What is the history behind ribbed raft waffle slabs?

Ribbed raft waffle slabs were first used in Australia using cardboard void formers. Subsequently a range of void forming materials from precast plastic domes to recycling empty glass bottles neck down in sand or waste car tyres have been promoted. Polystyrene 'pods' have quickly emerged as the dominant void form material.

Ribbed raft waffle slabs have become increasingly popular in New Zealand with a surge in their use as a means of meeting tight time frames when construction activity peaked early this century. Now 20% of Auckland's domestic and light commercial constructions are on ribbed raft waffle slabs. 

The increasing focus on the deficiencies of traditional concrete slab foundation construction following the Christchurch earthquakes has seen the rapid uptake of ribbed raft waffle slabs nationwide.