The effect of one-part activator on drying shrinkage and mechanical properties of lightweight alkali-activated slag concrete

In order to reduce the negative environmental effects of Portland cement production, lightweight alkali-activated slag concrete can be considered as a new building material in the construction industry. According to the studies conducted by the authors, there is no research about drying shrinkage of one-part lightweight alkali-activated slag concrete. In the present study, the effect of slag content, the dosage of one-part alkali-activator and aggregate combination on the compressive strength and drying shrinkage of lightweight one-part alkali-activated slag concrete were considered. Also, two types of curing methods i.e. water curing and plastic cover curing were selected to investigate the effect of curing conditions on drying shrinkage and compressive strength. To make lightweight concrete, lightweight aggregate (Leca) was used in combination with natural aggregates and two aggregate combinations, one containing lightweight fine aggregate and normal weight coarse aggregate and one other containing both lightweight fine and coarse aggregates, were considered for conducting the experimental tests. A Portland cement mix was also used to make a reference mix of concrete. Compressive strength of the samples was measured at the ages of 7, 28 and 90 days and the drying shrinkage up to the age of 180 days. According to the results, slump and setting time decreased with increasing slag and activator content, while compressive strength and drying shrinkage increased. Examination of the curing condition of lightweight one-part alkali-activated slag concrete showed that drying shrinkage increased and compressive strength decreased with plastic cover curing.