纳米C-S-H-PCE对沿海地铁管片用C50免蒸养混凝土性能的影响

Effects of Nano-C-S-H-PCE on performance of C50 non-steam cured concrete for coastal subway segment

针对蒸汽养护造成的混凝土热损伤问题,利用纳米C-S-H-PCE制备了沿海地铁管片用C50免蒸养混凝土,并采用电导仪、傅里叶红外光谱仪等研究了纳米C-S-H-PCE对水泥净浆水化、混凝土抗压强度、耐久性性能和自收缩性能的影响.结果表明,纳米C-S-H-PCE能够为水化硅酸钙凝胶的形成提供晶核,降低水化硅酸钙凝胶成核的离子临界浓度,促进水化硅酸钙凝胶的形成和Ca^(2+)、SiO_(4)^(2-)的继续溶出,进而缩短水泥水化的诱导期;促进水泥浆体中水化硅酸钙凝胶的聚合,从而提高混凝土的早期抗压强度,提升程度可达312%,但对后期抗压强度影响不大.掺入纳米C-S-H-PCE后,混凝土抗氯离子能力提高了2%~28%,抗碳化能力提高了10%~40%,自收缩变形降低,抗冻性变化不大.

To solve the thermal damage of concrete caused by steam curing,C50non-steam cured concrete for the coastal subway segment was prepared with nano C-S-H-PCE(calcium silicate hydrate polycarboxylate ether).The effects of nano C-S-H-PCE on the hydration of cement paste,the compressive strength,the durability,and the autogenous shrinkage of concrete were studied by conductivity instrument and Fourier infrared spectroscopy instrument.The results show that nano C-S-H-PCE can provide a crystal nucleus for the formation of C-S-H gel and reduce the critical ion concentration of C-S-H gel nucleation,leading to the formation of C-S-H gel and the continuous dissolution of Ca^(2+)and SiO_(4)^(2-).Then,the induction period of cement hydration is shortened.Meanwhile,the polymerization degree of hydrated calcium silicate gel is improved,thus increasing the early compressive strength of concrete by up to 312%.However,it has little effect on the late compressive strength.After the addition of nano C-S-H-PCE,the chloride ion resistance of concrete increases by 2% to 28%,and the carbonation resistance increases by 10% to 40%.It makes the autogenous shrinkage decrease but has almost no effect on the frost resistance.