A mix proportion design method of manufactured sand concrete based on minimum paste theory

•We propose a mix proportion design method of manufactured sand concrete (MSC) based on a minimum paste theory.•The microfines is included in the proposed mix proportion design method of MSC.•The effect of microfines on the workability and mechanical properties of MSC is investigated.•The proposed design method is expected to improve the volume stability and cracking-resistant performance of MSC. The mix proportion of manufactured sand concrete (MSC) was designed based on a minimum paste theory, where microfines was added to replace part of cement. The effect of microfines content on the workability and mechanical properties of MSC was investigated. The study reveals that the microfines can be used as an ingredient of MSC and a moderate amount of microfines can improve the workability of MSC. The compressive strength, axial compressive strength, splitting tensile strength and elasticity modulus of MSC increase gradually with the increasing of microfines. However, too much amount of microfines makes the mechanical properties of MSC decrease. Mixing microfines in MSC can reduce the dosage of cement, carbon emission, concrete cost and benefit from environment protection. The use of the minimum paste theory in the mix proportion design of MSC is expected to improve the volume stability and cracking-resistant performance of MSC.