Influence of Coarse Aggregate on Drying Shrinkage of Concrete
Junji NAKAMOTO, Ryou MASAKI and Keita TAKAGI
Abstract:The large drying shrinkage of concrete can cause cracks in concrete structures. For solving the cracking problem, it is required to clarify the relationship between the shrinkage of concrete and the quality of aggregate in it. The main purpose of this study is to obtain data on the drying shrinkage of coarse aggregate available at the stockyard in ready-mixed concrete plants, and its static modulus of elasticity and its compressive strength in order to utilize the coarse aggregate as local resources efficiently. The length change test of concrete and the drying shrinkage cracking test of restricted concrete are also carried out on the three types of concrete mixtures. The results are follows: The quality of coarse aggregate is one of the crucial factors affecting the quality of concrete. The drying shrinkage of the aggregate increases the shrinkage of concrete. The shrinkage of coarse aggregate is also related to the static modulus of elasticity as well as the rate of water absorption. The drying shrinkage of coarse aggregate can be estimated in 3-7 days by using the strain gauge method. Key Words:Coarse aggregate, Drying shrinkage, Static modulus of elasticity, Rate of absorption, Compressive strength, Crack, Concrete