's physical and mechanical properties, with silica flour performing better than talc powder. The performance of composite gypsum at elevated temperatures depends on the treatment temperature and reflects the combined effects of gypsum phase change and the filler effects of silica flour or talc powder. Thermal treatment at ≤200 °C increased the thermal resistance of all gypsum boards but decreased their compressive strength. Thermal treatment at ≥300 °C significantly increased the compressive strength of gypsum with silica flour and talc powder but induced intensive microcracks and thus failed the thermal insulation. This investigation indicates that silica flour can potentially raise the mechanical performance of gypsum. At the same time, talc powder can hold water and lubricate, which may help with the continuous hydration of gypsum phases and the rheology of its mixtures. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Modelling of fresh properties and strength activity index with microstructure characterisation of ternary cement incorporating waste glass and granulated blast furnace slag.
- Author
-
Daguiani, Salah Eddine, Kessal, Oussama, Kriker, Abdelouahed, and Mokhtari, Abdessamed
- Subjects
- *
GLASS waste , *CEMENT composites , *CEMENT , *MICROSTRUCTURE , *CONSTRUCTION materials , *POWDERED glass , *PORTLAND cement - Abstract
Research in innovative construction materials has focused on utilising supplementary materials in cementitious composites to promote sustainable development and reduce CO2 emissions. Within this context, this study aims to investigate the fresh properties and assess the pozzolanic activity of ternary blended cement by incorporating two industrial waste materials, namely waste glass (WG) and granulated blast furnace slag (GBS), as cement replacements up to 30%. A mixture design approach was employed for composition optimisation, and mathematical models were implemented to achieve this. XRD and SEM/EDS analyses were conducted to examine the structure and composition of the cementitious matrix. The results indicate that the setting time was prolonged compared to the reference mixture. Furthermore, based on the results of the SAI (Strength Activity Index) test, an acceptable level of strength development was demonstrated, confirming that WG and GBS possess the potential to replace cement while meeting the minimum strength requirements outlined in the specifications. Microstructure analyses revealed good adhesion between WGP, GGBS, and the cementitious binder. This research contributes to the development of eco-efficient binders that exhibit increased cement replacement ratios and qualities comparable to, or even superior to, traditional cement systems. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. ULTRA-HIGH PERFORMANCE CONCRETES WITH PHENOLIC FOUNDRY SAND: MECHANICAL AND MICROSTRUCTURAL EVALUATION
- Author
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Bóris Casanova Sokolovicz, André Lübeck, Geraldo Cechella Isaia, and Heliton Weide
- Subjects
UHPC ,Microstructure ,Mineral additions ,Waste foundry sand ,Architecture ,NA1-9428 ,Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
In this investigation, the properties of ultra-high-performance concretes (UHPC) produced with different binders and aggregates were analyzed. Ternary and quaternary mixtures were tested, including structural white Portland cement (WPC), silica fume (SF), hydrated lime (HL), rice husk ash (RHA), fly ash (FA), and limestone filler (LF), in combination with industrial sand (IS) and discarded foundry phenolic sand (DFPS). The mixtures underwent two types of curing: moist curing until the testing age and moist combined with thermal curing. The concretes were evaluated for compressive strength and microstructure using thermogravimetric analysis (TG/DTG) and Fourier transform infrared spectroscopy (FTIR) techniques. The results showed that all mixtures achieved the desired levels of strength for UHPC (150 MPa). Up to 28 days, the mixtures with RHA exhibited higher strength compared to those with FA, regardless of the curing type. However, at 91 days, the mixtures with FA and thermal curing were more resistant than the mixtures with RHA. Among the quaternary mixtures, at 7 days, the strengths of the mixtures were equivalent, indicating that FA did not react at earlier ages.
- Published
- 2023
12. Desarrollo de mezclas para impresión 3d basadas en cemento portland y adiciones de metacaolín, micro sílice y carbonato.
- Author
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Muñoz, Miguel A., Rincón, Daniel A., Robayo–Salazar, Rafael, and de Gutiérrez, Ruby Mejía
- Subjects
- *
THREE-dimensional printing , *FLEXURAL strength , *MINERALS , *PORTLAND cement , *SCANNING electron microscopy , *COMPRESSIVE strength , *SELF-consolidating concrete - Abstract
This article focuses on the utilization of additions such as microsilica (MS), metakaolin (MK), and calcium carbonate (CaCO3) for the design of cementitious materials based on ordinary Portland cement (OPC) suitable for 3D printing (additive manufacturing). The additions were incorporated into the mixes as replacements for OPC in quantities of 5-10% (MS), 5-15% (MK), and 5-15% (CaCO3). The effect of the additions on the fresh and hardened state properties of the mixes was evaluated. The properties studied included extrusion capability, workability (mini slump), flowability (flow table test), setting time, open time, and printability. Additionally, microscopic inspection of the 3D printing mixes was conducted using scanning electron microscopy (SEM), and physical-mechanical characterization was performed through tests for density, absorption, porosity, flexural strength, and compressive strength. The results demonstrated that the additions directly influence the aforementioned properties. It was concluded that the mix 90%OPC-5%MS-5%CaCO3 (mixture 1) and the mix 90%OPC-5%MS-5%MK (mixture 2) exhibited the most suitable set of characteristics to be implemented as 3D printing cementitious materials. From these mixes, it was possible to 3D print beam-type specimens (160 x 40 x 40 mm), achieving flexural strength values at 28 days of 3.4 MPa (mixture 1) and 4.0 MPa (mixture 2), and compressive strength values of 44 MPa (mixture 1) and 50 MPa (mixture 2). These results are considered as a starting point for future research related to the use of these types of additions in 3D printing of OPC-based cementitious materials. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
13. Fresh, hardened and thermal properties of coating mortars containing mineral additions and vermiculite
- Author
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K. dos Santos, A. Figueirêdo, D. de Paiva, F.L. Maia, J.A. da Silva, I.M. da Silva, and I. Costa
- Subjects
Thermal mortar ,Vermiculite ,Mineral additions ,Rheology ,Squeeze-flow ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Efforts are made to alleviate thermal problems in buildings. The use of thermal mortars for coating with vermiculite as aggregate is used for this purpose, but the use with mineral additions is still scarce, especially the rheology through squeeze-flow. Thus, it was aimed to evaluate the behavior in fresh, hardened state and in the thermal conductivity of these mortars. Mortars containing Portland cement, lime, vermiculite, sand, and additions of metakaolin or ceramic brick waste, in the proportion of 1:1:6 (Cement: Lime: Sand), were evaluated. The sand was replaced by vermiculite in 40%, and the additions added in the proportion of 20% to the cement mass, and the water content determined with the spread obtained on the consistency table. Mixtures containing 20% mineral addition and 40% vermiculite proved to be feasible, reaching minimum values according to the respective standards.
- Published
- 2023
- Full Text
- View/download PDF
14. Enhancing Concrete Performance with Crumb Rubber and Waste Materials: A Study on Mechanical and Durability Properties
- Author
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Karan Moolchandani, Abhay Sharma, and Dharavath Kishan
- Subjects
rubberized concrete ,crumb rubber ,mineral additions ,sustainable construction ,waste material utilization ,eco-friendly concrete ,Building construction ,TH1-9745 - Abstract
In addressing the dual challenges of sustainable waste management and environmental conservation in the construction industry, particularly the disposal of waste tire crumb rubber (CR) and the demand for eco-friendly building materials, this study explores a novel solution. It examines the sustainable incorporation of waste tire crumb rubber and mineral additions—namely silica fume (SF), marble slurry powder (MSP), and fly ash (FA)—as partial substitutes for natural fine aggregates and cement in concrete. Through comprehensive testing of seventeen concrete samples, the study reveals that the specific mix of R10S5M10F15 that contained 10% crumb rubber as replacement of fine aggregates, and 5% silica fume, 10% marble slurry powder and 15% fly ash as replacements of cement, not only achieves compressive and split tensile strength comparable to the control mix, while the 90 days flexural strength was improved by 4.48%; credited to SF’s pozzolanic action and the filler effects of MSP and FA, but also that the inclusion of CR, while reducing compressive strength due to material variations, enhances ductility and improves resistance to sulfate and acid attacks, despite increasing water absorption. The primary goal of this research is to investigate the feasibility and effectiveness of using waste materials in concrete to foster more sustainable construction practices. The objectives include a detailed assessment of the mechanical properties and durability of concrete incorporating these waste materials, aiming to determine the optimal mix proportions for their effective utilization. This study’s novelty lies in its detailed analysis of the synergistic effects of combining CR, SF, MSP, and FA in concrete, contributing to the field by offering a sustainable alternative approach to traditional concrete formulations and highlighting the delicate balance required for optimized concrete performance.
- Published
- 2024
- Full Text
- View/download PDF
15. Experimental investigation of the impact of additives in low clinker cementitious materials on multi-ion transference numbers and diffusion coefficients.
- Author
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Cherif, Rachid, Andrade, Carmen, and Aït-Mokhtar, Abdelkarim
- Subjects
- *
FLY ash , *DIFFUSION coefficients , *CEMENT clinkers , *CELL migration , *LIMESTONE - Abstract
In this paper, multi-ion transference numbers were determined throughout the chloride migration testing of low clinker cement-based materials. For this purpose, five cement pastes were studied: pure Portland paste (as a reference) and four other pastes, based on limestone filler, fly ash, slag or silica fume. The transference numbers were calculated from the concentration evolution in the three zones of the migration cell (catholyte, anolyte and sample), considering that: (i) ions moved in the catholyte and anolyte; (ii) ions leached from the sample; (iii) ions were generated from the electrode processes, and (iv) the pore solution of the sample evolved during the test. The chloride transference numbers of pastes with pure Portland cement, limestone filler, fly ash, slag or silica fume are almost zero at the beginning of the migration test but 0.23; 0.18; 0.06; 0.05 and 0.20 at the end of the test, respectively. The ion transference numbers obtained were used for the calculation of diffusion coefficients of chlorides, sodium and potassium using the Nernst-Einstein equation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
16. Improving the Self-Compacting Concrete Properties by Incorporating a New Micronized Limestone Filler.
- Author
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Sassi, Raoudha, Jelidi, A., and Montassar, S.
- Subjects
SELF-consolidating concrete ,LIMESTONE ,CONCRETE ,MINERALS - Abstract
Self -compacting concrete composition results from several approaches to satisfy specific criteria. SCCs must be able to fill small, confined formwork without the need for vibration. To ensure the homogeneity and mechanical characteristics of the concrete, they must have good resistance to segregation throughout the setting time. The self-compacting aspect is controlled by a high volume of paste and an important fines content ensured by incorporating mineral additions that are expensive and not always available. The main objective of this paper is to utilize a new type of micronized limestone filler that may be characterized and incorporated into concrete to guarantee self-compacting quality. In the first part, a detailed characterization of the limestone filler was carried out to investigate its effects on the concrete properties. The identification has been physical, chemical, and specific to the concrete's formulation. The second part is devoted to the experimental tests on different SCCs mixed with various amounts of filler to determine the optimal incorporation percentage. Moreover, a parametric study, involving the content of filler, the granular structure, and the quantity of superplasticizer, allowed an evaluation of the effect of limestone filler incorporation on fresh and hardened concrete characteristics. Through this study, it was demonstrated that with a proportion of limestone filler of about 25% of the quantity of cement used, the quality of the concrete has recognized appreciable improvements. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
17. Prediction of the Compressive Strength of Waste-Based Concretes Using Artificial Neural Network.
- Author
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Amar, Mouhamadou, Benzerzour, Mahfoud, Zentar, Rachid, and Abriak, Nor-Edine
- Subjects
- *
COMPRESSIVE strength , *FEEDFORWARD neural networks , *SILICA fume , *ARTIFICIAL neural networks , *CONCRETE , *FLY ash , *NUMERICAL calculations - Abstract
In the 21st century, numerous numerical calculation techniques have been discovered and used in several fields of science and technology. The purpose of this study was to use an artificial neural network (ANN) to forecast the compressive strength of waste-based concretes. The specimens studied include different kinds of mineral additions: metakaolin, silica fume, fly ash, limestone filler, marble waste, recycled aggregates, and ground granulated blast furnace slag. This method is based on the experimental results available for 1303 different mixtures gathered from 22 bibliographic sources for the ANN learning process. Based on a multilayer feedforward neural network model, the data were arranged and prepared to train and test the model. The model consists of 18 inputs following the type of cement, water content, water to binder ratio, replacement ratio, the quantity of superplasticizer, etc. The ANN model was built and applied with MATLAB software using the neural network module. According to the results forecast by the proposed neural network model, the ANN shows a strong capacity for predicting the compressive strength of concrete and is particularly precise with satisfactory accuracy (R² = 0.9888, MAPE = 2.87%). [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Mix design of high performance concrete with different mineral additions
- Author
-
Hadji, Tarek, Guettala, Salim, and Quéneudec, Michèle
- Published
- 2021
- Full Text
- View/download PDF
19. Effect of gamma irradiation on the mechanical properties of carbonation reaction products in mortar.
- Author
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Jóźwiak-Niedźwiedzka, Daria, Dąbrowski, Mariusz, Dziedzic, Kinga, Jarząbek, Dariusz, Antolik, Aneta, Denis, Piotr, and Glinicki, Michał A.
- Abstract
Prediction of carbonation progress in concrete exposed to ionizing radiation is important for the durability assessment of nuclear power plants, eventually needed for operational license extension. The objective of this work is to reveal the influence of gamma irradiation on the carbonation development and resulting microstructural features of cement mortar. The composition of mortar was varied by using mineral additions. Canned specimens at elevated CO
2 concentration environment were exposed to gamma irradiation up to the absorbed dose of 1.6 MGy in the vicinity of spent nuclear fuel rods in pool of research reactor. Micromechanical properties of carbonation reaction products were determined using nanoindentation tests. The carbonation depth was found to increase with increasing absorbed γ dose. The size of calcite crystals was about three times greater in irradiated specimens. Gamma irradiation improved the micromechanical properties of carbonation products. Effects of mineral additives on the characteristics of irradiated mortar are discussed. [ABSTRACT FROM AUTHOR]- Published
- 2022
- Full Text
- View/download PDF
20. Effects of incorporating bentonite, metakaolin, microsilica, and calcium carbonate on the rheological properties of portland cement-based 3D printing inks.
- Author
-
Robayo-Salazar, Rafael, Muñoz, Miguel A., Vargas, Armando, and Mejía de Gutiérrez, Ruby
- Subjects
- *
RHEOLOGY , *YIELD stress , *THREE-dimensional printing , *PORTLAND cement , *CALCIUM carbonate , *SELF-consolidating concrete - Abstract
Cementitious mixtures for 3D printing require specific rheological properties in the fresh state, which is why it is necessary to incorporate admixtures and/or mineral additions (modifiers) into such mixtures. The objectives of this article were to compare the effects of bentonite (Ben) (1 %–5 %) and mineral additions, such as metakaolin (MK) (5 % and 10 %), microsilica (MS) (5 % and 10 %) and calcium carbonate (Ca) (5 % and 10 %), on the rheological properties in the fresh state and to determine the printability of cementitious mixtures based on ordinary Portland cement (OPC). Among the rheological properties, the static yield stress (τ 0), flow behavior, viscosity (η) and thixotropic of the mixtures were evaluated. Complementarily, the properties of materials in the fresh state, such as the settlement (minislump), flow rate (flow table) and buildability, were determined. The printability was evaluated through laboratory-scale additive manufacturing tests by printing from a hollow cylinder (unfilled) 50.8 mm in diameter and 208 mm in height (≈52 layers). The results showed that the incorporation of Ben between 1 % and 5 % had a significant effect on the rheological properties of the mixtures in the fresh state, increasing τ 0 to 203.8 % (5 % Ben) and structural regeneration (thixotropy) to 98.5 %. Ben decreased the fluidity of the mixtures while significantly increasing the buildability. Among the mineral additions used, MS and MK increased the rheological properties of the mixtures as a function of the amount incorporated (5 % and 10 %, respectively), while Ca had a fluidifying effect on the mixtures, thereby affecting the buildability during the 3D printing process. This phenomenon was corrected by simultaneous adding 3 % Ben. The results obtained were considered a starting point for the design of OPC-based 3D printing mixtures with these modifiers (Ben, MK, MS and Ca). • The effect of bentonite, metakaolin, microsilica and calcium carbonate was studied. • Bentonite had a significant effect on the rheological properties of the mixtures. • Bentonite and microsilica increase the buildability of the 3D printed mixes. • Calcium carbonate does not generate significant changes in the flow behavior. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Characterization and modelling of the rheological behaviour of blended cements based on mineral additions.
- Author
-
Bouglada, Mohammed Salah, Naceri, Abdelghani, Baheddi, Mohamed, and Pereira-de-Oliveira, Luiz
- Subjects
- *
CEMENT , *MINERALS , *CEMENT clinkers , *YIELD stress , *GEOMETRIC shapes , *SLAG , *VISCOSITY - Abstract
This paper presents an experimental study to evaluate the effect of local mineral additions (pozzolan, slag and limestone) on the rheological behaviour of based cement binder's pastes. The binary, ternary and quaternary binder pastes were prepared with the partial clinker cement replacement limited up to 20%, according with type CEM II specifications. The cements were characterized by their geometric shapes, the reactivity and the chemical composition. An experimental design plan was used to modelling the rheological behaviour of pastes. The relatives yield stress and plastic viscosity of binder's pastes, with normal consistency, were determined. The results showed that all the tested compositions with additions follow the same rheological behaviour law according to the Bingham model. The binder pastes rheological parameters (yield stress and viscosity) are affected by mineral additions. The highest values of the rheological parameters were measured in binary and ternary cements with limestone and pozzolan. On the other hand, the lower viscosity among the tested pastes was obtained with slag addition. The statistical approach allowed us to obtain a satisfactory modelling of viscosity and yield stress with a coefficient of determination R2 = 0.91 and 0.92, respectively and a satisfactory correlation between the viscosity and the water/binder ratio (W/B) for a normal consistency with a coefficient of determination R2 = 0.91. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
22. Prediction of the basic creep of concrete with high substitution of Portland cement by mineral additions at early age.
- Author
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Delsaute, Brice, Torrenti, Jean‐Michel, and Staquet, Stéphanie
- Subjects
- *
CONCRETE , *MINERALS , *PORTLAND cement , *CREEP (Materials) , *BLAST furnaces , *SLAG - Abstract
The present work analyses the basic creep of concrete compositions for which 75% of Portland cement is substituted by limestone filler and/or blast furnace slag. Compressive creep tests are performed during and after the peak of hydration of the slag in order to track the effect of the slag on the development of the creep properties. An adapted version of the Model Code 2010 (MC2010) is used to model basic creep. It is observed that the high substitution rate of cement by limestone filler and/or slag leads to a significant change in the evolution of the viscoelastic properties of concrete till a significant degree of reaction of slag is reached. It corresponds to the end of the second peak of hydration due to slag. After the slag peak of hydration, the basic creep is similar to ordinary Portland cement concrete with equivalent water‐to‐binder ratio. For very early age, a new model is developed and is composed of two terms, which consider the hydration of (a) Portland cement and (b) slag in the aging of the specific creep function. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
23. Effect of fly ash and silica fume on rheology, compressive strength and self-compacting in cement mixtures
- Author
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Jaime Arturo Correa-Yepes, Néstor Ricardo Rojas-Reyes, and Jorge Iván Tobón
- Subjects
cement rheology ,mineral additions ,yield stress ,viscosity ,self-compacting cements ,Technology ,Mining engineering. Metallurgy ,TN1-997 - Abstract
In this research the effect of the addition of silica fume (SF) and fly ash (FA) to the ordinary Portland cement (OPC), individually and in combination, on rheology, compressive strength and self-compacting capacity in mixtures of cement were evaluated. At the beginning, the physicochemical characterization of the raw materials was carried out using XRF, SEM and PSD. Subsequently the rheological analysis was done in order to determine yield stress and plastic viscosity, then the compressive strength was measured at 7 and 28 days of normal curing. Finally, the measurement of the selfcompacting capacity by means of a V-funnel was performed. It was found that the FA influences positively because it reduces yield stress and selfcompacting test times, but decreases the compressive strength in comparison to control sample. The addition of SF increases the yield stress and selfcompacting times, but positively influences the compressive strength. By analyzing the combinations of FA and SF additions the effects of each one are maintained allowing finding an addition range that delivered efficient values for the performance of fresh and hardened state of the blended cement pastes.
- Published
- 2018
- Full Text
- View/download PDF
24. Influence of inorganic and organic additives on spectrophotometry of lime mortars
- Author
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Judith Alejandra Velazquez, Wilfrido Martínez Molina, Elia Mercedes Alonso Guzmán, Hugo Luis Chávez García, and Mauricio Arreola Sanchez
- Subjects
spectrophotometry ,lime ,mineral additions ,mortars ,restoration ,Fine Arts ,Arts in general ,NX1-820 - Abstract
Variation in colors in lime base mortars by adding materials like clay, manufacturing brick ash, quarry powder, and maize starch have been analyzed in this research. Such additions were compared with a sample mortar made only of sand and clay. In order to quantify the color, Chromatic coordinates, expressed in coordinates C.I.E. (L*, a* and b*) were measured. These analyses determine the median chromatic coordinates which are between red and yellow, maybe as orange. To design a mortar in that original color the measured values L*, a* and b* were taken into account. The present work shows the results of color of lime mortars which provides acceptable aesthetic results according to the original colors of the monuments that is intended to be restored but without diminishing the mechanical resistance of them.
- Published
- 2017
- Full Text
- View/download PDF
25. Evaluation of hydration of cement pastes containing high volume of mineral additions.
- Author
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Anjos, M. A. S., Reis, R., Camões, A., Duarte, F., and Jesus, C.
- Subjects
- *
CEMENT composites , *CEMENT , *PORTLAND cement , *HYDRATION , *MINERALS - Abstract
The use of mineral additions is a common practice in the production of cementitious materials. Recently proposed usage of high amounts of cement replaced by mineral additions requires the study of the chemical interaction of these additions with the cement. This study intends to evaluate, by means of TG/DTG techniques, XRD and compressive strength, the effect of high volume of mineral additions in the hydration of cementitious pastes. Pastes with 50–70% of cement replaced by mineral addition and with different combinations of fly ash and metakaolin were evaluated, two pastes without mineral addition and two other pastes with lime addition. Results showed TG/DTG and XRD techniques are more suitable for evaluating kinetics of reactions of hydration, making it possible to quantify the substantial reduction in the levels of portlandite in hydrated pastes containing high volumes of mineral additions. These techniques allowed to find important differences in the evaluation of calcium hydroxide, because its morphology can change in the presence of additions. Also showed that it is possible to achieve, enhanced or even high compressive strength (50–80 MPa) in concretes containing reduced cement contents. As well as more resistance against harmful agents and carbonation attack. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
26. Fresh and hardened properties of self-compacting concrete with different mineral additions and fibers
- Author
-
Naima Haddadou, Rabah Chaid, Youcef Ghernouti, Naima Adjou, and Malik Bouzoualegh
- Subjects
self-compacting concrete ,mineral additions ,workability ,fibers ,hardened properties ,Building construction ,TH1-9745 - Abstract
In this work, several reinforced self-compacting concretes were prepared by using three types of fibers made of steel, polypropylene and glass, and three different types of mineral additions (marble powder, metakaolin and limestone powder). The water to cement ratio was kept constant at 0.34 and fibers were used in combination, keeping the total fiber content constant at 60 kg/m3. Slump flow diameter, L-Box, stability and air content were performed to assess the fresh properties of the concrete. Compressive strength, flexural strength, splitting tensile strength and ultrasonic pulse velocity of the concrete were determined for the hardened properties. Noteworthy performances were generally obtained, particularly in hardened properties for the self-compacting concretes prepared with steel fibers in association with polypropylene fiber and marble powder as mineral addition.
- Published
- 2016
- Full Text
- View/download PDF
27. Effect of mineral additions incorporated in concrete on thermodynamic and kinetic parameters of chloride-induced reinforcement corrosion.
- Author
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Oliveira, Andrielli Morais de and Cascudo, Oswaldo
- Subjects
- *
CHLORIDES , *THERMODYNAMICS , *CHEMICAL kinetics , *CORROSION & anti-corrosives , *POZZOLANIC reaction , *POZZUOLANAS - Abstract
Highlights • Resistivity is an expressive indicator of concrete durability regarding Cl− attack. • Concretes with pozzolanic additions have significantly high resistivities. • It has been found an inverse correlation between R p and ER before Cl− attack. • Concretes with pozzolans showed a better performance regarding the steel corrosion. • The impedance for systems with pozzolans was slightly altered after Cl− attack. Abstract In this article, the beneficial effects of pozzolanic mineral additions incorporated in concrete under the attack of chlorides are evaluated. Three different mineral additions incorporated in binary combinations with Portland cement (silica fume, metakaolin and fly ash) were studied. By monitoring and analyzing thermodynamic and kinetic parameters, the corrosion performances of reinforced test specimens were evaluated over an extended period of chloride attack (44 weekly cycles of wetting in a solution of NaCl and air drying, equivalent to 308 days of attack). The electrochemical techniques (E corr , R p and EIS) 1 Electrical resistivity (ER), corrosion potential (E corr), polarization resistance (Rp), electrochemical impedance spectroscopy (EIS), corrosion rate (i corr), control concrete (C), concrete with silica fume (SF), concrete with fly ash (FA), concrete with metakaolin (MK). 1 , added to the electrical resistivity technique (ER), are allowed to evaluate the protection capacity of the concretes under study, in relation to this strong attack on the reinforcement. They also allowed the production of subsidies capable of generating scientific discussion about the mechanisms of protection, imparted to concrete by mineral additions, in this specific aggressive medium rich in chlorides. The results showed that the used mineral additions produced significant increases in the resistivity of concretes, which is probably due to physical changes in the pore structure of cement paste, besides the improvement of paste-aggregate interface and the changes in the conductivity of pore solution. This higher resistivity certainly delayed the transport of chlorides and their attack on the reinforcement, seen by small changes in the values of E corr , R p and i corr in concretes with pozzolans. The EIS results showed that there was little change in the impedance values at the steel-concrete interface in these systems with mineral additions, in spite of the strong and prolonged attack. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
28. Effect of fly ash and silica fume on rheology, compressive strength and self-compacting in cement mixtures.
- Author
-
Correa-Yepes, Jaime Arturo, Rojas-Reyes, Nestor, and Tobón, Jorge I.
- Subjects
- *
FLY ash , *SILICA fume , *RHEOLOGY , *CEMENT , *SUSTAINABLE development - Abstract
In this research the effect of the addition of silica fume (SF) and fly ash (FA) to the ordinary Portland cement (OPC), individually and in combination, on rheology, compressive strength and self-compacting capacity in mixtures of cement were evaluated. At the beginning, the physicochemical characterization of the raw materials was carried out using XRF, SEM and PSD. Subsequently the rheological analysis was done in order to determine yield stress and plastic viscosity, then the compressive strength was measured at 7 and 28 days of normal curing. Finally, the measurement of the selfcompacting capacity by means of a V-funnel was performed. It was found that the FA influences positively because it reduces yield stress and selfcompacting test times, but decreases the compressive strength in comparison to control sample. The addition of SF increases the yield stress and selfcompacting times, but positively influences the compressive strength. By analyzing the combinations of FA and SF additions the effects of each one are maintained allowing finding an addition range that delivered efficient values for the performance of fresh and hardened state of the blended cement pastes. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
29. CARACTERIZAÇÃO E AVALIAÇÃO DAS PROPRIEDADES DE CONCRETOS AUTOADENSÁVEIS COM ADIÇÕES MINERAIS E BAIXO CONSUMO DE CIMENTO.
- Author
-
DINIZ, H. A. A., OLIVEIRA, J. N., SILVA, L. P., MACÊDO, M. S., and SOUZA, M. M.
- Abstract
The self-compacting concrete (SCC) has a high content of fine materials and has been widely used due to its characteristics of high fluidity and cohesion. Fines from industrial waste or by-products may be used for the sake of sustainability, considerably reducing the consumption of cement associated with the possibility of maintaining or improving mechanical or durability properties. In this way, this article aims to study the properties of concrete in the fresh state and hardened state, analyzing the feasibility of the development of SCC made with high levels of mineral additions. For this, the cement was replaced by mineral additions (sugar cane biomass residue or pozzolan from rice husk and metakaolin) in the 50% content, based on the reference trait, which consumes 442.6 kg/m3 of cement, giving new traits with cement consumption between 215.9 kg/m3 and 216.2 kg/m3. The SCC were characterized in the fresh state by the Slump-Flow Test, T500, J-ring, V-funnel and L-box assays, assessing the influence of the insertion of the additions on the rheological properties and the superplasticizer additive consumption. In order to evaluate the mechanical performance of the SCC, compressive strength tests were performed. The SCC with mineral additions presented satisfactory mechanical performance. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
30. CHARACTERIZATION OF THE REACTIVITY OF MINERAL ADDITIONS BY DIFFERENT MICROSTRUCTURAL AND MECHANICAL APPROACHES.
- Author
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BOUGLADA, Mohammed Salah, NACERI, Abdelghani, and BAHEDDI, Mohamed
- Subjects
MICROSTRUCTURE ,POZZUOLANAS ,MECHANICAL behavior of materials ,COMPRESSIVE strength ,MICROPOROSITY ,HYDRATION - Abstract
This paper presents an experimental study aimed at evaluating the reactivity of natural and industrial local mineral additions (pozzolan, slag and limestone) by different microstructural and mechanical approaches. Binary, ternary and quaternary cement compositions were prepared with partial replacement of the clinker by additions limited to 20%, according to CEM II / A cement specifications. The reactivity during the hydration process is characterized by the hydraulic power of the additions to react with the water and the hydrates of the cement and the pozzolanic capability of fixing the portlandite to form new mineral phases which contribute to the resistance as much as the hydrated products of cement. An experimental methodology was established for the reactivity illustration of the additions by a microstructural approach based on a study of the physicochemical and microstructural properties realized by X-ray diffraction (XRD), the scanning electron microscopy (SEM) on pastes. Further, thermogravimetric analysis (TGA), mercury microporosity (MIP) on mortars at 28 days of age was performed. A mechanical approach based on compressive strength at 2, 7 and 28 days to determine the activity index according to ASTM C 618 has been undertaken. The results obtained show a good correlation between the microporosity, X-ray diffraction and the resistance activity index, in particular for the slag, as for the thermogravimetric analysis that clearly confirms the pozzolanic activity of the pozzolan addition. As for mechanical performance, a binary mortar with 20% slag showed a better compressive strength at 28 days (49.40 MPa) with a reactivity index (87.90%) compared to the control mortar. Further, the slag developed better resistance (49.53 MPa) in combination with the other additions for quaternary mortars (pozzolan, limestone and slag) with an optimal rate of 5, 5 and 10%, respectively. Nevertheless, the pozzolan showed better compressive strength values compared to the slag for the binary mortars at young age 2 and 7 days of 25.67 and 32.07 MPa, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
31. Quantification and analysis of heat hydration of blended cement at different temperature.
- Author
-
Boubekeur, Toufik, Ezziane, Karim, and Kadri, El-Hadj
- Subjects
- *
EFFECT of temperature on cement , *HEAT of hydration , *MORTAR , *HIGH temperature chemistry , *THERMOCHEMISTRY - Abstract
The study of the hydration kinetics appears as a prerequisite for understanding the physical and mechanical phenomena that control the behavior of cementitious materials. This research is based on monitoring the evolution of the degree of hydration for ordinary cement and those containing 10% of limestone powder, 20% of natural pozzolana or 30% of the blast furnace slag under high temperatures. The results provide a better understanding the effect of cure temperature on the hydration kinetics and understand the contribution of mineral additions on improving the cement properties. A new model proposed gives the satisfaction results for predicting in later age the heat of hydration of cements blended kept under constant temperatures. The latter has a wider appreciation of the results, where it gives correlation coefficients very close of unity. This justifies the reliability of this new model proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
32. Durability of reinforced concrete exposed to aggressive conditions
- Author
-
A. M. Aguirre and R. Mejía de Gutiérrez
- Subjects
reinforced concrete ,steel corrosion ,mineral additions ,electrochemical rehabilitation ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
Reinforced concrete is the most widely used construction material in the world. The combination of high compressive strength, afforded by concrete and, and the excellent mechanical properties that characterise steel make it an ideal composite for all manner of structures. One of the main weaknesses of this material, however, is that when the concrete is exposed to aggressive environments, in particular high concentrations of chloride ions or carbon dioxide, reinforcing steel corrodes, shortening service life. This article reviews the state of the art on concrete durability, along with the conditions that affect its useful life by inducing reinforcing steel corrosion. It also discusses the prevention and control methods, in particular electrochemical prevention and rehabilitation techniques, that have been developed to mitigate the problem.
- Published
- 2013
- Full Text
- View/download PDF
33. Effect of the substitution of cement by limestone filler on the rheological behaviour and shrinkage of microconcretes.
- Author
-
Varhen, Christian, Dilonardo, Isabela, de Oliveira Romano, Roberto Cesar, Pileggi, Rafael Giuliano, and de Figueiredo, Antonio Domingues
- Subjects
- *
FILLER materials , *LIMESTONE , *CEMENT , *CONCRETE mixers , *YIELD stress - Abstract
This study analyses the impact of substituting limestone fillers for cement on the rheological behaviour and drying shrinkage of microconcretes that are used for repair coatings. Three microconcretes were formulated with limestone filler contents of 80%, 60% and 20% by weight in relation of the total fines (cement and limestone filler). The total fines and water contents were kept constant in all of the formulations result in mixtures with similar volume of paste. The rheological behaviours of the mixtures were evaluated using a rheometer with planetary motion. The specimens were then moulded for mechanical characterisation and to measure the drying shrinkage. The porosity of the pastes was also evaluated using the mercury intrusion porosimetry (MIP). Rheological properties such as the yield stress and viscosity were influenced by the amount of cement that was replaced by fillers. Larger volumes of filler in the paste produced lower yield stresses and, consequently, higher slump values were obtained. However, the plastic viscosity increased with the filler content. In the hardened state, greater substitutions of cement by fillers decreased the drying shrinkage. This will cause lower differential shrinkage between the repair material and the existing substrate, generating lower tensile stresses in the repair material (repair coating) and therefore less potential for cracking of this. The experimental shrinkage results were compared to values that were obtained by the ACI 209, CEB-FIP90, B3 and GL2000 shrinkage prediction models. The models were found to overestimate the amount of shrinkage with increased substitution of cement by filler in the paste. Therefore, these models should be calibrated considering other factors such as the quantity of filler used in cement replacement. That consideration could optimize the use of these models in the design stage to verify if the values of expected shrinkage are within usually accepted limits for this application. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Influence of mineral additions on flexural fatigue performance of steel fibre reinforced concrete.
- Author
-
Kaur, Gurbir, Singh, S., and Kaushik, S.
- Abstract
An experimental investigation is conducted to study the flexural fatigue performance of steel fibre reinforced concrete containing fly ash (FA), silica fume (SF), metakaolin (MK) and limestone powder (LP) as mineral additions in terms of theoretical fatigue lives. Seven mix combinations are prepared by replacing 30 % of cement by weight with FA, SF, MK and LP in different proportions to form binary and ternary blend systems. Rectangular corrugated steel fibres at 1.0 % volume fraction are incorporated in all seven mix combinations. Beam specimens are tested at four fatigue stress levels ranging from 0.90 to 0.75. The Weibull distribution is employed to incorporate the failure probabilities into the fatigue life data of all mix combinations. The theoretical fatigue lives of all mix combinations are calculated using single-logarithm fatigue equation. The theoretical fatigue lives of concretes containing mineral additions get enhanced in different extent as compared to control concrete. The concrete containing SF and FA in the amount of 10 and 20 % by weight of binder respectively has shown the best flexural fatigue performance, which is much better than that of the control concrete. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
35. Reuse of recycled crushed concrete fines as mineral addition in cementitious materials.
- Author
-
Oksri-Nelfia, L., Mahieux, P-Y., Amiri, O., Turcry, Ph., and Lux, J.
- Abstract
Environmental issues have led European stakeholders to join around an ambitious project, the reuse 70 % of inert wastes from construction and demolition by 2020. Among available solutions, the reuse of fine recycled aggregates as substitute of natural sand is somewhat problematic due to their high water absorption. The aim of the present research is to study a new way of recovery for fine recycled aggregates. We propose to use them as mineral addition, after a process of crushing and sieving resulting in powder (particles diameter lower than 80 µm). For this purpose, Recycled Crushed Concrete Fines (RCCF) were prepared from a 5 years old concrete and characterized by a physico-chemical approach. Attention was paid to assess the content of anhydrous cement. Mortars with different substitution levels of Portland cement by RCCF (Recycled Crushed Concrete Fines) or limestone filler were also studied at both fresh and harden states. The studied RCCF were found to have low content of anhydrous cement and thus low hydraulic properties. However, RCCF (Recycled Crushed Concrete Fines) was found to play a similar role than limestone filler on cement hydration. Portland cement could be substituted by RCCF (Recycled Crushed Concrete Fines) up to 25 % without altering properties of mortars. These results are encouraging and lead us to continue our research with inert wastes from real demolition sites. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
36. Deterioration of hardened cement paste under combined sulphate-chloride attack investigated by synchrotron XRD.
- Author
-
Stroh, J., Meng, B., and Emmerling, F.
- Subjects
- *
SULFATES , *SYNCHROTRONS , *CHLORIDE ions , *X-ray diffraction , *PORTLAND cement - Abstract
The exact mechanisms of the phase transitions caused by a combined sulphate-chloride attack are discussed controversially. The main points concern the mutual influences of sulphate and chloride ions during the secondary binding processes of these anions within cement hydrate phases. We simulated combined sulphate-chloride attack under laboratory conditions using solutions containing NaCl and Na 2 SO 4 in different concentrations. Three sample compositions were used for the preparation of the specimens. In two of them, 30% of Portland cement was replaced by supplementary cementitious materials (fly ash, slag). The phase distribution in the samples was determined using synchrotron X-ray diffraction. The analysis with high spatial resolution allows the localisation of the secondary phase formation in the microstructural profile of the sample. A mechanism of the phase developments under combined sulphate-chloride attack is derived. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
37. Monitoring of sulphate attack on hardened cement paste studied by synchrotron XRD.
- Author
-
Stroh, J., Meng, B., and Emmerling, F.
- Subjects
- *
SULFATES , *CEMENT , *SYNCHROTRONS , *X-ray diffraction , *CONSTRUCTION materials , *PHASE transitions , *MICROSTRUCTURE - Abstract
The complex matter of external sulphate attack on cement-based construction materials is still not completely understood. The concentration of sulphate is a crucial factor for the formation of secondary phases and phase transitions of cement hydrates due to sulphate ingress into the microstructure. The sulphate attack on building materials for high and low sulphate concentrations was monitored by laboratory experiments. Hardened cement paste consisting of ordinary Portland cement (CEM I) were exposed to aqueous solutions of sodium sulphate for 18 months. Three sample compositions were used for this research, including different supplementary cementitious materials (SCM). The phase composition was determined for different time spans by high resolution synchrotron X-ray diffraction. Cross sections of exposed cement prisms were investigated as a representation of the microstructural profile. Based on the data, a temporal and spatial determination of the stages of the sulphate attack and the deterioration course was possible. Cement matrices blended with slag showed the highest resistance against sulphate attack. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
38. The Influence of Wastes Materials on the Rheology of Rendering Mortars
- Author
-
de Oliveira L. A. Pereira, Gomes J.P. Castro, and Nepomuceno M.C.S.
- Subjects
cement-based mortar ,mineral additions ,wastes materials ,flowability ,rheology ,Materials of engineering and construction. Mechanics of materials ,TA401-492 - Abstract
The objective of this paper is to present the results of a research about the effect of mineral additions and specific lightweight aggregates obtained from wastes materials (crushed EPS and cork) on the rheological properties of renderings mortars. Four series of mortar formulations were prepared. Each series was composed by four mortars mixes with different mineral additions: hydrated lime, glass powder, tungsten mine waste mud, and metakaolin. The proportions of the mortars expressed in terms of apparent volume of cement, mineral addition and sand was 1:1:5. Flowability of mortar was measured using a standard flow table test. The density and the water retention capacity of mortars were also determined. The mortar rheological parameters were evaluated using a rheometer. The results show that the mortar yield stress is strongly influenced by the water amount, binder fineness and mineral addition nature. The mortars plastic viscosity is also influenced by the nature of mineral addition and the partial replacement of sand by EPS aggregates introduce incongruent values, caused by the segregation, in the mortar yield stress, whereas, the cork aggregates is responsible by the yield stress reduction.
- Published
- 2013
- Full Text
- View/download PDF
39. Effects of some mineral additions to Portland cement on reinforcement corrosion.
- Author
-
Andrade, Carmen and Buják, Renata
- Subjects
- *
MINERALS , *PORTLAND cement , *CORROSION & anti-corrosives , *MIXING , *FLY ash , *SLAG , *REINFORCED cement - Abstract
Abstract: In the present the paper, various tests are described using white and ordinary Portland cement blended with fly ash and a slag to assess their effect on reinforcement corrosion. Natural and accelerated chloride diffusion, carbonation and corrosion tests were performed. The results indicate that the most resistant cement against chloride attack is the slag cement which on the other hand, performed as the less resistant to carbonation in the conditions of the test. The most resistant to carbonation is the ordinary Portland cement having the higher portlandite content. As there is the demand to link microstructure and observed performance of the different cementitious materials, an attempt is made. The work emphasizes the effect of mineral additions on the corrosion process in order to collect systematic information about the controlling parameters in the different periods of the service life of reinforced concrete structures. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
40. Characterization of the degradation of self-compacting concretes in sodium sulfate environment: Influence of different mineral admixtures.
- Author
-
Siad, H., Kamali-Bernard, S., Mesbah, H.A., Escadeillas, G., Mouli, M., and Khelafi, H.
- Subjects
- *
SELF-consolidating concrete , *BIODEGRADATION , *MIXTURES , *SODIUM sulfate , *POZZUOLANAS , *FLY ash , *LIMESTONE , *FILLER materials - Abstract
Highlights: [•] Vibrated concrete and limestone filler SCCs present low performances in sodium sulfate environment. [•] Incorporation of the natural pozzolan or fly ash in SCCs improve sensitively their resistance to sodium sulfate attack. [•] The benefic effect of the studied natural pozzolan is comparable to the one of fly ash. [•] Sulfate penetration depth can be quantified using SEM–EDS. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
41. Early age and hardened performance of cement pastes combining mineral additions.
- Author
-
Barluenga, Gonzalo, Palomar, Irene, and Puentes, Javier
- Abstract
To asses the influence of mineral additions (MA) at early age and on hardened performance of fluid cement based pastes, an experimental program was carried out. The design of the mixtures correspond to paste compositions used in self compacting concretes of moderated strength, as those employed for architectural applications. Two types of fillers (limestone and quartzite) have been used to substitute 50 % of cement in a reference paste, with and without a high range water reducing admixture. Then, three active MA (microsilica, nanosilica and metakaolin) were combined. A physical and mechanical characterization in the hardened state showed that the inclusion of MA to a cement-filler mixture can moderately improve the hardened performance of the pastes. Air and water cured samples were tested in order to evaluate the influence of curing conditions. At early ages (24 h), in situ temperature and ultrasonic pulse velocity were monitored on samples with limestone filler, combined with the three active MA, to study the reaction process and microstructure development, respectively. The reaction degree of the samples under study during the first 24 h was related to the microstructure development. Evaporation, drying shrinkage and cracking at early age were also monitored, considering an air flow of 3 m/s on the exposed sample surface. Some relations were described linking cracking risks at early ages with the chemical and physical phenomena involved at early age microstructure evolution. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
42. A method for allocation according to the economic behaviour in the EU-ETS for by-products used in cement industry.
- Author
-
Habert, Guillaume
- Subjects
CEMENT industries ,WASTE products ,ENVIRONMENTAL impact analysis ,PORTLAND cement ,BLAST furnaces ,LIFE cycle costing - Abstract
Purpose: The most efficient way to reduce the environmental impact of cement production is to replace Portland cement with alternative cementitious materials. These are most often industrial waste such as blast-furnace slags (GBFS) and coal combustion fly ashes (FA). However, a recent European directive no longer considers these products as waste but as by-products. Therefore, the impact of their production has to be considered. Within this new framework, this study develops an evaluation method of their environmental impacts. Method: This paper presents pre-existing methods and underlines their limits. Through our evaluation of these methods, it has become clear that the allocation procedure is necessary; however, results depend highly on the chosen allocation procedure. This study presents a new allocation method, based on the fact that both cement and the alternative materials, GBFS and FA, are produced by energy-intensive industries (cement iron and coal) which are all subjected to the European Union Greenhouse Gas Emission Trading System. In this carbon trading system, it is economically beneficial for industries to reduce their environmental impact, like for when, by example, by-products from one industry are used as alternative 'green' material by another industry. Our allocation coefficient is calculated so that the economic gains and losses are the same for all of the industries involved in these exchanges and provides the overall environmental benefit of the exchanges. Results and discussion: The discussion shows that whilst this method has much in common with other allocation methods, it is more accurate as it allocates the environmental costs fairly over the industries involved and is more robust because of its constant value. One of its limits is that it cannot be used for life cycle inventories; however, we test the possibility of choosing a coefficient from one impact category and applying it to all the others. Conclusion: Lastly, the technical term of the equation this paper presents could be employed for consequential life cycle assessment, to calculate the most environmental uses by-products could be put to. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
43. A statistical approach of binary and ternary concrete mixtures with mineral additions
- Author
-
Isaia, G.C., Furquim, P., and Gastaldini, A.L.G.
- Subjects
- *
MIXTURES , *MINERALS , *BINDING agents , *MATERIALS compression testing , *REGRESSION analysis , *CONCRETE durability - Abstract
Abstract: This work presents the statistical influence of type and content of mineral additions, water/binder ratio and axial compressive strength of binary and ternary concrete mixtures with mineral additions. Using simple and multiple linear regressions and analysis of variance, the main parameters that influenced the microstructure and the durability were determined. Among the dependent variables, the mineral addition content presented the highest significance, followed by water/binder ratio, mineral addition type and at last, compressive strength. The statistical results confirm the beneficial behavior that the mineral additions quantity show upon the concrete properties, according to what is mentioned by literature. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
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44. A method developed to quantify lime and gypsum consumed by mineral additions
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Aubert, J.E., Segui, P., Husson, B., and Measson, M.
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LIME (Minerals) , *GYPSUM , *REACTIVITY (Chemistry) , *POZZUOLANAS , *SEWAGE sludge ash , *MATHEMATICAL optimization - Abstract
Abstract: This paper presents an original method developed to quantify the reactivity of mineral additions based on the measurement of the lime (CaO) and gypsum (CaSO4, 2H2O) consumed by mineral additions in a paste. Three mineral additions were tested: a Siliceous Filler (SF), a natural pozzolan (Poz) and a Wastepaper Sludge Ash (WSA). The results obtained on SF, considered as a reference, show the efficiency of this method. Its application to Poz and WSA permits the quantity of lime and gypsum consumed by these additions to be evaluated and, thus, the amount of each component to be optimized in Hydraulic Road Binders. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
45. Étude du retrait et du fluage des bétons autoplaçants à base de pouzzolanes naturelles et de fines siliceuses algériennes.
- Author
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Ayed, Kada, Benaissa, Abdelatif, Vidal, Thierry, and Pons, Gérard
- Subjects
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CONCRETE additives , *CONCRETE research , *CONCRETE defects , *CONCRETE construction , *CIVIL engineering - Abstract
The use of natural Algerian fine as a mineral addition in self-compacting concrete (SCC) is a way of ecological and economic exploitation of these materials. An experimental program was established to study the fresh state behaviour and the instantaneous and long-term mechanical behaviours of three self-compacting specimens with the same mix proportions. Only the nature of their mineral additions was different. The study of SCC fresh properties shows compliance with the Association française de génie civil (AFGC) recommendations. The higher compressive strengths of concrete with pozzolanic and siliceous fines reveal a pozzolanic effect of these materials. The delayed deformations of the SCC made with Algerian fine and with limestone filler are quite similar. The comparison with the behaviour of an equivalent strength vibrated concrete shows a slightly higher deformability of SCC. Finally, the comparison with Eurocode 2 model predictions reveals an underestimation of the amplitudes of delayed strains. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
46. Relating ultrasonic measurements on fresh concrete with mineral additions to the microstructure development simulated by Cemhyd3D
- Author
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Robeyst, Nicolas, Grosse, Christian U., and Belie, Nele De
- Subjects
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CONCRETE , *PORTLAND cement , *SIMULATION methods & models , *MINERALS , *CALORIMETRY , *BLAST furnaces , *PERCOLATION - Abstract
Abstract: Ultrasonic measurements can be used to monitor concrete setting. To relate these measurements to fundamental changes in the cement paste, the results have been compared to the microstructure development as simulated with an adjusted version of the pixel model Cemhyd3D. The adjustments were validated by comparison with results of isothermal calorimetry, electron microscopy and thermal analysis. Mixtures in which the Portland cement was replaced by different dosages of blast-furnace slag and fly ash were tested. A multi-variate and multi-way regression was then performed between the ultrasonic results and the microstructure quantities. For most microstructure parameters, the smallest difference between the simulated and predicted values is achieved with the models starting from the ultrasound frequency spectra. However, the difference with the ones based on the velocity and energy ratio remains often restricted. The degree of cement hydration, solid percolation and formation of hydration products is clearly related to the ultrasonic measurements. Only the pore space percolation does not relate to the measurements at all. [Copyright &y& Elsevier]
- Published
- 2011
- Full Text
- View/download PDF
47. Influence of curing time on the chloride penetration resistance of concrete containing rice husk ash: A technical and economical feasibility study
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Gastaldini, A.L.G., Isaia, G.C., Saciloto, A.P., Missau, F., and Hoppe, T.F.
- Subjects
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PENETRATION resistance of concrete , *CONCRETE curing , *RICE hulls , *FEASIBILITY studies , *CHLORIDES , *CONCRETE additives , *MECHANICAL behavior of materials , *MATERIALS compression testing , *PORTLAND cement - Abstract
Abstract: This study investigates the influence of the curing time on the chloride penetration behavior of concrete produced with different concentrations of rice husk ash. Compressive strength and chloride penetration at 91days were assessed according to ASTM C1202. Concentrations of 10%, 20% and 30% of rice husk ash were used and the results were compared with a reference mix with 100% Portland cement and with two other binary mixes with 35% fly ash and 50% ground blast furnace slag. Increases in rice husk ash content produced lower Coulomb charge values. Longer curing times reduced Coulomb charges values for all mixes investigated. However, the extent of the effect of curing times on compressive strength and chloride penetration in concrete is related to the type of mineral addition, the concentration of the substitutions used, the w/b ratio and the curing time used. This behavior points at an optimal curing period for each type of binder to meet specific technical and economical criteria, namely durability and compressive strength specifications for the structure. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
48. Mix design of concrete with high content of mineral additions: Optimisation to improve early age strength
- Author
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Khokhar, M.I.A., Roziere, E., Turcry, P., Grondin, F., and Loukili, A.
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- *
CONCRETE , *MINERALS , *STRENGTH of materials , *CARBON dioxide , *FIELD emission , *CHEMICAL processes , *HIGH temperatures , *BLAST furnaces - Abstract
Abstract: The concrete industry is an important source of CO2 gas emissions. The cement used in the design of concrete is the result of a chemical process linked to the decarbonation of limestone conducted at high temperature and results in a significant release of carbon dioxide. Under the project EcoBéton (Green concrete) funded by the French National Research Agency (ANR), concrete mixtures have been designed with a low cement quantity, by replacing cement by mineral additions i.e., blast-furnace slag, fly ash or limestone fillers. Replacement of cement by other materials at high percentages generally lowers the early age strength of the resulting concrete. To cope with this problem, an optimisation method for mix design of concrete using Bolomey’s law has been used. Following the encouraging results obtained from mortar, a series of tests on concretes with various substitution percentages were carried out to validate the optimisation method. [Copyright &y& Elsevier]
- Published
- 2010
- Full Text
- View/download PDF
49. Evaluation of self-compacting concretes produced with ternary and quaternary blends of different SCM and hydrated-lime.
- Author
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Fonseca, Thiago V., dos Anjos, Marcos A.S., Ferreira, Ruan L.S., Branco, Fernando G., and Pereira, Luis
- Subjects
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SELF-consolidating concrete , *KAOLIN , *SUPPLY chain management , *RICE hulls , *COMPRESSIVE strength , *PHYSICAL mobility - Abstract
• Evaluation of self-compacting concretes produced with MK, RHA, limestone filler and hydrated-lime. • Metakaolin and rice husk improve the viscosity of SCC due to their higher specific surfaces. • Even with low PC consumption it was possible to obtain SCC with compressive strength up to 46 MPa. • Incorporation of SCM reduced the Cl- ion diffusion and increased the resistivity of the SCC. Self-compacting concrete (SCC) is a high-performance concrete that has gained prominence in recent years due to its high fluidity and cohesion characteristics. In this material, the use of supplementary cementitious materials (SCM) is necessary for the consolidation properties and durability requirements to be achieved. SCM obtained from waste or industrial by-products can improve SCC properties and reduce the environmental impact associated to Portland Cement (PC) production. In light of these facts, the present paper addressed the effects of high levels of mineral additions (metakaolin, rice husk ash and limestone filler) and hydrated-lime on the physical (ultrasonic pulse and capillary absorption), mechanical (compressive strength) and durability (carbonation resistance, chloride ion diffusion and electrical resistivity) properties of SCC. The results showed that metakaolin and rice husk ash increase the viscosity of SCC due to their larger specific surface area. The simultaneous incorporation of high content of mineral additions reduced the compressive strength of SCC. However, it was possible to obtain concretes with compressive strength between 22 and 46 MPa at 28 days and with adequate physical performance and durability. The addition of hydrated-lime to SCC proved efficient, mainly due to reduced carbonation depth associated to alkaline reserve replacement. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
50. Multiphasic finite element modeling of concrete hydration
- Author
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Buffo-Lacarrière, L., Sellier, A., Escadeillas, G., and Turatsinze, A.
- Subjects
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HYDRATION , *COLD (Temperature) , *SILICA , *COAL ash - Abstract
Abstract: This paper presents a model predicting the development of hydration and its consequences on temperature and water content. As it considers the effects of climatic conditions, the proposed model is a promising tool to evaluate the temperature, hydric and hydration fields of structures in situ. The hydration model predicts the hydration evolution of several main species (not only clinker but also mineral additions like fly ash or silica fume for instance). For each component, the modeling considers hydration development and chemical interaction between reactions. It also takes into account temperature and water content effects on reaction kinetics through thermal and hydric activation. Hydration development in turn modifies the thermal and hydric states of material. The result is a numerical model coupling hydration, and the thermal and hydric states of cement-based material. The model was tested on a 27 m3 concrete block in situ equipped with temperature sensors situated in the core and close to the face exposed to solar radiation. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
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