水玻璃模数对地聚物再生混凝土尺寸效应的影响

Influence of sodium silicate module on size effect of geopolymerrecycled aggregate concrete

设计了4种不同边长立方体(70、100、150和200 mm)和9种不同水玻璃模数(0.3、0.6、0.9、1.2、1.5、1.8、2.1、2.4和2.7)的地聚物再生混凝土试件,研究了不同水玻璃模数条件下的地聚物再生混凝土的抗压强度及其尺寸效应。通过试验发现:水玻璃模数过低导致地聚物胶凝材料无法凝结,地聚物再生混凝土没有强度;水玻璃模数过高导致地聚物胶凝材料闪凝,地聚物再生混凝土也没有强度。通过微观分析发现,地聚物中存在两种结构的水化产物,随着水玻璃模数的降低,两种水化产物逐渐密实,其强度也逐渐提高。通过对地聚物再生混凝土的尺寸效应研究发现地聚物再生混凝土的换算系数不能采用《普通混凝土力学性能试验方法标准》(GB/T 50081—2002)中规定的换算系数,给出2种方法来进行地聚物再生混凝土尺寸换算系数的取值,第1种是平均数方法,第2种方法为线性拟合法。边长为200、150和100 mm的地聚物再生混凝土立方体试件抗压强度均符合BA ANT的尺寸效应理论曲线,采用无量纲的方法可以得到地聚物再生混凝土抗压强度与水玻璃模数和尺寸参数耦合作用影响的预测方程,并且得出了不同水玻璃模数条件下地聚物再生混凝土的临界尺寸和临界强度值。

The effect of sodium silicate module(0.3、0.6、0.9、1.2、1.5、1.8、2.1、2.4 and 2.7)on the size effect of geopolymer recycled aggregate concrete was studied by four different size specimens(70,100,150,and 200 mm).The results show that the conversion coefficient of geopolymer recycled aggregate concrete cannot be used as specified in GB/T 50081—2002 Standard for Testing Methods for Mechanical Properties of Ordinary Concrete.In this study,two methods were used to evaluate the size conversion coefficient of regenerated aggregate concrete.The first method was the mean method,while the second method was linear fitting method.The compressive strength of recycled aggregate concrete of 200,150 and 100 mm are in line with the BA ANT's theory of size effect curve,adopt the method of dimensionless can get polymer compressive strength of recycled aggregate concrete and sodium silicate module and size parameters of the prediction equation of coupling effect,the applicability of the proposed equation is better,and it is concluded that the different conditions of recycled aggregate beneath gathered the strength of recycled aggregate concrete critical size and critical value.