Green options for anti-sulfate of slag cement concrete containing pozzolans

Abstract

This study mainly adopted densified mixture design algorithm (DMDA) with pozzolans (fly ash and slag), different fineness slag cement (1:1; MF40 and HF40) and Type I cement (E40) to construct the mixtures for w/cm=0.40, and applied ACI 211.1R and Type II cement as control group (CII40, w/c=0.40). Life cycle inventory of LEED suggested by PCA for cementitious materials (kg/m3) contained cement use, CO2 emission, raw materials, energy consumption, compressive strength, and immersed in different concentration Na2SO4 solution. Results showed cement content, CO2 emission, raw materials and energy consumption for E40, MF40 and HF40, with respect to CII40, were 14% ∼ 26%, 14% ∼ 26%, 13% ∼ 26% and 17%∼28%. At 28 days, compressive strength(all mixtures) were greater than 41MPa. Repeatedly 25 cycles, specimens immersed in 5000ppm Na2SO4 solution and oven-dried at 105°C, the exterior had no damage, and weight loss (n) and pulse velocity change (nv) were less than -1% and -5%. But in saturated Na2SO4 solution, the n and nv were ranged from - 0.91% (E40) to -2.62% (MF40) and -6.7% (E40) to -10.9% (MF40). The exterior had been obviously scaling (chalking) or spalling at the second (CII40), the fifth (MF40 and HF40) and the ninth cycle (E40). The comprehensive evaluation of green options for anti-sulfate indicated that the merits of all mixtures were respectively E40 > HF40 > MF40 > CII40.