Graft copolymerization of black liquor and sulfonated acetone formaldehyde and research on concrete performance

The copolymer (BSAF) was prepared by black liquor and sulfonated acetone formaldehyde (SAF) through graft copolymerization, which was characterized by FT-IR, and its synthetic principles were also introduced. The influences of black liquor ratio, reaction temperature, and reaction time on properties of BSAF were investigated respectively. Compared with blank concrete, water-reducing rate, setting time, and compressive strength of concrete made with BSAF were tested. Based on the cement past fluidity data, the optimum technology of synthesis of BSAF was obtained. The results revealed that the water-reducing rate of concrete was 28.6%, initial and final setting time of concrete prolonged 373 min and 189 min respectively when 1.8 wt.% of BSAF was used. Mercury intrusion porosimetry (MIP) and X-ray Diffraction (XRD) results implied that BSAF changed the microscopic structure of the concrete, and promoted the hydration of cement, which improved the later compressive strength of concrete.