固废及纳米掺料对水泥基材料性能的影响研究

Research on the Effects of Solid Waste and Nano-admixtures on the Properties of Cementitious Materials

掺入固废矿物掺合料(SCM)及纳米材料可提升水泥基材料的力学及耐久性能。为响应智能建造及绿色建材发展的需要,通过对34组水泥基材料单掺/复掺硅灰(SF)、粉煤灰(FA)及漂珠(UFFA)等SCM,并外掺纳米SiO_(2)(NS)以研究其作为3D打印混凝土(3DPC)的流变性能与3D打印性的关系。结果表明:单掺SF,同时增大水泥基材料的粘度与屈服应力;单掺FA与UFFA,则减小水泥基材料的粘度与屈服应力,但掺量较高(20%~25%)时,能在保持SCM的粘度提高较低的条件下,明显提高屈服应力,这有利于打印建造性;与单掺SCM相比,复掺SCM在有助于增加水泥基材料粘度(降低流动度)的同时,显著提升屈服应力,从而将新拌(未掺)砂浆的易流动状态调至适用于3DPC的挤出及建造状态。外掺低掺量(<2.5%)NS对浆体的流变性能有调控作用,但需注意控制其粘度,防止影响打印效果。对选出的5组代表配合比进行3D打印试验,其中SF5-FA5-UFFA10-NS0.5组因具备较大的屈服应力,且流动度较好,粘度合适,其3D打印的连续性与建造性均较好。

Incorporating solid waste supplemental cementitious materials(SCM)and nano-materials can improve the mechanical and durability properties of cement-based materials.In response to the current development needs of intelligent construction and green building materials,studies the relationship between the rheological properties and 3D printability of 34 groups of cement-based materials,including single/composite addition of silica fume(SF),fly ash(FA),and cenosphere(UFFA),and external addition of nano-SiO_(2)(NS),as 3D printing concrete(3DPC).The results show that the addition of SF alone increases both viscosity and yield stress.The addition of FA or UFFA alone reduces viscosity and yield stress,however,the high content of FA or UFFA(20%~25%)leads to a significant increase in yield stress with lower viscosity increases,which is beneficial for printability.In comparison,adding multiple types of SCMs is more helpful in increasing the viscosity of the matrix(reducing flowability)while significantly increasing yield stress,thereby adjusting the flowing state of freshly mixed mortar to improve extrusion and buidabiliy state suitable for 3DPC.The addition of low content(<2.5%)NS has an adjusting effect on the rheological properties of the mortar,but attention should be paid to controlling its effect on viscosity reduction to prevent its impact on printing performance.Selects the five representative mix proportions for printing tests,among which the SF5-FA5-UFFA10-NS0.5 group has good printing continuity and construction performance due to its high yield stress,good flowability,and appropriate viscosity.