固废基低钙固碳水泥熟料组成设计及烧成过程

Composition Design and Sintering Process of Solid Waste-Based Low-Calcium Carbon-Fixing Cement Clinker

以城市垃圾焚烧飞灰(MSWIFA)和焚烧底灰(BA)为原料,成功制备了一种以β型硅酸二钙(β-C_(2)S)为主的低钙固碳水泥熟料.结果表明:熟料在1150~1250℃之间均可被烧结,且实际所需的n(Ca)/n(Si)值要高于理论设计值,即n(Ca)/n(Si)>2.6,否则容易过烧且易形成钙铝黄长石,不利于水泥强度的发展;n(Ca)/n(Si)值对水泥早期抗压强度和碳化程度的影响较大,总体来说抗压强度随着n(Ca)/n(Si)值的增加呈递减趋势,n(Ca)/n(Si)=2.8~3.2时水泥碳化养护2 d的抗压强度基本维持在50 MPa以上,甚至高达72 MPa;当n(Ca)/n(Si)值升至3.3~3.7时,水泥的抗压强度降至25~30 MPa,CaCO_(3)生成量基本维持在12.00%左右;关于熟料各矿物的水化及碳化作用对其强度的贡献还需要进一步探究.

A low-calcium carbon-fixing cement clinker mainly composed of β-C_(2)S was successfully manufactured using from municipal solid waste incineration fly ash and bottom ash.The results show that the clinker can be sintered at 1150-1250℃,and the actual n(Ca)/n(Si)value required is higher than the theoretical design value,that is,n(Ca)/n(Si)>2.6.Otherwise,it is easy to over sinter and prone to produce calcium alumina feldspar,which is not conducive to the clinker strength development.n(Ca)/n(Si)value has a significant influence on the early compressive strength and carbonation degree of cement,and the compressive strength decreases with the increase of n(Ca)/n(Si)value.The produced cement with n(Ca)/n(Si)=2.8-3.2 upon 2 days of carbonation can attain a compressive strength of 50 MPa,or even up to 72 MPa.However,when the n(Ca)/n(Si)value increases to 3.3-3.7,the compressive strength drops to 25-30 MPa with CaCO_(3) content of about 12.00%.Future research is needed to elucidate the role of hydration and carbonation mechanism of various minerals in contributing the strength development.