Effect of aggregate size on the restrained shrinkage of the concrete and mortar

Mostly, there are investigations about the shrinkage of the concrete.In that research, only the effect of the coarse aggregate on shrinkage is investigated; the fine aggregate is taken into account with the coarse aggregate.When the aggregate grain size increases or decreases, which results will be obtained and how this situation affecting the shrinkage should be determined.In this study, firstly, a widely literature research related to the effect of the aggregate grain size on the shrinkage were carried out.Then, with the help of the experimental studies, it is possible to determine the effect of the aggregate grain size on the shrinkage of the concrete and mortar whether if the aggregate grain size decreases or increases.These experimental researches are on the restrained and drying (free) shrinkage, moreover the compressive and tensile strength tests were carried out.When the effect of the aggregate grain size on the shrinkage, the shrinkage of the mortars with the 4mm maximum grain size is low if the amount of the aggregate is high.Compared to the mortars (especially maximum grain size is 9mm) the shrinkage value is lower.When the concrete with the 16mm maximum grain is produced according to the same ratios of the mortar, the shrinkage of the concrete is less than the shrinkage of the mortar.According to these results, the shrinkage decreases while the maximum grain size is bigger than 9 mm.Coarse aggregate restrains the development of the crack and supply as a micro-crack.The aggregate restrain the shrinkage if the strength of the concrete is high.The compressive and tensile strengths of the mortar and concrete are high at 28 days and decrease at 42 days because the microcracks reduce the strengths a little.