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AbstractIn this study, the life cycle and performance of normal concrete containing 35% limestone and 2% gypsum made in different ratios of water to binder (w/b) were examined. Its cost and CO2 emissions were found to be 13% and 35% lower compared to the control concrete. However, because of the greater replacement of cement with limestone filler, there is a reduction in its workability, the development of heat and strength, and the penetration resistance of water and chloride ions, especially in the early ages. The addition of gypsum marginally improved these concrete properties, but its quantity should be limited to 2% by weight of the binder. The use of gypsum beyond this limit led to a significant decrease in the properties of concrete. Anorthite, a calcium aluminosilicate mineral, was found in this concrete, and its fractured morphology was found to be more occupied with unreacted angular limestone particles. This low-carbon concrete showed an improvement in compressive strength with decreasing w/b ratios. The limestone reserve in India is abundant and spread evenly across its length and depth, and its use as the main replacement for cement in normal strength mixes would greatly reduce the impact of CO2 on the environment. [ABSTRACT FROM AUTHOR]

A human figurine carved on a large limestone cobble was found in the excavations of Horbat Sasay, conducted on behalf of the Israel Antiquities Authority. It schematically portrays eyes and a mouth and, like other types of human head representations found in the region, it is suggested that it belongs to the southern Levantine Neolithic period. Together with the description of the figurine, comparisons are presented to other known figurines depicting the human face from the Levant and other nearby regions, as well as an interpretation of these human faces and their expressions in relation to the drastic changes that occurred in these regions during the so-called Neolithic revolution and the social organization of the late prehistoric communities of the Levant. [ABSTRACT FROM AUTHOR]

This study demonstrates an integrated approach using a seismic-coloured inversion to derive the hydrocarbon potential of a field in the Upper Assam basin. The well-log analysis indicated the presence of hydrocarbon in the form of gas, oil, and water in sandstones with thin streaks of limestone and shale layers. The Acoustic Impedance (AI) model was generated from post-stack seismic data using a coloured inversion. Shale volume (Vshale), density, porosity and water saturation are the petrophysical parameters spatially populated using a multilayered feed-forward neural network on the inversion-based AI model. The estimated range of model-derived parameters varies as Velocity: 2136–5034 m/s, Vshale: 0–48%, Density: 2.14–2.72 gm/cc, Porosity: 6–29%, Water saturation: 9–28%, and demonstrates a reasonable correlation to well-log data. Seismic attribute for thin-fault likelihood was used to interpret the major faults. From the combined analysis based on interpreted faults and modelled parameters, the northwestern part of the study area displays a thick hydrocarbon-bearing zone (due to increasing thickness and reservoir quality). This interpretation is based on the consideration that faults are open. Thus, assuming continuity in the sequence, this northwestern region can be considered as one of the promising candidates for further exploration. [ABSTRACT FROM AUTHOR]

Highlights: A relaxation test data set is reinterpreted with a focus on radial strain Specimens loaded below the crack damage stress contracted more than predicted by elasticity theory The rate of lateral contraction increased when the stress had dropped by between 50% and 80% of the total stress relaxation observed at the end of the test One specimen loaded just above crack damage changed from dilation to contraction at the transition from primary to secondary relaxation [ABSTRACT FROM AUTHOR]

The examination of non-uniform deformation and re-crushing characteristics of crushed rock and coal is fundamental to understand porous structure evolution of the caved zone. This paper proposed a new index to evaluate the re-crushing degree of mixed crushed limestone based on an innovative compression–acoustic emission (AE) location method. Results showed that the evolution of the AE characteristic parameters was closely related to the deformation stages. The AE cumulative count and energy curves exhibited different trends corresponding to the initial, linear and plastic compression stages of the stress–time curve, respectively. However, the AE amplitude was mostly lower than 50 dB, and the peak frequency was concentrated at 20–40 kHz during the compression. In addition, the three-dimensional (3D) AE location event energy level (LEEL) was proposed to illustrate particle re-crushing degree. There was layered re-crushing phenomenon in the compression process of crushed limestone. Comparing the quantity and energy level of 3D AE location events in each layer, we discovered that the re-crushing behaviour in the middle layer was the most active, and that in the upper layer was approximately twice than that in the lower layer. High energy level AE location events could significantly influence the evaluation of re-crushing degree. [ABSTRACT FROM AUTHOR]

This article contains the description, translation, and discussion of Boston MFA 38-2-5, a limestone block found during excavation works at mastaba G(iza) 1203 carried out in 1938 under the supervision of G. A. Reisner. The object bears a dated hieratic inscription in red paint that for the first time is comprehensively translated and analysed. Using up-to-date digital image-enhancement processes, the reading of the date is improved, and certain lexical and grammatical features (the apparent use of a cardinal number instead of an ordinal, names of workforce units, etc.) are discussed. It is argued that the object had been deposited intentionally within the filling of the mastaba during its construction. The article contains a small palaeographic overview of the hieratic signs employed in the inscription. [ABSTRACT FROM AUTHOR]

The effect of different filler types on the properties of asphalt mortar before and after water saturation was studied by laboratory tests. Under both dry and water-saturated circumstances, four alternative fillers, limestone powder, hydrated lime, PO42.5 cement, and brake pad powder, are used, evaluated, and compared. The study methodology included characterizing the micromorphology, while X-ray diffraction imaging analysis and scanning electron microscopy were used to determine the chemical composition of the asphalt mortar following water saturation. To quantify the effects of moisture on the bonding mechanisms, surface energy concepts were employed to compute the surface free energy parameters of the asphalt mortar made with different filler materials. Dynamic shear rheometry was employed in the investigation to describe the rheological characteristics of the asphalt mortar as a function of filler under different water saturation conditions. The bonding strength of the asphalt mortars with various fillers was then quantitatively measured using pullout tests to account for the coupling effects of moisture and temperature. The findings of the laboratory tests generally showed that the asphalt mortar's effectiveness declined following moisture conditioning and saturation in water. However, hydrated lime, brake pad powder, and cement showed promise in strengthening the bonding of fillers and asphalt, with hydrated lime being superior. Likewise, the asphalt mortar's ability to tolerate moisture and resist water damage was also generally improved by hydrated lime. [ABSTRACT FROM AUTHOR]

Relationships between drilling parameters and the uniaxial compressive strength (UCS) of rocks are typically established through measurement while drilling (MWD) by analyzing either drilling speed or specific energy. This study enhances the commonly utilized specific energy formula by considering the frictional dissipation energy of the drill bit, along with the initial thrust and torque exerted by the drilling machines. A novel specific energy index, ηp, optimized for rotary drilling applications, was introduced. The modified expressions significantly mitigate the impact of variations in drilling parameters on the specific energy. Employing the concept of a minimum specific energy coefficient, a model was developed that directly relates drilling parameters to the UCS of rocks. An iterative solution method for determining the minimum specific energy coefficient was provided. Extensive MWD tests on intact granite samples, conducted on a specially developed indoor drilling test platform, facilitated the calibration of the minimum specific energy coefficient. The model's efficacy in UCS estimation was further validated through additional MWD tests on sandstone and limestone. For sandstone, the model's estimated UCS showed a relative error (RE) ranging from 0.62% to 21.22%, a mean relative error of 11.7%, and a maximum absolute error of 9.75 MPa. Limestone tests revealed an RE range of 1.99%–12.86%, with absolute errors between 2.53 and 16.4 MPa. The UCSs of sandstone and limestone were estimated to lie between 39.65 and 55.71 MPa and 113.29 and 143.90 MPa, respectively, demonstrating close alignment with the results of uniaxial compressive strength tests and confirming the model's accuracy and reliability for UCS prediction using MWD data. [ABSTRACT FROM AUTHOR]

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The orthotropic anisotropy of sedimentary rocks has a significant impact on the force and deformation behavior of the project. In this paper, radial pressurization tests were carried out in the borehole in a typical northern karst area to obtain the deformation properties and orthotropic anisotropy of the rock masses. The test results showed that the deformation modulus and elastic modulus of the limestone rocks in the dam site area obeyed normal distribution. The deformation modulus was basically larger than the proposed deformation modulus of Class II rocks (10 GPa). The deformation behavior and anisotropy degree of the limestone showed a weak correlation with the elevation, but a strong correlation with the development density of the rock joints. The larger development density of the rock in the right bank test section leads to a larger degree of orthotropic anisotropy and frequency of occurrence.Article Highlights: The orthogonal anisotropy coefficient is proposed on the ratio of the deformation modulus in the vertical and horizontal directions. The anisotropy characteristics of limestone rocks are not obvious, and the existence of joints leads to anisotropy. The anisotropy coefficients of the rock mass are spatially differentially distributed, and the frequency of occurrence is positively correlated with the density of joint development. [ABSTRACT FROM AUTHOR]

When semi-coke is co-combusted with bituminous coal with higher sulfur content in a circulating fluidized bed (CFB) boiler, the necessity of desulfurization in furnace increases. Meanwhile, limestone, which is a widely used desulfurizing agent, also has an effect on NO emission. In order to explore its effect during co-combustion, the combustion experiments were conducted in both a CFB test rig and a fixed bed reactor. The results show that blending semi-coke with bituminous coal will change the occurrence forms of nitrogen in the fuel and more fuel NO is released during the devolatilization stage. During the desulfurization process, CaO will be generated through the calcination reaction. It has catalytic effects on both the oxidation and reduction reactions of NO, and the catalytic strength in these two types of reactions decides the final effect on NO emission. For the blended fuel with 50% semi-coke and 50% bituminous coal (SC50BC50), the NO emission initially increases and then decreases as the Ca/S molar ratio increases from 0 to 4 at 900°C. Compared to the situation of burning semi-coke alone, semi-coke in the blended fuel has more opportunities to contact with CaO under the same Ca/S molar ratio, leading to the heterogeneous reduction reaction of NO enhanced. As the combustion temperature increases from 800°C to 1000°C, the effect of limestone on NO emission will change from promotion to inhibition. This is because the higher combustion temperature can intensify not only the catalytic reduction of NO precursors in the dense-phase region, but also the reaction between NO and unburnt char in the dilute-phase region in the CFB. Besides, the lower O2 concentration in the atmosphere is also favorable for enhancing the catalytic effect of CaO on the NO-char reduction reaction for semi-coke and SC50BC50, so the conversion of fuel-N/NO will be inhibited compared with the cases without limestone. The achievements of this study are beneficial for the coordinated control of NOx and SO2 during the co-combustion of semi-coke and bituminous coal. [ABSTRACT FROM AUTHOR]

A sustainable, eco-friendly, and effective adsorbent has been employed for the removal of eriochrome black T (EBT) toxic dye from the effluent. This adsorbent, derived from natural chalky limestone, underwent thorough characterization using various investigative tools, including X-ray diffraction, energy-dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, field emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, zeta potential, thermogravimetric analysis (TGA), and ultraviolet–visible technique. The chalky limestone exhibited distinctive properties, achieving an efficient removal percentage and high capacity within a short timeframe. Kinetic studies were conducted to assess the reaction speed, employing both pseudo-first-order and pseudo-second-order models, yielding R2 values of 0.67 and 0.62, respectively. Furthermore, thermal studies were carried out using Langmuir and Freundlich models to elucidate the interaction nature between the active sites of chalky limestone and EBT dye molecules, resulting in R2 values of 0.75 and 0.91, respectively. The research findings indicated that the adsorption process achieved equilibrium in just five minutes with adsorption capacity (qt) about 1.99 mg g−1, and the chalky limestone showed the ability to be reused for up to five cycles without any decrease in removal efficiency or requiring a desorption step. [ABSTRACT FROM AUTHOR]

Manufactured sand concrete (MSC) has increasingly applied in engineering. However, how to enhance the thermal crack resistance of MSC has not clearly studied yet, which limits the wide applications of manufactured sand in engineering. We have adopted the method of mixing limestone powder (LP) to make MSC with four mass fractions (wt.%) of 5%, 10%, 15%, and 20% of LP content, designed the mix proportion of concrete, tested their mechanical properties, observed their microstructure by scanning electron microscopy (SEM) and investigated the effect of LP on anti-cracking performance using temperature stress testing machine (TSTM). These findings reveal that the mechanical properties and thermal crack resistance of 15% LP MSC are the best. Our results also provide a research basis for the MSC to be widely used in engineering. [ABSTRACT FROM AUTHOR]

In order to explore the damage law of freeze-thaw effect on the physical and mechanical properties of limestone, uniaxial compression tests were carried out on Basu limestone with 0,20,40,60 and 80 freeze-thaw cycles. The effects of freeze-thaw deterioration on the macroscopic physical and mechanical parameters and failure modes of rock were analyzed, and the energy evolution law of freeze-thaw damage samples under uniaxial compression was explored. Secondly, considering the coupling effect of freeze-thaw and load, based on the assumption of generalized Lemaitre strain equivalence, a piecewise damage constitutive model of freeze-thaw limestone with Weibull distribution was established. The results show that the mass, elastic modulus and compressive strength of limestone decrease with the increase of freeze-thaw cycles, and the failure mode changes from a single tensile failure to a combination of tensile and shear failure. The failure samples of 60 times and 80 times of freeze-thaw cycles show obvious bulging effect, indicating that freezethaw action causes ductile failure of limestone. Under the condition of uniaxial compression, the theoretical model curve is basically consistent with the experimental data curve in the pre-peak section. The non-compaction section parameter m is an important index of rock plasticity. The non-compaction section parameter m is reduced from 39. 8 to 4. 32, which is reduced by 89. 15% . The model reveals the transformation of limestone from brittleness to ductility. The research results provide theoretical support for the related problems of seasonal geotechnical engineering. [ABSTRACT FROM AUTHOR]

Modern-day terrestrial amphibians pale in comparison to their monstrous ancient relatives, the Late Carboniferous and Early Permian trematopid temnospondyls. With a skeleton that clearly indicated a terrestrial mode of life and armed with an impressive set of large, recurved marginal dentition and palatal fangs for holding their prey—this group of terrestrial temnospondyls roamed North America and Central Europe as a top predator. Lack of substantial informative fossil material has previously limited our understanding of trematopid diversity and ontogeny. Fortunately, this has improved in the last few decades with the help of exceptional localities like the Early Permian locality Richards Spur. While multiple species of dissorophid temnospondyl have been described from Richards Spur, only one trematopid species has been confidently recognized -Acheloma dunni. Here, we report on the presence of a new large, relatively mature trematopid skull from this famous locality, found encased within a limestone rich block composed mostly of skeletal remains from several other taxa. With the help of neutron computed tomography (nCT), a non-invasive method of analyzing internal and external morphologies, this specimen has revealed several features consistent with the genus, Acheloma, but distinct from Acheloma cumminsi and Acehloma dunni. The identification of these new features, in addition to the characters it shares with other Acheloma species, not only constitute it as a new species of this genus, but also challenges the notion of having synonymized Acheloma dunni with Acheloma cumminsi. In this study, we also unveil new anatomical characters that are potentially independent of ontogeny and could therefore help clarify some of the phylogenetic relationships of this fascinating group of Paleozoic terrestrial predators. [ABSTRACT FROM AUTHOR]

Uniaxial compressive strength (UCS) of rocks is one of the main parameters required in the design of geotechnical projects such as tunnels, dams, or rock slopes. According to the literature, there are a large number of predictive regression equations to evaluate the UCS from the point load index (PLI) and Brazilian tensile strength (BTS). However, the equations developed in previous studies have different accuracies in UCS prediction. A more accurate prediction of the UCS will result in a more appropriate design of the geotechnical project, and thus ensure its success during operation. In the present paper, a comparative study was conducted between the accuracy of PLI and BTS in predicting the UCS of the limestone and sandstone. Moreover, the role of porosity (n) on the accuracy of predicting the UCS from PLI and BTS was investigated. Some statistical indices were used to investigating the accuracy of predictive regression equations of UCS. The results revealed that the UCS of rocks can be predicted with a higher accuracy using BTS compared with PLI. Also, the findings showed that the n had a significant role in increasing the accuracy of PLI- and BTS-based regression equations of the UCS predictive. The predictive equations established in the present study can be used in practical applications for indirect evaluation of limestone and sandstone UCS in the site of a geotechnical project. [ABSTRACT FROM AUTHOR]

Undocumented collections and new field studies have revealed a diverse chondrichthyan assemblage within the Upper Mississippian (Serpukhovian/middle-upper Chesterian) Bangor Limestone in northern Alabama, U.S.A. which includes multiple new occurrences of holocephalians. Included in these new records are the first occurrences of Obruchevodidae (Euchondrocephalii, Petalodontiformes) outside of the synchronic Bear Gulch Limestone Member of the Heath Formation in Montana, U.S.A. Isolated teeth from Fissodopsis robustus and Netsepoye hawesi represent the first specimens to provide three-dimensional tooth morphology that is otherwise obscured in the holotypes. Additionally, these specimens represent the first reported occurrences from the southern coast of the subcontinent Laurentia. The significance of these new specimens is discussed in regard to the comparative morphology of Petalodontiformes and the paleobiogeography of Obruchevodidae. [ABSTRACT FROM AUTHOR]

A new rhynchonellide brachiopod genus and species, Skadarirhynchia semicostata gen. et sp. nov., is described from the late Pliensbachian of Livari, Rumija Mountain, southeastern Montenegro. It occurs in shallow-water brachiopod-crinoid packstone beds (bioclastic limestones) of the periplatform facies of the Dinaric Carbonate Platform. Stratigraphy is constrained by means of 87Sr/86Sr dating indicating a late Pliensbachian age, and by the fact that the brachiopod beds lie immediately below the Toarcian marly limestones, which is consistent with the regional stratigraphical position. The new species has a circular to roundly pentagonal outline and semicostate shells with 10‒12 strong angular ribs. Internally, it shows reduced dental plates, narrow and thin hinge plates inclined dorsally with small crural bases, crescent-like and laterally convex, and hamiform crura. The shell microstructure of the new taxon is characterised by a homogeneous secondary layer (a single layer with no sublayers) built of rhombic fibres that are typically of coarse-fibrous type (eurinoid pattern) 35‒50 μm wide and 20‒30 μm thick. Other co-occurring rhynchonellide species such as Prionorhynchia fraasi and Cuneirhynchia dalmasi are also described. Shell microstructures for the genus Cuneirhynchia are presented. [ABSTRACT FROM AUTHOR]

This study examines limestone properties and calcination process to enhance product quality. Limestone burning produces lime (CaO, calcium oxide) and carbon dioxide (CO2). Lime is a substance highly reactive and turns into slaked lime (Ca(OH)2, calcium hydroxide) when exposed to water. Six limestone samples from Tuscan Nappe sedimentary sequence, outcropping in the Monti d'Oltre Serchio area (NW Tuscany, Italy), were selected and calcined at different temperatures (800, 900, 1000 and 1100 °C). The obtained lime was slaked, and chemical, mineralogical and petrographic analyses were conducted to study its reactivity during slaking process. Key factors influencing lime reactivity were identified: calcination temperature/time and limestone characteristics (chemical and mineralogical composition). The lime reactivity was measured through the rate of lime hydration reaction. Results showed that higher reactivity in lime, lower calcination temperature. The increase in temperature and time leads to an increase of CaO grain size and, consequently, to a decrease in reactivity. Temperature increase has a more significant effect on the increasing of grain size and reactivity than time. The optimal calcination temperature was found to be 900 °C, like that of ancient limekilns. The study emphasized the close link between lime reactivity and chemistry/mineralogy of limestone. Overall, the research provides insights for improving limestone calcination processes and obtaining superior products. [ABSTRACT FROM AUTHOR]

In addition to the surrounding climatic environment, the intrinsic characteristics of the stones used in construction are a critical factor to understand a building's conservation state and define the necessary planning and conservation management activities. The use of environmentally susceptible stones, such as carbonate stones, in heritage buildings can be especially problematic. The present investigation presents an overview of past research and contributes to identifying the types of carbonate stones used over time in Coimbra's Old Cathedral in Portugal, which was classified as a National Monument and integrated into the Coimbra World Heritage site by UNESCO. Our mineralogical and chemical analyses revealed the use of carbonate stones from different quarries (Coimbra region), including Ançã limestone and dolostone (Porta Especiosa portal), Portunhos limestone and Outil limestone (in the perimeter of windows), and marlstones and Outil limestone (side facades). These stones, which were installed at various times during the construction and alteration of the monument, represent a great challenge for conservation planning due to their intrinsic vulnerability to adverse environmental conditions and pollution. [ABSTRACT FROM AUTHOR]

Predicting facies and petrophysical properties along and between wells is challenging in carbonate reservoir modeling. In the Nullipore carbonate reservoir, Ras Fanar field, depositional and long-term diagenetic processes result in a high degree of heterogeneity and complex distribution of facies, which in turn affect the reservoir quality. This provides a significant obstacle to building accurate geological models. This study integrates thin sections, routine core analyses, and well logging data to overcome such difficulties and model the Nullipore carbonate facies and permeability. The detailed petrographic analysis revealed the existence of seven microfacies in the reservoir, which are summed up into three facies associations (FAs), each of which represents a specific reservoir rock type (RRT): (1) supratidal FA, (2) intertidal FA, and (3) shallow subtidal FA. The three FAs were correlated with the gamma-ray logs to create facies logs for the studied wells, which were further populated via the Truncated Gaussian Simulation method. Cross-validation was used to evaluate the model's accuracy. The analysis of the available core data infers that the three RRTs are prospective and have a wide permeability distribution. However, RRT3 constitutes the best reservoir quality. The sedimentological analysis revealed that the long-term diagenetic events, involving the dolomitization of limestone and the dissolution of allochems have a major role in improving the pore connectivity and permeability of the reservoir. Fracture characterization discloses that fractures play a significant role in fluid storage and migration. Three Machine Learning (ML) models, including Adaptive boosting (AdaBoost), Gradient Boosting (GB), and Extreme Gradient Boosting (XGB), were developed to integrate the RRTs, porosity, and permeability to improve permeability prediction. Statistical analysis revealed that the XGB model outperforms other models and exhibits the highest prediction performance. The present study provides further insights into the characterization and modeling of facies and permeability of complex carbonate reservoirs. It can be applied in similar geological settings to better interpretation of depositional and diagenetic controls on reservoir quality assessment and aid in the field development plan. [ABSTRACT FROM AUTHOR]

This study challenges the conventional perception of waste as a discarded object devoid of use and aims to redefine its nature by dissociating it from the boundaries of value. To achieve this, the term sslgi (sweeping) is proposed to shift the focus of waste management from relegation to obsolescence to active disposition that retains latent value. This conceptual shift redefines "reuse" in design as the activation of the inherent value in objects. This research also explores the creation of novel materials, exemplified by the extraterrestrial material StarCrete, which is composed of dust, soil, and minimal organic additives, along with designers' use of new materials derived from limestone dust and material-driven speculative design that experiments with synthetic (plastic) and natural substances. These cases illuminate the inherent [re]usability of material entities that are ready for activation in multiple interconnected contexts. From this perspective, we can re-view the role of the designer as [re]assembling existing materials and negotiating various influencing factors. Ultimately, this research demonstrates that transcending the binary perceptions of value and worthlessness allows designers to approach [re]use beyond the confines of the production-consumption-disposal paradigms, thereby decoupling objects from the deterministic use values imposed on them. [ABSTRACT FROM AUTHOR]

The Pliensbachian (Lower Jurassic) age-based Lower Marly Limestone Formation of the Moulay Idriss Zerhoun area (Morocco) and the Ain Ouarka Formation of the Ksour Mountains (Algeria) have yielded rare crinoids. Although crinoids have previously been described from the Jurassic of Algeria, their Pliensbachian occurrence is being reported here for the first time. On the other hand, one isocrinid taxa [Terocrinus subsulcatus (Münster in Goldfuss)] was also recorded from the Pliensbachian strata of Morocco. Additionally, now, from both Morocco and Algeria, Seirocrinus subangularis (Miller), belonging to the family Pentacrinitidae, is documented. This is a cosmopolitan and pseudoplaktonic crinoid species that is well-known from Asia, Europe, and North America. The taxonomic evaluation of the genus Seirocrinus is provided. The present records from Algeria and Morocco are the first finds of Seirocrinus from the African continent. Ticinocrinus moroccoensis sp. nov. represented by a cup of a rare cyrtocrinid (Cyrtocrinida) is associated with S. subangularis from Morocco. Globally, this is the second record of the genus; the first Ticinocrinus being described from the Pliensbachian of Switzerland. Thus, the present records from Morocco and Algeria are also the oldest cyrtocrinids from the southern margin of the Tethys. [ABSTRACT FROM AUTHOR]

Pumping is a high shear process used in the placement of concrete. The lubrication layer (LL), a thin layer of micromortar, forms at the inner periphery of the pipe during the pumping of concrete, facilitating its movement inside the pipe. Although this process is essential for effective concrete placement, challenges arise during interruptions, prompting a shift in focus toward understanding the behavior of concrete at rest in the pipe. This shift led to the exploration of the structural buildup properties of the equivalent LL during concrete pumping operations. The investigation systematically considers the influence of various factors, including supplementary cementitious materials [fly ash, ground granulated blast-furnace slag, and limestone calcined clay (LC2)], the water-to-binder ratio (w/b), and the addition of superplasticizer (SP) on the LL's structural buildup properties (percolation time and structuration rate). The research highlights a significant finding: a higher deformation ratio in the lubrication layer benefits concrete at rest during pumping interruptions. For instance, the optimized superplasticizer dosage in slag-based LL mixtures offers a handling time of 30 min, whereas LC2 -based mixtures provide an extended 45 min for managing potential pumping interruptions. Intermittent shearing tests revealed negligible formation of hydration products, confirming the dominant role of colloidal interactions in the structural buildup of the LL. The study also addresses potential anomalies in investigations and analyzes the evolution of the structuration rate, providing a comprehensive understanding of the viscoelastic properties of cementitious suspensions. In a broader context, this work significantly contributes to our fundamental understanding of the lubrication layer's behavior in high shear applications like concrete pumping. Beyond academic insights, the findings hold practical implications for optimizing concrete pumping operations and ensuring smoother resumption after interruptions by providing an informed time for managing potential interruptions, thereby enhancing the overall efficiency of construction processes. [ABSTRACT FROM AUTHOR]

Fractures are common in rock masses, and the examination of the electrical properties of fractured rocks under the combined scenario of thermal-hydro-mechanical is of great significance for the application of electrical methods for deep underground engineering investigation. The resistivity of limestone specimens containing prefabricated fractures was measured under different combinations of confining pressure, pore pressure and temperature. The formation factor was then calculated. The results showed that the formation factor increased with the increase in confining pressure and decline in pore pressure and temperature. The coupling effect between the three factors in changing resistivity is very significant. After comparing the specimen strain, the fracture specimen formation factor was found to be closely related to the fracture deformation. The difference between confining pressure and pore pressure in changing the rock formation factor was analyzed, and the concept of effective stress for the fractured rock formation factor was proposed. A formation factor model for single-fractured rocks under the thermal-hydro-mechanical coupling was derived, and its accuracy was verified by comparison with experimental results. Finally, the consistency of the effective stress coefficient of fractured rock deformation and the effective stress coefficient of formation factor was analyzed. [ABSTRACT FROM AUTHOR]

To reveal the enrichment conditions and resource potential of coal-rock gas in the Ordos Basin, this paper presents a systematic research on the sedimentary environment, distribution, physical properties, reservoir characteristics, gas-bearing characteristics and gas accumulation play of deep coals. The results show that thick coals are widely distributed in the Carboniferous-Permian of the Ordos Basin. The main coal seams Carboniferous 5# and Permian 8# in the Carboniferous-Permian have strong hydrocarbon generation capacity and high thermal evolution degree, which provide abundant materials for the formation of coal-rock gas. Deep coal reservoirs have good physical properties, especially porosity and permeability. Coal seams Carboniferous 5# and Permian 8# exhibit the average porosity of 4.1% and 6.4%, and the average permeability of 8.7×10-3 µm2 and 15.7×10-3 µm2, respectively. Cleats and fissures are developed in the coals, and together with the micropores, constitute the main storage space. With the increase of evolution degree, the micropore volume tends to increase. The development degree of cleats and fissures has a great impact on permeability. The coal reservoirs and their industrial compositions exhibit significantly heterogeneous distribution in the vertical direction. The bright coal seam, which is in the middle and upper section, less affected by ash filling compared with the lower section, and contains well-developed pores and fissures, is a high-quality reservoir interval. The deep coals present good gas-bearing characteristics in Ordos Basin, with the gas content of 7.5-20.0 m3/t, and the proportion of free gas (greater than 10%, mostly 11.0%-55.1%) in coal-rock gas significantly higher than that in shallow coals. The enrichment degree of free gas in deep coals is controlled by the number of macropores and microfractures. The coal rock pressure testing shows that the coal-limestone and coal-mudstone combinations for gas accumulation have good sealing capacity, and the mudstone/limestone (roof)-coal-mudstone (floor) combination generally indicates high coal-rock gas values. The coal-rock gas resources in the Ordos Basin were preliminarily estimated by the volume method to be 22.38×1012 m3, and the main coal-rock gas prospects in the Ordos Basin were defined. In the central-east of the Ordos Basin, Wushenqi, Hengshan-Suide, Yan'an, Zichang, and Yichuan are coal-rock gas prospects for the coal seam #8 of the Benxi Formation, and Linxian West, Mizhi, Yichuan-Huangling, Yulin, and Wushenqi-Hengshan are coal-rock gas prospects for the coal seam #5 of the Shanxi Formation, which are expected to become new areas for increased gas reserves and production. [ABSTRACT FROM AUTHOR]

This paper gives an overview of various factors that influences the performance of Limestone Calcined Clay Cement (LC3) concrete. Among the various research related to ternary cements, this paper discusses the influential factors, based on the strength and durability aspects. The factors such as the type and purity of kaolinite, limestone, gradation of the limestone, concentration of gypsum, calcined clay, limestone ratio, clinker content, water-to-binder ratio, method and effect of calcination, grinding criteria, optimum temperature of calcination, calcined clay content, method of curing and other factors are interpreted. Even low-grade materials with minimum purity have also been found to achieve the desired properties. Therefore depending upon the knowledge of the importance of every parameter, the best quality concrete could be developed with the available source and facilities. With the available quality and quantity of material, sustainable ternary cement could be obtained. By optimizing the various factors that influence the behavior of LC3 concretes, more economical and durable concrete can be produced. [ABSTRACT FROM AUTHOR]

To explore the optimal ratio of limestone powder and calcined clay in the limestone calcined clay composite cementitious material system, the response surface method was adopted to optimize. The prediction model was established by taking ordinary Portland cement, calcined clay and limestone powder as variable factors, and 28 d compressive strength and 28 d flexural strength of cement mortar as response variable. Mechanical properties were tested, and the regression model between the proportion of mineral admixture compounding and the mechanical properties was established. At the conditions of mineral admixture proportion of 15%, 30% and 45% (mass fraction, the same below), the regression model was used to optimize the mixing ratio of limestone powder and calcined clay in the limestone calcined clay composite cementitious material system. The optimization results are as follows: calcined clay accounts for 15%, without limestone powder. Calcined clay accounts for 25%, and limestone powder accounts for 5%. Calcined clay accounts for 30. 5%, and limestone powder accounts for 14. 5%. The predicted values of 28 d compressive strength of system are 63. 26, 58. 57 and 48. 10 MPa, respectively, while the measured values are 63. 74, 57. 21 and 47. 02 MPa, respectively. The absolute relative errors between the predicted and measured values are less than 5%. It provides a new solution idea and test basis for the optimal proportioning problem of limestone calcined clay composite cementitious material system. [ABSTRACT FROM AUTHOR]

The resilient modulus (MR) and the backcalculated modulus from the FWD testing (EFWD) of the unbound layers are critical inputs in the analysis/design of pavements. Several studies have tried to develop a conversion factor between these two parameters, while the nonlinear stress dependency of unbound materials and the pavement strain response are mostly missing from the literature. This study aims to compare the laboratory-measured MR of recycled aggregate base (RAB) materials and a virgin aggregate base using field-based EFWD and tries to establish pavement's responses to loading using vertical strains from both the MR and EFWD values of the respective materials as comparability parameters between the two. For this purpose, a control virgin aggregate (VA, limestone) and three types of RAB materials were selected to construct four test sections. The test sections were modeled in layered elastic- and finite-element-based pavement response models to calculate the vertical strains at the mid-depth of the base and top of the subgrade layers. A comparison of the lab-calculated vertical strains using MR with actual vertical strains in the field from EFWD showed that there was no relationship between the two stiffness parameters in all tested RABs. The vertical strains, based on the lab MR, undermined the stiffness of the recycled aggregates in the field. In contrast, the values of EFWD based on the vertical strains remained close to the MR strains of limestone (VA) throughout the testing period, establishing an EFWD vs. MR relationship (MR = 0.87 EFWD). The results also show that fine RCA was a better-performing material over three years. This research not only explores how the hydration process in RABs limits the development of MR-EFWD correlations but also underscores the need to consider real-world conditions when assessing their performance. [ABSTRACT FROM AUTHOR]

A ternary system comprising Ca20Al26Mg3Si3O68 (Q-phase), limestone, and metakaolin is proposed, and its hydration behavior, hydration product phases, microstructure, and mechanical properties are investigated and compared with pure Q-phase cement. The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40 °C environment, significantly outperforming pure Q-phase. The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase. Meanwhile, the interactions among Q-phase, limestone, and metakaolin further enhance the cementitious performance. The ternary system effectively addresses potential issues of strength loss in Q-phase cement application, and as a low-carbon cementitious material system, it holds promising potential applications. [ABSTRACT FROM AUTHOR]

In this study, asphalt mixtures made by steel slag (SSA), copper slag (CSA), limestone (LA) and siliceous (SA) aggregates were subjected to different aging conditions; and were evaluated using Marshall, indirect tensile strength (ITS), Cantabro abrasion loss and semi-circular bending (SCB) tests. Results reveal that the moisture damage, raveling and fracture resistance of asphalt mixture decrease with aging and the ITS and Marshall properties improve with aging. After 7-day long-term aging, the TSR of the mixtures made by LA, SA, SSA and CSA, decreases, 28.8%, 48.5%, 8.8% and 15%, respectively, while, the ITS in dry condition increases, 61.9%, 33%, 62% and 81%, respectively. The fracture properties and moisture damage resistance of asphalt concrete made by SSA and CSA are less affected by aging than those made by LA and SA. Statistical analysis revealed that the effect of aggregate type, aging condition and their interaction on the mixture properties is significant. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Primulina magnifica F.Wen & W.C.Chou, a new species of Gesneriaceae from the limestone areas of Yizhou District, Hechi City, Guangxi, China, is described and illustrated here. It morphologically resembles P. mollifolia (D.Fang & W.T.Wang), J.M.Li & Yin Z.Wang in leaf blades. Still, it can be easily distinguished from the latter by noting a combination of characteristics, especially in its tube infundibuliform, and obviously broader bracts. We found only one population, about 300 mature individuals, at the type locality. According to the IUCN Red List Categories and Criteria (ver. 3.1), the new species is tentatively designated as Critically Endangered (CR). [ABSTRACT FROM AUTHOR]

Limestone calcined clay cement (LC3) presents a promising alternative material due to its reduced CO2 emissions and superior mechanical properties compared to traditional Portland cement (PC). This study investigates the synergistic effect of calcined coal-series kaolinite (CCK) and limestone (LS) on the hydration behavior of cement, specifically focusing on varying mass ratios. The combination of CCK and LS promotes the formation of strätlingite and carboaluminates, which enhances early-age strength development. Additionally, the inclusion of CCK facilitates the formation of carboaluminates during later stages of hydration. After 56 days of hydration, the content of carboaluminates is over 10%wt. This stimulation of secondary hydration products significantly refines the evolution of pore structure, with the harmful large pores gradually transformed into harmless medium pores and gel pores, leading to marked improvements in compressive strength from 7 to 28 days. Replacing 45% PC with CCK and LS at mass ratio of 7 to 2, the compressive strength of blends reaches 47.2 MPa at 28 days. Overall, the synergistic interaction between CCK and LS presents unique opportunities to minimize the CO2 footprint of the cement industry without compromising early and long-term performance. [ABSTRACT FROM AUTHOR]

The paper presents the lithologies used in the stone products of Neviodunum (modern Drnovo in Slovenia), a Roman municipium in south‐western Pannonia. For this purpose, 95 stone monuments were assessed. Petrographic and biostratigraphic analyses were carried out on 56 archaeological and 57 geological samples. Our research shows that, besides some rare exceptions, most stone products refer to three lithostratigraphic units: the Middle Miocene ‘Lithothamnium’ Limestone Member of the Laško Formation, the Upper Cretaceous Krško Formation and the Early Jurassic Krka Limestone Member of the Podbukovje Formation. [ABSTRACT FROM AUTHOR]

Fungal studies are scant within this region of Borneo, and the potential effects of anthropogenic disturbance on fungal communities in Sabahan caves have not been explored. This study involved opportunistic sampling of guano, speleothems, and cavern water from four caves in Sabah, Malaysia, categorised according to the level of anthropogenic activity. The dilution method was used for fungal isolation and abundance calculations. Morphological identification of axenic cultures was conducted, and DNA barcoding of the ITS region of cryptic species corroborated identification. A total of 170 axenic cultures were attained, composed of 69 morphological taxonomic units (MTUs), 33 genera, ten orders, and two divisions -- Ascomycota and Basidiomycota. Fifty-seven of the 69 MTUs were identified to the species level. The genera Aspergillus and Penicillium were particularly prevalent, with a combined total of 86 isolations (50.6%). Notably, twelve species were documented for the first time in cave ecosystems of Sabah. The average fungal abundance across all substrates and fungal taxa occurrence was found to be higher in samples found in active caves. A significant difference in relative abundance was observed between active and non-active cave conditions. Beta regression modelling indicated that anthropogenic activity is a significant factor influencing the composition of cave fungal communities. While anthropogenic activity seems to affect cave mycobiomes, especially by selecting for ubiquitous fungi, it is likely not the sole influencing determinant of their composition. [ABSTRACT FROM AUTHOR]

Lithological cycles with a repetitive pattern of sandstone overlain by limestone or shale comprise the middle Minnelusa Formation in the Black Hills region, USA. At least eight lithological cycles were observed at Boulder Canyon Road (BCR), eight at Vanocker Canyon Road (VCR) and four at Hot Brook Canyon (HBC). These rocks were deposited in a nearshore to offshore marine environment, and the shale and limestone intervals at the top of these cycles yielded conodonts. Five biostratigraphically distinct Middle to Upper Pennsylvanian conodont faunas were recovered from these marine units. An upper Desmoinesian assemblage was recovered from VCR cycle 1. Two Missourian assemblages were recovered, one indicative of the Idiognathodus cancellosus Zone from VCR cycle 3 and the other indicative of the Streptognathodus gracilis Zone from VCR cycle 6. Two Virgilian assemblages were recovered, one indicative of the Heckelina simulator Zone from VCR cycle 7, VCR cycle 8 and HBC cycle 2 and the other indicative of the lower part of the "Streptognathodus" group 4 virgilicus Zone from HBC cycle 3. Two conodont biofacies were recognized within the middle Minnelusa, the low energy, offshore, Idiognathodontidae-Idioprioniodus biofacies and the higher energy, nearshore Idiognathodontidae-Hindeodus biofacies. [ABSTRACT FROM AUTHOR]

Nummulitic Limestones deposits are preserved along the tectonic contact between the Variscan basement and Alpine units of Corsica. These marine carbonates, dated from the Late Palaeocene to the Middle Eocene, were deposited within a foreland flexural basin that is considered to be the southern continuation of the Alpine foreland basin of southeast (SE) France. However, in contrast with the Nummulitic Limestones of SE France, those of Corsica are far less documented. This field‐based study constrains the sedimentology, stratigraphy and structure of the Nummulitic Limestones of Corsica in three localities (Balagne, Corte and Sari‐Solenzara) to identify factors that controlled foreland basin development and to clarify its significance within the early alpine orogen. The microfacies, microfaunal assemblages and siliciclastic fractions are characterised throughout the succession at each locality. The results indicate the existence of an important Variscan basement relief to the west of the basin (West Corsican Massif) that supplied early alluvial fans found at the base of the foreland succession in the northernmost Balagne area. Continuous high clastic input strongly reduced the development and diversity of the overlying Nummulitic Limestones facies and fauna. Further south, limestones in the Corte and Sari‐Solenzara areas are thicker and contain richer fauna. Three depositional models corresponding to the carbonate ramp system are proposed for the Nummulitic Limestones and used to construct paleogeographic maps illustrating the transgressive evolution of the Corsican foreland basin from the Early to the Late Eocene. Based on our results and available regional tectonic data and LT thermochronological data, we propose that the Nummulitic marine transgression took place within a continuous foreland basin encompassing southern Corsica and SE France during the early development of the western alpine arc. [ABSTRACT FROM AUTHOR]

The erosion phenomena of the natural stone in cultural heritage are induced by various sources. Consequently, the development of multifunctional protective materials that combine two or more useful properties is an effective strategy in addressing the synergistic effects of various erosion mechanisms. A multifunctional coating, consisting of a silane-based precursor and zinc oxide (ZnO) nanoparticles (NPs), is produced and tested for the protection of limestone. The hybrid coating combines the following three properties: superhydrophobicity, including water-repellency, photocatalytic self-cleaning and biocidal activity. The relative concentration of the NPs (0.8% w/w), used for the suggested composite coating, is carefully selected according to wetting studies, colourimetric measurements and durability (tape peeling) tests. The non-wetting state is evidenced on the surface of the composite coating by the large contact angle of water drops (≈153°) and the small contact angle hysteresis (≈5°), which gives rise to a physical self-cleaning scenario (lotus effect). The photocatalytic chemical self-cleaning is shown with the removal of methylene blue, induced by UV-A radiation. Moreover, it is shown that the suggested coating hinders the incubation of E. coli and S. aureus, as the inhibitions are 94.8 and 99.9%, respectively. Finally, preliminary studies reveal the chemical stability of the suggested coating. [ABSTRACT FROM AUTHOR]

The Mateur aquifer system in Northern Tunisia was examined using data from 19 water boreholes, 69 vertical electrical sounding (VES) stations, and a Sentinel-2 satellite image. Available boreholes and their corresponding logs were compared to define precisely the multi-layer aquifer system, including the Quaternary and Campanian aquifers of the Mateur plain. Quantitative interpretation and qualitative evaluation of VES data were conducted to define the geometry of these reservoirs. These interpretations were enhanced by remote sensing imagery processing, which enabled the identification of the Mateur plain's superficial lineaments. Based on well log information, the lithological columns show that the Quaternary series in the Ras El Ain region contains a layer of clayey, pebbly, and gravelly limestone. Additionally, in the Oued El Tine area, a clayey lithological unit has been identified as a multi-layer aquifer. The study area, exhibiting apparent resistivity values ranging between 20 and 170 Ohm·m, appears to be rich in groundwater resources. The correlation between the lithological columns and the interpreted VES data, presented as geoelectrical cross-sections, revealed variations in depth (8–106 m), thickness (10 to 55 m), and resistivity (20–98 Ohm·m) of a coarse unit corresponding to the Mateur aquifer. Twenty-three superficial lineaments were extracted from the Sentinel-2 image. Their common superposition indicated that both of them are in a good coincidence; these could be the result of normal faults, creating an aquifer system divided into raised and sunken blocks. [ABSTRACT FROM AUTHOR]

In order to study the deformation and damage characteristics of the limestone specimens with high strength and brittleness under constant amplitude cyclic loading, the deformation and the acoustic emission (AE) characteristics were analysed, and the relationship between them was sought. The damage variables under different amplitude cyclic loading were defined by AE counts. The results showed that the radial deformation of the limestone specimens was more sensitive and unstable than the axial deformation. The concept of apparent residual strain was proposed to describe the specimen deformation characteristics, and it resulted that the radial apparent residual strain produced at higher stress state would recover at lower stress state. The limestone specimens showed obvious Kaiser effect and Felicity effect under cyclic loading. When the upper limit of the cyclic loading was close to the peak stress of the specimen, the AE counts generated in unloading sections were almost the same as that in the loading sections. The damage was increased as the amplitude and the stress level increased and the unloading process at higher stress level would also lead to the aggravation of damages. Specimens would absorb more energy under cyclic loading than under uniaxial loading. Reasonable driving parameters should be controlled in underground excavation practice, to ensure that the stress level of surrounding rock mass in a periodic stress state is located before peak stress and such that to limit the occurrence of rock burst to a certain extent. [ABSTRACT FROM AUTHOR]

Simple Summary: Plant-based ingredients are the major constituents of poultry diets and supply a significant portion of dietary phosphorus (P). However, approximately two-thirds of the P of plant origin is bound to phytic acid, which is poorly available to monogastric animals. Broiler diets have been formulated based on non-phytate P (NPP), which might lead to the excessive use of inorganic P sources and reduced P availability for birds. Recent research has suggested using digestible P to assess availability, and due to nutritional interactions, there is also increasing interest in determining calcium (Ca) digestibility. The objectives of this study were to determine the standardized ileal digestibility (SID) of Ca and P in the feed ingredients for broilers. On day 18 post-hatch, 512 male and female broilers were individually weighed and randomly allocated to eight treatments with four replicates for each sex (eight birds/cage) in a randomized complete block design based on body weight and sex. No significant interaction between experimental diets and sex regarding the SID of Ca or P was found, and no effect of sex on the SID was observed. There were significant differences in the SID of the feed ingredients. This study aimed to determine the standardized ileal digestibility (SID) of calcium (Ca) and phosphorus (P) in various feed ingredients using the direct method. This study comprised eight experimental diets: a Ca–P-free diet and seven experimental diets, each containing monocalcium phosphate (MCP), dicalcium phosphate (DCP), monosodium phosphate (MSP) + limestone, corn, and soybean meal (SBM) as the sole sources of Ca and/or P. These diets provided 4.21 g/kg of non-phytate P from MCP, DCP, or MSP, and the MSP + limestone diet included 7.50 g/kg of Ca. The corn and SBM diets formulated to determine P digestibility maintained a dietary Ca/total P ratio of 1.4 through the addition of limestone. Chromic oxide was added to the diets as an indigestible index. On day 18, 256 male and 256 female broilers were individually weighed and randomly assigned to eight treatments, each with four replicates for each sex (eight birds per cage). This allocation followed a randomized complete block design based on body weight. On day 21, the birds were euthanized using carbon dioxide, and ileal digesta samples were collected from the distal two-thirds section of the ileum. No significant interactions between the experimental diets and sex regarding the SID of Ca or P were detected, and no effect of sex on the SID was observed. The standardized ileal Ca digestibility of MCP, DCP, limestone, corn, and SBM was found to be 84.7%, 70.1%, 52.6%, 88.6%, and 81.6%, respectively. The standardized ileal P digestibility of MCP, DCP, MSP, corn, and SBM was determined to be 91.8%, 76.8%, 94.4%, 73.1, and 88.4%, respectively. Given the variable digestibility of Ca and P across different feed ingredients, the consideration of the specific type of ingredients used in diet formulation is crucial. [ABSTRACT FROM AUTHOR]

This paper aims to bring to light and edit nine Byzantine funerary inscriptions discovered in the town of El-'Irāq (western Governorate of Karak, southern Jordan). All these pieces belong to the period ranging from the 5th to the 6th centuries ce. Like the majority of the inscriptions from the area, these epigraphs consist of short epitaphs engraved on rectangular tombstones made of local limestone and adorned with Christian symbols. The main novelty of this work is the appearance of two anthroponyms that have not been attested to date in the local epigraphic record: Γομολλα and Ἠλίος. [ABSTRACT FROM AUTHOR]

Shear wave velocity is an essential parameter in reservoir characterization and evaluation, fluid identification and prestack inversion. However, conventional data‐driven or model‐driven shear wave velocity prediction methods exhibit several limitations, such as lack of training data sets, poor model generalization and weak model robustness. In this study, a model‐ and data‐driven approach is presented to facilitate the solution of these problems. We develop a theoretical rock physics model for fractured limestone reservoirs and then use the model to generate synthetic data that incorporates geological and geophysical knowledge. The synthetic data with random noise is utilized as the training data set for the artificial neural network, and a well‐trained shear wave velocity prediction model, random noise shear wave velocity prediction neural network, is established by parameter tuning, which fits the synthetic data with noise well. The neural network is applied directly to the real field area. Compared with conventional shear wave prediction methods, such as empirical formulas and the improved Xu–White model, the prediction results show that the random noise shear wave velocity prediction neural network has better prediction performance and generalization. Furthermore, the prediction results demonstrate the efficacy of the proposed approach, and the approach has the potential to perform shear wave velocity prediction in real areas where training data sets are unavailable. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to make use of moderate and low-grade limestone in cement manufacturing for sustainable and economic benefits. In the present work, limestone from clinkers of different grades is explored for producing Portland limestone cement (PLC) replacing with different percentages, viz. 0, 5, 10, 15, 20, 25 and 30% in ordinary Portland cement (OPC). OPC clinkers with three different qualities of limestone are interground to develop different types of PLC-based cements. From the experimental results, it is inferred that an appropriate choice of clinker quality, limestone quality and percentage of limestone can lead to production of limestone cement with desired properties. Based on the strength and interaction factor values, it can be concluded that optimum replacement (15%) of low-grade limestone could satisfy the performance, similar to an OPC 43 grade cement. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Architecture & Civil Engineering is the property of Chang'an Daxue Zazhishe and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Carbonate muds are essential sedimentary components in geological carbon cycles. Model carbonate muds are prepared from crushed, sieved carbonate rock. The carbonate rock particles are primarily smaller than 62.5 µm. Steady-state shear viscosity was measured for model carbonate muds prepared from three types of carbonate rock: limestone Grey, limestone Marl, and limestone Castleton. Model carbonate muds were prepared using fresh water or 3.5 g/L NaCl solution. The carbonate particle concentrations were 1.81 volume percent and 26.95 volume percent, representing semi-dilute and concentrated particle regimes, respectively. Carbonate mud viscosity was measured at temperatures ranging from 8 °C to 35 °C. Shear rates ranged from 60 s−1 to 2500 s−1. Pseudoplasticity occurs at low shear rates and is caused by the release of occluded water during shear-driven breakup and dispersal of particle aggregates. Shear thickening occurs at high shear rates and is caused by transient particle clusters, called hydroclusters, that are reinforced by lubrication forces or frictional particle contacts. Carbonate mud viscosity decreases at increasing temperatures. The presence of 3.5 g/L NaCl in the aqueous phase slightly increased the mud viscosity in the semi-dilute particle concentration regime because of a weak viscosifying effect of NaCl on the aqueous phase. In the concentrated particle regime, electrolytes screened electroviscous effects, reducing the viscosity of muds containing particles with electrically charged surfaces. In aqueous solution, limestone Marl had a comparatively high concentration of charged particles on its surface. Limestone Castleton had a comparatively low concentration of charged particles on its surface. Surface charges were not rheologically evident on limestone Grey. [ABSTRACT FROM AUTHOR]

To know the sustainable performance of calcium-based adsorbents is one of the important aspects to realize efficient and economical carbon capture, and to systematically study the properties of natural adsorbents is conducive to their industrialization. The cyclic calcination and carbonation characteristics of a typical natural limestone were investigated using a thermal gravimetric analyzer. Two kinds of over-sintering conditions were selected to emphatically study the cyclic separation of CO2 from limestones through prolonging the calcination time and increasing the calcination temperature. The results showed that the untimely end of the chemical reaction control stage caused by excessive sintering is the direct reason for the reduction in cyclic carbonation conversion, and the changes in surface morphology of calcined products due to pore collapse and fusion are the fundamental reasons for the reduction in cyclic carbonation conversion. The excessive sintering caused by extending the calcining time or increasing the calcining temperature has great inhibition on this cycle only; the inhibition decreases rapidly in subsequent cycles. In addition, SEM and BET–BJH tests further confirm the influence of the over-sintering phenomenon. With the further increase in cycle number, the early excessive sintering has certain stimulative effects on the subsequent carbonation reaction. It is expected to provide a reference for the subsequent research and development of natural calcium-based adsorbents. [ABSTRACT FROM AUTHOR]