基于钙离子溶蚀量的水泥基材料耐久性试验

Cement-based materials durability experiments based on calcium ion dissolution

采用0.5 mol/L硝酸溶液浸泡方法,对净浆、砂浆和混凝土开展了加速溶蚀试验,研究了抗压强度、钙离子累计相对溶蚀量和溶蚀深度等之间的关系。研究结果表明:硝酸加速环境下的溶蚀过程满足Fick定律,砂浆和混凝土的溶蚀速度较接近,且明显快于净浆;抗压强度随钙离子累计相对溶蚀量和溶蚀深度的增长而线性下降;钙离子累计相对溶蚀量与溶蚀面积比有很强的线性相关性,且与试件类别和水灰比无关,0.5 mol/L硝酸加速环境下,两者之间的比例系数为0.56,表明溶蚀区约56%的钙离子被溶蚀掉。

In order to analyze the relationship between compressive strength,cumulative relative leached calcium and leaching depth,the accelerated leaching experiments of the cement paste,mortar and concrete in 0.5 mol/L nitric acid solution were carried out.Results show the calcium leaching process of cement-based materials in the nitric acid solution follows the Fick′s law.The leaching rates of mortar and concrete are similar and obviously faster than that of paste.The compressive strength decreases linearly with the increase of cumulative relative leached Ca2+and leaching depth.There is a strong linear relationship between the cumulative relative leached Ca2+and the leached area ratio,which is independent of the block type and the water cement ratio.For contact leaching,the porosities on block surface and in the leaching peak area increase sharply,and the leaching rate and degree decrease from the surface to the inside.In 0.5 mol/L nitric acid,the ratio coefficient between the two is 0.56,indicating that about 56%of the Ca2+in the leached area are leached away.