不同CaO/SiO2比的粉煤灰混凝土渗透溶蚀试验研究

通过压力水对混凝土渗透液的化学成份分析 ,发现粉煤灰混凝土中胶凝材料的主要化学成分 Ca O,Si O2 它们的比值不同其溶出规律不同 ,当 Ca O/ Si O2 的摩尔比 >1时 ,渗透液中 Ca O不断溶出 ,同一压力下 Ca O的溶出随时间延长先增加后渐渐减少 ,而 Si O2 开始有少量溶出而后吸收 ,当渗透水压力升高时 ,Ca O的溶出量及 Si O2 的吸收量无明显增加趋势 ,当 Ca O/ Si O2 <1渗透液中有 Si O2 溶出 ,同一压力下 Si O2 的溶出随时间延长变小 ,随着渗透水压的升高溶出量有上升趋势。其比值小的 Si O2 溶出量大 ,Ca O的吸收量也大。比值接近于 1的混凝土渗透液中 Si O2 溶出量、Ca O吸收量均小 ,因此可以推测对于粉煤灰混凝土 ,粉煤灰加入量应考虑 Ca O/ Si O2 的比值→ 1为宜 ,此比值其Ca O或 Si O2 的溶出量最小 ,吸收量也小 ,对混凝土的水化产物数量不会有很大影响。

Experimental Research about the Permeability and Corrosion of Fly Ash Concrete with Different Rate of CaO/SiO2 on the Condition of Pressured Water

By chemical analysis of the water permeated from the concrete, We find calcium oxide and silica, main chemcial composition of binding materials in fly ash concrete, the different rate of CaO/SiO 2,the different reyularity of corrosion. When the molar rate of CaO/SiO 2 is move than 1, calcium oxide in the permeated water dissolves out continuosly, Under the condition of the same pressure, the dissolution of calcium oxide increases at first and then decreases gradually along with time extension, but silica dissolves out a little at first and then is absorbed, When the pressure of pemeated water increases, the dissolving capacity of calcium oxide and the absorbing capacity of silica have no obviously increasing trend; When the molar rate of CaO/SiO 2, is less then 1, silica oxide in the permeated water dissolves out. Under the same pressure, the dissolution of silica becornes small along with time extension, and its dissolving capacity has increasing trend when the pressure goes up. the dissolving capacity of silica is larger when the rate is smaller, so is the absorbing capacity of calcium oxide. The dissolving capacity of silica and the absorbing capacity of calcium oxide in permeated water are both small when the rate approaches 1. Therefore, it is inferred that the volume of fly ash added in concrete must be considered and assure the rate of CaO/SiO 2 approaches 1. In this case, the dissolving capacity of calcium oxide and silica is the smallest and their absorbing capacity is also small, which will not greatly affect on the amount of hydrate of concrete.