Gas Concrete

gas concrete

Lightweight concrete produced by developing voids by means of gas generated within the unhardened mix (usually from the action of cement alkalies on aluminum powder used as an admixture). Also see aerated concrete and foamed concrete.

---

Gas Concrete 

a variety of cellular concrete; made by injecting a gas-forming agent (usually aluminum powder) into a mixture consisting of a binding component (such as portland cement or milled quicklime), a siliceous component (milled quartz sand), and water. The gas-forming process takes place as a consequence of the chemical reaction between the calcium hydroxide and the aluminum; the hydrogen that escapes during this reaction causes a foaming up of the solution, which then hardens, retaining a porous structure. For quick hardening and production of items made from gas concrete with the necessary strength factors, the products are subjected to heat and moisture treatment in autoclaves at a steam pressure of not less than 9 atmospheres and a temperature of 175° C.

Gas concrete is used chiefly as a heat insulating material, especially in construction during the fabrication of the outer enclosure of buildings. The density of gas concrete is 300, 400, 500, 600, and 700 kg/m³; its compressive strength is 0.8, 1.2, 2.5, 3.5, and 5.0 meganewtons per sq m (8, 12, 25, 35, and 50 kg per sq cm), respectively. There are a number of varieties of gas concrete, which differ according to the type of cementing or siliceous material used: for example, gas silicate (cementing component, quicklime), gas-cinder concrete (siliceous component, cinders from a heat and electric power plant).

REFERENCES

Stroitel’nye normy i pravila, part 1, section C, ch. 3: “Betony na neorganicheskikh viazhushchikh i zapolniteliakh.” Moscow, 1963.
Krivitskii, M. la. Zavodskoe izgotovlenie izdelii iz gazobetona. Moscow, 1963.

M. IA. KRIVITSKII