Integration of zinc anode and cement: unlocking scalable energy storage.

The significant volume of existing buildings and ongoing annual construction of infrastructure underscore the vast potential for integrating large-scale energy-storage solutions into these structures. Herein, we propose an innovative approach for developing structural and scalable energy-storage systems by integrating safe and cost-effective zinc-ion hybrid supercapacitors into cement mortar, which is the predominant material used for structural purposes. By performing air entrainment and leveraging the adverse reaction of the ZnSO4 electrolyte, we can engineer an aerated cement mortar with a multiscale pore structure that exhibits dual functionality: effective ion conductivity in the form of a cell separator and a robust load-bearing capacity that contributes to structural integrity. Consequently, a hybrid supercapacitor building block consisting of a tailored cement mortar, zinc metal anode and active carbon cathode demonstrates exceptional specific energy density (71.4 Wh kg-1 at 68.7 W kg-1), high areal energy density (2.0 Wh m-2 at 1.9 W m-2), favorable cycling stability (∼92% capacity retention after 1000 cycles) and exceptional safety (endurance in a 1-hour combustion test). By demonstrating the scalability of the structural energy-storage system coupled with solar energy generation, this new device exhibits great potential to revolutionize energy-storage systems.

Nanocrystalline Cellulose to Reduce Superplasticizer Demand in 3D Printing of Cementitious Materials.

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.

The Application of Converter Sludge and Slag to Produce Ecological Cement Mortars.

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.

Coal-derived char as new sand replacement material in cement mortars: A comprehensive experimental study.

Coal char is a coal-derived product produced by pyrolysis of char, which has valuable applications in the production of building materials. This paper presents the use of coal char in developing coal char-based cement mortar. Coal char is used to replace the sand, partially, at different proportions in cement mortar, and the change in properties is studied. Four cement types are used in the initial study, and one is selected for a detailed study based on the water retention, density, and compressive strength of the mortar. The properties of coal char-based mortar for the selected cement are comprehensively evaluated in terms of flow, water retention, air content, density, compressive strength, flexural strength, porosity, water absorption, drying shrinkage, thermal conductivity, thermogravimetric and differential thermal analysis, and scanning electron microscopy. The addition of coal char at an optimum sand replacement content of 5 % increases the compressive strength of mortar by 17.55 % and the flexural strength by 17.57 %, compared to conventional cement mortar. The thermal conductivity reduces by a maximum of 20 %, compared to traditional cement mortar. This paper also presents a study to compare the addition of coal char and commercial biochar on the properties of masonry cement mortar. The compressive strength of mortar with coal char is 44.39 % greater than that of mortar with the same content of biochar. The addition of coal char as a new sand replacement material shows good potential in improving the engineering properties of mortar.

Evaluating the Role of Mortar Composition on the Cyclic Behavior of Unreinforced Masonry Shear Walls.

The mechanical behavior of unreinforced masonry (URM) shear walls under in-plane cyclic loading is crucial for assessing their seismic performance. Although masonry structures have been extensively studied, the specific influence of varying lime content in cement-lime mortars on the cyclic behavior of URM walls has not been adequately explored. This study addresses this gap by experimentally evaluating the effects of three mortar mixes with increasing lime content, 1:0:5, 1:1:6, and 1:2:9 (cement:lime:sand, by volume), on the cyclic performance of brick URM walls. Nine single-leaf wall specimens 900 mm × 900 mm were constructed and subjected to combined vertical compression and horizontal cyclic loading. Key parameters such as drift capacity, stiffness degradation, and energy dissipation were measured. The results indicated that the inclusion of lime leads to a moderate improvement in drift capacity and ductility of the walls, with the 1:1:6 mix showing the highest lateral capacity (0.55 MPa), drift at cracking (0.08%), and drift at peak capacity (0.31%). Stiffness degradation and energy dissipation were found to be comparable across all mortar types. These findings suggest that partial substitution of cement with lime can enhance certain aspects of masonry performance. Further research is recommended to optimize mortar compositions for unreinforced masonry applications.

Molecular Insights into Adhesion at Interface of Geopolymer Binder and Cement Mortar.

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.

Seismic Performance of a Single-Story Timber-Framed Masonry Structure Strengthened with Fiber-Reinforced Cement Mortar.

Timber-framed masonry structures are widely used around the world, and their seismic performance is generally poor. Most of them have not been seismically strengthened. In areas with high seismic fortification intensity, there are great potential safety hazards. And it is urgent to carry out effective seismic reinforcement. However, due to the complicated construction process of the existing reinforcement technology, the poor durability of the reinforcement materials, and the significant disturbance to the life of the original residents, an efficient single-story timber-framed masonry structure reinforcement technology suitable for comprehensive promotion and application has not been explored. In this paper, a fiber-reinforced cement mortar (FRCM) material was proposed. A 1/2 scale model of a single-story timber-framed masonry structure was taken as the research object. The method of strengthening a single-story timber-framed masonry structure with FRCM layer was adopted. And the shaking table test of the model before and after reinforcement was carried out in turn. The dynamic characteristics, failure modes, acceleration response and displacement response of the FRCM layer-strengthened structure were analyzed through comparisons of the two cases. The experimental results showed that the FRCM layer significantly improved the seismic performance of the seismic-damaged single-story timber-framed masonry structures. The X- and Y-direction natural frequencies of the model structure were increased by 31.30% and 30.22%, respectively, after the structure was strengthened with FRCM. During a rare eight-degree earthquake, the inter-story displacement angles in the X- and Y-direction of the unreinforced model reached 1/98 and 1/577, respectively, and the structure was destroyed, while the inter-story displacement angle of the FRCM-reinforced model was only 1/2 of that the unreinforced model. During a rare nine-degree earthquake, the X-direction inter-story displacement angle of the model strengthened with FRCM reached 1/78 and the Y-direction inter-story displacement angle reached 1/178. At this time, the reinforced model structure was destroyed, but there was no collapse of the structural components, which met the seismic design objectives of "operational under the design minor seismic intensity, repairable damage under the design seismic precautionary intensity, and collapse prevention under the design rare seismic intensity", which proved that the FRCM layer was an effective and feasible way to strengthen the existing single-story wood-masonry rural building.

One-pot approach for synthesis of multi-layered nanosheets of N-dopped graphene derived from chitosan for reinforcing cement mortar.

The synthesis of graphene via traditional methods has several drawbacks, such as the release of poisonous gases, Most of these techniques are time-consuming and tedious, besides the absence of control over the structural composition of graphene during synthesis. In this study, a facile approach for the synthesis of graphene densely doped with nitrogen (N-dopped graphene (NG)) from novel precursor chitosan throughout the direct solvothermal treatment of chitosan under mild circumstances at 250 °C and 270 °C. Cetyltrimethylammonium bromide (CTAB) and ammonia are utilized as structural directing agents. FTIR, XRD, CHNS/O elemental analysis, XPS, and Raman spectroscopy are utilized to elucidate the chemical composition and purity of N-dopped graphene. The surface morphology of NG is studied by using SEM, HR-TEM, and selected area electron diffraction (SAED). The results approved that, the one-pot, single-step approach is a simple and cost-effective technique for producing a high throughput of NG, of charming microstructure features, including good graphitization, low oxidation state, good exfoliation level, and very extended lateral dimension sheets. Profound visions on the growing mechanism have been proposed. The incorporation effect of NG to cement mortar is also studied. Two percentages of NG 0.05 wt% and, 0.10 wt% from the total cement mass were utilized. A microstructural investigation of incorporated NG on cement mortar is studied by conducting AFM, and SEM. Furthermore, workability and mechanical characterizations including, compressive strength, and flexural strength are investigated. Also, the dynamic mechanical parameters including storage modulus and loss factor are studied. It is noticed that the workability decreased from 14.8 % to 7.8 % with the addition of 0.05 wt% and 0.1 wt% NG respectively. However, the maximum increments of the compressive strength were 35 % for the mortar containing 0.1 wt% NG and flexural strength increased three times than the unmodified one. Also, the cement mortar containing 0.1 wt% NG has a storage modulus of 12 MPa compared to unmodified 1 MPa and has the lowest loss factor (damping coefficient). These results verified that incorporating NG nanosheets in cement has a positive effect on reinforcing cement mortar.

Role of silicate-rich and silicate-less industrial solid wastes in the physicomechanical properties and durability of low quality metakaolin-blended cement.

Although calcined clay-blended cement offers higher performance and durability compared to neat Portland cement (PC), its extensive use of natural clay leads to the depletion of natural non-renewable resources. To address this concern, this study focuses on the utilization of supplementary cementitious materials-based waste products as a substitute for PC. The blended cement was optimized with a low replacement level of 10 wt.% calcined Fanja clay (FNJ) as a low-grade metakaolin (MK) and 90 wt.% PC. Various types of industrial solid wastes (ISWs) were incorporated into the PC-FNJ blend in place of PC. The ISWs utilized included silicate-rich wastes, such as silica fume (SF) and glass waste (GW) powder, as well as silicate-less waste, such as marble dust (MD). The results revealed that incorporating 10 wt.% SF into the PC-FNJ mixture resulted in a considerable decrease in the flow rate while improving its early mechanical strength. GW, as another silicate waste, also enhanced early mechanical properties but not as much as SF. However, the composite of PC-FNJ-GW exhibited higher workability than the neat PC, PC-FNJ, and PC-FNJ-SF. The mixtures of PC-FNJ-MD demonstrated the same trend. Embedding SF into PC-FNJ-GW and PC-FNJ-MD substantially decreased both their flowability and mechanical properties. Nonetheless, all composites containing ISWs showed higher flexural strength, higher resistivity to chloride diffusivity, and higher or comparable acid and salt resistivity.

Failure evolution and instability prediction of fiber-reinforced polymer-confined cement mortar specimens under axial compression.

In geotechnical engineering, a large number of pillars are often left in underground space to support the overlying strata and protect the surface environment. To enhance pillar stability and prevent instability, this study proposes an innovative technology for pillar reinforcement. Specifically, local confinement of the pillar is achieved through fiber-reinforced polymer (FRP) strips, resulting in the formation of a more stable composite structure. In order to validate the effectiveness of this structural approach, acoustic emission characteristics and surface strain field characteristics were monitored during failure processes, while mathematical models were employed to predict specimen instability. The test results revealed that increasing FRP strip confinement width led to heightened activity in acoustic emission events during failure processes, accompanied by a decrease in shear cracks but an increase in tensile cracks. Moreover, ductility was improved and deformation resistance capacity was enhanced within specimens. Notably, initial crack generation occurred within unconfined regions of specimens during failures; however, both length and width as well as overall numbers of cracks significantly decreased due to implementation of FRP strips. Consequently, specimen failure speed was slowed down accordingly. Finally, the instability of the partial FRP-confined cement mortar could be more accurately predicted based on the model of FRP-confined concrete. It was verified by the test results.

A Study on the Properties of Composite Modified Mortar with Styrene-Butadiene Rubber Latex and Silica Fume.

To solve the problem of the poor abrasion resistance of concrete pavement surface mortar, this study substituted cement with equal amounts of styrene-butadiene rubber (SBR) latex and silica fume (SF) to investigate the effects of organic/inorganic material composite modification on the fluidity, drying shrinkage, mechanical properties, and abrasion resistance of cement mortar. Also in this study, the microstructure, product, and pore structure characteristics of the composite modified cement mortar were investigated using scanning electron microscope (SEM), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and the Brunauer-Emmett-Teller (BET) method. This research found that the sole substitution of SF negatively impacted the mortar's fluidity and drying shrinkage yet enhanced its mechanical strength and abrasion resistance; the incorporation of SBR latex improved fluidity, reduced shrinkage, and increased flexural strength but adversely affected the compressive strength of the mortar. Additionally, the enhancement of the mortar's abrasion resistance with SBR latex was significantly greater than that with SF. When SBR latex and SF were used together as substitutes, the latex struggled to offset the negative impact of SF on mortar fluidity but effectively reduced shrinkage; SF compensated for the detrimental effect of the latex on compressive strength. Moreover, the primary role in enhancing the mortar's abrasion resistance was played by the latex. Microscopic tests showed that SBR latex and SF could increase the content of calcium silicate hydrate (C-S-H) gel, inhibit the formation of ettringite (AFt) and reduce carbonation, refine the pore size of cement mortar, and effectively improve the microstructure of mortar.

Characterization of lightweight aerated mortars using waste-to-energy bottom ash (WtE-BA) as aerating agent.

The management of Waste-to-Energy Bottom Ash (WtE-BA), generated during the incineration of waste, poses a global challenge. Presently, the majority of WtE-BA is disposed of in landfills due to the lack of alternatives. Meanwhile, the construction industry remains the primary consumer of raw materials and significantly contributes to Greenhouse Gas Emissions. This study attempts to address these issues by utilizing the fine fraction of WtE-BA (<2 mm) as a raw material for aerated mortar production. Thanks to its metallic aluminum content, WtE-BA is utilized as an aerating agent. The study investigates how the quantities of water and WtE-BA, as well as its granulometric sub-fractions, impact the properties of the final product. An analysis of properties such as density, compressive strength, and thermal conductivity was conducted. Additionally, the environmental impact of each raw material (i.e. WtE-BA, cement and sand) was assessed through leaching tests and elemental content analysis enabling the determination of their individual contribution to the presence of trace elements in the produced mortars. The aforementioned properties are discussed using microstructure and porosity analyses. The findings demonstrate that the quantity of water is a crucial factor in controlling the aeration of mortars, whereas the granulometry of the WtE-BA particles did not significantly affect their macro-properties. Furthermore, this study highlights that WtE-BA based mortars has the potential to exhibit better environmental and insulating performances than standard aerated mortar of equal density and strength. The differences in pore size and type between WtE-BA and aerated mortars can account for the variation in performance. Thus, WtE-BA proves to be an effective substitute for aerating agent in the production of aerated mortars.

Effect of filtering method on the pH measurement of cement mortar in ex-situ leaching.

The high alkaline condition of concrete naturally protects embedded steel bars from corrosion by forming a passive protective film. The pH of concrete is generally high, but concrete with different mix compositions may have various pH values. The pH of concrete may decrease over time due to long-term mechanical, chemical, biological and physical factors. Therefore, monitoring the pH value of concrete is crucial to checking if its alkalinity is within an acceptable range and ensuring that the concrete structure is in good health condition. However, the pH measurement for cement-based materials is not standardised. Ex-situ leaching, one of the recommended methods for pH measurement, is simple and practical. In this method, the sample will be crushed, leached and tested using a pH electrode probe. The lifespan of the pH electrode probe may decrease due to the existing suspended particles in the solution. Therefore, one recommendation is to filter the solution before using the probe. In this study, the effect of different filtering setups on the pH value of a cement mortar with a cement-to-sand ratio of 1:3 was evaluated. pH test results showed that filtering can produce similar outcomes to those without filtering, regardless of the type of filter paper and its pore size. However, filtering is strongly recommended for electrode protection of the pH meter. As an innovative filtering setup for cement-based materials, syringe filtering was introduced in this study because it is more economical and its operation is simpler compared to the other methods.

Assessment of the effect of different pulping by-products on enhancing the reuse of rubber waste in producing of cement-mortar.

This work deals with avoiding the pollution risks from paper pulping liquors and rubber wastes that result from routine disposal tools; moreover, finding an approach to minimize the drawback of incorporating the rubber waste in weakening the strength of building materials. In this respect, pulping black liquors (BLs) is assessed as a treating agent for rubber waste and substituting the water in cement mortar formulation. The assessment was achieved by testing the mechanical properties, water resistance (reduction in water absorption and dimensional change against water), and morphology. The results showed that all BLs from different pulping agents, used in mixtures with water, provided improvements in both strength and water resistance properties. Kraft black liquor is most effective in providing improvements in compressive strength and flexural strength, as well as resistance to water absorption and change in dimension after exposure to water for 24 h, where the improvements were 688.2 %, 494.3 %, 27 %, and 65.3 %, respectively. It is interesting to note that this investigated route provided improvements in the impact resistance property of mortar. This last property is essential for minimizing accidents on the highway.

Peeling Force Required for the Detachment of Non-Woven Plastic Tissue from the Surface of Mortar Prisms.

The purpose of this experimental paper is to examine the adhesion properties between non-woven plastic sheets and cement mortar. Specifically, the effect of w/c ratio and quantity of superplasticizer on the peeling force required for the detachment of tissue from the surface of prisms was studied in detail. Therefore, two types of mortar mixtures were prepared: (1) mixtures without superplasticizer with three different w/c ratios of 0.45, 0.50, and 0.55, and (2) mixtures with reduced amounts of water and three various percentages of superplasticizer of 0.0%, 1.11%, and 2.17% (by weight of cement). For this purpose, bond tests with a special setup, interferometry and microscopic analyses, and mechanical tests were performed. The results highlight that non-woven sheets had strong adhesion to cement mortar without using any adhesive materials. However, the peeling force improved by 15.78% as the w/c ratio increased from 0.50 to 0.55. Conversely, this force declined by 24.50% as the w/c ratio decreased from 0.50 to 0.45. In addition, the peeling force decreased by 20.62% as the w/c ratio decreased from 0.50 to 0.45 and 1.11% superplasticizer was added to the mixtures. This property decreased further by 38.29% as the w/c ratio lowered to 0.40, and the amount of superplasticizer increased to 2.17%. The interferometry and microscopic analyses clearly demonstrate that the adhesion between tissue and mortar is largely related to the surface texture, amount of cement paste, and quantity of residual fibers on the surfaces of samples. It indicates that mortar samples with higher w/c ratios had a smoother surface, and providing more contact area for microfilaments, which resulted in thicker layers of remaining fibers compared to the specimens with a lower w/c ratio. Even though there was not much difference in the surface texture of specimens with superplasticizer and lower w/c ratios, because of their similar workability. Still, thicker layers of microfilaments remained on the surface of specimens containing a lower amount of superplasticizer, which resulted in strong adhesion between sheet and cement mortar.

Bacterial Viability in Self-Healing Concrete: A Case Study of Non-Ureolytic Bacillus Species.

Cracking is an inevitable feature of concrete, typically leading to corrosion of the embedded steel reinforcement and massive deterioration because of the freezing-thawing cycles. Different means have been proposed to increase the serviceability performance of cracked concrete structures. This case study deals with bacteria encapsulated in cementitious materials to "heal" cracks. Such a biological self-healing system requires preserving the bacteria's viability in the cement matrix. Many embedded bacterial spores are damaged during concrete curing, drastically reducing efficiency. This study investigates the viability of commonly used non-ureolytic bacterial spores when immobilized in calcium alginate microcapsules within self-healing cementitious composites. Three Bacillus species were used in this study, i.e., B. pseudofirmus, B. cohnii, and B. halodurans. B. pseudofirmus demonstrated the best mineralization activity; a sufficient number of bacterial spores remained viable after the encapsulation. B. pseudofirmus and B. halodurans spores retained the highest viability after incorporating the microcapsules into the cement paste, while B. halodurans spores retained the highest viability in the mortar. Cracks with a width of about 0.13 mm were filled with bacterial calcium carbonate within 14 to 28 days, depending on the type of bacteria. Larger cracks were not healed entirely. B. pseudofirmus had the highest efficiency, with a healing coefficient of 0.497 after 56 days. This study also revealed the essential role of the cement hydration temperature on bacterial viability. Thus, further studies should optimize the content of bacteria and nutrients in the microcapsule structure.

Predicting the Gas Permeability of Sustainable Cement Mortar Containing Internal Cracks by Combining Physical Experiments and Hybrid Ensemble Artificial Intelligence Algorithms.

The presence of internal fissures holds immense sway over the gas permeability of sustainable cement mortar, which in turn dictates the longevity and steadfastness of associated edifices. Nevertheless, predicting the gas permeability of sustainable cement mortar that contains internal cracks poses a significant challenge due to the presence of numerous influential variables and intricate interdependent mechanisms. To solve the deficiency, this research establishes an innovative machine learning algorithm via the integration of the Mind Evolutionary Algorithm (MEA) with the Adaptive Boosting Algorithm-Back Propagation Artificial Neural Network (ABA-BPANN) ensemble algorithm to predict the gas permeability of sustainable cement mortar that contains internal cracks, based on the results of 1452 gas permeability tests. Firstly, the present study employs the MEA-tuned ABA-BPANN model as the primary tool for gas permeability prediction in cement mortar, a comparative analysis is conducted with conventional machine learning models such as Particle Swarm Optimisation Algorithm (PSO) and Genetic Algorithm (GA) optimised ABA-BPANN, MEA optimised Extreme Learning Machine (ELM), and BPANN. The efficacy of the MEA-tuned ABA-BPANN model is verified, thereby demonstrating its proficiency. In addition, the sensitivity analysis conducted with the aid of the innovative model has revealed that the gas permeability of durable cement mortar incorporating internal cracks is more profoundly affected by the dimensions and quantities of such cracks than by the stress conditions to which the mortar is subjected. Thirdly, puts forth a novel machine-learning model, which enables the establishment of an analytical formula for the precise prediction of gas permeability. This formula can be employed by individuals who lack familiarity with machine learning skills. The proposed model, namely the MEA-optimised ABA-BPANN algorithm, exhibits significant potential in accurately estimating the gas permeability of sustainable cement mortar that contains internal cracks in varying stress environments. The study highlights the algorithm's ability to offer essential insights for designing related structures.

Characterization and photocatalytic performance of cement mortars with incorporation of TiO2 and mineral admixtures.

As the main components of the building envelope, construction materials have a straight relation with air contaminants from anthropogenic origins. Titanium dioxide has been recently applied in construction industry products since its photocatalytic properties can be used for pollutant degradation purposes. This study evaluated the performance of cement-based mortars with the incorporation of TiO2 nanoparticles and mineral admixtures. Six mortar compositions were defined by considering two reference mixes (with and without TiO2 incorporation), two mineral admixtures (bentonite and metakaolin) as partial cement replacement and one waste from ornamental stone processing in two levels of partial substitution of natural sand. Consistency index, density, and entrained air content of mixtures were investigated at fresh state. Compressive strength, water absorption, sorptivity, and micrographs from scanning electron microscopy were used to characterize mortars at hardened state. It was observed that incorporation of TiO2 does not considerably change mortar's properties at fresh and hardened state, despite a denser microstructure and improved interfacial transition zone. In general, the relation between the water-to-cement ratio and porosity on the performances of TiO2-added mortars was shown, which is strongly related to their photocatalytic efficiency. Metakaolin mixtures were more efficient to NO conversion, and high selectivity was observed for the bentonite mortars.

The Use of Biosilica to Increase the Compressive Strength of Cement Mortar: The Effect of the Mixing Method.

In this work, the effect of biosilica concentration and two different mixing methods with Portland cement on the compressive strength of cement-based mortars were investigated. The following values of the biosilica concentration of cement weight were investigated։ 2.5, 5, 7.5, and 10 wt.%. The mortar was prepared using the following two biosilica mixing methods: First, biosilica was mixed with cement and appropriate samples were prepared. For the other mixing method, samples were prepared by dissolving biosilica in water using a magnetic stirrer. Compressive tests were carried out on an automatic compression machine with a loading rate of 2.4 kN/s at the age of 7 and 28 days. It is shown that, for all cases, the compressive strength has the maximum value of 10% biosilica concentration. In particular, in the case of the first mixing method, the compressive strength of the specimen over 7 days of curing increased by 30.5%, and by 36.5% for a curing period of 28 days. In the case of the second mixing method, the compressive strength of the specimen over 7 days of curing increased by 23.4%, and by 47.3% for a curing period of 28 days. Additionally, using the first and second mixing methods, the water absorption parameters were reduced by 22% and 34%, respectively. Finally, it is worth noting that the obtained results were intend to provide valuable insights into optimizing biosilica incorporation in cement mortar. With the aim of contributing to the advancement of construction materials, this research delves into the intriguing application of biosilica in cement mortar, emphasizing the significant impact of mixing techniques on the resultant compressive strength.

Strength and Electrical Properties of Cementitious Composite with Integrated Carbon Nanotubes.

The main objective of this work was to study the effects of carbon nanotubes (CNTs) on the strength and electrical properties of cement mortar. Molecular dynamic simulations (MDSs) were carried out to determine the mechanical and electrical properties of a cementitious composite and its associated mechanisms. To model the atomic structure of a calcium silicate hydrate (C-S-H) gel, tobermorite 11Å was chosen. Single-walled carbon nanotubes (SWCNTs) embedded in a tobermorite structure were tested numerically. In particular, it was concluded that a piezoelectric effect can be effectively simulated by varying the concentration levels of carbon nanotubes. The deformation characteristics were analyzed by subjecting a sample to an electrical field of 250 MV/m in the z-direction in a simulation box. The results indicated a progressively stronger converse piezoelectric response with an increasing proportion of carbon nanotubes. Additionally, it was observed that the piezoelectric constant in the z-direction, denoted by d33, also increased correspondingly, thereby validating the potential for generating an electrical current during sample deformation. An innovative experiment was developed for the electrical characterization of a cementitious composite of carbon nanotubes. The results showed that the electrostatic current measurements exhibited a higher electric sensitivity for samples with a higher concentration of CNTs.