Strength Of Mortar Research Articles

Residual textile reinforced mortar‐to‐concrete bond after exposure to harsh environments

AbstractTextile reinforced mortars (TRM) are materials whose mechanical behavior has been extensively investigated during the last few years. However, studies on the behavior of these materials after exposure to various aggressive environments are still limited and, hence, their performance during their entire service life remains to be determined. The present study contributes to the knowledge pool regarding the behavior of concrete specimens furnished with TRM overlays post their exposure to various harsh environments, specifically through the analysis of shear bond tests. More specifically, 120 concrete substrates were reinforced with one and two layers of carbon textile which were embedded into a high and a low strength cementitious mortar and exposed to various harsh environments (carbonation, chlorides, carbonation and chlorides, different number of freeze–thaw cycles). It was concluded that: (i) a reduction of more than 25% is possible regarding failure stress; (ii) the number of textile layers plays an important role in TRM‐concrete bond behavior; and (iii) the influence of mortar strength is limited.

The Effect of Alkali Activator to Binder Ratio on Workability, Density, and Compressive Strength of Fly Ash-Slag Based Geopolymer Mortar

The purpose of this study is to investigate the influence of variations in the alkali activator to binder ratio (Al/Bi) on the workability, density, and compressive strength of geopolymer mortar. This study used an experimental approach to assess mortar compressive strength and workability utilizing a flow table in accordance with SNI 03-6825-2002, as well as mortar density in accordance with SNI 1973-2016. Variations in the Al/Bi ratio used are 0.40, 0.45, 0.50, and 0.55, with a slag content of 20% and a ratio of sodium silicate to sodium hydroxide (SS/SH) 1.5. The materials used in this research are fly ash type F, slag, fine aggregate, and an alkali activator consisting of sodium hydroxide (SH) and sodium silicate (SS). The specimen is in the shape of a cube with dimensions of 50x50x50 mm and a total of 16 test objects. The results show that the higher the Al/Bi ratio, the workability of the geopolymer mortar increases, but the density decreases. The higher the Al/Bi ratio, the compressive strength of the geopolymer mortar increases to an optimal Al/Bi ratio of 0.50. At an Al/Bi ratio of 0.40, it has workability in accordance with SNI 03-6825-2002 standards. All variations of the Al/Bi ratio produce density that meets the SNI 1973-2016 standards. The maximum compressive strength of the geopolymer mortar was 12.15 MPa at an Al/Bi ratio of 0.50.

Effects of Fly Ash Particle Size and Chemical Activators on the Hydration of High-Volume Fly Ash Mortars

This study investigated the effects of the fly ash (FA) particle size and chemical activators on the hydration reactions of high-volume fly ash (HVFA) cement pastes and the mechanical properties of HVFA mortars, with five types of FA with varying proportions of particles smaller than 10 μm prepared to assess the influence of particle size. In addition, the effect of chemical admixtures on the early-age hydration of the HVFA cement paste was evaluated. Quartz powder with the same fineness as that of normal FA was prepared to specifically examine the pozzolanic reaction of FA. The hydration reactions of the HVFA cement pastes were analyzed using isothermal calorimetry to measure the heat of hydration for 72 h. The results showed that an increase in the contents of FA particles with a diameter lower than 10 μm increases specific heat flow. Chemical activators, including Na2SO4, triethanolamine (TEA), and triisopropanolamine (TIPA), promote early-age hydration of HVFA cement pastes. The mechanical properties of the HVFA mortar were evaluated by measuring its compressive strength at 3 d, 7 d, and 28 d, with the findings revealing that the compressive strength of HVFA mortar improved with an increased proportion of FA particles smaller than 10 μm. Na2SO4, TEA, and TIPA consistently increased the compressive strength of the HVFA mortars.

Enhancing the resilience of cement mortar: Investigating Nano-SiO2 size and hybrid fiber effects on sulfuric acid resistance

This article explores fortifying cement mortars against severe sulfuric acid (SLA) attacks by studying the impact of nano-SiO2 (NS), macro-steel (ST), and micro-polypropylene (PP) fibers. The aim is to assess their effects on workability, physical attributes, mechanical properties, and durability against SLA attacks when incorporated into mortar blends. Replacing 1 % of cement weight with NS, having average particle diameters of 15 nm (nm) (NS15) and 55 nm (NS55), and utilizing macro-ST and micro-PP fibers at volumes of 0.5 % and 1 % in singular and hybrid forms resulted in significant changes in mortar characteristics. While these additives increased fresh mortar viscosity and negatively affected workability, they substantially boosted mortar strength and durability against SLA attacks. The most substantial improvements were observed using smaller NS particle sizes and employing hybrid ST/PP fibers. The formation of calcium-silicate-hydrate (C-S-H) bonds by NS within the network emerged as a pivotal factor. NS's high pozzolanic activity and void-filling capacity significantly enhanced the mortars' strength and durability against SLA attacks. Furthermore, instead of their singular application, the combined use of ST and PP fibers proved more effective in restraining micro and macro cracks within the mortar matrix. The bridging effect of hybrid ST/PP fibers delayed crack propagation throughout the network, highlighting their superior efficiency against SLA attacks.Overall, these findings hold promise for designing cement-based composites resilient to harsh, acidic environments. Using smaller NS particles and hybrid fiber combinations presents potential pathways to prolong service life in challenging conditions.

Effect of pre-wetting treatment for waste waterglass foundry sand on the properties of alkali-activated slag

Waste waterglass foundry sand (WwFS) is a solid waste generated by the foundry industries that is commonly discarded in landfills and has urgent needs for disposal and recycling. Accordingly, this study suggests using WwFS as aggregates source for the preparation of alkali-activated slag mortars (AASM). Two different pre-wetting methods (24 h pre-wetting at 20°C and 1~6 h pre-wetting at 70°C) were used to treat WwFS and compared their performances with adding quartz sand and dried WwFS mortars. Compared to WwFS mortars without pre-wetting treatment, the compressive strengths of WwFS mortars containing WwFS pre-wetting in water at 70°C at 28d were increased by 1.3~10.0%, and the C-(A)-S-H average elastic modulus was increased by 16%. This study confirmed the feasibility of using hot water pre-wetted WwFS as the single aggregate source for AASM, which is important for the large-scale utilization of WwFS.

Preparation and characterization of core-shell structured CaCO3-SiO2 and hollow silica nanoparticles and evaluation of their effects on cement mortar properties

CaCO3-SiO2 particles having a core-shell nanostructure were produced by a modified Stöber process using CTAB as a surfactant. Then, a porous structure composed of a silica shell was formed after the removal of the CaCO3 cores as templates from the nanocomposite. To evaluate phase constitutions and microstructures of prepared nanoparticles, XRD, TEM, and FESEM–EDX techniques were utilized. The main aim of this work was to examine the usability of prepared CaCO3-SiO2 and SiO2 hollow shell nanoparticles instead of OPC in structural applications. In this way, the mixtures of cement mortar were made by partial replacement of 1% of cement mass with prepared nanoparticles. The amounts of calcium hydroxide (CH), bound water, and calcium carbonate for the prepared mortars have been calculated after 7 and 28 days of hydration through thermal analysis of TG/DTG. The results indicated that the CH content decreased by adding prepared nanoparticles as a cement replacement. As CaCO3-SiO2 and hollow SiO2 nanoparticles were used, the compressive strengths of mortars were enhanced by 34 and 59%, respectively, after 28 days, which were higher than the increasing influences on flexural strengths (29 and 55%). The increasing intensity of the XRD peaks related to the C-S-H phases and the decline of the orientation index of CH in a mortar containing silica shell suggest that hydration was further completed, leading to a strength improvement. The SEM micrographs indicated that the addition of prepared nanostructures improved the interface properties inside mortar and caused the microstructure to be denser.

Self-healing performance of silica nanoparticle-infused concrete based on microbial mineralization

This study investigates the effects of incorporating two substances–expanded perlite as a carrier for bacteria and nanosilica–into cement mortar. The objective of this study is to evaluate the effect of the dosage of these two substances on the strength and self-healing properties of mortars. The strengths of the specimens at different curing ages are tested using a pressure-testing machine and recorded. Additionally, precracks are introduced into the specimens. The cracks and their healing products are observed via electron microscopy, scanning electron microscopy, and X-ray diffraction to validate the experimental results. The results show that the self-healing agents agglomerate at the cracks and trigger a metabolic reaction, thus resulting in the formation of numerous calcium carbonate precipitates that sealed the cracks. Therefore, the addition of self-healing agents significantly improves the self-healing properties of the cement mortar. The nanosilica facilitates the hydration reaction of cement in mortar. Additionally, nanosilica undergoes a pozzolanic reaction with calcium hydroxide, which consumes calcium hydroxide and generates hydrated calcium silicate to fill the pores. Consequently, the incorporation of an appropriate amount of nanosilica effectively enhances the strength of the cement mortar. Therefore, simultaneously incorporating self-healing agents and nanosilica while controlling the dosage provides a new approach for optimizing both the mechanical properties and self-healing performance of concrete.

Electromagnetic absorption properties of composite mortar with graphene and manganese-zinc ferrite

Electromagnetic wave absorption of building structures plays a crucial role in safeguarding information and mitigating electromagnetic radiation. This study delves into the absorption capabilities of composite mortar made with graphene (GR) and manganese-zinc ferrite (MFO) across frequencies of 1−18 GHz. The mechanical strength, microstructural examinations, and numerical simulations to elucidate the underlying mechanisms of wave absorption in the composite mortar are investigated. The results indicate that incorporating 30% MFO reduces the strength of mortar due to its low bonding capacity and diluting effects, whereas GR enhances the strength of mortar by facilitating cement hydration. Electromagnetic examinations reveal that MFO boosts the magnetic loss performance, while GR augments dielectric loss properties. In addition, the presence of needle, rod, mesh, and flake hydration products in the pores of composite mortar also contributes to increased wave depletion. According to the simulation of electromagnetic absorption based on the finite difference time domain (FDTD) method, the composite mortar with GR and MFO exhibits a superior performance of electromagnetic wave absorption. With the 25 mm thickness of composite mortar with 30% MFO, an absorption below -10 dB, covering a bandwidth of 1.68−4.34 GHz are obtained, with a peak reflection loss of -22.13 dB at 3.23 GHz. Thus, by combination magnetic loss of MFO, dielectric loss of GR, and the reflective capabilities of porous mortar, a composite mortar with a better electromagnetic wave absorption can be achieved.

Exploring effects of supplementary cementitious materials on setting time, strength, and microscale properties of mortar

The concept of sustainability has become a crucial concern for safeguarding the planet. The current research has focused on developing affordable and eco-friendly mortar by using industrial wastes. This study explores the use of fly ash (FA) and ground granulated blast furnace slag (GGBFS), byproducts of steelmaking and coal burning, in mortar production. It examines their impacts on the compressive strength and setting times, when utilizing varying proportions of the materials. The study also evaluates water requirements for the workability, thus demonstrating the sustainability of these waste products in construction. The cementitious materials were employed in finely ground form and were replaced with further tertiary mixes including both supplements at 10%, 30%, and 50% of each. The mixtures were allowed to cure for 7, 14, and 28 days by immersion in water. The results showed improvements in the compressive strength of mortar samples incorporating FA and GGBFS at various curing ages. However, the water requirement and workability of mortar samples were altered as a result of utilizing these supplementary cementitious materials (SCMs). These findings will serve as a standard for environmentally responsible mortar using GGBFS and/or FA as SCMs.

Effect of N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt and triethanolamine on the hydration and compressive strength of steel slag-cement composite systems: A comparative study

To solve the problem of low cementitious activity of steel slag (SS), N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid sodium salt (BES-Na) and triethanolamine (TEA) were used in this study to improve the hydration activity of SS. However, there are no comparative studies on the effects of BES-Na and TEA on the hydration of SS-Portland cement (PC) systems. This study compared the hydration process and strength development of SS-PC systems in the presence of BES-Na and TEA, as well as the complexing ability of BES-Na and TEA. The results showed that both BES-Na and TEA improved the early compressive strength of SS-PC mortar, but TEA did not contribute to the late compressive strength, while BES-Na still improved the late compressive strength. At the same dosage, TEA accelerated aluminates hydration more than BES-Na and retarded/inhibited silicates hydration more than BES-Na. This difference in effect on hydration can be attributed to the difference in their complexing ability. TEA has a stronger complexing ability with metal ions than BES-Na, which is beneficial for accelerating aluminates hydration, but this not only prolonged the hydration induction period but also inhibited silicates hydration. BES-Na has a weaker complexing ability relative to TEA. Although BES-Na has a weaker accelerating effect on aluminates hydration, it has a lesser effect on silicates hydration and even accelerates silicates hydration at low dosage. This study also showed that BES-Na is an alternative additive to TEA, which could help expand the application of BES-Na in cementitious materials.

Enhancing mechanical strength and microstructural properties of alkali-activated systems through nano graphene oxide dispersion and polycarboxylate ether admixture

The dispersion of graphene oxide (GO) nanoparticles in alkali-activated concrete with / without superplasticizers can help in understanding the effect it has on its mechanical strength and microstructural properties. The dispersion of GO in alkali activator fluid of 10(M) and 12(M) with / without polycarboxylate ether (PCE) admixture has been explored in this study. The alkali activator solution of 10(M) NaOH solution with PCE shows better dispersion than 12(M) NaOH solution, as higher alkalinity leads to agglomeration of GO. The study investigated the effect of incorporating PCE in GO-based alkali-activated slag (AAS) mortar with 8(M), 10(M) and 12(M) of alkaline activator solution. The mechanical strength and microstructural characteristics of conventional AAS (without both GO and PCE), GO-based AAS (without PCE) and GO-based AAS with PCE of the respective molar concentration of activator fluid are analysed. The mechanical strength of the AAS mortars has been evaluated using compressive, flexural, and splitting tensile strength testing. The micro-structural and mineralogical characteristics of the binders are evaluated using Field Emission Scanning Electron Microscopy (FESEM with EDS), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The addition of only GO (0.06 % of binder w/w) and the addition of both GO and PCE in AAS have shown up to 30 % and 40 % mechanical strength improvement with respect to conventional AAS, respectively. The effectiveness of PCE and percentages of strength improvement are higher with a lower molarity of activator fluid, and vice versa. Adding GO and PCE to the AAS system improves its hydration rate and denser microstructure, enhancing its strength.

Applicability of few layer graphene derived from annoni grass biomass on the mechanical properties of cement mortars

In this work, we report the potential applicability of few layer graphene (FLG) synthesized from annoni grass (AG) biomass (Eragrostis plana Nees) by investigating its impact on the flexural and compression strength of cement mortars. For this purpose the AG biomass was collected and burnt at the temperature of 400 °C per 60 min, obtaining the AG ash (AGA). For FLG production, the AGA was mixture with the chemical reagent potassium hydroxide (KOH) and burnt at the temperature and time of 850 °C and 60 min, respectively. For the mechanical properties analysis, a reference sample (A0-without FLG) and samples with different percentage of FLG were prepared, specifically 0.02 % (A1), 0.03 % (A2), 0.05 % (A3), 0.07 % (A4) and 0.1 % (A5). Statistical analysis (Analysis of Variance, ANOVA) of the mechanical properties demonstrates a maximum flexural and compression strength in sample A2. The flexural and compression strength increase 25.2 % and 10.1 % compared to the reference mortar. These results indicate that the FLG produced from AG not only improves the mechanical properties of mortars but also presents significant environmental benefits, because AG is considered an invasive pest of agricultural fields of the southern region of Brazil. Therefore, with its removal from the fields it would be contributing to environmental preservation.

Accounting for Decarbonization Impacts across the Full Life Cycle of Alternative Concrete Materials: A case-study for graphene-amended cementitious composites

Concrete's extensive use worldwide comes with significant environmental cost, contributing to 8% of annual global carbon emissions. This study investigates the use of life cycle assessment (LCA) and technoeconomic assessment (TEA) as tools to quantify anticipated reductions in global warming potential (GWP) arising from use of novel concrete mixtures or innovative production techniques, with specific focus on a case study related to graphene nanoplatelets (GNPs) as functional fillers. LCA and TEA results are reported for several choices of functional unit (FU) and system boundaries (SB). This approach illustrates how various LCA and TEA framings are differently useful to articulate how changes in technical performance properties such as mechanical strength and durability influence overall life-cycle environmental impacts. Framing 1 make use of a nominal volume-based FU (1 m3) and cradle-to-gate SB. Under this framing, addition of GNPs to the base mix seems to increase GWP and production cost. Framing 2 makes use of a strength-normalized FU and cradle-to-gate SB. Under this framing, life-cycle GWP and production cost for the GNP-amended mortars are decreased relative to the control, due to the appreciable increase in mechanical strength of the GNP-amended mortars. Finally, Framing 3 makes use of the nominal volume-based FU (1 m3) and cradle-to-grave SB. Under this framing, GWP and production cost for the GNP-amended mortars again seem to decrease, due to improved durability which gives rise to longer estimated service life and reduced maintenance. This study illustrates that use of GNPs as function filler is a seemingly promising strategy for decarbonizing concrete. More broadly, it is concluded that LCAs and TEAs of novel concretes should be framed in a way that articulates how changes in mechanical strength and/or durability properties contribute to changes in environmental impacts over all stages of the concrete life-cycle (i.e., cradle-to-grave). Such framing will help ensure that results that are meaningful to support decision-making in the area of sustainable construction materials.

Groutability prediction model of coral sand reinforced by excess-sulfate phosphogypsum slag grouting material under permeation grouting

Excess-sulfate phosphogypsum slag grouting material (EPSGM) has strong advantages for stabilizing the coral sand foundation, which requires establishing a groutability prediction model involving multi-factors to ensure better stabilization. Specifically, the grain size (d85) and water-to-cement ratio (w/c) of the grout, particle size (D15), relative density (Dr), and fine content (FC) of coral sand, and grouting pressure (P) are considered. The results show that the optimal particle size d85 of EPSGM is 15.567 μm. As the w/c increases from 1.0 to 3.0, the compressive strength of mortar (EPSGM + coral sand) decreases from 11.74 MPa to 0.32 MPa, and the California Bearing Ratio (CBR) value meets the typical requirements (≥ 15%). The groutability criterion (N) is positively correlated with the D15, w/c, and P, while it is negatively correlated with the Dr and FC, namely, the model writes: N=1−0.071Dr1−1.54FC0.024D15d85+0.42w/c+0.897P−0.86. Particularly, the predictive accuracy can attain a level of 87.50% for systems characterized by varying grain sizes (D15 ≥ 0.431 mm) and densities (Dr ≤ 0.67) of EPSGM stabilizing coral sand foundations. Furthermore, it also applies to other systems in literature that exhibit accuracy ranging from 33.33% to 62.50%. Therefore, the derived predictive model performs greater engineering relevance in informing the selection of grout factors.

Preliminary investigation of the effects of high-temperature thermal activation on the activity of graphite tailings and the mechanical properties of graphite tailings mortar

The disposal of graphite tailings, a byproduct of graphite mining, poses significant recycling challenges. This study explores eco-friendly cement mortar by partially replacing sand with activated graphite tailings, focusing on waste utilization. Activating the pozzolanic properties of graphite tailings at various thermal activation temperatures converts them into high-quality binder materials. Quantitative assessments of graphite tailings' activity, conducted through ion leaching tests and raw material diffraction analysis, produce an activity index Ka, evaluating their performance under different thermal activation temperatures. Variable testing of substitution rates and activation temperatures examines changes in mechanical properties, microstructure, and pore distribution of the graphite tailings mortar. Optimum results reveal a 30 % substitution rate and a 750°C activation temperature. Graphite tailings, as pozzolanic binder materials, enhance mortar strength by improving particle size distribution, reducing "micro-area bleeding" and "boundary effects". After thermal activation, reactive minerals on the tailings' surface undergo secondary hydration reactions with cementitious products, modifying chemical structures and micro-morphology at the interface. Semi-quantitative XRD analysis and FT-IR spectroscopy characterize the ensuing chemical reactions, unveiling molecular bond and functional group changes. The superior performance of thermally activated graphite tailings primarily stems from increased active SiO2 and Al2O3 post-activation. The active SiO2 and Al2O3 reacts with cementitious products to form C-(A)-S-H gels, filling micro-pores at the tailings-mortar interface, which is the key characteristic that enables graphite tailings to serve as high-quality pozzolanic binder aggregates. A predictive model for compressive strength, utilizing reference models from solid waste mortar concrete, quantifies the positive impact of chemical activation. The theoretical results obtained from this predictive model closely align with the experimental findings.

Study curing of epoxy resin by Isophoronediamine/ Triethylenetetramine and reinforced with montmorillonite and effect on compressive strength

Epoxy is a widely used thermosetting resin recognized for its exceptional performance in adhesives, coatings, and various other applications, attributed to its high tensile strength, stiffness, electrical performance, and chemical resistance. Epoxy-clay nanocomposites are extensively employed across diverse industries. The physical and chemical properties of these nanocomposites are influenced by the processing methods, clay modifiers, and curing agents used during their preparation. In this study, epoxy/nanoclay composites based on Diglycidyl Ether Bisphenol-A (DGEBA) will be cross-linked using Isophorone Diamine (IPD), a cycloaliphatic amine, and Triethylenetetramine (TETA), a linear aliphatic amine. The initial phase of the research will assess the impact of different types of cross-linkers, both individually and in combination at various molar ratios (such as Isophorone Diamine: Triethylenetetramine (IPA: TETA) / 25:75 and 75:25), on the compressive strength of the epoxy mortar. In the subsequent phase, the epoxy formulation with an Isophorone Diamine: Triethylenetetramine (IPD: TETA / 75:25), which demonstrates the highest compressive strength, will be selected for further investigation. This formulation will be used to evaluate the effects of different weight percentages (3%, 5%, and 7%) of organically modified montmorillonite (OMMT). The prepared epoxy composites will be characterized using a range of techniques, including Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). The epoxy/nanoclay composite with an IPD: TETA / 75:25 and 3 wt % OMMT is expected to show the highest compressive strength, which is 94 MPa.

Effect of Waste Glass Powder Replacement of Hydraulic Lime on Properties of Natural Hydraulic Lime Mortars.

This paper investigates the effects of the partial replacement of natural hydraulic lime (NHL) with waste glass powder (GP) on the physical, mechanical, and microstructural properties of NHL mortars. In the experimental study, five mixtures containing up to 50% GP were prepared to evaluate its effect on the flow, carbonation, unit weight, water absorption, porosity, ultrasonic pulse velocity, capillary water absorption, compressive strength, and microstructure of NHL mortars. The experimental results suggest that the partial replacement of NHL with GP significantly affects the properties of NHL mortars. A reduction in compressive strength was observed with increasing GP content in mortars at both early and later stages. Nevertheless, the compressive strength difference between samples containing 50% GP and the reference was found to be relatively minor at 91 days, implying an enhanced pozzolanic reaction over time. The incorporation of GP improved the consistency and capillary water absorption of mortars, while the opposite was observed for ultrasonic pulse velocity, porosity, and water absorption. The microstructural analysis revealed distinct changes in the structure of samples incorporating GP. The partial substitution of hydraulic lime with GP could be beneficial in reducing the CO2 emissions of NHL mortars.

Investigating the impact of foundry by-product sand as an activator on workability improvement and strength development in alkali-activated blast furnace slag mortar

The substitution of alkali-activated furnace slag significantly reduces the necessity of cement manufacture and mitigates the continuous growth of carbon emissions. In addition, it shows superior mechanical properties compared to traditional concrete materials. However, rapid setting issues hinder its widespread applications. This study investigated the innovative use of zero-carbon waste sodium silicate-bonded sand as a substitute for the fine aggregate and sodium silicate in traditional alkali-activated blast furnace slag mortar. The primary objective is to analyze the impact of waste sodium silicate-bonded sand on the workability and mechanical properties of the mortar. The key properties such as flowability, setting time, temperature measurement, compressive strength, and microstructural were analyzed to determine the improvement in workability and the strength development of alkali-activated blast furnace slag mortar resulting from the use of waste sodium silicate-bonded sand. The research showed the integration of waste sodium silicate-bonded sand results in an eco-friendly and cost-effective material, which addresses limitations in traditional activated blast furnace slag mortars. The finding revealed that substituting fine aggregate and sodium silicate with waste sodium silicate-bonded sand significantly improved the mechanical and workability properties of alkali-activated mortars. Notably, the compressive strength of mortars incorporating waste sodium silicate-bonded sand exceeded that of traditional Portland cement and effectively mitigated rapid setting issues. In addition, this approach led to an environmentally friendly mortar with satisfactory workability. The research emphasizes the practical benefits of utilizing waste sodium silicate-bonded sand and offers new insights into its effects on mortar performance. This has provided more details for future exploration and refinement in the field of alkali-activated materials.

Influence of Glass Granular Class on the Compressive Strength of Glass-Sand Mortar

This study examines the effect of glass particle size and color on the compressive strength of mortars made from glass, sand, and cement. A range of water-to-cement (W/C) ratios was applied, and tests were conducted to measure density and compressive strength at both 2 and 7 days. The glass, available in green, brown, and white, was introduced as both fine and coarse particles. The findings reveal that incorporating glass significantly enhances compressive strength compared to traditional mortars without glass, regardless of its color. Brown glass, especially in its coarse form, exhibited the best mechanical performance. With a W/C ratio of 0.48, mortars containing coarse brown glass particles reached a peak compressive strength of 34.78 MPa, showing a relative increase of 134.52% compared to mortars without glass. Fine brown glass particles also demonstrated strong compressive strength, though lower than the coarse ones. The density analysis showed a positive correlation between density and compressive strength, suggesting that denser mortars perform better mechanically. The superior performance of coarse glass particles is likely due to their optimal granular distribution, which enhances the bonding between cement and glass particles, leading to greater overall strength. Keywords: Compressive strength – Particle size – Recycled glass – Mortar – Density

Experimental study on recycling rubber to increase the impact resistance of cement mortar

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.