Influence of ground pumice on compressive strength and air content of both non-air and air entrained concrete in fresh and hardened state

Study investigates the influence of ground pumice (GP) addition on compressive strength and air content of air entrained and non-air entrained concrete. Control Portland cement concrete was prepared by keeping the binder amount at 400 kg/m3 with water binder (W/B) ratio 0.45. Air entrained Portland cement concrete mixtures were also prepared by addition of 0.025%, 0.05% and 0.075% air entraining agent (AEA) dosages to control Portland cement concrete. All Portland cement concretes mixtures were modified by inclusion of 10%, 15%, 20% and 25% GP as cement replacement in mass basis, and then concretes containing ground pumice were obtained. Air contents of all fresh concretes were measured. Entrained air void area values on cut surface of hardened concrete were determined by image processing technique. Increase in air entraining agent dosage content in fresh concrete exhibited an increase not only in air content but also flow diameter value of fresh concrete. Addition of ground pumice as a cement replacement in concrete caused reduction in air content and flow diameter, however, it increased compressive strength of air entrained concrete. Compressive strength values related inversely with the air contents of fresh concrete as well as air void area values of hardened concrete computed by image processing technique. Air contents of fresh concrete and image processing void area values of hardened concrete has shown a good relationship between themselves. Image processing can be used to measure air content of hardened concrete.