超低水胶比水泥硬化体的早龄期显微结构与强度

Early-Age Strength and Microstructure of Hardened Cement Compacts with Ultra-Low Water to Binder Ratio

利用钢制模具制备干粉水泥压实体,再用毛细吸水的方法成型超低水胶比硅酸盐水泥、不同细度矿粉复合硅酸盐水泥压实体样品。利用压汞测孔、背散射电子成像和小角X射线散射技术测试了水泥压实体及其水化硬化体的早龄期结构,分析了超低水胶比水泥硬化体1 d强度性能。结果表明:水泥水化早龄期硬化体内、外层水化产物的堆积密度受水泥水化前颗粒堆积结构的影响,决定水泥早龄期强度的关键因素是硬化体内层水化产物的堆积密度。在含有较多细化堆积毛细孔的细矿粉复合硅酸盐水泥压实体中,水化早龄期硬化体生成最低堆积密度的外层水化产物和最高堆积密度的内层水化产物,抗压强度最高。

Anhydrous Portland cement or slag blended cement with different finenesses was compacted in a steel mould to absorb water for the preparation of hardened compacts with an ultra-low water to binder ratio. The structure of cement compacts and nanostructure of hardened compacts were investigated by mercury intrusion porosimetry, back scattered electron imaging and synchrotron small angel X-my scattering. The compressive strength of hardened compacts with an ultra-low water-binder ratio was analyzed. The result shows that the packing densities of the inner and outer hydration productions at early age are affected due to the packing of anhydrous cement particles. A key factor to obtain the early-age strength of hardened compacts with an ultra-low water-binder ratio is the packing density of the inner hydration productions. A compact with finer and more pores was prepared using a finer blended cement with slag. The lowest packing of the outer productions and the highest packing of the inner productions occur in the hardened compact at early-age hydration. Consequently, the maximum strength of the hardened compact can be achieved.