摘要
目的研究硅酸盐水泥-粉煤灰复合胶凝材料体系的抗开裂能力.方法通过实验测定了硅酸盐水泥-粉煤灰复合胶凝材料体系的自由干燥收缩应变和在环形约束条件下的受限干燥收缩应变随龄期的发展,并测试了环形试样的开裂时间及初始裂纹宽度.结果相同水胶比条件下,试样的自由干燥收缩应变随粉煤灰粉煤掺量的增加而增加;粉煤灰掺量为40%和60%时,试样的受限干燥收缩应变大于硅酸盐水泥体系,粉煤灰掺量为20%时,试样的受限干燥收缩应变与硅酸盐水泥体系的发展相近.试样的开裂时间在水胶比为0.28条件下随粉煤灰的掺量的增加而增加,在水胶比为0.50条件下,粉煤灰掺量40%时最长.相同水胶比时,粉煤灰掺量超过一定量时初始裂缝宽度下降.结论从受限状态下的环形试样的开裂时间可以看出,在较低的水胶比条件下粉煤灰提高复合胶凝材料的抗开裂能力较明显.
Free drying shrinkage strain of Portland cement-fly ash composite binder is investigated and its restrained drying shrinkage, cracking time and crack initial width are measured with ring test. The results denote that free drying shrinkage strain increases when dosages of fly ash increase, and for the dosage of 40 % and 60 % fly ash, and the restrained drying shrinkage strain decreases compared with Portland cement and for the dosage of 20% fly ash, the restrained drying shrinkage strain development is similar to that of the Portland cement. When the dosage of fly ash is 0, 20 %, 40 %, 60 %, respectively the crack time of samples increases with the dosage of fly ash increasing at W/B（water binder ratio）0.28 and the crack time reaches maximal value at W/B = 0.50 when the dosage of fly ash reaches 40%. The crack initial width decreases when the dosage of fly ash is 40 % at W/B = 0.28 and is 60 % at W/B = 0.50. The effect of fly ash on the crack resistant of binder is analyzed in this paper and the results show that at low W/B the fly ash can more obviously improve the crack resistant of composite binder than that at high W/B.
出处
《沈阳建筑大学学报（自然科学版）》
EI
CAS
2005年第5期519-522,共4页
Journal of Shenyang Jianzhu University：Natural Science
基金
863项目(2003AA33X100)
关键词
干燥收缩
粉煤灰
水胶比
早龄期
抗开裂能力
drying shrinkage, flay ash, water binder ratio, crack resistant
