氧化物组成对地聚物再生骨料混凝土尺寸效应的影响

Influence of Oxide Molar Ratio on Size Effect of Geopolymer Recycled Aggregate Concrete

为了研究地聚物再生骨料混凝土的尺寸效应,设计了边长分别为70、100、150和200 mm的地聚物再生骨料混凝土立方体试块,研究不同氧化物摩尔比条件下抗压强度的尺寸效应。结果表明:地聚物再生骨料混凝土的尺寸换算系数不能采用现行国家标准《普通混凝土力学性能试验方法标准》(GB/T 50081—2002)中规定的系数,采用线性拟合的方法给出了尺寸换算系数与氧化物摩尔比的关系;通过对尺寸效应的研究,发现边长为200、150和100 mm的地聚物再生骨料混凝土立方体试块抗压强度均符合Bazant尺寸效应理论,采用无量纲的方法得到抗压强度与氧化物摩尔比和尺寸参数耦合作用的预测方程,得出了不同氧化物摩尔比下的临界尺寸和临界强度值。通过研究发现,地聚物再生骨料混凝土相比于普通水泥混凝土的尺寸效应更加明显,在实际工程中应更多地考虑其对整个结构稳定性的影响。

In order to study the size effect of geopolymer recycled aggregate concrete,cubic test blocks of geopolymer recycled aggregate concrete with side lengths of 70,100,150 and 200 mm were designed,the size effect of compressive strength under different oxide molar ratios was studied.The results show that the conversion coefficient of geopolymer recycled aggregate concrete cannot be used as specified in Standard for Testing Methods for Mechanical Properties of Ordinary Concrete(GB/T50081—2002).Relationship of size conversion coefficient and oxide molar ratio was worked out.Through the size effect,it is found that the compressive strength of geopolymer recycled aggregate concrete cube with side length of 200,150 and 100 mm conforms to Bazant size effect theory.The prediction equation of the coupling effect of compressive strength with oxide molar ratio and size parameters was obtained by dimensionless method,and the critical size and critical strength values under different oxide molar ratio were obtained.It is concluded that compared with ordinary cement concrete,the size effect of geopolymer recycled aggregate concrete is more obvious,so its influence on the stability of the whole structure should be considered more in practical engineering.