基于响应面的路用高性能水泥混凝土配合比优化研究

Study on mix ratios optimization of high performance concrete used in roads based on response surface

如何充分利用当地材料,确定水泥混凝土最优配合比是路面结构设计的重要环节。水泥混凝土配合比优化对提高材料性能、延长路面使用寿命有着重要的影响。利用响应面法对影响混凝土路用性能的砂率、粉煤灰和减水剂三个主要因素进行了Box-Behnken中心组合设计,从而获得了上述三个因素对高性能水泥混凝土28 d抗折强度的影响规律和两两因素之间的交互作用关系。结果表明:随着粉煤灰和砂率的增加,高性能混凝土28 d抗折强度出现先升高后降低的趋势,在中间水平范围存在一个峰值,形成典型的二次曲面。当砂率为0.34左右的范围时,粉煤灰的掺量在38~42 kg/m3范围内可以得到较高的抗折强度。随着减水剂的增加,28 d抗折强度响应值缓慢增大,但幅度不是很大。研究结论可为高性能水泥混凝土配合比设计提供参考依据。

How to make full use of local materials to determine the optimal mix ratios of cement concrete pavement structure is an important part of the design.The optimization of mix ratios of cement concrete has important influence on improving material properties and prolonging service life of pavement.The response surface method was used to carry out the Box-Behnken central composite design for the three main factors that affect the performance of concrete pavement, such as sand ratio, fly ash and water reducing agent, the influence of the above three factors on the flexural strength of 28 days＇ high performance cement concrete and the interaction between the every two factors were obtained.The results show that with the increase of fly ash and sand ratio, the 28 dsys＇ flexural strength of high performance concrete increased first and then decreased,which a peak at the intermediate level, forming a typical quadratic surface.When the range of sand ratio is about 0.34, dosage of fly ash within 38 to 42 kg/m3 can get high flexural strength.With the increase of water reducing agent, the flexural strength of 28 d response value increases slowly,but the increase rate is not very big.The conclusion can provide reference for the design of high performance cement concrete mix ratios.