Effect of particle size of coarse aggregate on mechanical properties and freeze-thaw resistance of ceramsite concrete

As an indispensable component of ceramsite concrete [CC], the particle size of coarse aggregate affects the performance of concrete to a certain extent. To further investigate the effect of particle size of ceramsite on mechanical properties and freeze-thaw resistance of CC simultaneously, seven series of CC containing ceramsite with various particle sizes were designed based on three different particle sizes of coarse aggregate which were 5~6 mm, 10~11 mm and 15~16 mm respectively. The results showed that the compressive strength of CC at 28 days increased with the decrease in the average particle size. When the ceramsite with different particle sizes was incorporated, the compressive strength of CC increased faster in the early and middle curing stages. The splitting tensile strength and flexural strength of CC at 28 days also exhibited the same change trend as that in the compression test. However, incorporating ceramsite with large particle size could improve the freeze-thaw resistance of CC. After 100 freeze-thaw cycles, the mass loss rate of CC containing ceramsite with a particle size of 5~6 mm was 3.7 %, whereas that of 15~16 mm was only 2.1 % which was the lowest. Meanwhile, the former’s relative dynamic elastic modulus [RDEM] was 62.8 %, reaching the minimum value. By comparing the scanning electron microscopy images, the cracks of cement paste and interfacial transition zone [ITZ] of CC containing ceramsite with smaller particle size were wider after freeze-thaw cycles.