Effect of Supplementary Cementitious Materials on Corrosion Resistance of Reinforced Concrete Ayad A. Mousa, Jasim M. Abed, Mohammed H. Shukur Civil and Environmental Engineering, 2025 Reinforced concrete (RC) durability particularly in chloride and sulphate-rich environments is seriously compromised by corrosion. This study explores how Supplementary Cementitious Materials (SCMs) fly ash, silica fume, ground granulated blast furnace slag, and metakaolin collectively improve corrosion resistance and durability. A rigorous experimental regime, including compressive strength testing, water absorption, sorptivity, rapid chloride penetration tests, sulphate attack resistance, half-cell potential measurements, chloride diffusion assessments, and linear polarization resistance tests, was implemented. Multi-SCM mixtures significantly outperformed individual SCMs, exhibiting a 68% drop in chloride permeability, 64% less sulphate-induced expansion, and an 81% reduction in steel corrosion relative to conventional concrete. Notably, mix M13 achieved exceptional microstructural refinement and a compressive strength of 70.7 MPa 38% higher than the control alongside superior resistance to aggressive ions. However, this enhanced SCM content led to noticeable workability issues, reducing slump values by approximately 38%. Although the introduction of superplasticizers partially mitigated these drawbacks, practical implementation at a larger scale remains challenging. Further, uncertainties persist regarding long-term real-world performance, necessitating additional field validations. Ultimately, while SCM blends clearly offer substantial durability advantages, future investigations should prioritize optimizing mix proportions, addressing workability concerns, and verifying laboratory results in actual exposure conditions. This will support the advancement of sustainable, resilient RC infrastructures with enhanced corrosion resistance.
Impact of Substrate Surface Roughness on Bond Behavior of High-Performance Engineered Cementitious Composites Repair Mortar Jasim Mohammed Abed, Ghufran Taha Mohammed International Review of Civil Engineering, 2025 One of the most crucial elements for structural functionality, safety, and durability is the interfacial bonding between degraded concrete structures and overlaid repair mortar. A strong and effective bond at the concrete interfaces is essential to enhancing resistance against shear and tensile loads. The goal of this study is to look at the mechanical properties of the repaired substrate made of high-performance Engineered Cementitious Composites (ECC) by using different surface roughening methods on concrete. Four approaches have been evaluated: one-way scratching with parallel double grooves, two-way scratching, one-way scratching with column drilling, and screwing into the grooves. The flexural strength of 48 repaired prism specimens at 45° and 90° angles between the ECC mortar and substrate was tested. Splitting tensile strength and slant shear strength tests were done on cylinder specimens. Slant shear strength tests were done at a 30° angle between the substrate and ECC mortar. The repaired specimens were cured for 28 days at a temperature of 23±2 °C. According to the investigation results, the mixture (M5) containing 210 kg/m3 of silica fume and 210 kg/m3 of slag powder (as supplementary cementitious materials) with a limestone powder-to-cement ratio of 2.5 yielded the best mechanical properties for ECC mortar. The same mixture (M5) provided the best bond strength and slant shear resistance when the surface roughened (a 45° angle between the ECC mortar and the substrate) using a combined technique of scratching and precision drilling of the substrate, followed by screws set in the double grooves.
Impact of using recycled fine aggregate from demolition waste on mechanical properties of cement mortar Jasim Mohammed Abed, Hiba A. Abdul Kareem Al-Uzbaky, Muthanna Abbu Archives of Civil Engineering, 2025 The rapid expansion of the construction industry worldwide has led to a significant increase in resource use, hence depleting the existing reserves. Utilizing recycled aggregates might potentially reduce the use of natural raw materials in the production of concrete and mortar. This would further aid in reducing the quantity of waste thrown into the environment due to demolition procedures. This study investigated the feasibility of recycling recycled fine aggregate from construction and demolition waste. Limestone powder was utilized as a filler, together with waste from three different kinds of construction and demolition waste (concrete, clay bricks, and ceramics). Cement mortar mixtures of 1:3:0.5 and 1:4:0.5 were used to design 32 different mortar mixes (cement: fine aggregate: filler). Except for the control mixes, the following replacement ratios were tested: 0%, 20%, 40%, 60%, 80%, and 100% for construction and demolition waste as a partial replacement for natural fine aggregate. Cubes, prisms, and cylinders were all used to measure the physical and mechanical properties of the mortar. In this study, the physical properties (workability, dry density) were analyzed. In addition to investigating the mechanical properties (compressive, flexural, and splitting strength), The experimental results showed that the optimal percentage of natural fine aggregate replacing recycled aggregate from construction and demolition waste was 20%. Additionally, the research demonstrated that, due to its cementitious properties, recycled fine aggregate from concrete waste significantly outperformed the reference mixes in terms of all physical and mechanical properties.
The effect of real curing temperatures on early age concrete strength development in massive concrete structures Majid Al-Gburi, Jasim Abed, Asaad Almssad, A. A. Alhayani, Agnieszka Jędrzejewska, Martin Nilsson European Journal of Environmental and Civil Engineering, 2025 At the early maturity stage, the curing temperature has a significant impact on the mechanical properties of concrete. Concrete cubes are cured in water baths at different temperatures—5 °C, 20 °C, 35 °C, and 50 °C—in order to measure their compressive strength. This method is predicated on the knowledge that the pace of cement hydration is strongly influenced by the curing temperature. Then, the realistic curing temperature regime was imposed where the temperature of the curing water was modified based on the temperature patterns obtained from semi-adiabatic testing of concrete mixes to simulate curing conditions in the core of massive concrete structures. Ordinary Concrete: Compared to specimens cured at an isothermal curing at 20 °C, those cured in water baths at realistic curing showed an increase in compressive strength of 48% at seven days and 18.5% at 28 days. Fly Ash 18% Replacement: Compared to specimens cured at at 20 °C, the compressive strength of those cured at realistic curing increased by 45% at seven days, with a modest rise of 0.2% by the 28th day. Slag 18% Replacement: Compared to specimens cured at 20 °C, the compressive strength of those cured at realistic curing increased significantly by 121% at seven days and by 21.7% at 28 days.
Effect of Partial Replacement of Fly Ash and Expanded Polystyrene waste on Properties of Geopolymer Concrete Bricks Journal of Advanced Research in Applied Sciences and Engineering Technology, 2019
