This research studies the effect of waste marble powder (WMP) as substitute of Portland cement on strength and durability of self-compacting concrete (SCC) in order to produce SCC with reduced impact environmental. For this purpose, five mixtures were designed in which four mixtures contained WMP at substitution levels of 5, 10, 15, 20%, and mixture included only the Portland cement as control mix. The realized tests are compressive strength at 3, 7 and 28 days, water capillary absorption, water absorption by immersion and sulfate attack. The results show a reduction in the compressive strength with increasing WMP content. The use of WMP was found to increase both of the water capillary absorption and water absorption by immersion. SCC containing WMP subjected to magnesium sulfate attack presented a lower expansion and higher resistance to sulfate aggressions.

The performance of concrete / mortar is specially related to their composition and water to cement ratio. The use of Ordinary Portland cement [OPC] as binder increases the hydration heat and cost of cement and CO2 emissions. So the use of composite binder by reducing the amount of OPC and introducing mineral additions can be a useful solution. In this study, OPC was partially substituted with marble powder [MP] at various percentages (5, 10, 15 and 20%) and the effect of MP on the durability of self compacting mortars [SCM] exposed to chemical aggressions was investigated. Two aggressive solutions were used sodium sulfate [Na2SO4] and hydrochloric acid [HCl]. The dosages of the solutions were 5 and 1%, respectively. The results revealed that the use of marble powder is beneficial for improving the resistance of SCM to aggressive solutions. Adding 20% MP increased the resistance against sodium sulfate attack by 46% at 180 days. Using MP with content ranged between 10 to 20% was found to reduce mass loss by 1 to 0.47%.

Composite grids serve as reinforcement in concrete structures, offering alternatives to conventional steel reinforcement. These grids can be fabricated from various materials, including synthetic polymers, metals, and natural fibers. This study explores the use of composite grids as lateral confinement of self-compacting concrete (SCC) cylinders and examines their impact on the failure mode under axial compression. In the experiment, the types of grids and mesh shapes used were plastic grids of diamond mesh (PGD) and regular mesh (PGT), metallic grids of diamond mesh (MGD) and square mesh (MGS), vegetable grids of Alfa fiber mesh, 10 × 10 mm (VGAF-1) and 20 × 20 mm (VGAF-2), and vegetable grids of date palm fibers (VGDF). The binder of SCC mixtures incorporated 10% marble powder as a partial replacement for ordinary Portland cement (OPC). SCC mixtures were tested in the fresh state by measuring the slump flow diameter, V-funnel flow time, L-box blocking ratio, and segregation index. Cylinders with a diameter of 160 mm and a height of 320 mm were made to assess the mechanical properties of hardened SCC mixtures under axial compression. The results indicate that most of the confined cylinders exhibited an increase in ductility compared to unconfined cylinders. Grid types MGD and PGD provided the best performance, with ductility increases of 100.33% and 96.45%, respectively. VGAF-2 cylinders had greater compressive strength than cylinders with other grid types. The findings revealed that the type and mesh shape of the grids affects the failure mode of confined cylinders, but has minimal influence on their modulus of elasticity. This study highlights the potential of lateral grid confinement as a technique for rehabilitating, strengthening, and reinforcing weaker structural concrete elements, thereby improving their mechanical properties and extending the service life of building structures.

The present paper investigates the hardened properties of self-compacting concrete by reusing granite waste to replace natural fin aggregates. The reuse of solid wastes as powder or aggregates allows us to produce sustainable concretes that have lower environmental impacts and reduced cost. In this work, granite waste was used as a partial replacement to natural river sand in self-compacting concrete (SCC). For this purpose, four mixtures were designed in which three contained a combination of river sand (RS) and recycled granite (RG) and one only included river sand (RS) as reference mix. Compressive strength, flexural strength, ultrasonic pulse velocity and water absorption were investigated for the hardened SCC at 28 days of hydration. The results showed that the introduction of RG has no effect on compressive strength of SCC. Adding 30% of RG increased flexural strength by 12%. According to ultrasonic pulse velocity results, the use of RG resulted in more compactness and homogeneous SCC. In addition, SCC including RG showed less water absorption.

Introduction: Self compacting mortar is known as a highly fluid mortar that can flow and fill all spaces under its own weight without vibration or compaction. This experimental work aims to produce a self-compacting mortar (SCM) that can be used to repair damaged structural concrete by replacing a proportion of ordinary Portland cement with metakaolin (MK) and adding glass fibers (GF). Methods: Mixtures including various percentages of MK and GF were prepared and tested. All mixtures were tested in the fresh state to assess fluidity and viscosity through mini-slump flow and mini V-funnel flow time tests, respectively. Physical and mechanical properties of all mixtures were measured, such as compressive strength, flexural strength and water absorption. In order to check the performance of prepared SCM in structural repair two experiments were conducted on damaged reinforced concrete beam and cylindrical specimens. Results: The results showed that the addition of GF and MK needs an increase in SP dosage to reduce their negative effect on the fluidity and the viscosity of SCM mixtures. The use of MK up to 10% of cement as replacement resulted in a compressive strength gain of 11 MPa at 28 days and 13 MPa at 56 days. Similar behavior was observed in the mixture containing 0.4% of GF and 10% of MK. Adding GF with 0.2, 0.4, and 0.6% led to flexural strength gains of 4, 6, and 15%, respectively. Water absorption was reduced by 29% when 15% of MK was incorporated. Using MK improves the bond between the repair mortar and the concrete substrate. Conclusion: Following a rigorous analysis of the obtained results, it can be concluded that MK and GF can be used to improve mechanical properties and reduce water absorption of SCM mixtures. The mixture including 0.4% of GF and 10% of MK exhibited the best performance and was considered more suitable for repairing damaged SCC beams.