Study on the interface of sulphoaluminate cement concrete

The factors that influence the thickness and connectivity of interfacial transition zone (ITZ) of sulphoaluminate cement concrete are analyzed. Fine cement particle are coated on the surface of aggregates before concrete mixed. The quantity of fine cement particle can be calculated with a model of graph theory approximately. The pre-coated aggregates in concrete are used to decrease the thickness and the connectivity of ITZ, and improve the strength and impermeability of concrete. Porosities of both concretes incorporating uncoated and pre-coated aggregates have been measured. The result indicates that porosity of concrete of pre-coated aggregates is reduced and the strength is improved. In addition, ITZ of sulphoaluminate cement concrete is analyzed by SEM-EDS The results show that there is a large amount of ettringite crystal in the ITZ.