在全苏水利科学研究所(ВНИИГД)的泡沫和绝缘材料试验室里研究一种用于建筑无槽永久性过梁的耐水性混合物,它是以石膏为基础掺入水泥和其它建筑材料得到的。但是,这种外加水泥的石膏砂浆,在硬化时,由于生成水化硫铝酸钙(ГСАК)使其发生开裂。在砂浆尚未硬化时形成的ГСАК所占据的体职略小于各组份占的体积的总和,因此,砂 A water-resistant mixture for the construction of non-grooved, permanent lintels was studied in the Foam and Insulation Materials Laboratory of the Quanzhou Institute of Hydraulic Research (ВНИИГД), which was obtained by adding gypsum into cement and other building materials. . However, in the gypsum mortar with this additional cement, the hydratable calcium sulfoaluminate ((САК) is formed to cause cracking when it is hardened. The body occupied by ГСАК formed when the mortar has not yet hardened is slightly smaller than the sum of the volumes occupied by the components. Therefore, the sand