Properties of concrete made of multicomponent mixes of low-energy demanding binders

A series of tests was performed to investigate salient mechanical properties of concrete in which Portland Cement (PC) was replaced by different combinations of low energy-demanding materials, namely binary or ternary combinations of Pulverised Fuel Ash (PFA), Metakaolin (MK) and reactive magnesia (MgO) at various percentages. The potential use of the latter material in structural concrete has not been established and further research is needed prior to industrial scale applications. Tests investigated the setting times and soundness of the resulting cement, as well as the workability, cube compressive strength at various curing times, tensile splitting strength, flexural strength and water absorption of the resulting concrete. The results showed that mixes combining the above materials at the right proportions i.e. MK up to a maximum of 20%, PFA up to 20% and 5-10% MgO, show good potential for replacing high proportions of PC (up to 50%), giving good quality concrete in terms of strength and durability, with improved environmental impact.