矿物掺和料对自密实混凝土双K断裂参数的影响

Effects of mineral admixtures on double-K fracture parameters of self-compacting concrete

自密实混凝土中由于较多地掺入了矿物掺和料,导致其开裂趋势增加。本文采用楔入劈拉法对15组自密实混凝土和1组普通混凝土试件进行断裂试验,以双K断裂参数评价自密实混凝土的断裂性能,研究单掺粉煤灰、粉煤灰与矿渣复掺、粉煤灰与硅灰复掺3个因素对自密实混凝土断裂性能的影响。结果表明,自密实混凝土的起裂韧度随着粉煤灰单掺掺量的增加而降低,而失稳韧度在粉煤灰掺量为30%时为最高,达1.5534 MPa·m^(1/2);粉煤灰与矿渣复掺情况下,总掺量为30%,复掺比例为3:7时断裂性能最佳,其失稳韧度达到1.7122 MPa·m^(1/2);硅灰的掺入可以改善自密实混凝土的断裂性能。

Self-compacting concrete （SCC） is more likely to crack than normal concrete due to its greater content of mineral admixtures. Wedge splitting method was used in this work to conduct fracture tests on 15 sets of SCC specimens and one set of normal concrete specimens, and the fracture behaviors were estimated in terms ofdouble-K fracture parameters. This paper focuses on the influence of various mineral admixtures on SCC fracturing, including cases of fly ash only, fly ash and slag, and fly ash and silica fume. Results showed that in the case with fly ash only, the initial fracture toughness of SCC was decreased with an increase in the admixture content, and its unstable fracture toughness reached the highest at 1.5534 MPa.mv2 when the fly ash content was 30%. By the tests with two admixtures, total admixture content of 30% with fly ash-slag proportion of 3：7 was a condition leading to the best fracture property of SCC with an unstable fracture toughness of 1.7122 MPa＇m1/2. Doping silica fume was also able to improve the fracture property of SCC.