Influence of NaOH concentration on size effect of geopolymer recycled aggregate concrete
The effect of NaOH concentration(3 mol/L,5 mol/L,7 mol/L,9mol/L,and 11 mol/L)on the size effect of geopolymer recycled aggregate concrete was studied by 4 different size specimens(70 mm,100 mm,150 mm 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.Two methods were used to evaluate the size conversion coefficient of regenerated aggregate concrete.The first method was the mean method:α200=0.93,α100=1.1 3,α70=0.70.The second method was linear fitting:α200=0.973 5-0.006 5ε,α100=1.044 5+0.012 5ε,α70=0.718-0.002ε.The compressive strength of recycled aggregate concrete of 200 mm,150 mm and 100 mm are in line with the Bazant's theory of size effect curve,adopt the method of dimensionless can get polymer compressive strength of recycled aggregate concrete and NaOH concentration and size parameters of the prediction equation of coupling effect,the applicability of the proposed equation has 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.