Study on the preparation of cementitious grout for grout sleeve splicing of rebars based on a ternary composite material system

Abstract

In this study, through orthogonal experiments, a ternary composite material system of sulfoaluminate cement, Portland cement and gypsum with optimal proportions was developed for preparing cementitous grout for rebar sleeve splicing. The main factors affecting the performances of the grout were investigated. Also, the influences of water/binder ratio, Portland cement/sulphoaluminate cement ratio and gypsum content on the properties of the grout were studied. The experimental results show that: (1) The factors affecting the fluidity and compressive strength of the cementitious grout in order that from significant to non-significant were water/binder ratio, Portland cement/sulphoaluminate cement ratio and gypsum content. (2) To obtain comprehensive properties of good compressive strength and fluidity, it seems that the optimal ratio of the Portland cement to sulphoaluminate cement is 8:2. At this ratio, 1d compressive strength and 3d compressive strength were 35.7 MPa, 61.7 MPa, respectively, and the initial fluidity was 335 mm. (3) Gypsum is the main factor affecting the vertical expansion rate of the cementitious grout among the factors studied. The compressive strength and vertical expansion rate of cementitious grout both grew as the increase of gypsum content (from 0% to 3%), but the compressive strength experienced a drop, when the gypsum content even exceeds 3%.