This study examines the in-plane shear performance of clay-unit unreinforced masonry (URM) walls subjected to quasi-static cyclic loading, focusing on the simultaneous effects of mortar type and aspect ratio. Six full-scale wall specimens were tested using three mortar types—lime mortar (LM), cement mortar (CM), and lime-cement mortar (LCM)—and two aspect ratios of 0.95 and 1.93. Experimental results showed that mortar type had a more significant impact on failure behavior than aspect ratio. CM and LCM walls exhibited flexural rocking or sliding shear failures depending on the aspect ratio, while LM walls consistently displayed diagonal shear cracking irrespective of geometry. CM walls achieved up to 48% greater peak lateral strength compared to LM walls; however, LM walls exhibited superior energy dissipation and equivalent damping. Finite-element (FE) simulations using a macromodeling approach with the Engineering Masonry model (EMM) were conducted to replicate the experimental response. The model captured the global cyclic behavior of CM and LCM walls with reasonable accuracy, but it significantly underperformed for LM walls due to limitations in representing localized joint degradation. A shear modulus value of G=0.025E, calibrated through sensitivity analysis, yielded the best correlation with experimental data for CM and LCM walls, while G=0.4E worked well for LM walls. Numerical predictions of peak load deviated by 3.75% and 15.72% for high and low aspect ratio walls, respectively. Analytical formulations for lateral strength aligned well with test results. The findings emphasize the critical influence of mortar properties and aspect ratios in seismic behavior of URM walls and highlight the need for enhanced modeling approaches to predict the failure behavior of URM walls when both aspect ratio and mortar types are studied together.

Optimization in water absorption and desorption of bentonite modified superabsorbent polymer for improving internal curing effect of cement mortar

Study on the dynamic compressive properties of graphene oxide/carbon nanotubes synergistically reinforced cement mortar

Performance enhancement of recycled concrete powder cement mortars via tannic acid-induced stable 3D urchin-like hydrates

Multiscale modification of sulfoaluminate cement mortar using nano-calcium carbonate, polypropylene fiber and silane coupling agent: Mechanical performance, sulfate resistance and mechanism clarification

Combined effect of rice husk ash and copper slag on the mechanical performance of cement mortar

Volume expansion of steel slag cement mortar and synergistic effects of f-CaO content, particle size, and curing temperature

Optimization of natural fibre length in bacterial cement mortar using TOPSIS for enhanced mechanical properties.

Mechanical and protective properties of cement mortar modified with nanomagnetite under high temperature conditions

The incorporation of plastic waste into cement-based materials offers a promising strategy for improving sustainability; however, it is often associated with reduced mechanical performance due to weak interfacial bonding. This study investigates the effect of metakaolin on the interfacial transition zone (ITZ) and mechanical properties of cement mortars modified with polyethylene terephthalate (PET) flakes used for the partial replacement of natural sand. Mortars containing 10 and 50 wt% metakaolin (as cement replacement) and 5 vol.% PET flakes (as sand replacement) were prepared and tested after 28 days of curing. Compressive and flexural strength were evaluated, and microstructural analysis was conducted using scanning electron microscopy (SEM) with a focus on the ITZ. The results indicate that the incorporation of PET flakes leads to a reduction in mechanical properties due to the formation of a porous and weak ITZ. However, the addition of 10 wt% metakaolin significantly improved mechanical properties, enabling PET-modified mortars to achieve strength comparable to the reference mix. SEM observations revealed that metakaolin contributed to the refinement of the microstructure and reduction in ITZ porosity, which enhanced interfacial bonding and improved stress transfer between PET particles and the cement matrix. These findings demonstrate that metakaolin can effectively mitigate the negative effects associated with PET incorporation by improving the microstructural characteristics of the ITZ, thereby enhancing the performance of sustainable cement-based composites.

The Influence of the Water–Cement Ratio on the Mechanical Properties of Cement Mortars with the Addition of Sewage Sludge Biochar

ABSTRACT - The increasing demand for construction materials and the depletion of natural river sand have led to the widespread adoption of artificial sand as an alternative fine aggregate. Although artificial sand offers advantages such as controlled production, better availability, and environmental sustainability, its use in field applications has revealed several challenges related to workability, strength, permeability, and crack formation. These issues primarily arise due to the angular particle shape, higher fines content, and increased water absorption characteristics of artificial sand. This study investigates the performance of artificial sand in mortar applications, with particular emphasis on field-related problems such as shrinkage, reduced workability, and surface cracking. Experimental analysis was carried out using different mix proportions, and the influence of material properties such as gradation, silt content, and moisture behavior was evaluated. The results indicate that although artificial sand improves compressive strength due to enhanced interlocking, it simultaneously increases water demand and susceptibility to shrinkage-induced cracking. To address these limitations, the incorporation of Super Absorbent Polymer (SAP), specifically sodium polyacrylate, was examined as a potential solution. SAP acts as an internal curing agent by absorbing and gradually releasing water within the mortar matrix, thereby reducing moisture loss and internal stresses. The inclusion of SAP was found to improve crack resistance, enhance durability, and reduce external curing requirements. The study concludes that while artificial sand is a viable and sustainable alternative to natural sand, its performance can be significantly enhanced through the use of advanced materials such as SAP and proper control of mix design parameters. The findings provide practical insights for improving the field application of artificial sand in mortar and plastering works. Key Words: Artificial Sand, Manufactured Sand, Cement Mortar, Fine Aggregate Properties, Workability, Compressive Strength, Shrinkage Cracks, Gradation Analysis, Durability

High-pressure water jet (HPWJ) technology represents an efficient and environmentally friendly approach for demolishing performance-degraded cement mortar. This study investigates the breakage characteristics and damage evolution of double-layer cement mortar under HPWJ impact using SPH-FEM coupling algorithm. Results indicate that damage in C20-C30 mortar is predominantly localized in the upper layer, forming a pit with a wide middle and narrow bottom, accompanied by minor interface cracks. Conversely, the interface in C30–C20 mortar shows minimal inhibitory effect on crack propagation. The comprehensive damage resistance of C30-C20 mortar with a comprehensive destructive-damage factor of 0.17711 at 300 μs performs slightly inferior to monolithic C30 (by 0.22%) but significantly superior to C20 (by 5.7%). The internal energy shows a sudden surge and then slow change due to water-hammer effect and stable continuous impact. A time-lag effect was observed in damage progression, with failure modes transitioning from tensile-shear to compressive-shear failure. Interface elements are highly vulnerable due to the water wedge effect and weak bonding. The ‘high-strength upper, low-strength lower’ configuration effectively mitigates stress wave propagation and enhances damage resistance, offering a viable strategy for cement mortar structure repair. These findings provide theoretical insights for efficient cement mortar crushing using HPWJs.

Manufactured sand (M-sand) has emerged as a viable substitute for natural river sand in cement mortar applications. This study investigates the influence of mica content and mineralogical composition of M-sand sourced from six quarries in Karnataka, India, on expansion/contraction behaviour and compressive strength of cement mortar. Petrographic thin-section analysis and grain-size mineral counting were conducted on samples from quarries at Kotagal, Vishnupriya (Schoolagiri), Muddenahalli, Tekal, Peresandra, and Gudibande. An Accelerated Mortar Bar Test (AMBT) per IS 2386 Part VII was performed on 132 mortar bar specimens (25 × 25 × 285 mm) at mix ratios of 1:1 and 1:2.25 immersed in 1N NaOH at 80°C for 14 days. Compressive strength of 70.6 mm mortar cubes was evaluated at 28 days. Results reveal that mica content is the dominant factor governing volumetric instability: the sample with highest mica content (MSKotagal, 25%) exhibited greatest expansion (1.82 mm) and contraction (1.75 mm), while natural sand (9.17% mica) showed best dimensional stability. Compressive strength ranged from 48.56 N/mm² (MS-Kotagal) to 55.64 N/mm² (MS-Tekal), confirming the adverse effect of mica on mortar strength. These findings provide practical guidelines for selecting M-sand in plastering and masonry mortar applications.

Abstract Porous materials exhibit complex ionic transport processes that are relevant to many field applications, such as chloride-induced corrosion and the scavenging of radioactive isotopes in cementitious systems. In this work, a non-destructive method is presented to quantify local iodide concentration in cementitious mortar. X-ray Computed Tomography is used to detect changes in attenuation resulting from spatial and temporal variations in iodide concentration, while chemical analysis provides calibration to obtain absolute concentration values. Iodide is selected as a chemically similar tracer for chloride while offering substantially higher X-ray attenuation, enabling reliable contrast in tomographic imaging. Validation tests indicate very good agreement between measured and predicted concentrations when the method is applied to before–after comparisons on the same specimen under strictly controlled experimental conditions.

This study examined the use of five natural fibers (cotton, coconut coir, jute, sisal, and sheep wool) as reinforcements for cement mortars with a standard mix design. Sixteen fiber-reinforced mixtures were prepared with a constant fiber length of 10 mm. The mixtures were tested after 28 days for Water Absorption (WA) and mechanical performance. Fracture sections were visually assessed to evaluate dispersion quality, with some fiber additions improving flexural behavior. The highest flexural strength was obtained with sisal at 5% by volume (5.53 MPa versus 3.90 MPa for the control), and compressive strength was better at low dosages. Jute and coconut fibre of 1% reached 19.59 MPa and 19.50 MPa, respectively, while the initial mixture reached 14.62 MPa. WA generally increased with fiber content, reaching 30.44% for sheep wool at 4%, which led to severe strength reductions and visibly non-uniform fiber distribution. Overall, when the dosage remains within a dispersion-stable window, untreated natural fibers can improve mortar performance. Low contents of jute and coconut coir provided the most consistent compressive gains. However, excessive sheep wool led to connected porosity, high water uptake, and severe strength loss.

Interfacial mechanical behaviour of underwater-cast alkali-activated mortar and cement mortar: Quasi-static and dynamic responses and mechanisms

Ultra-strong green plastics from marine-sourced alginate dendritic colloids and chitin nanocrystals with a “cement–mortar” structure

Reliable hygrothermal data are essential for modelling heat and moisture transport in building envelopes. This study investigates six cement mortars in which quartz sand is progressively replaced by cenospheres from 0% (REF) to 100% by volume (C100). The composites were characterized in terms of bulk density, water absorption, sorption–desorption behaviour and thermal conductivity in dry and water-saturated states. The dry density decreased from 2.07 g/cm 3 (REF) to 0.85 g/cm 3 (C100), while water absorption increased from 8.1% to 23.7% by mass. The thermal conductivity in the dry state dropped from 1.77 W/mK to 0.25 W/mK, whereas water saturation increased λ in all mixtures, although this effect was less pronounced for high-cenosphere mortars. Dynamic vapour sorption tests (0–97% RH) showed that maximum hygroscopic moisture content increased from about 3% for REF to nearly 10% for C100, and that mortars with cenospheres released sorptive moisture significantly faster; for example, C100 lost 4.07% of its mass after 1 h of desorption and reached equilibrium much earlier than the reference mortar. Empirical relationships were derived between water absorption and density, and between thermal conductivity and both density and moisture content, providing practical input data for hygrothermal simulations of cement composites modified with cenospheres. • Oswin model accurately predicts sorption isotherms for cenosphere-cement composites • Mathematical coupling of sorption and thermal models predicts material performance • Cenospheres reduce mortar density to 0.85 g/cm 3 and thermal conductivity to 0.25 W/mK • Cenosphere composites achieve moisture equilibrium ∼3× faster than reference mortars • Desorption kinetics strongly correlate with cenosphere content and pore structure

Nonlinear ultrasonic test applied to discern factors controlling cracking of cement mortar affected by reinforcement corrosion