复合无机水合盐对磷酸镁水泥水化及性能的影响

Effect of Composite Hydrated Salt on Hydration and Properties of Magnesium Phosphate Cement

将三种无机水合盐Na_2B_4O_7·10H_2O、Na_2SO_4·10H_2O和Ca(NO_3)_2·4H_2O按照最优比例(质量比为1.5∶7∶1.5)复掺得到复合无机水合盐FH,比较了单掺硼砂的磷酸钾镁水泥(MKPC)NB10与不同FH掺量下MKPC(FH-MKPC)的工作性能、绝热温升及抗压强度。利用XRD、TG-DSC及SEM等微观分析手段,结合水化放热速率曲线研究了FH对MKPC早期水化历程的影响。结果表明:FH延缓了MKPC的水化,使得水化温升曲线出现诱导期和两个温度峰,水化放热速率和水化温峰值降低。FH的掺入(>8%)大幅延长了MKPC的凝结时间,增强了MKPC的施工可操作性。FH掺量越多,MKPC凝结时间不断延长,流动度提高,早期强度降低。FH掺量为8%的FH-MKPC初凝时间达到25.20min,较NB10延长了90.76%,同时水化产物的早期生成量和热稳定性更高,7h、1d和3d抗压强度略高于NB10。为保证MKPC符合施工需要又满足强度要求,FH的最佳掺量为8%。

According to optimal proportion(1.5∶7∶1.5,mass ratio),composite hydrated salt(FH)was prepared by blending three categories of hydrated salt Na 2B 4O 7·10H 2O,Na 2SO 4·10H 2O and Ca(NO 3)2·4H 2O.Work performance,hydration temperature and compressive strength of magnesium potassium phosphate cement(MKPC)mixed with borax NB10 and mixed with different content of FH(FH-MKPC)were compared.Combining hydration heat evolution curve,influence of FH on early hydration of MKPC was investigated by XRD,TG-DSC and SEM microcosmic analysis methods.The result showed FH slowed down the hydration of MKPC,which made hydration temperature rise curve have induction and two temperature peak,and diminished hydration heat evolution rate and hydration temperature peak value.The addition of FH(>8%)prolonged setting time of MKPC largely,enhancing construction operability.With the content of FH increase,setting time of MKPC prolonged,fluidity increased and early compressive strength decreased.Initial setting time of FH-MKPC mixed with 8%FH could reach 25.20 min,prolonged 90.76%,compared with NB10.At the same time,amount and thermal stability of hydration products of early hydration stage of FH-MKPC was higher,7 h,1 d and 3 d compressive strength were also slightly higher than former.In order to meet the requirement of construction and strength,optimal content of FH was 8%.