A Study On The Property Of Foam Concrete With Water Repellents

Classified as lightweight and porous material,foam concrete possesses various kinds of excellent performance,such as selfweight, excellent thermal insulation, sound insulation and utilization of wastes .Foam concrete can be obtained for application to building energy conservation, reducing structural weight and foundation displacement backfilling and other aspects.However, attributed to its main raw materials,oridinary Portland cement, and high porosity,water absorption of foam concrete is higher than ordinary concrete. Especially in water surroundings,the durability and other properity of foam concrete is reduced,so the usable range is limited.To improve the water repellency of foam concrete , zinc stearate emulsion, micro wax emulsion and polysiloxane solution were selected as waterproof agents in this experiment.Integral water repellent treatment was made to reduce the water absorption and permeated height.The compatibility between waterproof agents and foaming agent has great influence on the performances of foam concrete,so,firstly, the negative impact of waterproof agent on fluidity , wet density and volume stability were studied. Alkanolamide is effective to be used for improving the stability of fresh foam concrete with waterproof agents.Four different water-cement ratios of concrete rang from 0.3 to 0.6 have been selected,the experiment studied the effect of content of waterproof agents on the property of foam concrete,including compressive strength,water absorption and permeated height under 0.1MPa water pressure. which is expected to the best waterproof agent and the optimal content was found out by analyzing the parameter transformation.Compared with control foam concrete, the foam concrete mixed waterproof agents showed the same variation trend on compressive strength,water absorption and permeated height.The results showe that the zinc stearate emulsion not only reduces the 28d compressive strength and significantly retards the hydration of foam concrete,but aslo obtained the optimum waterproof efficiency; micro wax emulsion shows good waterproof property,but it also reduces the compressive strength; The waterproof principle decides the waterproofness of polysiloxane solution is worse than the other two,in contrast, the compressive strength is enhanced .In addition,the paper aslo studied the impact of air entraining agent on the property of foam concrete which has the best waterproofness.The result shows that the compressive strength is enhanced for the bubble diameter entrained by air entraining agent is smaller than the foam diameter of foaming agent,but also, the pore volume ratio decreases. Air entraining agent can not improve the waterproofness.