基于CO_(2)驱动固结的镁渣基3D打印材料的制备与性能研究

Preparation and Properties of CO_(2)Driven Magnesium Slag-based 3D Printing Materials

镁渣是一种含有大量硅酸二钙的工业固体废弃物,水化活性较差,但具有优异的碳化活性。提出一种镁渣基3D打印材料的制备方法,该方法以高碳化活性的镁渣为主要胶凝组分,加入硅灰、水、减水剂等成分制备流变可调的可打印浆体,在打印完成后通过预干燥处理与CO_(2)加速养护,在短时间内即可获得具有优异力学强度的3D打印制品。研究了预干燥处理和CO_(2)养护制度对打印试块的力学性能与微观结构的影响机理。结果表明:对打印试块进行适当的预干燥处理后再碳化有利于提升其力学强度,将打印试块预干燥至0.05水固比,在0.3 MPa的CO_(2)分压下养护3 h后,其抗压强度达到48.8 MPa。微观结构致密化和方解石型CaCO_(3)的形成是打印试块在CO_(2)养护后快速获得强度的主要原因。

Magnesium slag is an industrial solid waste containing a large amount of dicalcium silicate with poor hydration activity and good carbonation activity.A preparation method of magnesium slag-based 3D printing material is proposed.The method uses magnesium slag with high carbonation activity as the main cementitious component,and silica fume,water and superplasticizer are added to prepare printable paste with adjustable rheology.After printing,3D printing samples with excellent mechanical strength can be obtained in a short time through pre-drying and CO_(2)curing.The influence of carbonation curing conditions on the mechanical properties and microstructure of printed samples was investigated.Results show that,a proper pre-drying is beneficial to the carbonation strength.After pre-drying to 0.05 water to solid ratio before carbonation curing,then CO_(2)curing for 3h at 0.3 MPa,the compressive strength of the printed sample reaches 48.8 MPa;the densification of microstructure and the formation of calcite are the main reasons for the rapid strength gain of printed sample after CO_(2)curing.