Effects of workability modifiers blending on fresh properties of limestone metakaolin blended cement

It is widely acknowledged that metakaolin in blended cements improves engineering properties and durability. However, it reduces the blend's fresh flowability and shortens slump retention time. In this investigation, three workability modifiers (WM) were used to fluidize a mixture of ASTM C595 Type IL cement containing 15 wt.% metakaolin, called limestone metakaolin-blended cement (LMC). The study aimed to use WMs and their combinations to curb the workability loss of the LMC system. Dosages of each WM and blends of them for the LMC system were determined in which the LMC reached neat-cement equivalent yield stress and similar flowability and workability retention. Compressive strength and heat of hydration were also studied to evaluate the impacts of the WMs on the LMC system. The results highlighted the possibility of using combinations of WMs to deal with the loss in the rheological performance of calcined clay limestone blended cement.