水泥-石灰石粉体系抗碳化效应研究*

探讨石灰石粉比表面积、矿物掺合料、早强剂、防水物质及CO₂捕收剂对水泥-石灰石粉体系强度和碳化深度的影响。实验发现,硅灰替代20 kg/m³石灰石粉时28 d抗压强度达最高,为40 MPa,比空白高6 MPa,高比表面积(750 m³/kg)石灰石粉次之,为37 MPa,比空白高4 MPa,防水物质和过量硝酸钙会降低混凝土强度;掺入0.3%防水石蜡乳液可使体系碳化深度降至最低,达11 mm,比空白降低13 mm,掺入0.8%硝酸铁次之,碳化深度为13 mm,比空白降低11 mm,矿物掺合料替代石灰石粉不会有效降低碳化深度。因此可适度引入铁离子、防水组分或较高比表面积石灰石粉来提高该体系抗碳化性能。

The Resistance of Carbonation Raction on Cement-Limestone Powder System

The effects of specific surface area of limestone powder, mineral admixture, early strength agent, waterproof substance and CO₂ collecting agent on the compressive strength and carbonization depth of cement-limestone powder system were investigated. The results shows that, for the 28 d compressive strength of concrete: the strength reacthed the highest when 20 kg/m³ limestone powder was replaced by silica fume, 40 MPa, 6 MPa higher than that of blank, and the high specific surface area(750 m³/kg) of limestone powder was 37 MPa, 4 MPa higher than that of blank. Waterproof substances and excessive Ca(NO;);can be reduced the strength of concrete.For the resistance of carbonation raction: when the dosage of waterproof paraffin emulsion was 0.3%, which can minimize the carbonization depth of the system to 11 mm, 13 mm lower than the blank, followed by incorporation of 0.8% Fe(NO₃)₂, reacthed 13 mm, 11 mm lower than the blank. Replacing limestone powder with mineral admixture cannot effectively reduced the carbonization depth. Therefore,the resistance of carbonation raction of the system can be improved by using Fe;, waterproof component or limestone powder with higher specific surface area.