无碱液体速凝剂的有机-无机复合改性机理及应用性能研究

Study on the Organic-Inorganic Composite Modification Mechanism and Application Performance of Alkali-free Liquid Accelerator

摘要

为解决现有无碱液体速凝剂早期强度低、后期强度损失大、稳定性差等问题,基于有机-无机复合改性策略,以硫酸铝为铝源,二乙醇胺为有机络合剂稳定 Al³⁺,并复配硫酸镁、拟薄水铝石与碳酸锂,制备了一种新型无碱液体速凝剂。通过凝结时间、抗压强度测试及微观分析(XRD、SEM),系统研究了其性能与促凝机理。当速凝剂掺量为7%时,3种水泥净浆初凝时间≤4 min、终凝时间≤10min,28d抗压强度比≥90%;其中,曲寨水泥的1d抗压强度最高,达22.6MPa。微观分析揭示了硫酸铝与拟薄水铝石协同供铝、Li⁺与 Mg²⁺加速C₃S水化、二乙醇胺络合稳定的三元促凝机制。工程应用表明,该速凝剂配制的C25湿喷混凝土回弹率由30. 0%降至17. 6%,表现出优异的工程适应性。

Abstract

To address the problems of low early strength, significant later-stage strength loss, and poor stability in existing alkali-free liquid accelerators, a novel alkali-free liquid accelerator was prepared via an organic-inorganic composite modification strategy. Aluminum sulfate was used as the aluminum source, diethanolamine was used as an organic complexing agent to stabilize Al³⁺, and magnesium sulfate, pseudoboehmite, and lithium carbonate were compounded. The performance and accelerating mechanism were systematically investigated through setting time tests, compressive strength tests, and microstructural analysis (XRD, SEM). At a dosage of 7%, the initial setting time of the three types of cement pastes was ≤4 min, the final setting time was ≤10 min, and the 28 d compressive strength ratio was ≥90%; among them, the 1 d compressive strength of Quzhai cement reached 22.6 MPa. Microstructural analysis reveals a ternary accelerating mechanism consisting of synergistic aluminum supply from aluminum sulfate and pseudoboehmite, accelerated C₃S hydration by Li⁺ and Mg²⁺, and stabilization by diethanolamine complexation. Engineering application shows that the C25 wet-mix shotcrete prepared with this accelerator exhibited a reduction in rebound rate from 30.0% to 17.6%, demonstrating excellent engineering adaptability.

关键词

无碱液体速凝剂 / 喷射混凝土 / 早期强度 / 回弹率 / 促凝机理

Key words

alkali-free liquid accelerator / shotcrete / early strength / rebound rate / accelerating mechanism

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