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According to the latest studies, nanoparticles are the best additive materials to improve concrete's mechanical properties. Among these nanoparticles, Carbon Nanotubes (CNTs) are famous for their extreme tensile strength and flexibility. These particles can be used as a reinforcement to increase the mechanical properties of concrete. In the present study, the effects of using CNTs with different dosages were investigated on structural lightweight concrete’s mechanical properties. Structural Lightweight Expanded Clay Aggregates (LECA) were used in the mixture of Structural Lightweight Concrete (LWC) as a substitute for coarse aggregates. Along with LECA, CNTs as a partial replacement for cement with varied weight ratios were added to the lightweight concrete (0.02, 0.1, and 0.3 percent of cement weight). The effects of carbon nanotubes on fresh concrete performance, water absorption, compressive strength, tensile strength, and flexural strength of 7- and 28-day lightweight concrete were carried out. The results indicate that the presence of 0.02% of cement weight of CNTs increased compressive strength, tensile strength, and flexural strength of the 28-day-old lightweight concrete up to 29%, 44%, and 26%, respectively. Moreover, it reduced the water absorption of lightweight concrete by 28.3%. Utilizing more content of CNTs resulted in less mechanical properties. Having done experimental tests, nanoparticles and cementitious materials bonding have been visualized by Scanning Electron Microscopy (SEM) device.

Heavy metal-containing wastes pose long-term environmental threats. In the present work, cementitious binders in the presence of halloysite nanotubes (HNTs) at 1 wt%, 3 wt%, and 5 wt% by mass were used to immobilize lead (Pb(II)). Semi-dynamic leaching tests were used to quantify the Pb(II) leaching up to 64 days. The results showed that the addition of 1 wt%, 3 wt%, and 5 wt% HNTs particles strongly reduced the Pb(II) release. The optimal dosage of HNTs was 3 wt%, which decreased the cumulative release of Pb(II) by around 40.5% after 64 days. Isothermal calorimetry, X-ray diffractometry (XRD), thermogravimetry (TG), mercury intrusion porosimetry (MIP) and compression tests were then used to investigate better immobilization effect with HNTs addition. The results showed that HNTs particles promoted cement hydration, refined the pore structure of the hardened cementitious binders, decreased permeability, and enhanced mechanical strength. Zeta potential measurements indicated that the negative surface charge of the HNTs particles could adsorb Ca2+ ions from the pore solution of cement hydration, then facilitating adsorption of Pb(OH)3−.

Sodium carbonate (SC) activated ground granulated blast-furnace slag (GGBS) and fly ash (FA) is a potential substitute of traditional cement with ultra-low carbon footprint. However, its hydration rate and strength growth are limited, owing to the slow leaching of ions during the activation of weak base. In this work, 60% wet-grinded GGBS and 40% FA were blended as the binder, and two organic alkalis, i.e. triethanolamine (TEA) and triisopropanolamine (TIPA), were adopted to facilitate the ions dissolution and pozzolanic reaction of SC activated GGBS-FA blended cementitious material (SCSF). The compressive strength was tested and the hydration kinetics was studied by hydration heat and chemical shrinkage. Besides, ions leaching behavior was characterized by ICP; hydrates and microstructure were also detected by XRD, TG-DTG and SEM. Results indicated that the addition of TEA or TIPA significantly promoted the ions dissolution. 0.05% TEA increased the concentration of leached Ca2+, Al3+ and Fe3+ by 36%, 33% and 1545%, respectively. This solubilizing effect was also found in TIPA. Moreover, these two chemicals could promote the formation of hydrates, such as C-S(A)-H gel, hydrotalcite, calcite and aragonite, especially at the early period; these also activated the hydration process of SCSF effectively, and the compressive strength of the mortar reached above 40.0 MPa at 7 d and 48.0 MPa at 28 d. The carbon emission of the designed system is 85.9% and 55.9% lower than that of PC and strong base activated GGBS system, respectively.

The main motive of this research paper is to study the stabilization of sediment soil by utilizing a cementitious nanomaterial called Alccofine. Sediment soil is known to weaker in nature and has low shear strength due to presence of clayey sediments in large amount by volume. Clay soil is known to be problematic in nature. It is highly cohesive, has low shear strength and undergoes change in its volume with the change in its moisture content i.e., swelling and shrinkage with increase or decrease in water content, respectively. This type of soil, when used as a subgrade in construction of flexible pavements, can result in excessive cracking, loss of strength and hence can cause severe damage to the flexible pavement over time. In light of such behaviour of the sediment soil, an attempt has been made to enhance the engineering characteristics of the soil using Alccofine [1108]. Being a nano particle, Alccofine thoroughly blends with the sediment soil ensuring homogeneity throughout. Alccofine is added to the soil in various proportions i.e., 3%, 6%, 9%, 12% and 15% by weight to stabilize the soil. Unconfined Compression Strength test and California Bearing Ratio test were, then, conducted on the soil which revealed the increase in strength characteristics of the sediment soil.

A lot of CO2 is released into the atmosphere during the manufacturing process of cement, which causes a global warming problem. Calcined clay-limestone cement concrete (LC3) can be used to partially solve this problem. Limestone cement concrete is produced from calcined clay-limestone cement which is an advanced ternary mixed cement formed by the combination of 30 percent low-grade calcined clay, 15 percent limestone powder, and 5 percent gypsum and 50 percent cement clinkers. That means 50 percent of cement clinkers are to be replaced by additional cementitious materials which are beneficial for reducing CO2 emission at the time of production of cement. In the present study, calcined clay-limestone cement is used to prepared concrete and compare it with concrete using ordinary portland cement (OPC) of grade 53. The physical and chemical characteristics of prepared cement samples were carried out and compared with OPC. M30 grade of concrete was prepared by calcined clay-limestone cement; mechanical properties such as compressive strength (CS) test are carried out on prepared concrete. After the age of 28 days, M30 grade of concrete was exposed to 100 °C, 200 °C, 400 °C, 600 °C, and 800 °C temperature, surface texture, weight loss, compressive strength test were carried on the cubes of size 150 × 150 × 150 mm3. The SEM analyses were carried out over 100 °C and 600 °C temperature on OPC and calcined clay-limestone cement concrete. The result shows that the compressive strength reduces with an increase in exposed temperature. The compressive strength decreases after 200 °C and significant losses occur after 400 °C. When the temperature reached 400 °C, noticeable minute cracks started to appear on the surface of the cube specimens.

Permeability is one of the principal factors related to durability of concrete. The responsible factor for volume change is permeability. This paper attempt to mechanical and durability study of Supplementary Cementitious Concrete where cement has been replaced by fly ash & GGBS in combination of (30%, 0%), (20%,10%), (10%, 20%) and (0%, 30%).16 such concrete samples has been cast in which water binder ratio introduced as 0.35, 0.40, 0.45 & 50 for each 4 set .cubical and cylindrical concrete 16 samples has been prepared for curing period of 7 and 28 days with replacement of manufactured sand and coarse aggregates. Compressive strength, ultra sonic pulse velocity test (UPV) and Rapid chloride permeability test has been done value at the end of each curing period. The results of this research show that both UPV and compression strength have augmented with supplementary Cementitious materials (SCM) Incorporations. Various empirical models were proposed for pulse velocity and compressive strength. Models for the compressive strength and ultrasonic pulse velocity was developed at individual percentage levels (fly ash or GGBS) and then for each replacement stage four different models (FA percent + GGBS percent) were developed. Similarly after curing for 28 days, Chloride permeability test as per ASTM C1202 has been done. Diverse parameters mathematical models were developed to acknowledge the effect of various factors like SCM incorporations, water binder ratio, replacement of manufactured sand etc., and Models has been tested in full range by data and has strong precision, correlation with experimental data.

s Cracks are vitally detrimental to the load-bearing capacity of materials and further to the durability and service-life of various structures. Autonomous self-healing via embedded capsules or hollow fibres with healing agent has recently become more popular to repair the damage of structural materials. Figuring out the exact amount of capsules required to repair the cracks is indispensable to develop and design the capsule-based self-healing materials. In this paper, by means of surveying the irregular crack patterns appear on the surface of composite materials the approximated cracks models are induced in the self-healing materials and the probability model of capsules which are randomly dispersed intersecting with the crack networks is developed from the viewpoint of geometry probability. Further, the proposed probabilities for different crack patterns are applied to gain the theoretical solutions on the exact dosage of capsules containing healing agent that are used to obtain a specific self-healing efficiency in capsule-based self-healing materials (cementitious materials, for instance). Finally, the accuracies of these probabilities values and theoretical solutions are verified via computer simulation where the event of capsules intersection with different crack networks are reproduced.

Concrete structures are rigid in nature with high load carrying capacity but brittle nature. The volumetric changes that occur in concrete due to various reasons such as shrinkage during construction to chemical exposures and thermal stresses at later stages results in the formation of cracks in concrete. Cracking is the onset of distress in concrete and should be fixed at earlier stages to avoid rapid deterioration of the structure. Concrete and mortar are not a viable solution to fix cracks, as they do not bond with the old concrete resulting in low finishing strengths. Materials such as epoxy, hydraulic cement, polyurethane and acrylic modified mortar have high adhesion to concrete and hence can be used to repair concrete structures. This paper reports an extensive study on the behaviour of epoxy, hydraulic cement, polyurethane, and acrylic resin modified mortar in their effectiveness as crack filling materials when subjected to loads using finite element analysis.

This paper investigated the effect of rice husk ash (RHA) on chloride permeability, water absorption, and permeable pore space of cementitious mortar. It was observed that the permeability, water absorption, and permeable pore spaces of mortar mixtures having rice husk ash as partial replacement of cement decreased as the amount of rice husk ash increased while the compressive strength increased. The reduction in chloride permeability, water absorption, and permeable pore space ranged between ∼3 to ∼52, ∼2 to 10%, and ∼2% to 18% with 4% to 12% RHA dosages without RHA mixture. In addition, linear co-relation exists between water absorption and permeable pore space and permeable pore space and charge pass with a coefficient of correlation of 0.93 and 0.90, respectively; quadratic polynomial co-relation exists between compressive strength and water absorption and compressive strength and permeable pore space.

The following review paper thoroughly enables the readers to emulate the flexural behavior and impact test method for textile reinforced cementitious composites (TRCCs). The flexural parameters of ECCs corresponding to type of fiber material, fiber volume fraction, fiber volume length and strength parameters were discussed. For the textile reinforcement, the parameters like type of weaving pattern, mesh size, roving tex, fiber volume fraction and number of layers were discussed. Based on the tensile strength of textile fiber material, carbon, AR-glass, aramid and basalt fiber mesh were used for strengthening, repair works, plastering and reinforcement for thin elements. And also, the impact test performance on cementitious concrete composites is addressed as well as methods adopted for finding impact performance are discussed from the numerous literatures. This paper provides summary about the flexural and impact performance of textile fibers introduced into the concrete composites in different mesh sizes and fiber volume fractions. Generally, inclusion of textile fibers gives much more performance in tensile, toughness, flexural, energy absorption capacity and ductility in ECC composites. Many of the researchers have tried with different fiber materials for producing ECC and TRC composites separately, but only few of them used both have been discussed. Finally, from the literatures mostly artificial fibers are used for making textile reinforced composites.

Sustainable construction practices require transformation in construction industry aiming at reduction of environmental pollution along with enhancement of performance and durability of cementitious structures. Application of pozzolanic materials have been proven promising in this concern as auxiliary cementitious materials for partially replacing cement in mortar and concrete with a positive impact on strength and microstructure of cement matrix. Use of industrial wastes with pozzolanic properties in this category is exceedingly required in order to abate the issue of environmental pollution. Fly ash (FA) and red mud (RM) are the two industrial wastes that pose an issue of safe disposal. Although, FA is already in use as a pozzolanic material, yet not much work is available on the use of RM in concrete. This study examines suitability of RM for use in presence of FA for strength enhancement of concrete. In this analysis, FA was utilized in a dosage of 0–24% by weight of cement while RM was varied from 0 to 24% in presence of 8% FA for partial replacement of cement in concrete. Mechanical strength analysis of concrete specimens was performed and compared with control specimen. The results show that optimized use of FA leads to strength enhancement and the effect is more pronounced in presence of optimized dosage of RM. Thus, RM in presence of FA can be used as a strength modifier and can decrease the cement demand leading to sustainable construction practices.

The main components of concrete are cement and river sand (R-sand). Due to excessive production of cement, CO2 emission also increases which causes air pollution. On using R-Sand, large scale depletion of natural sources creates environmental problems. In view of the increasing national and global consensus on the environmental protection, the governments have put restrictions on mining of R-Sand from the river beds. To overcome these problems, there is a need of cost effective alternatives materials so as to make the construction sustainable without compromising its quality. In the production of Self Compacting Concrete (SCC), fly ash (FA) is utilized as an additional cementitious ingredient, which improves its performance. It solves the problem of FA disposal and environmental pollution too. The manufactured sand (M-sand) is also an alternative material which may solve the problem of shortage of R-Sand, if found suitable. In this study, M-Sand and FA were incorporated in the preparation of a sustainable SCC. After optimisation of FA and M-sand doses in the final mix, two types of SCC mixtures were developed: M-1, which consisted of 100% OPC + 100% R-Sand, and M-2, which consisted of 80% OPC + 20% FA + 50% R-Sand + 50% M-sand. Fresh properties of all SCCs were determined as per EFNARC/BIS recommendations. For destructive testing standard size specimens were cast to determine desired strengths after curing in tap water for 90 days. Rebound Hammer (RH) and Ultrasonic Pulse Velocity (UPV) were utilised in Non-Destructive Testing (NDT) to determine the strength, homogeneity, and integrity of both SCCs. Further, the water absorption of the specimen was measured up to 90 days. XRD analysis was also performed.

This paper reviews the impact of cement industry towards the global environment and solutions to the problem. The increasing harvesting of raw materials for mounting cement manufacturing causes reduction in quantity of the non-renewable resources such as limestone. The activities linked to harvesting of the resources from natural surroundings, damages the green landscape which is the habitat of flora and fauna exposing to the risk of ecological imbalance. The continuous reaping of these precious resources, exposes it to the risk of depletion in future. Furthermore, the raw materials processing phases in the factory releases dust, noises, greenhouse gases especially carbon dioxide that contaminates the environment and aggravates the climate change. These uninvited environmental issues cause distress to the lifestyle of mankind. Therefore, enhancing the manufacturing technology of cement plant for cleaner production is one of the resolutions to this issue. Approach of using industrial waste as supplementary cementitious material or cement free concrete also would reduce dependency on cement demand. Success in utilizing other alternative material which production consumes lesser natural resources, economic and has lesser harm to the nature to act as binder in concrete would contribute to sustainable and healthier environment for future generation.

The rapid progress in the industrial development has increased the concern about the waste generated that may produce genuine environmental pollution. The use of supplementary cementitious materials (SCMs) from different sources may decrease a lot of non-renewable energy consumption. In the presented comprehensive study, SCMs such as ground granulated blast furnace slag (GGBFS), fly ash (FA), silica fume (SF), metakaolin (MK) and limestone (LS) with their various physico-chemical, mineralogical, morphological and durability properties have been addressed along with life cycle assessment (LCA) studies. Based on the detailed literature survey, current challenges for conventional utilization of SCM based mortar have been identified along with future research gaps. It has been observed that GGBFS and SF are very effective in enhancing the fresh and hardened properties of low carbon cementitious paste and mortar. The ongoing research work on effective use of low-grade limestone slurry to develop low clinker factor cementitious binder, is also discussed.

To improve the performance of the superfine-tailings cemented paste backfill (SCPB) and thus improve the utilization rate of superfine tailings, a blended binder (BB, containing high-volume mineral admixtures) and superplasticizer (SP) were employed. BB was designed based on the proposed model that coupled wet packing method and compressible packing model (CPM). The fluidity, the mechanical and microstructure properties of SCPB with various dosages of BB and SP were evaluated. Moreover, the coupling mechanism of BB and SP on the fluidity of fresh SCPB was also discussed. The results showed that the proposed coupling model could accurately predict the packing density of the multi-mixed cementitious system. The addition of BB and SP can improve the fluidity and strength of SCPB, and the coupling mechanism that affects the fluidity mainly by changing water film thickness (WFT). Therefore, using BB and SP is an effective method for improving the performance of SCPB.

The stringent early-age strength requirements for production of prestressed hollowcore (HC) slabs have restricted the use of alternative cementitious materials, such as ground granulated blast furnace slag (GGBS). In the present paper, an experimental study conducted in a precast factory is described in which GGBS-concrete HC slabs with 30 and 50% GGBS are compared with concrete slabs made from control samples (using 100% CEM II A-L cement, as used in summer mixes). The use of a novel admixture, thermal curing and a new early-age strength determination technique enables confirmation of the development of the required very early strength, such that cutting and lifting of the HC slabs can occur within 20 h of pouring. The HC slabs are instrumented to study the internal temperatures in the different slabs, leading to early-age strength development whereby these slabs are tested for immediate transportability and ultimate capacity. Further, the control and 30% GGBS slabs are tested for early-age creep under a flexural test in the factory. At later ages, using the new technique for making cube specimens, cubes and cores cut from the actual HC slabs are shown to have similar 28-day strengths and density.

Pozzolans are available in natural resources as raw materials that are potentially applicable in the cement and concrete industries. Proper identification and exploration methods are crucial in relation to their technical and economical purposes. In this paper, a two-phase study is employed, based on geochemical data processing and experimental investigations. Chemical and petrography of natural pozzolans were utilised to develop the proposed method. This method proposes three geochemical indexes: the limiting values of silica/calcium oxide (SiO2/CaO), alumina saturation and alkali content to qualify the natural pozzolan according to the supplementary cementitious requirements. Then, based on ASTM C618 and EN 196-5 standards and complementary tests, the chemical and physical properties of two natural pozzolans were assessed to validate the proposed method. The results showed that this method could be used as a robust and direct way to identify natural pozzolans.

The paper is an analysis of the experimental and theoretical behavior of cementitious plate containing waste ethylene vinyl acetate (EVA) with and without reinforcement with glass fiber woven fabric (GFRP) under low-velocity impact load effect. Cementitious plates of 150 mm × 150 mm size and three different thicknesses (15 mm, 30 mm, 50 mm) are produced by replacing the cement mixture aggregate with EVA at 0%, 18%, 32%, 45%, and 56% by volume of aggregate. Then, the cementitious plates are coated with GFRP using vacuum infusion method. The effect of EVA and GRFP coatings on the dynamic impact behavior of cementitious plates is investigated by applying a low-velocity impact test on the produced cementitious plates with an impactor of 18 mm diameter, 10.50 kg weight, and 500 mm height. The data obtained from the experimental results are analyzed based on the mass-plate theory, lightweight (LWC) and normal weight (NWC) concrete, and the consistency of the theoretical results with the experimental results is compared. It has been determined that the use of NWC is more suitable for cementitious plates with an EVA replacement rate in the range of 0–32%, while the use of LWC offers more optimum results if the EVA ratio is in the range of 32–56%. Especially when the EVA displacement exceeds 32%, it causes excessive void formation in the structure, resulting in a reduction in the dynamic impact loads of cementitious plates. GFRP coating with vacuum infusion method is not recommended for cementitious plate structures when the EVA replacement rate exceeds 32% by volume of aggregate.

Cellular concrete is a lightweight solid cementitious foam that is used mainly for thermal insulation and sound absorption. Either partially or wholly, when the Portland cement in the binder is replaced with ash, the environmental impact of the material is reduced. However, the resulting changes in the cell structure and their subsequent impact upon the physical properties of the material have not been well examined. In this study, cellular concrete was prepared from alkali activated fly ash binders and separately, from Portland cement binders blended with wood ash. The cell structure was photographed using laser confocal microscopy and the images were analyzed to quantify the cellular network in terms of the porosity and the fractal dimension of the porous phase. Alongside, the cellular concrete specimens were tested for their thermal constants and sound absorption. The results show that there was an increase in the fractal dimension and an associated drop in thermal conductivity for an increase in the porosity.

The traditional cementitious product is prone to suffer from a high degree of deterioration in the case of exposure to acid solutions because of the decomposition of the binder network. However, the degradation of concrete structures in service by mild concentrations of acid under conditions involving sewage, industrial waters, and acid rain is more common and results in a significant environmental problem. The utilization of alkali-activated materials has been seen to potentially offer an attractive option with regard to acceptable durability and a low carbon footprint. With the aid of visual observation, mass loss, compressive strength tests, X-ray diffraction, Fourier transform infrared spectroscopy, and field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, the acid resistance of alkali-activated fly ash mortars in which the precursor was partially replaced (0-30% by mass proportion) with ordinary Portland cement (OPC) was evaluated after 180 days of exposure to mild-concentration sulfuric and acetic solutions (pH = 3). A conventional cement mortar (100% OPC) was used as a reference group. The results demonstrate that the addition of OPC into the alkali-activated system causes a significant increase in compressive strength (around 16.08-36.61%) while showing an opposite influence on durability after acid attack. Based on a linear mean value and nonlinear artificial neural network model simulation, the mass losses of the specimens were evaluated, and the alkali-activated pure-fly ash mortar demonstrated the lowest value (i.e., a maximum of 5.61%) together with the best behavior in the aspect of discreteness at 180 days. The results from microstructure analysis show that the coexistence of the N-A-S-H and C-S-H networks in the blend system occurred by both OPC hydration and FA. However, the formation of the gypsum deposition within the fly ash-OPC blend systems at sulfuric acid was found to impose internal disintegrating stresses, causing a significant area of delamination and cracks. In addition, alkali metal ion leaching, dealumination, as well as the disappearance of some crystalline phases occurred in specimens immersed in both types of acids.

Solid waste-based cementitious material is friendly to the environment. The machine-learning technique brings the advantage of high efficiency to the study of physical properties of cementitious materials. In this study, the activation mechanism of soda sludge (SS) on blast furnace slag (BFS) was investigated using X-ray diffraction and thermal gravimetric; the compressive strength and Cl− of the BFS-SS-based cementitious material was evaluated using back propagation (BP) neural network model and nine other machine-learning models (Tree, Bagged Trees, Boosted Trees, Linear Support Vector Machine, Quadric Support Vector Machine, Cubic Support Vector Machine, Gaussian Support Vector Machine, Linear Regression, and Gaussian Process Regression). The potential correlation between the compressive strength and Cl− was investigated using Python 3.6. Results show that the hydraulicity phase of the BFS-SS-based cementitious material was CaAl2Si2O8·4H2O, 3CaO·Al2O3·CaCl2·10H2O, and 3CaO·Al2O3·3CaSO4·32H2O; when the BFS to SS was 40:60, the compressive strength and the solidification ratio of the Cl− were the highest with 4.04 MPa and 5.36% at 2 days and 10.47 MPa and 22.58% at 30 days. The BP neural network model with LM training algorithm is the lowest on mean squared error for the compressive strength and Cl−, with 0.0013 and 0.0061 at 2 days and 0.0794 and 0.4794 at 30 days, which has a best predictive ability comparing to the other machine-learning approaches motioned in this study. Pearson correlation coefficient was 0.9749, indicating that the compressive strength and the solidification ratio of the Cl− is a positive and extremely strong correlation.

Interlayer is the weakest plane of the entire roller-compacted concrete (RCC) structure and is easily deteriorated under the pressure of water and other environmental factors. Shearing force induced by the different shrinkage in interlayer part is the main reason for that poor performance of the RCC. In this paper, the deformation of RCC concrete and interlayer treatment mortar with supplementary cementitious materials (SCMs, including fly ash and silica fume) and double expansive resources admixtures (HME, containing calcium sulphoaluminate (CSA) and CaO) were studied. Deformation of concrete (produced RCC) and interlayer treatment materials was modeled and compared. Porosity characters of interlayer treatment materials and water absorption of interlayer-treated RCC samples were tested. Results showed that the HME significantly reduced the shrinkage of mortar and the deformation difference degree between layers was shortened. Modified interlayer treatment materials with HME could modify the macroscopic properties of RCC, the low porosity of interlayer and water absorption of interlayer-treated RCC was resulted. The suitable HME content is necessary in interlayer treatment materials and which could improve the performance of RCC.

The present study evaluated the engineering properties and microstructure of an alternative binder composed of calcium carbide residue and silica fume. The cementitious mechanisms of this alternative binder based on the pozzolanic reaction in raw materials. The ratio of calcium carbide residue and silica fume was decided based on the chemical composition of raw materials and their chemical reaction. The calcium carbide residue-silica fume mortar was prepared and tested for its compressive strength at several curing periods, with results then compared to conventional mortar made with ordinary Portland cement. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to investigate the microstructure of hardened mortars. The test results suggest that the compressive strength of calcium carbide residue-silica fume mortar continuously developed throughout the curing period. The relative compressive strength of calcium carbide residue-silica fume mortar reached 72.78% of the ordinary Portland cement mortar strength at 28 days curing age.

The current study presents the laboratory investigation on the use of nano-silica (0.2, 0.4, 0.8 and 1.0%) and polypropylene fiber (0.25, 0.50, 0.75 and 1.0%) in problematic clayey soil to enhance the shear strength and compaction characteristics. From the Transmission electron microscopy (TEM) analysis, it is observed that the diameter of nano-particles used in this study was in the range of 10–20 nm. The nano-particles have a spherical shape and amorphous in nature. Extensive laboratory tests such as the standard Proctor compaction test and unconfined compressive strength test have been conducted on untreated and polypropylene fiber along with nano-silica treated clayey soil. The outcomes showed that the addition of polypropylene fiber in poor soil, increase the maximum dry density and reduce the optimum moisture content of the soil. Whereas, the addition of nano-silica to the clay soil results in reduced maximum dry density and increased optimum moisture content. Unconfined compressive strength of clay soil is increased with the addition of polypropylene fiber and nano-silica to the clay soil. The optimum dosage of polypropylene fiber and nano-silica added to the poor soil was 0.75% and 0.8%, respectively. The Young’s modulus of clay soil was increased with the addition of polypropylene fiber and nano-silica. The microscopic analysis confirmed that C–S–H gel was the main cementitious product, and the inclusion of nano-silica can contribute to a denser packing of soil particles.

Cement has been well documented to positively affect the early-age strength of the cement asphalt emulsion mixtures (termed as CAEM) without compromising workability. However, the long-term performance of the CAEM incorporating multiple cement combinations is not conclusive. This study explored the effect of the combined usage of ordinary portland cement (OPC) and sulfoaluminate cement (SAC) on the long-term performance and microstructural properties of a CAEM system in detail. Three tasks were conducted, including (1) designing six CAEM formulations by introducing different types (OPC and SAC) and contents (2–6 wt%) of cement; (2) evaluating the long-term performance by moisture susceptibility, frost damage, abrasion resistance, and rutting resistance; and (3) characterizing the microstructural properties by scanning electron microscopes and energy-dispersive spectrometers. The experimental results revealed that the relative dynamic elastic modulus of CAEM was increased to 69.7% when admixing 90 wt% OPC and 10 wt% SAC. The mixture incorporating 90 wt% OPC and 10 wt% SAC demonstrated excellent rutting resistance up to ~ 31,000 cycles/mm of dynamic stability. The improved long-term performance actually originated from the reduced voids and produced a dense microstructure. The outcomes could facilitate tailoring CEAM products with better long-term performance.

Gypseous soils are capable of presenting ground construction challenges to civil and geotechnical engineers due to their unpredictable deformation characteristics. These undesirable responses are sometimes caused by environmental changes in moisture content due to temperature variations, fluctuation of underground water table, surface water, and gypsum content. Hence, the adoption of effective and economical means of stabilising gypseous soils is imperative. This study’s focus is on the early age strength and microstructural characteristics of gypseous soils treated with lime and GGBS. Treated and untreated gypseous soils with 5%, 15%, and 25% gypsum content were subjected to wet–dry cycles while investigating unconfined compressive strength (UCS), water absorption, pH, microstructural changes, and swell. The analysis of the results shows that at zero cycle, the UCS of the untreated gypseous soils increases from 0.62 to 0.79 MPa and swell decreases from 69 to 23%, respectively, as gypsum content increases. However, upon subjection to wet–dry cycles, the UCS reduced from 0.16 to 0.08 MPa at the end of the sixth cycle due to dissolution of gypsum within the soil pores which reduced the strength. The result also shows that gypsum content increases water absorption and reduces the pH of the untreated gypseous soils because of the neutral pH of gypsum. Furthermore, lime-GGBS-treated gypseous soils maintained a higher pH after six wet–dry cycles compared to untreated gypseous soils due to the high pH of lime and the increase in calcium content which improved bonding. In addition, microstructural analysis using SEM indicated early age precipitation of cementitious compounds (CSH) for increasing strength of lime-GGBS-treated gypseous soils compared to untreated gypseous soils.

This research focuses on studying the effect of different supplementary cementitious materials (SCMs) such as waste ceramic powder (WCP), lime powder (LP), and ground granulated blast furnace slag (GGBS) in combination on strength characteristics and microstructure of quaternary blended high-strength concrete. To achieve the aims of the study, necessary physical and chemical composition tests were done for the raw materials. Then, mixes were designed into control mix with 100% Ordinary Portland Cement (OPC) and experimental mixes containing 30%, 40%, 50%, and 60% of GGBS, WCP, and LP in combination. Tests were conducted during casting and at curing ages of 7 and 28 days. Accordingly, the control mix which is concrete grade 50 (C-50) as per American Concrete Institute (ACI) mix design is used as a reference for comparison of test results with those specimens produced by partial replacement of SCMs. The characterizations of high-strength concrete are done using consistency, setting time, workability, compressive strength, flexural strength, and morphological tests. The optimum percentage replacement is 50% OPC replacement by 30% GGBS + 10% WCP + 10% LP. Based on the experimental investigations, the workability increases as the replacement level of SCMs increases from 30% to 60% by weight. Compressive strength and flexural strength results increase up to 11.41% and 20% when the percentage replacement increases from 30% to 50% of SCMs replacement at 28 days of curing time, respectively. There are also improvement in the microstructure and significant cost saving due to replacing OPC partially with SCMs with proportions mentioned above. Therefore, the practice of utilizing increased percentage of SCMs in quaternary blend in concrete can be beneficial for the construction industry and sustainability without compromising the quality of the concrete product.

Carbonated wollastonite clinker (CS) may be suitable as supplementary cementitious material (SCM) for mortar and concrete. The microstructure of unground CS clinker, carbonated CS slurry and a mortar blended with carbonated CS are investigated by scanning electron microscopy. Additionally, a reference mortar with pure Portland cement and one with a cement replacement level of 30 mass-% by carbonated CS are produced to assess its contribution to compressive strength development. The calcium silicates are decalcified during carbonation resulting in CaCO3 and amorphous SiO2 . The latter reacts when used as SCM in mortar influencing the Ca/Si ratio of calcium-silicate-hydrate and contributing to compressive strength development.

With increasing global research on the recycling of construction waste, the recycling of waste concrete aggregates has gradually attracted attention. Researches have shown that recycled aggregate (RA) has a certain degree of influence on the mechanical properties and durability of recycled aggregate concrete (RAC) owing to its high water absorption, high porosity, and large number of microcracks. Therefore, how to improve the mechanical properties and durability of RAC is a key issue of concern for scholars. Based on the review of related literature and comprehensive analysis, the reinforcement theories and methods such as self-reinforcement of recycled coarse aggregate (RCA), optimization of preparing technology of RAC, and external spiral constraint of RAC were systematically summarized in this paper. The results indicate that the adherent mortar of RCA can be enhanced by carbonation, and weak acid treatment can effectively remove the old adhesion of RCA, which is economical and environmentally friendly. The denseness of RAC can be improved by adding cementitious materials with volcanic ash effect, and the reduction of microcracks in mortar can be improved by adding fibers. The load-bearing capacity and mechanical properties of RAC are significantly improved by the spiral constraint of materials such as fiber reinforced polymer (FRP) and so on. The optimization of the production process not only improves the quality of RAC, but also enhances the production efficiency. The microstructure analysis of RAC was also summarized in this paper. Moreover, the results of this study can provide a technical reference for research on the mechanical strength and durability of RAC, develop the further research ideas, and promote the application of RAC. Finally, some potential opportunities and development directions have been suggested for future research on the improvement methods of RAC.

This research aimed to present the improvement of the cementitious material in high-volume fly ash using only one alkali activator. Fly ash was used as a partial replacement for Portland cement type I, varying from 0 to 60% by weight of the binder. Concentrations of NaOH varying from 0.00 to 1.25 molar were used as alkali activator. Paste properties and mortar compressive strength at the ages of 3, 7, 14, 28, 60, and 90 days of water curing were investigated. The results reveal that fly ash paste with an alkali activator provides shorter initial setting time when compared to control paste without alkali activator. The use of 0.50 molar NaOH concentration in mortar containing fly ash not exceeding 50% by weight of binder provides the highest compressive strength at any age of curing. At that concentration, there is a significant increase in the 28-day compressive strength of up to 45% over that of the control mortar. In addition, higher NaOH concentration (not exceeding 1.00 molar) has a significant positive effect on the compressive strength of mortar with higher fly ash content, especially over longer curing periods.

Self-compacting concrete (SCC) is a highly stabilized flowable concrete that can be used in both dynamic and static states without segregation. Additionally, the exceptional homogeneity of the material contributes to its strength and durability. To produce sustainable SCC, it is necessary to incorporate appropriate supplementary cementitious materials (SCMs) to enhance mass construction applications. Thus, this review of SCC examines the stages of development and adoption, with a particular emphasis on the role of various calcium-rich, silica-rich, and engineered/reactive silica-rich SCMs as blends in achieving sustainable concrete. By summarising and comparing the properties of SCC in the plastic and hardened states in terms of workability, segregation, strength, and durability. According to the annotations in this review, researchers proposed that during the early stages of developing studies on SCC, the limits of constituent material proportioning be designed with the influence of ultra-fine fly ash (UFFA), an improved reactive supplementary material with a more appropriate particle size that is engineered from high silica-rich fly ash. Additionally, prior research indicates that an artificial neural network (ANN) is a more effective prediction tool for conducting and validating SCC experiments. However, no comprehensive study has been conducted on the effect of ultra-fine fly ash (UFFA) on SCC in the plastic and hardened states; additionally, the ANN can be an excellent tool for validating those properties, which is the novel scope of this review.

This paper focuses on the disposal of iron tailings sand (ITS) and reclaimed inorganic binder stabilized aggregate (RAI), and a new “ITS plus RAI” solid waste treatment method is innovatively proposed, which uses ITS and RAI as a new base course material to replace of new aggregates by 100%. It is found that the new ITS and RAI mixture has excellent compressive performance by designing the material composition of the mixture, which can meet the design strength of different levels of pavement under various load conditions. A series of laboratory tests are used to study the effect of the content of special cementitious material and iron tailings on the uniaxial compressive strength, flexural-tensile strength, compressive resilience modulus, and flexural-tensile resilience modulus of recycled mixture. And, the scanning electron microscope test (SEM) and X-ray diffraction test (XRD) are used to compare the surface morphology characteristics and hydration products of the recycled mixture under different ratios and to discuss the formation mechanism of the strength of the mixture. The test results show that the macroscopic change pattern in laboratory tests is basically consistent with the results in microanalysis. The relationship between compressive strength and compressive resilience modulus and flexural resilience modulus is also established by linear regression. This solid waste treatment method is applied to the pavement renovation project of national and provincial roads in Shanxi Province (within Linfen), to replace the existing base material by using recycled mixture, and the results show that it can save not only the carbon emission from stone mining and processing but also the construction cost, while producing good social and economic benefits and promoting the process of carbon neutralization in the world.

Solidification/stabilization (S/S) has been widely used for effective treatment of dredged sediment (DS) for many years, with the objective of improving the mechanical properties of DS through the addition of inorganic cementitious materials. Most previous studies have reported the short-term performance of S/S. However, long-term effectiveness is critical, as contaminants remain underground and are subjected to a variety of environmental stresses that can degrade S/S materials. In this regard, this experimental work investigated the long-term efficacy of solidification/stabilization of dredged contaminated sediments (DCS) treated with a new integrated method, namely PHDVPSS, which uses a prefabricated horizontal drain (PHD) assisted by vacuum pressure (VP) as well as solidification/stabilization. The DCS were treated with Portland cement (PC) as binder in the PHDVPSS method (abbreviated as VP-PC) at different zinc (Zn) concentration levels and compared with the traditional cement-based solidification/stabilization method (abbreviated as SS-PC). A series of experimental tests such as unconfined compressive strength (UCS), toxicity characteristics leaching procedure (TCLP), X-ray diffraction (XRD) and scanning electron microscopy in conjunction with energy-dispersive spectroscopy (SEM–EDS) were performed to assess the long-term strength, leaching and microstructural characteristics of high-water-content DCS, respectively. The UCS test results indicated that the strength of VP-PC mixes increased significantly with curing time compared to the limited strength development of SS-PC mixes. After 180-day curing, VP-PC mixes exhibited 3.5–5.5 times higher UCS values than the SS-PC mixes. Furthermore, when compared to the SS-PC mixes, the VP-PC mixes had 14.7–36.4% lower leached Zn concentrations at different Zn levels. This is attributed to an increase in the least reactive F4 (residual) fraction and a decrease in the most mobile F1 (acid-soluble) fraction as confirmed by the BCR method. Microstructural tests including XRD and SEM–EDS revealed that calcium silicate hydrate–like compounds were identified as the main hydration products of both the VP-PC and SS-PC mixes. However, portlandite, a major hydration product of PC, was not detected in either case, which is attributed to the retardant effect of Zn on cement hydration. Overall, the experimental results showed that the PHDVPSS method, when compared to the conventional solidification/stabilization method, is a viable choice for treating high-water-content DCS at different Zn concentration levels with low cement content.

This work is an extensive experimental study on the corrosion behavior of reinforced cementitious mortars containing industrial byproducts and waste materials. In particular, calcareous (C-class) fly ashes, iron mill scale and Electrolytic Manganese Dioxide (E.M.D.) waste were used as additives in mortars production. The abovementioned materials were used without any prior treatment or management and replaced the cement in concrete mixing by 10% wt. of cement weight. For the experimental set-up, reinforced mortars were prepared and exposed to coastal area for 12 months, while some of them were remained in a salt spray cabin for 60 days. The corrosion monitoring was performed by electrochemical and mass loss measurements, while chloride content, porosity, carbonation and mineralogy of mortars were also estimated. The results indicate, that there is a development in durability and chloride penetration resistance of composites comparing with the conventional mortars at late ages. At the same time, it was also observed that their chemical composition and fineness, control the diffusion of CO2 into the pore system and lead to increased carbonation of composite mortars. The challenge of this work is the production of eco-friendly composites with high chloride and carbon dioxide penetration resistance.

This research pioneers at investigating several mixture designs of mortar for preplaced ballast concrete, utilizing silica fume and superplasticizer in order to obtain the optimal mechanical behavior of mortar. For this purpose, a series of lab tests including compressive and flexural strength, and mortar fluidity have been performed and a model was presented to predict the mortar compressive strength. Secondly, adopting the Andesite ballast with 2–6 cm grading size, its point load index and consequently the mother rock compressive strength have been measured via a series of point load tests performed on ballast aggregates. Afterwards, using the proper mortar mixture design, many concrete samples have been constructed by injecting the mortar into ballast as coarse aggregate materials using developed injection apparatus and subsequently, their compressive strength have been measured. The achieved results demonstrate that the highest compressive strength is 53.4 MPa, which refers to the mortar with water to cementitious materials (w/c) ratio of 0.35, cement content of 850 kg/m3, and silica fume percentage of 10 respect to the cement weight. Moreover, as an applicable outcome of the research, a regression equation has been derived between concrete compressive strength versus the mortar compressive strength, w/c ratio, cement content and silica fume percentage.

The balanced amelioration of mechanical characteristics of fat clay with an additive refers to the attainment of high strength without compromising ductility, which is unattainable by solitary usage of a cementing additive. For this purpose, an amalgamated binary admixture (ABA) is proposed by assimilating shredded face mask (FM) waste, which is posing serious environmental concerns these days, with a cementitious waste material, i.e., silica fume (SF). However, for such ABA, the optimization of mix design is desirable because an excessive amount of one component could disturb the required balance. To address this issue, response surface methodology (RSM) is used in the current study, which is a strong technique used during the process of production to develop, improve, and optimize product inputs. Several experiments are designed and conducted to evaluate mechanical responses, i.e., unconfined compressive strength (qu), brittleness index (IB), deformability index (ID), and California bearing ratio (CBR) value, of treated fat clay by varying mix designs of ABA. Based on the test results, mathematical models are developed which are found to be statistically valid to predict the subjected responses using SF and FM as inputs. Afterward, an optimized mix design is determined by integrating developed models with a desirability function model and setting maximization of strength and ductility as the optimization goals. An ABA having 7.9% SF and 1.2% FM is observed to provide the highest strength and ductility for multiple applications, i.e., road and buildings, with desirability factor close to unity; responses of which are also validated by performing tests. Furthermore, analysis of cleaning aspect shows that the use of optimized ABA in place of cement for subgrade improvement of 1 km two-lane road could avoid CO2 emission of around 79,032 kg of C, save 42,720 kWh and 1174.8 GJ of electrical and thermal energy, respectively, and clean 43 Mg of FM waste; however, astute protocols of COVID-19 FM waste handling and disinfection are needed to be established and followed.

Supplementary cementitious materials (SCMs) are usually employed to replace partial cement and the pore-solution chemistry of blended cements is extremely essential for their cement hydration and d...

Nanomaterials are widely used in cement to improve the various properties of cement-based materials. Nano-CSH is considered as an effective accelerator for the hydration of cement. This paper studi...

The effect of graphene oxide (GO) nanosheets on the spatial distribution of cement paste pores has been investigated. In this study, a scheme based on the radial distribution function is developed to analyze the spatial distribution of pores in GO-cement composites. By applying the developed scheme, the addition of 0.04% GO is found to reduce the spatial inhomogeneity of pores in cement paste by around 20% at all curing ages. The test results show that the compressive strength of the cement paste sample containing GO is increased by 30-40%, indicating the negative correlation between the spatial inhomogeneity of pores and mechanical properties of GO-cement composites. Besides the spatial homogenization effect of GO on pores, pore structure refinement by GO is also found to increase the mechanical properties of cementitious materials. The findings suggest the great potential of using GO to modify cementitious materials by homogenizing the spatial distribution of pores. The spatial distribution analysis scheme presented in this study can be used for the future structure-property study of nanoengineered cementitious materials with enhanced performance.

Cement grouted asphalt mixture (CGAM) is developed with both flexible and rigid materials. It can be used to enhance the anti-rutting performance and increase the load bearing capacity of the pavement. However, the influences of cementitious grouting materials and asphalt binders on CGAM’s failure behavior have not been fully understood yet. In this study, the indirect tension (IDT) test, the compression test and the semi-circular bending (SCB) test were conducted to evaluate the strength and cracking resistances of CGAM with different cementitious grouting materials and asphalt binders. With different binders and bitumen/aggregate ratios, two kinds of cementitious grouting materials and six asphalt mixture skeletons were used in mixture design. IDT test results showed that the indirect tensile strength of CGAM would decrease as the bitumen/aggregate ratio increases. The addition of additives would also lower CGAM’s IDT strength. CGAM samples with high-strength cementitious grouting materials exhibited a higher strength than those with early strength cementitious grouting materials. However, there were not any distinct differences in the CGAM’s compression strength when different cementitious grouting materials and asphalt binders were used. SCB results showed that increasing the asphalt binder content and using additives can enhance the cracking resistance of CGAM. CGAM with high-strength cementitious grouting materials would crack more rapidly due to its rigidity. In the end, a two-way ANOVA was conducted on the results of the three tests. It is found that the type of grouting materials impacts the failure behavior of CGAM more significantly than the influences of the asphalt binder content. The addition of additives would also affect the failure of different CGAM samples. The findings in this paper can provide guidance for designing CGAM with better pavement performance.

PurposeSelf-healing concrete is a revolutionary building material that will generally reduce the maintenance cost of concrete constructions. Self-healing of cracks in concrete structure would contribute to a longer service life of the concrete and would make the material more durable and more sustainable. The cementitious mortar with/without incorporating encapsulates at different percentages of slag replacement with the cement mix improves autogenous healing at different ages. Therefore, this study’s aim is to develop a self-healing cementitious matrix for repair and retrofitting of concrete structures.Design/methodology/approachIn the present work, waste straw pipes are used as a capsule, filled with the solution of sodium hydroxide (NaOH), sodium silicate (Na2SiO3) and colloidal nano-silica as self-healing activators. An artificial micro-crack on the control and blended mortar specimens at different percentages of slag replacement with cement (with/without encapsulation) is developed by applying a compressive load of 50% of its ultimate load-carrying capacity. The mechanical strength and ultrasonic pulse velocity, water absorption and chloride ion penetration test are conducted on the concrete specimen before and after the healing period. Finally, the self-healing activity of mortar mixes with/without encapsulation is analysed at different ages.FindingsThe encapsulated mortar mix with 10% of slag content has better self-healing potential than all other mixes considering mechanical strength and durability. The enhancement of the self-healing potential of such mortar mix is mainly due to hydration of anhydrous slag on the crack surface and transformation of amorphous slag to the crystalline phase in presence of encapsulated fluid.Research limitations/implicationsThe self-healing activities of the slag-based cementitious composite are studied for a healing period of 90 days only. The strength and durability performance of the cracked specimen may be increased after a long healing period.Practical implicationsThe outcome of the work will help repair the cracks in the concrete structure and enhances the service life.Originality/valueThis study identifies the addition encapsulates with a self-healing activator fluid that can recover its strength after minor damage.

Calcium silicate (CS) composite materials are widely applied in cementitious materials and bone tissue engineering. Extensive studies focused on the traditional organic templates (e.g., surfactant)...