Effects of foam content on chloride ingress and steel corrosion in foamed concrete

The effect of foam porosity on absorption, chloride ingress and resistance to corrosion of embedded steel under a chloride environment was studied. Performance of mixes with water/cement (w/c) ratio of 0.5 and moderate and high foam contents of 20 and 50% were determined and compared with those of a base mix with the same proportions but without foam incorporation. A structural grade foam concrete with w/c ratio of 0.4 and foam content of 20% was also considered, together with a conventional concrete of equal strength level. The results show increased absorption of the paste fraction owing to foam incorporation as some of the foam porosity became saturated when submerged in water. Foam incorporation also resulted in increased chloride ingress and reduced durability against steel corrosion compared with the base mix with the same w/c ratio. However the structural grade foam concrete, owing to its lower w/c ratio, achieved similar levels of performance as the base mix and performed better than the conventional concrete of equal strength level.