煤气化渣溶出特性及对水泥基材料的影响

Dissolution Characteristics of Coal Gasification Slag and Its Effect on Cement-Based Materials

我国洁净煤技术不断发展,带来大量的工业副产品气化渣。从气化渣用作水泥矿物掺合料的角度,使用电感耦合等离子发射光谱法(ICP)测定其在不同环境的溶出特性,观察其水化活性,研究气化渣对二元复合体系工作性与力学性能的影响。结果表明:气化渣Ca^(2+)溶出率较低,缺乏自硬性;Si^(4+)、Al^(3+)随时间溶出率增大,气化渣存在水化活性。碱性与高温环境促进Si^(4+)、Al^(3+)溶出,表明气化渣在适当的激发下,化学键更易断裂,水化活性增大。气化渣的形态效应可改善二元体系工作性,掺30%、50%(质量分数)气化渣其流动度分别提高约8.8%、19.4%,二元体系符合Herschel-Bulkey所描述的流体模型,并且发现了剪切变稀现象。低掺量气化渣火山灰反应可改善复合胶凝体系力学性能,90 d抗压强度达到90 MPa,高掺量气化渣替代过多水泥,水化产物减少,环境碱性降低,气化渣活性无法被完全激发,导致孔隙率增大,结构疏松,力学性能下降。

The continuous development of clean coal technology in our country has brought a large amount of industrial by-product gasification slag.From the point of view that gasification slag was used as cement mineral admixture,the dissolution characteristics of the gasification slag in different environments were determined by ICP,and its hydration activity was observed.Then the effect of gasification slag on the workability and mechanical properties of the binary composite system was studied.It is concluded that the dissolution rate of Ca^(2+)is low and the gasification slag has no self-hardening property.The dissolution rate of Si^(4+)and Al 3+increases with time,and the gasification slag has hydration activity.Alkaline and high temperature environments promote the dissolution of Si^(4+)and Al 3+,indicating that the gasification slag is more likely to break chemical bonds and increases hydration activity under appropriate excitation.The morphological effect of the gasification slag improves the workability of the binary system,and the fluidity of the system with 30% and 50%(mass fraction)gasification slag increases by approximately 8.8% and 19.4%,respectively.The binary system conforms to the fluid model described by Herschel-Bulkey,and shear thinning is found.The pozzolanic reaction of low content gasification slag improves the mechanical properties of the composite cementitious system,and the 90 d compressive strength reaches 90 MPa.The high content gasification slag replaces too much cement,reduces hydration products and environmental alkalinity,the activity of the gasification slag cannot be fully excited,resulting in the increase of porosity,loose structure,and decrease of mechanical properties.