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This study focuses on improving the mechanical properties and microstructure of cement-based materials, which are crucial for the durability and safety of construction projects. Conventional cement, although commonly used, has certain limitations in terms of its mechanical strength and durability. Therefore, there is a requirement for innovative methods to enhance these properties. This study investigates the potential of nano-TiO2 (titanium dioxide) as an additive to overcome these limitations. The objective of this research is to perform a thorough experimental analysis to examine how different concentrations of nano-TiO2 impact the mechanical performance and microstructural changes in cement paste and mortar. The study examines the influence of nano-TiO2 on the compressive and flexural strengths of cementitious materials. It also explores how nano-TiO2 modifies the microstructure to enhance compactness and resilience. The results suggest that incorporating nano-TiO2 into cement leads to a substantial improvement in both compressive and flexural strengths. This enhancement is particularly notable when the nano-TiO2 concentration is at an optimal level of 1.0% by weight. The SEM and XRD analyses demonstrate that this concentration enhances the microstructure by decreasing voids and facilitating the development of C-S-H crystals. However, excessive concentration may have negative consequences, such as the creation of extra empty spaces. The results indicate that nano-TiO2 has considerable promise in enhancing cement-based materials, thereby aiding the advancement of construction materials that are more long-lasting and effective. This study contributes to the knowledge of how nano-TiO2 improves cement and emphasizes its potential uses in the construction sector. [ABSTRACT FROM AUTHOR]

The integration of organic wastes into cement-based materials shows promise as a solution to mitigate environmental pollutants. It achieves this by minimizing waste sent to landfills and in some conditions decreasing Portland cement use. One of these organic wastes that produces positive effects when used in cement products is olive seed. In this study, the effect of a new generation bio-polymeric admixture on the physical and mechanical properties of cement mortars is examined in detail. The bio-polymeric admixture is prepared by grinding olive seeds in 0/125 μm sizes. The olive seeds have been used as bio-polymeric admixture in cement mortars at different rates, i.e., 0, 0.2, 0.35, 0.5, 1 and 1.5% of total weight. The olive seed is characterized by XRD, FT-IR analysis and by determining extracts, pectin, cellulose, hemicellulose and lignin content. The characteristics of hydration products were analyzed by SEM/EDS and XRD investigations. Effect of bio-polymeric admixture addition on the unit weight, flowability, setting time, compressive and flexural strength and capillary water absorption was analyzed. The results suggested that the bio-polymeric admixture hindered the cement hydration at low usage rates but promoted at high usage rates. Accordingly, 28 days compressive and flexural strength of test samples decreased. However, 1.5 wt% bio-polymeric admixture was associated with a slight increase of 150-days compressive strength. Bio-polymeric admixture improves the hydrophobicity property of the hardened mortar samples by declining effect on the water absorption. Another important effect of the bio-polymeric admixture contribution was also observed on the flowability property of the cement mortars. As the bio-polymeric admixture increased, the flow diameter values of the mortar were also significantly increased. The research outcomes suggested for the first time the beneficial effect of bio-polymeric admixture as a natural and bio-degradable alternative of chemical admixtures on especially flowability, set retarder and hydrophobicity of cement mortars with comparable mechanical properties. [ABSTRACT FROM AUTHOR]

The construction industry faces increasing pressure to reduce its environmental impact while meeting the growing demand for infrastructure. One approach to achieving this goal is the use of industrial waste as a replacement for traditional supplementary cementitious materials (SCMs). This study investigates sugarcane bagasse ash (SCBA), addressing the future scarcity and increased cost of other commonly used SCMs. Despite existing literature, the use of SCBA is hindered by several unknowns. This research evaluates SCBA's performance in mortars, focusing on the effects of curing temperature and particle size variation. Mortar samples were prepared with SCBA replacements from 0% to 30% by mass of cement and cured at 21 °C and 45 °C for 7, 28, and 90 days. The results suggest potential for SCBA replacement up to 30%, emphasizing its sustainability and economic benefits. A cost analysis was also conducted, demonstrating the economic viability of SCBA as an alternative to traditional cement for practical applications. [ABSTRACT FROM AUTHOR]

In the current study, the high-volume replacement of river sand (20%, 30%, 40%, 50%, 60%, 80%, and 100%) by pond ash in cement mortar was considered using a 1∶3 volumetric mix proportion to evaluate the engineering properties, sustainability aspects, and cost of mortar mixes. The compressive strength, tensile bond strength, and adhesive strength increased by 30%, 21%, and 24%, respectively, at 30% replacement and were in line up to 60% replacement as compared with the reference mix. However, the drying shrinkage was observed to increase with volume replacement of river sand. The life-cycle assessment of mixes containing pond ash showed reductions in the environmental impacts. Four different scenarios were considered on the basis of the preference advantage of the indicators. Considering the engineering properties, sustainability aspects, and cost as the primary indicators, the gray clustering analysis showed that the mix with 60% volume replacement exhibited the best performance among the mixes under Scenario S-1, while TOPSIS and VIKOR showed that the mix with 50% volume replacement exhibited best performance under Scenario S-1. Overall, the comparison of all scenarios showed that the mix of 60% pond ash had the best performance followed by the mix with 50% pond ash, irrespective of the multicriteria decision-making techniques and preference advantages. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has led to a surge in medical waste generation, posing hazards to both the environment and global health. The impacts of the COVID-19 pandemic's medical waste hazard may persist long after the pandemic itself subsides. Improper disposal of medical waste can contaminate environment, posing risks to ecosystems and public health. Discarded medical rubber gloves, for example, can become a source of infection, improper disposal of these gloves can escalate the spread of infectious diseases and increase the risk of transmission of the virus to the general public. This study proposes an innovative and sustainable method to reinforce cement mortar by adding recycled glove rubber as an additive to cement mortar to increase its resistance to impact loads. This study conducted uniaxial compression tests, separating hopkinson pressure bar (SHPB) experiments and SEM observations to evaluate the quasi-static compressive strength and dynamic stress of recycled rubber fiber mortar (RRFM) with varying recycled rubber fiber (RRF) contents (0, 1%, 2%, 3%). Strain curves, dynamic increase factor (DIF), energy absorption rules, failure modes, and microstructure of RRFM mixtures. The experimental results demonstrate that with the addition of RRF, the dynamic stress-strain curve flattens and the peak strain gradually increases. The RRFM sample shows stronger toughness. In comparison to regular cement mortar (NM), RRFM has a higher DIF and specific absorbed energy, a faster increase in dynamic compressive strength, and the ability to absorb more energy per unit volume. Under the same impact load, RRFM has fewer and smaller cracks than NM. Scanning electron microscopy (SEM) testing also observed that RRF formed a strong connection pattern with the cement mortar matrix. [ABSTRACT FROM AUTHOR]

In the lab experiments, the compressive strength (CS) of cement mortar, three pre-setting water/binder (W/B) ratios, five substitution rates of burned joss paper ash (SR-BJPA), and three curing temperatures (T) were tested for the 45 samples. The results were recorded at 3, 7, 28, 56, 90, and 120 days after curing (#days) for each sample. The correlations between CS and each experimental factor (W/B ratio, SR-BJPA, T, and #days) and the effects of each factor or pair of factors on CS were determined using four univariate and six bivariate regression models. All the models were significant (i.e., the factors and the pairs of factors can be used to predict CS); however, each model had a different ability to fit the data and explain the data variance, making some models not that suitable. The effects on CS of substituting cement with different BJPA proportions and curing the mortar at different temperatures were mainly identified. A knowledge base for predicting the CS was established before any sample is to be made in future practise. Finally, using an SR-BJPA of 5% and raising the curing temperature to 50 °C (or 75 °C, if additional heating energy consumption needs not be considered) while keeping the W/B ratio at 0.4 is recommended to obtain an optimal CS for the full-aged sample (i.e., at #days = 120) in future practise, subject to the aim to consume the BJPA wastes by using it to replace Portland cement, in order to reduce the vast volume of carbon emitted along with the production of the cement material. [ABSTRACT FROM AUTHOR]

The use of construction and demolition waste (CDW) for the treatment of dye-contaminated water can be an effective way to minimize environmental impacts. This study evaluates its adoption as a potential adsorbent for methylene blue (MB) in aqueous solution. Cement mortar, roof tiles, and tiles were disintegrated and sieved for physicochemical characterization (pH, potential redox – Eh, electrical conductivity – CE, cationic exchange capacity—CEC, point of zero charge – PZC, specific surface area – SSA, pore distribution, functional groups, and elemental composition). The effect of initial concentration, pH, granulometric fraction and time were evaluated in adsorption and desorption studies. The results of adsorption studies were analyzed using nonlinear kinetic models and equilibrium data were analyzed by Langmuir, Freundlich, Sips, and Temkin isotherm models. The CDW evaluated has alkaline pH (pH 8.4 – 11.6) with high EC (680.5 – 1054.5 µS cm−1), reductive environment (-223 – -66 mV), low CEC (0.45 – 1.40 cmolc kg−1), SSA (1.83 – 11.06 m2 g−1), and basic PZC (8.3 – 10.0). Initial concentration, pH and adsorbent particle size affected the removal efficiency and desorption rate. Roof tiles showed higher MB removal efficiency (84.5%), followed by cement mortar (61.1%) and tiles (41.6%), and the materials displayed the following maximum adsorption capacities (qm): tiles (13.983 mg g−1) > roof tiles (8.389 mg g−1) > cement mortar (1.305 mg g−1). Pseudo-first order model best described the chemical kinetics. Freundlich isotherm best described the adsorption process of MB onto tiles and Sips model best described the process onto roof tiles and cement mortar. Therefore, the materials can be used for removing MB from aqueous solutions. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, the effect of carbon black (CB) on the mechanical and electromagnetic performance of cement-based materials was investigated using modified polyether for CB dispersion. Results show that, with suitable CB content and dispersant ratio, the average pore diameter and compressive strength will be decreased and improved with the adding of CB. Moreover, as CB content increases, the electrical conductivity of cement mortar decreases notably. Notably, at a 3% CB content, changes in the electromagnetic properties of cement mortar were observed. Below 3% CB content, dispersants reduce electromagnetic parameters and increase electrical conductivity. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the effective use of a mixture of steel sludge (S1) and slag (S2) from the converter process of steel production for the production of cement mortars. Metallurgical waste used in the research, which is currently deposited in waste landfills and heaps near plants, posing a threat to groundwater (possibility of leaching metal ions present in the waste), was used as a substitute for natural sand in the range of 0–20% by weight of cement (each). The obtained test results and their numerical analysis made it possible to determine the conditions for replacing part of the sand in cement mortars with a mixture of sludge and slag from a basic oxygen furnace (BOF) and to determine the effects of such modification. For the numerical analysis, a full quadratic Response Surface Model (RSM) was utilized for two controlled factors. This model was subsequently optimized through backward stepwise regression, ensuring the inclusion of only statistically significant components and verifying the consistency of residual distribution with the normal distribution (tested via Ryan-Joiner's test, p > 0.1). The designated material models are helpful in designing ecological cement mortars using difficult-to-recycle waste (i.e., sludge and converter slag), which is important for a circular economy. Mortars modified with a mixture of metallurgical waste (up to 20% each) are characterized by a slightly lower consistency, compressive and flexural strength, and water absorption. However, they show a lower decrease in mechanical strength after the freezing–thawing process (frost resistance) compared to control mortars. Mortars modified with metallurgical waste do not have a negative impact on the environment in terms of leaching heavy metal ions. The use of a mixture of sludge and steel slag in the amount of 40% (slag/sludge in a 20/20 ratio) allows you to save 200 kg of sand when producing 1 m3 of cement mortar (cost reduction by approx. EUR 5.1/Mg) and will also reduce the costs of the environmental fee for depositing waste. [ABSTRACT FROM AUTHOR]

One challenge for 3D printing is that the mortar must flow easily through the printer nozzle, and after printing, it must develop compressive strength fast and high enough to support the layers on it. This requires an exact and difficult control of the superplasticizer (SP) dosing. Nanocrystalline cellulose (CNC) has gained significant interest as a rheological modifier of mortar by interacting with the various cement components. This research studied the potential of nanocrystalline cellulose (CNC) as a mortar aid for 3D printing and its interactions with SPs. Interactions of a CNC and SP with cement suspensions were investigated by means of monitoring the effect on cement dispersion (by monitoring the particle chord length distributions in real time) and their impact on mortar mechanical properties. Although cement dispersion was increased by both CNC and SP, only CNC prevented cement agglomeration when shearing was reduced. Furthermore, combining SP and CNC led to faster development of compressive strength and increased compressive strength up to 30% compared to mortar that had undergone a one-day curing process. [ABSTRACT FROM AUTHOR]

Adhering to ASTM C109/C109M-20 standards ensures quality in cement mortar specimens. However, achieving the required sand gradation per ASTM C778-21 can be challenging. This paper presents a faster method for adjusting sand gradation without compromising ASTM quality standards. The proposed method involves analyzing six silica sand samples of different gradations, pre-screening sands, using Excel Solver for optimal mixture ratios, making automated gradation tweaks with precise calculations, and validating the gradation to ensure ASTM compliance. After making the adjustments, compressive strength tests were conducted on mortars with the modified sands, and the results were compared with those of standard-graded sand. Based on statistical analysis, the new method yielded reliable outcomes with compressive strengths similar to standard sands. This innovation offers a more efficient alternative, paving the way for streamlined practices in civil engineering. [ABSTRACT FROM AUTHOR]

In this paper,the influence of fly ash and silica fume on the compressive strength,flexural strength and frost resis tance of cement mortar after ultra-low temperature freeze-thaw cycle(-190-20 )was studied under different dosage of fly ash and silica fume. The results show that the deterioration degree of cement mortar after ultra-low temperature freeze-thaw cycle is much greater than that of low temperature freeze-thaw cycle(-20-20 ). Among them,when the double-doped fly ash is mixed with 15% and the silica fume is mixed with 10%,the mechanical performance of cement mortar is the best. After 10 super-low temperature freeze-thaw cycle,the flexural strength and compressive strength reach 10.06 MPa and 38.29 MPa respectively. At this time,the loss rate of cement mortar strength is the lowest and the frost resistance is the best the pore size reaches a minimum of 33.15 nm,and the porosity is also a minimum of 13.58%. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office 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.)

This study examined the effects of silane-modified polyimide polymer (PIS) on cement mortar. The PIS was added to replace cement in a specified ratio. Obtained results revealed that the PIS caused retardation on setting time, and accelerated UPV mostly by encapsulating unhydrated cement particles, filling pores, or reacting with C–S–H and Ca(OH)2 with shifting to Si–O vibrations. SEM results showed a good compact interface without forming considerable agglomeration and voids on the microstructure, and this improved flexural and compressive strength properties. In conclusion, silane-modified polyimide as an admixture or cement replacement can be recommended for construction industries to enhance the properties of cement mortar. [ABSTRACT FROM AUTHOR]

Rubberized cement-based materials are widely utilized because of their good ductility, impact resistance, and fatigue resistance. This research investigated the effect of the rubber aggregates content, particle size of rubber aggregates, and water–cement ratio on the early-age mechanical properties and deformation behaviors of mortar through laboratory tests, and strength reduction coefficient fitting models were established according to the testing results. The results show that the compressive strength growth rate of cement mortar is about 15% slower than that of flexural strength. The existence of rubber aggregates lowers the strength increase rate of mortar. The reduction coefficient of strength decreases with increasing rubber aggregates content and increases with the age of mortar. Increasing rubber aggregates content and decreasing particle size of rubber aggregate can lower the autogenous shrinkage in the initial stage, but the autogenous shrinkage of the later stage increases as the rubber aggregates content increases, with a turning point between 30 h and 50 h. After 3 days, the dry shrinkage of mortar accounts for about 70–80% of the total shrinkage, and it increases with higher rubber aggregate content, smaller particle size of rubber aggregates, and higher water–cement ratios. [ABSTRACT FROM AUTHOR]

Abstract The COVID-19 pandemic has led to a surge in medical waste generation, posing hazards to both the environment and global health. The impacts of the COVID-19 pandemic’s medical waste hazard may persist long after the pandemic itself subsides. Improper disposal of medical waste can contaminate environment, posing risks to ecosystems and public health. Discarded medical rubber gloves, for example, can become a source of infection, improper disposal of these gloves can escalate the spread of infectious diseases and increase the risk of transmission of the virus to the general public. This study proposes an innovative and sustainable method to reinforce cement mortar by adding recycled glove rubber as an additive to cement mortar to increase its resistance to impact loads. This study conducted uniaxial compression tests, separating hopkinson pressure bar (SHPB) experiments and SEM observations to evaluate the quasi-static compressive strength and dynamic stress of recycled rubber fiber mortar (RRFM) with varying recycled rubber fiber (RRF) contents (0, 1%, 2%, 3%). Strain curves, dynamic increase factor (DIF), energy absorption rules, failure modes, and microstructure of RRFM mixtures. The experimental results demonstrate that with the addition of RRF, the dynamic stress-strain curve flattens and the peak strain gradually increases. The RRFM sample shows stronger toughness. In comparison to regular cement mortar (NM), RRFM has a higher DIF and specific absorbed energy, a faster increase in dynamic compressive strength, and the ability to absorb more energy per unit volume. Under the same impact load, RRFM has fewer and smaller cracks than NM. Scanning electron microscopy (SEM) testing also observed that RRF formed a strong connection pattern with the cement mortar matrix.

This study focuses on investigating the chemical degradation characteristics of cementitious barriers used in low- and intermediate-level radioactive waste repository by reactive transport modeling. The impact of the blending with supplementary cementitious materials (SCMs) in the barriers on the chemical degradation was evaluated to find the optimum barrier design. A number of different barrier designs were examined by replacing ordinary Portland cement (OPC) by SCMs (i.e., fly ash, silica fume, and blast-furnace slag). The simulation results showed that silica fume blended barrier has better durability against chemical degradation by rainwater compared to fly ash or blast-furnace slag blended barriers. In addition, the chemical durability of silica fume-based barrier increased with increasing replacement level up to about 20 %. It seems that the amount of formed calcium silicate hydrate (CSH) in the initial cement-based barrier highly affects the overall chemical durability. The newly developed reactive transport model demonstrated its capability for understanding the barrier performance and investigating the optimal design of the barrier system.

The construction industry has been constantly expanding and is, consequently responsible for a high consumption volume of natural raw materials and for generating large amounts of waste. In detriment of this scenario, this research proposes the reuse of Construction and Demolition Waste (CDW), especially that from plaster for making mortars. The residue was thermo-activated at 650 °C for a period of 2h, a heating rate of 10 °C/min, it was crushed in a jaw crusher and passed through an ABNT N° 16 sieve. The mortars were prepared with a (cement:sand) ratio of 1:6 by mass, the sand was partially replaced by the residue in proportions of 0, 10, 20 and 30%, using Ordinary Portland Cement (OPC). Tests were carried out on consistency index, mass density, incorporated air content, isothermal calorimetry, water retention, mass density in the hardened state, flexural strength, compressive strength, water absorption and void index, in addition to testing techniques characterization, such as laser granulometry, pozzolanic activity using the Modified Chapelle method and Lúxan method, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) as well as Mercury Intrusion Porosimetry (MIP). It was possible to observe that the residue has amorphous phases, through XRD and heterogeneous nucleation of smaller particles, proven by the calorimetry test, contributing to the increase in mechanical strength. The results indicate that the mixture with 30% replacement achieved a greater increase in mechanical strength, lower absorption rates and consequently, a reduction in the distribution of pore sizes.

Abstract The present study investigated the microstructural properties of ordinary Portland cement (OPC)-modified with minimum dosage of nano TiO2 on fresh and hardened cement mortar surfaces and intermixed samples. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to analyze the morphology and hydration products of the OPC specimens doped with nanotitanium (NT).Additionally, XRD coupled with Rietveld refinement was employed to quantify the crystal phases and refine the crystal structure model through the comparison of the calculated diffraction pattern to the measured pattern. Subsequently, crystallographic analysis was conducted to evaluate the crystallographic structure and to confirm the existence of specific atoms and bonds within the crystal structure altered with NT. The findings revealed that the addition of minimal NT resulted in a more compact and denser microstructure, characterized by increased formation of calcium silicate hydrate (CSH) gel and a reduction in calcium hydroxide (CH) crystals.This led to a reduction in the porosity of the hardened coating surface, with similar improvements observed for the fresh coating and intermixed samples compared to those of the control mortar. A decrease in the lattice parameters, accompanied by an increase in the number of atoms, bonds and polyhedra in the crystal structure, led to alterations in the interatomic spacing and contributed to the densification of the cementitious matrix.The findings also showed that NT integration led to a more compact structure with shorter bond distances and smaller polyhedral volumes for the Ti samples than for the control sample. Moreover, compared with the freshly cast and hardened coating samples, the NT-intermixed samples exhibited the shortest Ti–O bond distances and the smallest polyhedral volume. Overall, the analysis presented in this study significantly contributes to the development of novel and environmentally friendly photocatalytic cementitious materials at minimal dosages.

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal 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.)

Corrosion of reinforcement bar caused by chloride ions diffusion is a crucial durability problem for concrete structures. Deoxyribonucleic acid (DNA) is a new type of corrosion inhibitor. Previous research has concentrated primarily on the influence of DNA on the corrosion of reinforcement bar caused by chloride salts in simulated concrete pore solution and cement-based materials, with scant attention to the chloride diffusion behavior of cement-based materials with DNA. In this work, the chloride diffusion behavior of cement-based materials with DNA was studied using chloride binding isotherm, chloride rapid migration (RCM), and natural diffusion tests. The composition, content, and morphology of the hydration products and pore structure were monitored using X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) tests. The results show that DNA can improve the chloride-binding capacity and enhance the chloride diffusion resistance in cement-based materials. The lowest chloride migration coefficient and chloride diffusion coefficient were found in cement mortar with 4% by weight DNA, which were 45.58% and 42.36% lower than those of the reference group, respectively. DNA can stimulate the cement hydration reaction to produce more C-S-H gels and can increase the Ca/Si ratio of C-S-H. This is conducive to physical chloride adsorption. DNA can be combined with calcium ions to form insoluble aggregates that can fill the pore structure of mortar. Mortar with 4% by weight DNA maintained the lowest porosity, which effectively enhanced the chloride diffusion resistance. [ABSTRACT FROM AUTHOR]

The degradation of concrete and reinforced concrete structures is a significant technical and economic challenge, requiring continuous repair and rehabilitation throughout their service life. Geopolymers (GPs), known for their high mechanical strength, low shrinkage, and durability, are being increasingly considered as alternatives to traditional repair materials. However, there is currently a lack of understanding regarding the interface bond properties between new geopolymer layers and old concrete substrates. In this paper, using advanced computational techniques, including quantum mechanical calculations and stochastic modeling, we explored the adsorption behavior and interaction mechanism of aluminosilicate oligomers with different Si/Al ratios forming the geopolymer gel structure and calcium silicate hydrate as the substrate at the interface bond region. We analyzed the electron density distributions of the highest occupied and lowest unoccupied molecular orbitals, examined the reactivity indices based on electron density functional theory, performed Mulliken charge population analysis, and evaluated global reactivity descriptors for the considered oligomers. The results elucidate the mechanisms of local and global reactivity of the oligomers, the equilibrium low-energy configurations of the oligomer structures adsorbed on the surface of C-(A)-S-H(I) (100), and their adsorption energies. These findings contribute to a better understanding of the adhesion properties of geopolymers and their potential as effective repair materials. [ABSTRACT FROM AUTHOR]

Cement mortar with sticky rice pulp is an innovative composite material. Investigating its mechanical properties and strength mechanism is essential for the future engineering application. Taking the pulp concentration and the mortar ages as the variables, we tested five groups of blocks for the compressive strength and flexural strength, and observed their microstructures with a scanning electronic microscope. The results indicated that the microstructure got dense if the added pulp had a concentration of about 0.3%, and thereby its flexural strength would significantly improve, while the hydration products agglomerated and the microstructure got loose if the added pulp had a concentration of more than 1.0%, which caused a substantial decline in flexural strength. Besides, the hydration reaction was hindered at the early stage due to the addition of the pulp; hence the early strength of the mortar is on the low side. According to the strength mechanism analysis, all the results are mainly attributed to the effects: "water-reduction", agglomeration and retarding, caused by the addition of the pulp. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office 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.)

In this study, a viscosity-reducing polycarboxylic acid superplasticizer (VRPCE) was synthesized using methylallyl polyoxyethylene ether (HPEG), acrylic acid (AA), and maltodextrin maleic acid monoester (MDMA) as the main raw materials. The influences of the VRPCE on the microscopic properties of cement paste were studied by gel permeation chromatography (GPC), total organic carbon test (TOC), zeta potential, laser particle size analysis, XRD, MIP, TG, and SEM. Finally, the effects of the VRPCE on the macroscopic properties of cement mortar were evaluated through flow time, slump flow, compressive strength, shrinkage, and creep. The results showed that the VRPCE can improve the hydration degree of the cement, optimize the pore structure, increase the porosity, improve the fluidity, compressive strength, and creep, and decrease the shrinkage resistance of the cement mortar. [ABSTRACT FROM AUTHOR]

The present study investigated the microstructural properties of ordinary Portland cement (OPC)-modified with minimum dosage of nano TiO2 on fresh and hardened cement mortar surfaces and intermixed samples. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to analyze the morphology and hydration products of the OPC specimens doped with nanotitanium (NT).Additionally, XRD coupled with Rietveld refinement was employed to quantify the crystal phases and refine the crystal structure model through the comparison of the calculated diffraction pattern to the measured pattern. Subsequently, crystallographic analysis was conducted to evaluate the crystallographic structure and to confirm the existence of specific atoms and bonds within the crystal structure altered with NT. The findings revealed that the addition of minimal NT resulted in a more compact and denser microstructure, characterized by increased formation of calcium silicate hydrate (CSH) gel and a reduction in calcium hydroxide (CH) crystals.This led to a reduction in the porosity of the hardened coating surface, with similar improvements observed for the fresh coating and intermixed samples compared to those of the control mortar. A decrease in the lattice parameters, accompanied by an increase in the number of atoms, bonds and polyhedra in the crystal structure, led to alterations in the interatomic spacing and contributed to the densification of the cementitious matrix.The findings also showed that NT integration led to a more compact structure with shorter bond distances and smaller polyhedral volumes for the Ti samples than for the control sample. Moreover, compared with the freshly cast and hardened coating samples, the NT-intermixed samples exhibited the shortest Ti–O bond distances and the smallest polyhedral volume. Overall, the analysis presented in this study significantly contributes to the development of novel and environmentally friendly photocatalytic cementitious materials at minimal dosages. [ABSTRACT FROM AUTHOR]

Construction materials are at the forefront of global economic development as they provide the foundation for the infrastructure of other industries, with cementitious materials being predominantly used in construction projects. To promote sustainable development, alternative materials are added to cement mortar to increase durability and reduce emissions. In this regard, graphene oxide (GO) and fly ash (FA) are two alternative materials commonly used in cement mortar, which are readily available or are just the waste from other local material production. With different ratios, the amount of GO and FA can affect the properties of cement mortar positively or negatively. This study aims to determine the effects of GO and FA on cement mortar mixtures under material conditions. Research results show that 10 wt% FA and 0.036 wt% GO will give cement mortar the best physical and mechanical properties while ensuring other necessary properties, such as workability. When increasing FA to 30 wt% or GO to 0.05 wt%, the strength of the mortar mixture tends to decrease. Another issue is that the specific surface area of graphene is very high, which poses a significant challenge when uniform dispersion in the cement paste mixture is required. Polycarboxylate combined with a specific mixing sequence has demonstrated good dispersibility and high stability. Through this research, it is demonstrated that the addition of GO and FA has the potential for sustainable development of the construction industry by considering the contexts of the local recycled cementitious replacement materials. [ABSTRACT FROM AUTHOR]

This paper addresses the imperative need for understanding the mechanical properties of clay brick masonry with gypsum mortar, the primary construction material in Persian historical buildings, to facilitate accurate restoration efforts. Given the constraints of heritage preservation, destructive tests on large-scale specimens are unfeasible. As a viable alternative, this research employs scaled-down specimens to investigate the flexural strength. For the first time, Persian clay brick masonry with gypsum mortar assemblages have been tested at three scales of 1:2, 1:4 and 1:6 to determine the flexural strength. The paper introduces new relationships between the flexural strength of brick masonry and brick size. Furthermore, it establishes a correlation between the flexural strength of the brick masonry specimens and the flexural strengths of both the brick and the gypsum mortar. Additionally, some specimens incorporate cement mortar instead of gypsum mortar for result comparison. The obtained results reveal the profound influence of mortar type and thickness, along with brick dimensions, on flexural strength. The flexural strength of brick masonry increases with decreasing brick size. By reducing the size of bricks, the ratio of compressive strength to flexural strength decreases, offering key insights for restoration efforts. [ABSTRACT FROM AUTHOR]

Thermal activated coal gangue as an auxiliary cementing material to replace part of cement to prepare cement mortar, systematically studies the effects of different amounts of thermal activated coal gangue on the compressive strength and flexural strength of cement mortar, and the mechanism of thermal activation of coal gangue to enhance the mechanical strength of cement-based materials was explored. The results show that in the process of using thermally activated coal gangue to replace part of cement to pre-pare mortar, proper amount of thermally activated coal gangue has good pozzolanic effect and micro aggregate effect, which can promote the formation of cross-linked network C--S--H gel in mortar matrix, enhance the filling effect of pores in mortar matrix, improve the microstructure of mortar matrix, and then achieve the purpose of improving the mechanical strength of cement-based materials. When the amount of thermal activated coal gangue is 20%, the compressive strength and flexural strength of the mortar sample for 28 d after hydration can reach 46.2 MPa and 6.79 MPa, and the mechanical strength is equivalent to that of pure cement mortar, which can fully meet the requirements of the general construction industry. [ABSTRACT FROM AUTHOR]

It is widely recognised that green building, environmental sustainability, and technical performance have recently become requirements in the field of civil engineering. For this reason, the new trend in research is to focus on the recycling and recovery of materials, even if some of them such as industrial waste are still underexplored. In this perspective, the main objective of this work is to study the influence of brick powder on the thermophysical and mechanical properties of mortars containing this type of waste, in different environments, and within the temperature range between ambient temperature and 50 °C. To this end, a number of mortar mixtures, in which cement was replaced by brick powder in different proportions, were studied and characterised according to technical standards in order to define the optimal substitution percentage. Three batches of samples were examined at different ages, i.e., 3, 7, 28, and 90 days. The samples of the first batch were kept in water at a temperature of 20 ± 2 °C with a relative humidity RH = 100 %, while those of the second batch were immersed and stored in water at 50 °C in order to simulate a hot and humid climate. As for the samples of the third batch, they were kept in a dry oven at 50 °C in order to investigate the effect of the hot and dry climate. The results obtained revealed that the partial replacement of cement by brick powder makes it possible to improve the thermal insulation characteristics but reduce the mechanical strength of the mortar. In addition, it was shown that in a hot and dry environment, the mechanical characteristics of the different mortars decrease as the rate of weight substitution of cement by brick powder rises. However, in a hot and humid environment, a reverse trend is observed. The findings also suggested that the optimal recommended rate of substitution of cement by brick powder is 20 %. [ABSTRACT FROM AUTHOR]

This paper presents an optimization study of spent coffee grounds (SCG) as cement mortar additives to enhance mortar strength. In recent years, sustainable materials have begun finding their way into cement mortar, with SCG being one. There is limited optimization study on the SCG addition in mortars, hence this study was performed to optimize the curing time and SCG addition in cement mortar to achieve the highest compressive strength through response surface methodology. Scanning Electron Microscopy (SEM) characterization was carried out on the SCG particles to identify their physical properties. An Energy Dispersive X-ray (EDX) analysis was carried out to identify its chemical properties. Simultaneously, a workability test, the flow table test, is conducted to study the effect of SCG on the flowability of the cement mortar mixes. The synergistic effect between SCG content in cement mortar mixes and the curing period was statistically studied and analyzed. Both parameters were then optimized to obtain the best performance mix of SCG in cement mortar. It was found that 1.1% SCG and a curing day of 68 days produced the highest compressive strength (33.4MPa) of cement mortar. The Response Surface Methodology (RSM)-optimized cement mortar mix presented at least a 12.62% improvement in compressive strength from control cement mortar without SCG additives (28.77MPa). Experimental validation of the optimum condition showed a good agreement with a deviation of 3.12% in three replicates, thus indicating that the optimum model in this work can be used to model the compressive strength of the SCG-cement mortar mixture.Article Highlights: The addition of spent coffee grounds (SCG) in cement mortar enhanced its strength by 12.6%. The optimum SCG addition that corresponds to the highest mortar strength is 1.1%. The flowability of cement mortar mix decreases as the percentage of SCG addition increases. [ABSTRACT FROM AUTHOR]

The application of seawater concrete is receiving increasing attention due to the advantage of using seawater in alleviating water scarcity. One concern with seawater concrete applications is the potential for alkali–silica reaction (ASR) due to the elevated alkali concentration. In this paper, the ASR risk induced by mixed seawater in cement mortar incorporating non-reactive or reactive aggregates (RAs) was studied through short-term and long-term experiments. Experimental results indicate that seawater only increased ASR in the presence of RAs due to the high alkali concentration. Replacing cement with 70% ground granulated blast-furnace slag (GGBS) prevented expansion, although very few ASR products may be observed. SEM results indicated that seawater decreases the (Na + K)/Si ratio and increases the Ca/Si ratio of ASR products slightly. Compared with cement mortar, C–S–H in GGBS blended cement mortar has a higher (Na + K)/Si ratio, which indicates its higher alkali binding capacity. [ABSTRACT FROM AUTHOR]

Self-cleaning cementitious materials have gained significant attention due to urban environmental pollution. In this study, nano-TiO2 (NT) was first mixed with cement mortar. Second, NTs were coated on fresh cast mortars and on hardened surfaces. Photocatalytic efficiency was evaluated using Rhodamine B under natural sunlight with three types of cement: white Portland (WPC), ordinary Portland (OPC), and Portland pozzolana cement (PPC). Among them, PPC cement mortars exhibited superior photocatalytic performance compared to WPC and OPC even with lower dosages of NT. The order of photocatalytic efficiency was highest for the hard-coat followed by fresh-coat and then intermix sample. Furthermore, Rietveld analysis for crystal structure refinement was used, and crystallography analysis (VESTA software) confirmed the presence of specific atoms and bonds in the crystal structure of PPC with NT. Microstructural analysis using XRD, SEM, and EDAX revealed underlying structural changes and thus quantified the hydration products. [ABSTRACT FROM AUTHOR]

Recent studies on microencapsulated self-healing cementitious materials have primarily focused on the particle size and preparation methods of the microcapsules. However, there has been limited attention paid to the microscopic aspects, such as the selection of curing agents and the curing duration of these materials. In this study, urea-formaldehyde resin/epoxy resin E-51 microcapsules were synthesized through in situ polymerization. This research investigates the feasibility of self-healing from a molecular mechanism perspective and evaluates the repair performance of microencapsulated self-healing cement mortar with varying microcapsule concentrations, curing agent types, and curing ages. The findings demonstrate that the microcapsule shells bond effectively with the cementitious matrix, with radial distribution function peaks all located within 3.5 Å. The incorporation of microcapsules enhanced the tensile strength of the modified cement mortar by 116.83% and increased the failure strain by 110%, indicating improved adhesion and mechanical properties. The restorative agent released from the microcapsule core provided greater strength after curing compared to the uncured state. Although the overall strength of the microencapsulated self-healing cement mortar decreased with higher microcapsule concentrations, the repair efficiency improved. The strength recovery rate of 28-day aged modified cement mortar had a significant improvement with the addition of X and Y curing agents, respectively. [ABSTRACT FROM AUTHOR]

In China, airports predominantly utilize airport cement concrete pavement, which inevitably undergoes deterioration in service. To uphold pavement durability and functionality, and ensure aircraft operational safety, prompt repairs of affected areas are imperative. Therefore, ordinary Portland cement mortars were used as the control group to compare and analyze the bonding performances of two common airport pavement repair materials: modified Portland cement mortars and phosphate cement mortars. Meanwhile, through microscopic experiments, the microscopic characteristics of the interfacial transition zone (ITZ) were studied, and the interface bonding mechanism was analyzed. The research results indicate that the interface bonding strength between phosphate cement mortar and old concrete pavement is the highest. This was because the elements in phosphate cement penetrated the old concrete pavement through hydration reactions, forming van der Waals forces and chemical bonding forces. In addition, the research results indicated that the presence of old concrete pavement made the three repair materials produce similar sidewall effects with the old concrete pavement, leading to a low hydration degree of the repair materials. However, the chemical bonding and penetrating structure of phosphate cement compensated for the weakening effect of the ITZ in the repair materials. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry 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.)

Cement-based materials are fundamental in the construction industry, and enhancing their properties is an ongoing challenge. The use of superabsorbent polymers (SAP) has gained significant attention as a possible way to improve the performance of cement-based materials due to their unique water-absorption and retention properties. This study investigates the multifaceted impact of kaolin intercalation-modified superabsorbent polymers (K-SAP) on the properties of cement mortar. The results show that K-SAP significantly affects the cement mortar’s rheological behavior, with distinct phases of water absorption and release, leading to changes in workability over time. Furthermore, K-SAP alters the hydration kinetics, delaying the exothermic peak of hydration and subsequently modifying the heat release kinetics. Notably, K-SAP effectively maintains a higher internal relative humidity within the mortar, reducing the autogenous shrinkage behavior. Moreover, K-SAP can have a beneficial effect on pore structure and this can be ascribed to the internal curing effect of released water from K-SAP. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry 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.)

It is widely recognised that green building, environmental sustainability, and technical performance have recently become requirements in the field of civil engineering. For this reason, the new trend in research is to focus on the recycling and recovery of materials, even if some of them such as industrial waste are still underexplored. In this perspective, the main objective of this work is to study the influence of brick powder on the thermophysical and mechanical properties of mortars containing this type of waste, in different environments, and within the temperature range between ambient temperature and 50 °C. To this end, a number of mortar mixtures, in which cement was replaced by brick powder in different proportions, were studied and characterised according to technical standards in order to define the optimal substitution percentage. Three batches of samples were examined at different ages, i.e., 3, 7, 28, and 90 days. The samples of the first batch were kept in water at a temperature of 20 ± 2 °C with a relative humidity RH = 100 %, while those of the second batch were immersed and stored in water at 50 °C in order to simulate a hot and humid climate. As for the samples of the third batch, they were kept in a dry oven at 50 °C in order to investigate the effect of the hot and dry climate. The results obtained revealed that the partial replacement of cement by brick powder makes it possible to improve the thermal insulation characteristics but reduce the mechanical strength of the mortar. In addition, it was shown that in a hot and dry environment, the mechanical characteristics of the different mortars decrease as the rate of weight substitution of cement by brick powder rises. However, in a hot and humid environment, a reverse trend is observed. The findings also suggested that the optimal recommended rate of substitution of cement by brick powder is 20 %.

In recent years, nanoaprticules with different sizes have been incorporated in the cement mortar in order to improve their mechanical characteristics. The present work focuses onto the influence of the silica nanoparticles (SiO2) with low and high surface area over the stability and mechanical properties of the cement mortar. The quantities of nanosilica added into the cement mortar to ameliorate their mechanical characteristics vary from 0.5 % to 1.5 %wt. The obtained material after the incorporation of the SiO2 nanoparticles have been characterized by several techniques such as TG, DTG, DSC and their morphologies were determined by using SEM analysis. The workability, water absorption, compressive and flexural strengths of these materials have also been evaluated. The results obtained show that the introduction of the SiO2 nanoparticles into the cement mortar has been greatly improved their compressive and flexural strengths, and the specimens incorporated by nanosilica with high surface area are found more effective than those containing the silica nanoparticles with low surface area, suggesting that the specific surface play a crucial role in the improvement of their mechanical properties. The results show also that the appropriate dosage of silica nanoparticles in the cement mortar to have a maximum enhancement of their mechanical properties was found around 1.5 wt% by weight of cement for the nanosilica with high surface area.