To provide the most effective comprehensive performance grouting material ratio, in this experimental investigation, a total of eight grouted specimens with two water-cement ratios (0.45:1, 0.55:1) and four different superfine cement contents (0%, 30%, 70%, 100%) were evaluated. Based on a uniaxial compression test, the fractal dimension of the fragments, a mercury injection test, and scanning electron microscopy, the effects of the superfine cement content on the strength characteristics and microscopic characteristics of the grouted specimens were studied. The results showed that increasing the superfine cement content could enhance the compressive and tensile strength of the grouted specimens and reduce the fractal dimension of the fragments and the porosity of the grouted specimens. The superfine cement content increased from 0% to 70% when the water-cement ratio was 0.45:1. The compressive strength of the grouted specimens increased from 16.7 MPa to 26.3 MPa, and the fractal dimension decreased from 1.8645 to 1.2301. When the water-cement ratio was 0.55:1, the compressive strength of the grouted specimens increased from 10.5 MPa to 20.6 MPa, and the fractal dimension value decreased from 2.2955 to 1.4458. When the superfine cement content increased from 0% to 100%, the water-cement ratio was 0.45:1. The porosity of the grouted specimens was reduced from 28.41% to 21.62%. When the water-cement ratio was 0.55:1, the porosity of the grouted specimens was reduced from 33.33% to 29.46%.
Keywords: fractal dimension of debris; mercury intrusion porosimetry; scanning electron microscopy; superfine cement; uniaxial compression test.