掺合料对砼早期抗裂性的影响

The Resistance to Cracking of Concrete with Additive at Early Age

采用平板法研究了掺合料对砼早期抗裂性的影响。试验结果表明 ,在同水胶比情况下 ,矿粉、粉煤灰取代水泥 ,可明显改善砼的早期抗裂性 ;掺量越高 ,改善效果越明显。在同标号 (R2 8)情况下 ,掺加Ⅱ级粉煤灰对砼的早期抗裂性仍有改善效果。掺合硅灰使砼早期出现裂缝的可能性明显增加。

The relationship between the varieties of additive and the resistance to cracking of concrete at early age was studied by using plain concrete specimen. The results show that the resistance to cracking of concrete at early age can be improved by ground slag or fly ash replacement of cement at the same water-binder ratio; the more the addition of ground slag of fly ash, the more obvious the effect of improvement. When the 28-day compressive strength of concrete is the same, the resistance to cracking of concrete with grade Ⅱ fly ash early age is able to be remarkably improved. There is negative effect to the resistance to cracking of concrete at early age with silica fume.