2026· Journal of materials in civil engineering· 0 citations· 50 references
Abstract
The use of desert sands as an alternative to river sand in concrete may be limited by the presence of internally sourced sulfate and chloride ions, which may affect hydration and long-term performance. This study investigates the influence of naturally contaminated desert sands on the fresh and hardened properties of cement-based materials. Mortar mixtures produced with sands from three sites of the Atacama Desert were compared with mixtures containing artificially contaminated sands designed to reproduce equivalent ionic release during mixing. Hydration kinetics by isothermal calorimetry, strength development, and susceptibility to internal sulfate attack (ISA) were evaluated using isothermal calorimetry, compressive strength testing, and length change measurements. Results show that chloride contents up to 1.0% by mass of dry sand accelerated early hydration and increased 7-day compressive strength by up to 15% relative to the reference mixture. Conversely, sulfate contents of 0.24% reduced 28-day compressive strength by up to 18% and promoted long-term expansion associated with ISA. Mixtures containing combined moderate sulfate and high chloride levels exhibited enhanced early hydration without significant strength loss at later ages. The novelty of this study lies in linking ion release from natural desert sands to equivalent artificial contamination, enabling a systematic evaluation of internal sulfate–chloride interactions in cement-based materials.
Stabilization of marginal desert soils while enhancing sustainability through reduced CO₂ emissions and the use of industrial by-products, remains a challenging task. Cement-stabilized soil can be improved by adding silica fume (SF), leading to enhanced physical and mechanical properties. Moreover, SF is both economically viable and environmentally friendly. This study investigates the effect of SF on the compaction and strength properties of cement-stabilized fine to medium sand. Laboratory tests included the modified Proctor test, unconfined compressive strength test (UCS), ultrasonic pulse velocity (UPV), California bearing ratio test (CBR) and microstructure tests comprising of scanning electron microscope (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared Spectroscopy (FTIR) to examine and quantify changes responsible for variations in mechanical behavior. Three cement contents (8%, 12%, and 16%) and varying SF contents were used for compaction and strength evaluation, with curing periods of 3, 7, and 28 days. Results show that silica fume positively influences the engineering properties of cement-stabilized sand, increasing dry unit weight, compressive strength, and stiffness with increasing SF content. From both efficiency and economic perspectives, 12% silica fume is identified as the optimum ratio.
Ibrahim F. Eldemary, Mostafalou Yousef, Mohamed Eleiche et al.· International Journal of Geo...· 0 citations
This study examines the effect of water salinity levels on the mechanical geotechnical properties of clay-rich soil. Laboratory tests were conducted on a set of soil samples with varying salinity levels, including unconfined compressive strength (UCS), Atterberg limits, oedometer, and direct shear tests. The conducted test results are further used to evaluate alterations in soil properties resulting from exposure to sodium chloride (NaCl) concentrations ranging from 0 mM (pure water) to 600 mM (seawater). The findings show a progressive decrease in liquid limit, plastic limit, and plasticity index with increasing salt concentration, indicating reduced water affinity and significant physicochemical alterations to the soil structure. These trends are consistent across all experimental observations and have been confirmed by zeta potential measurements and mineralogical analyses using X-ray diffraction (XRD). However, maximum dry density increased in parallel with a decrease in optimum moisture content. The increase in salinity led to a decrease in compressive strength, indicating a weakening of the soil structure. The shear strength parameters (cohesion and Internal friction angles) experience a decrease due to the presence of saline water. Therefore, soils with high salinity will also exhibit lower shear strengths. The results of this study provide reliable information to support road construction activities in coastal environments.
Bachi Kahina, Bouzeroura Mansour, Bouragaa Kheira et al.· Research on Engineering Stru...· 0 citations
Matrix acidizing is a popular stimulation method in oil and gas well that increases the permeability of sandstone reservoirs by dissolving minerals that block pore spaces. The success of this process is dependent on the mineral composition of the rock and the type of acid used. In this work the effects of HCl on sandstones from Sitakundo were studied in the laboratory. Pre and post acidize analysis is performed to observe alteration in porosity, permeability and uniaxial compressive strength (UCS). A significant enhancement in porosity from 11-13 to 22-25% and more than 70% permeability increase were achieved, ensuring an effective dissolution of minerals and an enhancement of porous structure. This implies that the UCS was reduced by 14% approximately as a result of mechanical weakening consequent to the dissolution of cementing materials. These results underline the two fold effect of acidizing - increasing flow capacity while decreasing rock strength and open avenues to more optimized acid treatment design for effective & stable reservoir stimulation.
S. Ebrahim, I. Khan, M. A. Md Yusof et al.· Engineering· 0 citations
Conventional concrete specification relies heavily on compressive strength, water-to-binder ratio, minimum cement content, and nominal cover, none of which directly measures the resistance of hardened concrete to chloride ingress, gas penetration, or capillary water absorption. This study reports a comparative experimental investigation of 41 concrete mixtures incorporating Ordinary Portland Cement (OPC), two sources of Ground Granulated Blast-furnace Slag (Slag), Class F fly ash, and Class C fly ash at replacement levels of 15–70%, together with binary and ternary combinations, across water-to-binder ratios of 0.35–0.50 and binder contents of 350–450 kg/m³. Compressive strength, surface electrical resistivity, rapid chloride penetration (RCPT) charge, oxygen permeability index (OPI), and water sorptivity were measured at 28 and 90 days. Mean compressive strength increased by 16.7% between 28 and 90 days, mean surface resistivity increased by 79.9%, and mean RCPT charge decreased by 27.9%. Surface resistivity and RCPT charge were strongly and inversely correlated at both ages (r = −0.704 at 28 days; r = −0.725 at 90 days), whereas compressive strength showed only a weak association with RCPT (r = −0.258) and an essentially negligible association with resistivity (r = +0.008) at 90 days. In a controlled comparison at w/b = 0.50 and 310 kg/m³ binder content, a 50% slag mixture achieved the most balanced performance, exceeding the OPC control in strength (59.23 vs. 54.62 MPa) while improving resistivity by 7.38×, RCPT resistance by 6.40×, and sorptivity resistance by 3.03×. A 50% Class F fly ash mixture achieved comparable or superior chloride-related resistance (RCPT resistance 7.17×) but at a substantial strength penalty (0.57× the OPC strength). The results demonstrate that compressive strength alone cannot rank the durability performance of SCM concretes, and that a multi-parameter, exposure-specific assessment framework combining resistivity, RCPT, OPI, and sorptivity is required for dependable material selection.
Keywords: Supplementary cementitious materials; Concrete durability; Surface electrical resistivity; Rapid chloride penetration; Oxygen permeability index; Water sorptivity; Correlation analysis.
P. Ramya, Momin Atharuddin· International Journal of Cre...· 0 citations
Portland cement production is currently one of the major sources of global carbon dioxide emissions. This makes Portland cement production a significant contributor to global climate change. To mitigate these environmental impacts, Supplementary Cementitious Materials (SCMs) are expected to provide an appropriate and effective solu - tion. This study focuses on examining the potential of quartz sand and kaolin from Aceh, Indonesia, as materials utilized as SCMs in the production of foam concrete. These two materials were selected due to their pozzolanic activity, which allows them to react with the calcium hydroxide formed during cement hydration and act as additional binding agents. The primary objective of this study is to reduce the carbon footprint of foam concrete and to sustainably enhance its mechanical properties. The percentage variations of quartz sand and kaolin used as SCMs were investigated at 0% (as a control), 5%, 10%, 15%, and 20%. The physical, chemical, and microstructural properties of the specimens were tested at curing ages of 7, 28, and 56 days. The results of the study indicate that quartz sand and kaolin can function as SCMs. This is because quartz sand and kaolin contain calcium silicate hydrate (C-S-H) as a binding agent. The use of SCMs at 10% of the cement weight has a very significant impact on mechanical properties as the curing age of the concrete increases. Based on these conditions, it can be proven that quartz sand and kaolin derived from local mineral rocks in Aceh have very effective potential for use as SCMs in foam concrete, as demonstrated by the microstructural patterns, and can serve as sustainable alternative materials.
Keumala Citra Sarina Zein, Abdullah Abdullah, S. Mulyati et al.· Journal of Ecological Engine...· 0 citations
Introduction
. The sand of many deposits, especially in the far east of our country, contains a large amount of chlorides, which makes it unsuitable for use in reinforced concrete. This is because chloride ions are the most aggressive corrosive agent for steelreinforcement. The Laboratory of Corrosion and Durability of Concrete and Reinforced Concrete Structures at the A.A. Gvozdev Research Institute of Concrete and Reinforced Concrete Structures conducted research on the corrosion of steel reinforcement in concrete and cement-sand mixtures that contained sand with a high chloride content.
Aim
. To determine the possibility of using sand from the Kamchatka Territory deposits in concrete mixtures in terms of corrosion aggression to steel reinforcement.
Materials and methods.
The studies were conducted on a model cement-sand mixture (CPM) and concrete with smooth rod reinforcement of 6 mm in diameter. The sand contained 0.08 % by mass (based on chlorine ion) of water-soluble chlorides and 0.55 % by mass (based on chlorine ion) of total chlorides in the sand. An electrochemical method was used to accelerate the determination of the corrosion effect of the environment on steel reinforcement. The method is based on obtaining the dependence of the electric current density on the electric potential of the steel reinforcement, which is known as the potential-dynamic method.
Results
show that sand with a high content of water-insoluble chlorides does not cause corrosion of steel reinforcement when the samples are in a non-aggressive (neutral) environment. In the initial state and exposure in the humidification – drying mode for 3, 6 months, neither in the cement-sand mixture samples nor in the concrete samples, the current density at a potential of plus 300 mV did not exceed 10 μA/ cm2, as well as the potential after (60 ± 5) s after the current was turned off did not drop below + 5mV.
Conclusions.
Sand with a high content of water-insoluble chlorides can be recommended for use in reinforced concrete structures that are guaranteed to be free from aggressive environments even during operation.
V. F. Stepanova, N. Spivak, L. P. Kharitonova· Bulletin of Science and Rese...· 0 citations