Properties of High-Strength and High-Fluidity Lightweight Concrete

High-strength and high-fluidity lightweight concretes have been developed using silica fume blended cement and belite-rich cement with a designed compressive strength from 40 to 60 MPa. Test conditions and parameters were water-cement ratio of 0.22, 0.33 and 0.40, curing temperature of 5, 20 and 35 deg C, curing method of standard and sealed curing and 3 types of high-range AE water-reducing agent. Influences of above factors upon flow, flow time, compressive strength, permeability, pore size distribution and total pore volume were studied. The major findings of this study are as follows: (1) Compressive strength of silica fume blended cement concrete was higher than that of belite-rich cement concrete and the effect of water-cement ratio was small. Compressive strength at 7 days was 80 to 90% of the 28-day strength at any curing temperature. (2) Compressive strength of belite-rich cement concrete significantly increased at water-cement ratio of 0.3 to 0.4, and its evolution from 28 to 91 days became larger at lower curing temperatures. (3) Total pore volume of silica fume blended cement concrete at the age of 28 days was smaller than that of belite-rich cement concrete at all curing temperatures of 5, 20 and 35 deg C, and compressive strength became larger with a decrease of total pore volume.