基于薄层毛细渗透技术的水泥和矿物掺合料动态接触角测定

Determination of dynamic contact angles of cement and mineral admixtures based on thin-layer wicking technique

为表征水泥和矿物掺合料与水的润湿性，采用薄层毛细渗透方法对水与不同水化时间的水泥净浆粉末及粉煤灰、矿渣粉、硅灰粉等矿物掺合料粉体的动态接触角进行了测试．结果表明，选用无水乙醇做参比液，水与水泥颗粒粉末表面的初始相对动态接触角约56。，随着水化的进行，动态接触角逐渐降低，最终稳定在（22±1）°．水在粉煤灰粉体和矿渣粉体表面的相对动态接触角分别为56°～60°和53°～63°，在硅灰粉体和CaC03粉体表面的相对动态接触角分别约为43°和70°．就亲水性而言，由强到弱的顺序依次为：硅灰、水泥、粉煤灰、矿渣粉、CaCO3．水化水泥浆体粉末与水的接触角随水化进行逐渐减小并最终趋于恒定．

To test the wettabilities of cement and mineral admixtures with water, the dynamic contact angles between water and cement paste powders, fly ash, slag, silica fume and other mineral admixtures with different hydration times were characterized by using thin-layer wicking technique. The results show that by using ethanol as the reference liquid, the relative dynamic contact angle of water and cement particles is initially about 56°; as the hydration proceeds, the contact angle gradually de- creases and eventually stabilizes at （22±1 ）°. The relative dynamic contact angle of water and fly ash powder and that of water and slag powder are 56° to 60° and 53°to 63°, respectively. The relative dynamic contact angle of water and silica fume powder and that of water and CaCO3 powder are about 43° and 70°, respectively. The order of the hydrophilicities of these powder materials, from strong to weak, is silica fume, cement, fly ash, slag and CaCO3 powder. As the hydration proceeds, the contact angle between cement paste and water decreases gradually and finally tends to be constant.