Experimental Study On Evaluation Of Cracking Resistance Of Dam Concrete Based On TSTM

The anti-cracking performance of dam concrete is one of the focuses to the engineering. Avoid and reduce cracks has always been the emphasis and difficulty in concrete dam, so the anti-crack performance evaluation method and evaluation index is particularly important. At present, the study of crack resistance involved in the temperature stress, most of them adopt the cement hydration heat, concrete adiabatic temperature rise and contraction deformation measurement methods.In the evaluation of early age cracking of concrete, it does not consider the effect of temperature record and the degree of the constraint conditions, which is different with the engineering practice of concrete.So it needs to explore a new method to evaluate concrete crack resistance, the method can provide useful information when choosing concrete material for engineering, in order to effectively guarantee the service requirements under various environmental conditions.In this paper, three different types of cement (i.e:MH, LHA,LHB) as an object, based on the laboratory standard curing conditions of test specimen, measuring the related mechanical performance index:tensile strain capacity, the tension and compression ratio and the ratio of elastic modulus and compressive. Use the above three evaluation indexes to evaluate the anti-cracking performance of concrete. And according to the evaluation results of the three traditional evaluation index, to judge the consistent characteristics between them. In addition, with the temperature stress testing machine (TSTM) for uniaxial restrained test, get real-time monitoring data of concrete under different temperature process parameters and anti-crack performance metrics. According to the evaluation system of the TSTM, judge the anti-cracking performance of concrete. Finally comparing two anti-cracking performance evaluation methods to find out which of them is more scientific and reasonable.Through the above test, the results show that:1、In two different evaluation system, the anti-cracking performance of0.4water-binder ratio was better than the0.5water-binder ratio, micro expansion properties of magnesium oxide showed beneficial effects on the properties of concrete cracking.2、In the TSTM under the condition of different two temperature, three kinds of cementing materials (MH, LHA and LHB), the anti-cracking performance order would be change.3、 Through the creep analysis, the expansion of three kinds of cementing materials after the temperature rise stage is more advantageous to the crack resistance of concrete.4、 Comparing two test methods, and two sets of anti-cracking performance evaluation index, The results show that the traditional evaluation method can not reflect very well to the influence of different material against cracking performance. Also can’t reflect the potential advantages of low thermal cement, micro expansive cement in control of dam concrete’s early crack. And the evaluation results of three kinds of traditional evaluation index evaluation are not consistent. With a single index to judge the credibility of concrete crack resistance performance is not reliable.By using weighted statistical mixture ratio under the same conditions, TSTM anti-cracking performance evaluation results and the traditional anti-cracking performance evaluation result has good similarity. But in terms of evaluation details, TSTM contains mechanics, deformation and thermal evaluation information, so that the evaluation results more reasonable and comprehensive.