Foamcrete is also known as Foamed Concrete, cellular light weight concrete or reduced density concrete.
It is a cement based slurry with minimum of 20% Foam entrained into the plastic mortar.
production of foamed concrete was first carried out in the 1950s and 60s. Following that, new admixtures were developed in the late 1970s and early 80s, which led to the commercial use of foamed concrete in construction projects.
Foamed concrete typically consists of a slurry of cement and fly ash or sand and water, although some suppliers recommend pure cement and water with the foaming agent for very lightweight mixes. This slurry is further mixed with a synthetic aerated foam in a concrete mixing plant. The foam is created using a foaming agent, mixed with water and air from a generator. The foaming agent used must be able to produce air bubbles with a high level of stability, resistant to the physical and chemical processes of mixing, placing and hardening.
Foamed concrete mixture may be poured or pumped into moulds, or directly into structural elements. The foam enables the slurry to flow freely due to the thixotropic behaviour of the foam bubbles, allowing it to be easily poured into the chosen form or mould. The viscous material requires up to 24 hours to solidify (or as little as two hours if steam cured with temperatures up to 70 °C to accelerate the process, depending on variables including ambient temperature and humidity. Once solidified, the formed produce may be released from its mould.
Foamed concrete can be produced with dry densities of 400 to 1600 kg/m³, with 7-day strengths of approximately 1 to 10 N/mm² respectively. Foam concrete is fire resistant, and its thermal and acoustical insulation properties make it ideal for a wide range of purposes, from insulating floors and roofs, to void filling. It is also particularly useful for trench reinstatement.
The energy absorption capacity of foamed concrete was approximated from drop testing and found to vary from 4 to 15 MJ/m3 depending on its density. With optimum absorption estimated from a 1000 kg/m3 moderate density mix at water to cement (w/c) ratios from 0·6 to 0·7.
Improvement and recent trend:
The development of synthetic-enzyme based foaming agents, foam stability enhancing admixtures and specialised foam generating, mixing and pumping equipment has improved the stability of the foam and so foam concrete, making it possible to manufacture as light as 75 kg/m³ density. The synthetic enzyme based foaming agents are a new and innovative foaming agent technology developed recently. It consists of highly active proteins of biotechnological origin and is not based on the unattractive protein hydrolysis. In recent years foamed concrete has been used extensively in highways, commercial buildings, disaster rehabilitation buildings, schools, apartments and housing developments in countries such as Germany, USA, Brazil, Singapore, India, Malaysia, Kuwait, Nigeria, Botswana, Mexico, Indonesia, Libya, Saudi Arabia, Algeria, Iraq and Egypt.