Circulating Fluidized Bed Combustion Fly-Ash-Activated Slag Concrete as Novel Construction Material

The performance of a novel concrete made with an eco-binder, referred to as SCA binder, that only contains raw slag (S) and raw circulating fluidized bed combustion (CFBC) fly ash (CA) without ordinary portland cement was evaluated. The major hydration products of SCA binders are ettringite, C-S-H, and C-A-S-H, which lead to SCA pastes with proper setting times, dense microstructures, and high compressive strengths up to approximately 80 MPa (11,600 psi). The SCA concrete, which is suitable for practical applications, has compressive and tensile strengths at 91 days of approximately 50 MPa (7250 psi) and nearly 5 MPa (725 psi), respectively. In addition, the SCA concrete shows moderate expansion at early ages and a low rate of shrinkage after 91 days of exposure. The regression equations that relate the splitting tensile strength, modulus of elasticity, and ultrasonic pulse velocity to, the compressive strength are presented with a satisfactory coefficient of determination.