对半个世纪水泥质量发展道路的反思(Ⅱ)——水泥质量与混凝土耐久性之间的矛盾

Reflection on developm e nt path of cement prop erties in last half century (Ⅱ):contradiction between cement properties and concrete durability

较低的渗透性是混凝土耐久性的重要保证,而开裂是影响混凝土渗透性的重要因素。在试验室进行的基于分解论的耐久性试验,未能体现开裂对耐久性的影响。导致结构中混凝土开裂有多种原因,半个世纪以来水泥质量的变迁是一个重要因素。水泥碱含量增加、细度变细及C3S含量增加,使得水泥早期水化速率和早期水化热增加,导致混凝土开裂风险增加。

The better performance of concrete permeability should get better durability. On the other side, inner fissure of concrete is the main cause to influence the permeability. Test in laboratory based on the decomposition theory, couldn't reflect the effect of crack on concrete durability. Since the beginning of 1960 s, application of SP and PC kiln, the improvement of cement properties, including finer particle of cement and high C3 S content, as well as the higher alkali content, might be the most important factor to raise the risk of concrete cracking.