The effects of aggregate properties on lightweight concrete

This paper describes a study of the effects of several factors on the strength of lightweight aggregate concrete composites: aggregate strength, w/c ratio and the porosities of the interfacial zone and within the hardened cement paste. Concrete samples with three different water cement ratios (i.e. 0.4, 0.44, 0.48) were compared. The crushing strengths of three grades of expanded clay lightweight aggregates (i.e. 25, 15, 5 mm) and the pore distributions of the hardened cement pastes were measured. Increasing the water/cement ratio was found to decrease the strength of lightweight aggregate concrete. The numbers of pores within the cement paste and in the aggregate/cement paste interfacial zone were found to increase.