预制构件混凝土纳米早强剂的制备及免蒸性能

Preparation and Non-autoclave Curing Performance of Nano-early Strength Agent for Precast Concrete

采用不同钙硅比和不同PC-M用量制备不同类型纳米早强剂,探讨其稳定性、强度和免蒸性能。当PC-M用量为11%,钙硅比为1.5时,体系稳定性最好。当纳米早强剂掺量为5%时,16h的C30混凝土抗压强度达12.5MPa,比空白增加60%,16h的C50混凝土抗压强度达14.5MPa,比空白增加80%;当溴化钙掺量为0.25%时,混凝土早期强度最明显,20h抗压强度增加35%,24h抗压强度增加30%。当纳米早强强度掺量为5%,溴化钙掺量为0.25%时,C50标养16h抗压强度达16.5MPa,已超过蒸养4.5h抗压强度50%,标养20h抗压强度已接近蒸养9h的抗压强度。因此采用纳米早强剂和无机早强剂可有效缩短蒸养时间甚至免蒸养。

Different kinds of nano-early strength agents were prepared by different calcium silicon ratio and different dosage of PC-M,and their stability,strength and non-autoclave curing performance were investigated.When the dosage of PC-Mwas 11% and the ratio of Ca to Si was 1.5,the stability of the system was the best.When the dosage of nano-early strength agent was 5%,the C30 concrete compressive strength of 16 h reached12.5 MPa,which increases by 60% compared with blank,and the C50 concrete compressive strength of 16 h reached 14.5 MPa,which increases by80% compared with blank.When the dosage of calcium bromide was 0.25%,the early strength of concrete was the most obvious,20 h compressive strength increases by 35%,24 h compressive strength increases by 30%.When the dosage of nano-early strength agent was 5% and the dosage of calcium bromide was 0.25%,the compressive strength of C50 at 16 h of standard curing reaches 16.5 MPa,which was 50% higher than that at 4.5 h ot steam curing,and the compressive strength at 20 h of standard culture was close to that at 9h of steam curing.Therefore,To use the nano-early strength agent and inorganic early strength agent can effectively shorten the steaming time and even avoid steaming.