Alkali-silica reactivity of foam glass granules in structure of lightweight concrete

Lightweight aggregate concrete (LWAC) made with foam glass granules (FGG) are subjected to alkali silica reactions (ASR) between FGG and cement matrix. The aim of the study was to identify the effect of different cements on the ASR which occurs between FGG and binder. Eight cements with different chemical composition and Na2O equivalent were used for production of LWAC specimens. Loose bulk density, water absorption, material density and porosity were determined for FGG. Properties of fresh LWAC, like density, flow table test and cone slump as well as air content were tested. Mechanical and physical properties, such as flexural and compression strength tests, were performed for 28 days old LWAC specimens. Tests with scanning electron microscope and microstructural investigations were performed for foam glass granules and hardened concrete specimens before and after exposure to alkali solution. The ASR test was performed according to RILEM TC 106-AAR testing recommendations. Relative expansion of 0.160-0.205% was detected which does not comply with standard recommendations (0.054%). Moreover, flexural strength reduction up to 73% and compression strength reduction up to 43% were detected due to deleterious ASR. It was detected that Na2Oeq. is only one of the criteria that determine choice of cement for production of sustainable LWAC. Therefore other measurements must be provided to limit deleterious expansions and comply with the standard requirements.