Deformation and mechanical properties of quaternary blended cements containing ground granulated blast furnace slag, fly ash and magnesia

Shrinkages of cementitious materials may lead to cracking under restrained conditions. This study was motivated to develop non-shrinkage quaternary blended cements through blending slag and fly ash with Portland cement containing reactive MgO. The hydration process, autogenous shrinkage at early age, long-term volume deformation, mechanical properties, and microstructure of cement specimens were investigated. Results showed that the autogenous shrinkage of the cement pastes was effectively mitigated due to the compensation of the MgO present and the reduction of cement content owing to the partial replacements with slag and fly ash. The mechanical strengths of the blended cement mortars were lower than that of the corresponding plain Portland cement mortars at early age of 3d, but increased significantly to be similar or higher at late ages of 28d and 90d. This is attributed to the microstructure densification and the interface microstructure enhancement due to the reaction of SCMs with clinker phases.