Ca(OH)_(2)对再生混凝土粉活性激发的研究

Study on Activation of Recycled Concrete Powder by Calcium Hydroxide

混凝土破碎过程中会产生粒径小于0.16mm的细小颗粒(称再生混凝土粉),但该再生混凝土粉活性相对较低,利用率不高,大掺量时难以满足实际工程需求。本研究针对再生混凝土粉活性低的问题,采用再生混凝土粉部分替代水泥胶凝材料,将质量分数0%、3%、6%和9%的Ca(OH)_(2)掺入再生混凝土粉-水泥复合胶凝材料中制备再生砂浆,研究Ca(OH)_(2)对再生砂浆的力学性能(抗压强度)、水化产物(XRD、TG-DSC)及水化放热特性(TAM-Air)的影响。通过试验发现,Ca(OH)_(2)可以明显提升再生砂浆试样抗压强度,且其掺量为6%时再生砂浆的抗压强度较未掺入Ca(OH)_(2)的再生砂浆提高了63%;TAM-Air及XRD结果表明,Ca(OH)_(2)会明显提升再生砂浆水化放热速率,使放热峰提前出现、放热总量增加,促进再生砂浆水化产物C-S-H、钙矾石等的形成,进而提高再生砂浆水化程度。

In the process of concrete crushing,fine particles with particle size less than 0.16mm(called recycled concrete powder)will be produced,but the activity of recycled concrete powder is relatively low,the utilization rate is not high,and it is difficult to meet the actual engineering needs when the mixing amount is large.This study on the problem of low activity of recycled concrete powder.Using recycled concrete powder partly to replace cement gelled material,mass fraction of 0%,3%,6%and 9%of the calcium hydroxide powder is mixed with recycled concrete-cement composite gelled material to prepare regeneration in the mortar.The calcium hydroxide on the mechanical properties of recycled cement mortar compressive strength,hydration products(XRD,TG and DSC),and the influence of the hydration heat release characteristics(TAM Air)are studied.The results show that calcium hydroxide can significantly improve the compressive strength of recycled mortar samples,and the compressive strength of recycled mortar is 63%higher than that of recycled mortar without calcium hydroxide when the dosage of calcium hydroxide is 6%.The results of TAM-Air and XRD show that calcium hydroxide can significantly improve the hydration exothermative rate of recycled mortar,make the exothermative peak appear in advance,increase the total amount of heat release,promote the formation of hydration products of recycled mortar,such as C-S-H and ettringite,and then improve the hydration degree of recycled mortar.