Durability aspect of concretes composed of cold bonded and sintered fly ash lightweight aggregates

This study reports the finding of an experimental study carried out on the durability related properties of the lightweight concretes (LWCs) including either cold bonded (CB) or sintered (S) fly ash aggregates. CB aggregate was produced with cold bonding pelletization of class F fly ash (FA) and Portland cement (PC) while S aggregate was produced by sintering the fresh aggregate pellets manufactured from FA and bentonite (BN). Two concrete series with water-to-binder (w/b) ratios of 0.35 and 0.55 were designed. Moreover, silica fume (SF) with 10% replacement level was also utilized for the purpose of comparing the performances of LWCs with and without ultrafine SF. The durability properties of concretes composed of CB and S aggregates were evaluated in terms of water sorptivity, rapid chloride ion permeability, gas permeability, and accelerated corrosion testing after 28 days of water curing period. The compressive strength test was also applied to observe the strength level at the same age. The results revealed that S aggregate containing LWCs had relatively better performance than LWCs with CB aggregates. Moreover, the incorporation of SF provided further enhancement in permeability and corrosion resistance of the concretes.