Kuziak Justyna, Zalegowski Kamil, Jackiewicz-Rek Wioletta, Stanisławek Emilia
Department of Building Materials Engineering, Warsaw University of Technology, 00-637 Warsaw, Poland.
Materials (Basel). 2021 May 29;14(11):2927. doi: 10.3390/ma14112927.
The study of the effect of cement type on the action of an admixture increasing the volume of concrete (containing aluminum powder), used in amounts of 0.5-1.5% of cement mass, was presented. The tests were carried out on cement mortars with Portland (CEM I) and ground granulated blast-furnace slag cement (CEM III). The following tests were carried out for the tested mortars: the air content in fresh mortars, compressive strength, flexural strength, increase in mortar volume, bulk density, pore structure evaluation (by the computer image analysis method) and changes in the concentration of OH ions during the hydration of used cements. Differences in the action of the tested admixture depending on the cement used were found. To induce the expansion of CEM III mortars, a smaller amount of admixture is required than in the case of CEM I cement. Using the admixture in amounts above 1% of the cement mass causes cracks of mortars with CEM III cement due to slow hydrogen evolution, which occurs after mortar plasticity is lost. The use of an aluminum-containing admixture reduces the strength properties of the cement mortars, the effect being stronger in the case of CEM III cement. The influence of the sample molding time on the admixture action was also found.
本文介绍了水泥类型对一种增加混凝土体积的外加剂（含铝粉）作用效果的研究，该外加剂用量为水泥质量的0.5 - 1.5%。试验在波特兰水泥（CEM I）和磨细粒化高炉矿渣水泥（CEM III）制成的水泥砂浆上进行。对试验砂浆进行了以下测试：新拌砂浆中的含气量、抗压强度、抗折强度、砂浆体积增加量、堆积密度、孔隙结构评估（采用计算机图像分析方法）以及所用水泥水化过程中OH离子浓度的变化。发现了根据所用水泥不同，试验外加剂作用效果存在差异。为使CEM III砂浆产生膨胀，所需外加剂用量比CEM I水泥情况下少。当外加剂用量超过水泥质量的1%时，由于砂浆失去可塑性后氢气缓慢析出，会导致CEM III水泥制成的砂浆出现裂缝。使用含铝外加剂会降低水泥砂浆的强度性能，在CEM III水泥情况下这种影响更强。还发现了样品成型时间对外加剂作用的影响。
