Experimental Study for Effects of Hydrate Products on Shrinkage Behaviour in Low Volume Blast Furnace Slag Cement Concrete

Blast furnace slag (BFS) cement concrete is reported to be prone to shrinkage cracking at high temperature in tropical climate. To solve this problem is important to extend BFS cement concrete which is known as a key to reduce carbon footprint in concrete production. This study focuses shrinkage reducing effects to increase gypsum and calcium carbonate in low volume BSF cement concrete as trace additives. Free shrinkage experiment and hydration analysis experiment are conducted to clarify the focused issues. These two experiments clarified that: i) increasing gypsum amount up to 4.5% of binder mass effectively reduced free shrinkage strain subjected to 30 degree of ambient temperature, ii) this free shrinkage reduction is considered due to restraining transformation of Ettringite to Monosulfate, which is known to lead serious volume reduction in hydrate products, iii) increased gypsum amount up to 4.5% appeared not a source of Delayed Ettringite Formation.