Unsaturated soils and granular materials play a pivotal role in geotechnical and environmental engineering, with water under tension markedly influencing their mechanical behavior, particularly strength and deformation. To elucidate the impact of matric suction on the macroscopic mechanical response, this study presents a modeling approach for capillary interactions between spherical particles in a partially saturated medium using the Discrete Element Method (DEM). The PFC3D software is employed to calibrate mesoscale interparticle contact parameters to replicate uniaxial compression tests performed on a reference material under saturated conditions. Suction effects are incorporated via an intergranular contact force based on the Hill contact model, which considers matric suction magnitude, particle radius, and interparticle spacing. Numerical results demonstrate that suction can be realistically represented by an adhesion force at particle contacts. The model is further extended to simulate triaxial tests, examining the evolution of cohesion and internal friction angle with increasing suction. Both parameters exhibit an upward trend with suction, reflecting the influence of capillary forces and suction-induced densification. Finally, a mathematical model using logarithmic functions is developed to describe the evolution of mechanical parameters as a function of suction, yielding high coefficients of determination (R² > 0.95) and providing reliable predictive capabilities.

This paper presents an experimental study to investigate some of the thermal and strength behaviors of a new mortar material which was prepared by adding some of the residues of agricultural Iraqi biomass materials such as wood sawdust, reed, corn cobs, and their blending. These biomass materials are available in plenty of amounts in Iraq / Karbala City. These materials are blended with sand and cement, which are raw materials for mortar preparation, in different percentages to produce new types of mortar. The major focal area of interest is to identify the likelihood of applying these products as external wall insulating material to minimize heat transfer from outside to a building. Thermal conductivity, water absorption and skeletal density, and compressive strength at 7 and 28 days of the new mortars was also determined in the work. Comparing the performances obtained it was found that the new mortar containing wood sawdust had the highest compressive strength values While the best improvement in heat insulation was recorded in the mortar containing corn cobs compared to the other types. The results presented here prove that this mortar can be recommended for building purposes, specifically for exterior wall cladding. It provides good thermal resistance and improves the fortification of building walls; it also affords an added benefit of being cheaper and therefore fashionable for construction related uses.

A lack of natural aggregates in the future is unavoidable, which generates issues for building development. For many industries, natural resources constitute a significant source of revenue. As a result, light artificial aggregate is produced to anticipate the decreasing source of natural aggregate. Production of artificial geopolymer aggregates, fly ash from the burning of coal has been proposed. This paper investigates the optimal proportion of epoxy resin and coal fly ash-based synthetic aggregates. The artificial aggregates are produced following specific gravity and compressive strength standards that may be used as a component of lightweight structural concrete (LWC). The production polymer lightweight aggregate (PLA) comes from a combination of coal fly ash and epoxy resin. The results show that PLA 50:50 to PLA 74:26 can be used for 6 hours to make structural concrete with a strength of more than 17 MPa. PLA 80:20 could achieve compressive strength with the range of 7-17 MPa. PLA 84:16 achieves a compressive strength range of 0.35 to 7 MPa and is utilized as a non-structural element. However, the flexural strength values in concrete LWC 70:30 and LWC 80:20 are higher, at 46.1% and 7.63%, respectively.

The effect of the chemical composition of geopolymer pastes on compressive strength was investigated in high-calcium fly ash and copper slag blends. In synthesizing the pastes, soda ash at activator to binder ratio of 0.4 was used. The characterization of material samples and the hardened fly ash-copper slag pastes was conducted through X-ray fluorescence (XRF), and X-ray diffraction (XRD) for the major oxide and phase composition. The hardened paste cubes which were cured at 80 °C were tested for compressive strength at ages 3, 7, and 28 days to obtain the mechanical performance property of each respective mix. The findings establish the impact of variation in the individual material and paste composition on the compressive strength of fly ash-copper slag geopolymer. The result shows that increase in the SiO₂/Al₂O₃ and Na₂O/Al₂O₃ ratios of paste products of samples corresponded to an increase in compressive strength. Whilst Fe₂O₃ wt.% increase in products from slag addition and positively influenced the compressive strength as fillers. However, CaO had no positive influence on the matrix of the activated product. The optimal blend mix design was 40 wt.% of copper slag which achieved a 28-day compressive strength of 24.66 MPa.

Nowadays, the significant demand for concrete has become a problem in concrete using aggregate from waste. Using standard concrete is recommended to reduce the breakdown of buildings. Unfortunately, standard materials used to produce previous concrete are not entirely environmentally friendly. As a result, many researchers have committed their awareness to identifying eco-friendlier substitutions in manufacturing concrete substitution aggregate from waste. In this respect, this paper discussed the proposed efficient procedure to indicate the compressive strength from mixed proportioning cockle shell, glass powder, and epoxy resin as concrete under hot water curing conditions (60°C, 4 hr) using response surface methodology. The experimental design used in this research uses a response surface methodology. There are three aggregates to be investigated, namely cockle shell powder, glass powder and epoxy resin under hot water curing condition (60°C, 4 hr). Under hot water curing conditions, this research discovered that adding 4.0% cockle shell powder and 10.0 % glass powder increased the compressive strength to 104.68 MPa. On the other hand, 4.0% cockle shell powder, 10.0% glass powder and 2% epoxy resin under hot water curing conditions improved the compressive strength to 115.70 MPa. It was therefore inferred that the use of both cockle shell powder and glass powder to produce cleaner and compressive strength concrete is applicable, both mechanically and environmentally.

Nowadays, with increased demand for aggregates for concrete and an awareness of the need of protecting natural resources, experts are becoming increasingly interested in waste material as a building material substitute. However, the compressive strength is influenced by the composition of concrete. In this study, the compressive strength of concrete under substitution using waste from cockle shells and glass was investigated using Response Surface Methodology (RSM). Central Composite Design (CCD) based on RSM was used to assess the influence of epoxy resin, cockle shells powder, and glass powder on compressive strength responses. RSM developed first-order and second-order mathematical models with findings from experimental design. Analysis of variance was used to determine the correctness of CCD's mathematical models. Desirability analysis was then employed to optimize epoxy resin, cockle shells powder, and glass powder yielding maximum compressive strength. The RSM analysis revealed that the empirical results fit well into linear and quadratic models of concrete compressive strength. The mixing components will produce cement with compressive strength in each formulation of 54.71 MPa (4.88% epoxy resin and 4.0% cockle shells powder), 47.82 MPa (6.85% epoxy resin and 8.0% glass powder), 147.0 MPa, (4% cockle shells powder and 8% glass powder), and 56.08 MPa (4.4% epoxy resin, 4.0% cockle shells powder, and 8.0% glass powder). The results confirmed that a reasonable compressive strength of concrete could be achieved using epoxy resin, cockle shells powder, and glass powder.

With the increase of construction activities in Ghana, there is an increasing demand in building materials leading to the shortage of the conventional materials. The informal sector is gradually seeing the introduction of quarry dust as a substitute of sand in block production. This paper focuses on a comparative analysis of the quality of sandcrete blocks and quarry dust cement blocks. Block samples were gathered from various suppliers around the Prampram and Dawhenya areas and through various laboratory tests were tested for their dimension tolerance, water absorption and compressive strengths. Aggregate samples were also taken from suppliers for sieve analyses. The study revealed that the quarry dust cement blocks contained relatively higher percentages of coarse grade particles compared to the sandcrete blocks. The total average water absorption of sandcrete blocks was found to be 3.90% while quarry dust showed an improved value of 3.28%. Sandcrete blocks were averagely found to be of a higher compressive strength of 4.31N/mm2, with quarry dust at 3.0N/mm2. The study suggested the likelihood of a lesser use of cement in the production of quarry dust cement blocks due to the similarities in colour between the quarry dust and cement, hence, negatively affecting its compressive strength.

Lightweight concrete is a suitable constructional material, which can decrease the weight of buildings and the hazards of earthquake loads. Hence, a large number of research studies have been focused on designing and manufacturing high strength lightweight concretes. In this research using the natural and industrial lightweight aggregates frequently found in the south-east region of Iran (Kerman province), high strength and low cost light weight concretes were manufactured. The effects of aggregate type, aggregate size, and concrete mixture were studied experimentally on the compressive strength of concretes and the density and cost of manufactured samples.