Preparation and microstructure analysis of alkali-activated ground granulated blast furnace slag-steel slag grouting materials

Abstract

To solve the problems of large storage requirements for iron and steel solid waste piles, environmental pollution, and low utilization, an alkali-activated ground granulated blast furnace slag (GGBFS)-steel slag (SS) grouting material (AAGM) was prepared, quicklime was used as an additive, and the activity of SS and GGBFS was activated by NaOH and water glass. Through a full factor analysis test, the effects of alkali content (AC), GGBFS/SS, and quicklime content (QC) on the fluidity, initial setting time (IST), and final setting time (FST) of AAGM were investigated. The strength formation mechanism of AAGM was analyzed using mechanical property testing, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). These studies showed that the fluidity of the slurry decreased with increasing QC, AC, and GGBFS/SS, and the IST and FST of the slurry continuously shorten with increasing QC, increasing AC, and decreasing GGBFS/SS. The 28-day unconfined compressive strength (UCS) of AAGM decreased with decreasing QC and increasing AC, and first increased and then decreased with increasing GGBFS/SS. As the age increased, the hydration reaction inside the specimen was sufficient and the compactness was stronger, reducing the porosity inside the specimen; the hydration products inside AAGM were mainly plate-like crystals (anhydrite, calcite), a small amount of columnar crystals (ettringite), and a large amount of gel-like substances (C-S-H/C-A-S-H) attached to its surface. When the GGBFS/SS ratio was 1:1.3, the QC was 3 %, the AC was 13 %, the water glass modulus was 1.6, and the water/cement ratio was 0.6; additionally, the fluidity, IST, FST, and 28-day UCS of AAGM were 137 mm, 255 min, 280 min, and 27.07 MPa, respectively, which can meet various performance indicators required for engineering grouting.