Study On Correlation Of Drying Shrinkage Between Cement Mortar And Concrete

The process of drying shrinkage is one of the most popular dimensional changes in concrete. Thus, it's of great sense to do research on correlation of drying shrinkage between cement mortar and cement concrete.Test methods for drying shrinkage of cement mortars and concretes were established at first, and the drying shrinkage values were tested by these methods. At last, the correlation of drying shrinkage between cement mortar and concrete was obtained.Drying shrinkage testing method of cement mortar was established on the foundation of studying drying shrinkage characteristics, in which each batch for four test specimens consist of 450g of cement, 1350g of sand, and 225g of water and the prisms are 25×25×280mm. By this method, the volume of work was cut down and it's no need to add water according to fluidity. Meanwhile, the testing method of concrete was improved, which is more convenience and more accurate.There are many factors influencing drying shrinkage of cement mortar. It was observed that increase in cement-water ratio and fly ash content decrease drying shrinkage. Significant shrinkage reduction is obtained by adding mineral admixture. Presence of water reducing agent increases the drying shrinkage. It was found that the longer the curing time the higher the drying shrinkage. The drying shrinkage of cement mortars after curing at 20°C and 60°C before drying was investigated. Results show that: for reference cement mortar, the higher the curing temperature the lower the drying shrinkage while for cement mortars with mineral admixture, the situation is the reverse.The effects of the following factors which affect drying shrinkage of concrete were investigated: water-cementitious materials ratio, unit water consumption, mineral admixture, and fly ash content. Decrease in water-cementitious materials ratio will increase drying shrinkage when water-cementitious materials ratio is below 0.5,...