Study on Shrinkage Deformation of High Flexural Strength Concrete at Early Age

Abstract

Shrinkage deformation of concrete in early age, which mainly varies with factors such as cement quantity, bonder type, air content and sand aggregate ratio, was studied. Test species, which sizes are 100 mm×100 mm×515 mm, were put into temperature and humidity controlled box. Value of shrinkage deformation in different humidity was recorded by micrometer gauge. Humidity will vary automatically with need in (20±1)°C temperature level in the box. Humidity increases from current value to 99 percent in 30 minutes. Initial value of shrinkage deformation should be achieved after 180 minutes with humidity of 99 percent. Then humidity decreases from 99 percent to 10 percent in 30 minutes. Value of shrinkage deformation should be achieved after 180 minutes with humidity of 10 percent. It will experience three loops around. It is shown that: (1) early age shrinkage deformation of cement concrete is enlarged with increasing cement quantity; (2) early age shrinkage deformation of high flexural strength concrete (HFSC) with pure silica is larger than those with fly ash and silica and those with pure fly ash. The late two are almost with the same shrinkage deformation; (3) early age shrinkage deformation of HSFC is enlarged with increasing air content at 3 days age; (4) after 28 days age, early age shrinkage deformation of HSFC is reduced with increasing air content when it is below 6.8 percent and it will enlarge with air content when above 10 percent.