气泡混合轻质土试样制备研究

Study of the preparation of air-foam treated lightweight soil samples

由于气泡消泡的缘故,室内制备和现场浇筑气泡混合轻质土时存在塌陷问题。为分析和解决该问题,以砂土为原料土,开展了不同温差、湿度和掺砂与否条件下3种密度气泡混合轻质土的制备试验,并测定了各试样的高度和强度,基于热力学理论分析了3种因素对试样制备和强度的影响规律。试验结果表明,试样制备时温度与养护温度之间的温差是影响气泡混合轻质土胀缩性的决定性因素,轻质土中的气泡含量越高,受温差影响越大,通过控制温差即可解决塌陷问题;湿度和掺砂与否对气泡混合轻质土的试样制备影响不明显,但是湿度高会延长试样脱模时间以及影响试样的完整性;温差和温度共同影响气泡混合轻质土的早期强度,其中温差主要影响试样密实度,温度主要影响水泥水化反应速率。试验结果可为气泡混合轻质土制备和施工时间点选择提供借鉴。

In consequence of froth breaking, there is a caved problem about air-foam treated lightweight soil after casting indoor and in-site. To analyze and solve the problem, a series of samples preparation experiments on sand were conducted on air-foam treated lightweight soil with three specific densities under different conditions, i.e., temperature, humidity and sand mixing or not. Meanwhile, the height and strength of samples were measured. Based on the thermodynamics theory, the effects of three factors on the preparation and strength of the samples were analyzed using experimental data. The results show that temperature difference is the decisive factor affecting the shrinkage and expansion of air-foam treated lightweight soil. The temperature difference impact greatly in sample of high bubble content. Humidity and sand mixing barely affect sample preparation while the mold unloading time of samples will be extended and the integrity of samples will be affected when ambient humidity becomes higher. Early strength of samples is influenced by temperature and temperature difference. temperature difference mainly affects the density of samples, and the temperature mainly affects the rate of hydration reaction of cement. The results of this study provide reference for the preparation and construction time of air-foam treated lightweight soil.