EFFECTS OF WATER AND CARBON DIOXIDE GAS CURING ON THE DEVELOPMENT OF LIGHTWEIGHT CONCRETE MADE WITH WATER-SHIELD CEMENT AND CARBIDE WASTE

Concrete is pivotal to modern building construction and infrastructure. This study aimed to develop and evaluate carbide –waste- blended, and CO2 gas- cured lightweight concrete materials. Concrete mixes were prepared with CWRs as a partial replacement for watershed Portland cement. Concrete mixes were developed using 0% (control), 5%, 10 %, and 15% CWRs by weight. To evaluate the curing methods, one set of fresh concrete mixes was poured in 100mm × 100mm × 100mm cube moldsand placed in CO2 -_gas- filled air bag, while the other set was kept under ambient laboratory conditions for 24 h. After demolding, they underwent either water curing or curing in CO2 gas chamber, which was regulated by a gas flowmeter connected to a steel cylinder equipped with a pressure gauge set at 20 MPa. Fresh and hardened properties – including the slump tests, density, water absorption, and compressive strength tests, -were assessed after 7, 14, and 28 days of curing. Data-driven evidence showed that slump values increased as the CWR replacement level increased 0-15%. Density analysis revealed that higher CWR content resulted in less dense concrete specimens. However, strong bond kinetics among competing cementing agents contributed to WA reduction. Conversely, an inverse relationship was observed between mechanical performance and the addition of CWRs, as the compressive strength decreased from 0 to 15% replacement levels. Peak strength was achieved at 5% CWR replacement combined with CO2 gas curing. Ultimately, CWRs and CO2 gas curing can be effectively used to produce low-cost, lightweight concrete materials, thereby promoting sustainable waste reuse and eco-friendly construction protocols.