Limestone powder, calcined clay and slag as quaternary blended cement used for green concrete production

Cement is among the most widely used building materials in recent years. In addition, the accumulation of massive waste has impacted the city's appearance. As a result, there was a need to reduce waste by using by-products from industrial waste to replace cement and reduce greenhouse emissions to produce mortar or concrete green that has good performance, environmentally and sustainably. This research study aims to design green concrete with the highest feasible replacement level with different cement content that satisfies fresh and mechanical characteristics used for structural application and eliminate negative environmental impacts simultaneously. The empirical work was conducted by preparing 12 blends to produce green concrete by substituting cement with three ratios of various by 30% (10% LMP +10% SS + 10% CC), 40% (10% LMP +10% SS + 20% CC), and 50%(10% LMP +15% SS + 25% CC) with three binder contents (355 kg/m3, 400 kg/m3, and 460 kg/m3). The mix design was carried out according to the American Concrete Institute (ACI) Code. Then environmental influences of green concrete blends were calculated by evaluating the declines in carbon dioxide (CO2) emissions. The results showed that adding limestone powder (LMP),calcined clay (CC), and steel slag (SS) as partial cement replacement decreased the slump properties of fresh concrete, so an increased dosage of superplasticizer (SP) in the fresh properties is needed. Green concrete containing quaternary cement by 30%, 40%, and 50% with SP dosage certain gave higher compressive, flexural, and splitting strength values at 90 days compared to normal concrete. However, UPV values indicate that all green concrete is of suitable quality. While water absorption has slightly increased in quaternary cement containing 50% for binder content 355, 400, and 460 kg/m3 increased by 4.2%, 2.7%, and 2.1%, respectively, compared with plain concrete. The evaluated reduction of carbon dioxide emissions study indicated that the green concrete, when increased in cement replacement percentages by up to 50% for binder content 355, 400, and 460 kg/m3 reduced CO2 emissions by 35.9%, 36.4%, and 37.1%, respectively. As a result, adopting the idea of green concrete is a promising strategy for reducing carbon dioxide emissions and conserving natural resources.