Effect of Fly Ash and Silica Fume Contents on Mechanical Properties of Alkali-Activated Slag-Based Concrete
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摘要:
为研究粉煤灰和硅灰取代率对碱矿渣混凝土(AASC)性能的影响,通过凝结时间和基本力学性能试验,探究AASC凝结时间、立方体抗压强度、立方体劈拉强度、抗折强度和弹性模量的变化规律,基于试验结果,采用回归分析的方法,建立立方体劈裂抗拉强度、抗折强度以及弹性模量与立方体抗压强度的转换关系方程,并结合AASC的微观形貌和物相组成,揭示粉煤灰和硅灰对AASC性能的影响机理. 结果表明:粉煤灰和硅灰的取代可延长AASC的凝结时间;AASC力学性能指标随粉煤灰和硅灰取代率的增大而呈现出先增强后减弱的趋势,粉煤灰和硅灰最优取代率分别为20%和10%;提出的AASC立方体劈拉强度、抗折强度以及弹性模量的经验公式拟合精度高;粉煤灰(取代率≤20%)和硅灰(取代率≤10%)的取代促进了AASC的水化反应,使微观形貌更为密实.
Abstract:In order to study the effect of fly ash and silica fume contents on the properties of alkali-activated slag-based concrete (AASC), the changes in setting time, cubic compressive strength, cubic splitting tensile strength, flexural strength, and elastic modulus of AASC were investigated by conducting tests on setting time and basic mechanical properties. Based on the test results, a regression analysis method was used to establish the conversion relationship equation of cubic splitting tensile strength, flexural strength, and elastic modulus with cubic compressive strength, and the effect of fly ash and silica fume on the properties of AASC was revealed according to the microstructure and phase composition. The results show that the fly ash and silica fume can prolong the setting time of AASC; the mechanical property indicators of AASC tend to strengthen and then weaken with the increase in the contents of fly ash and silica fume, and the optimal contents of fly ash and silica fume are 20% and 10%, respectively. The proposed empirical formulae for cubic splitting tensile strength, flexural strength, and elastic modulus of AASC have a high fitting precision. The appropriate contents of fly ash (silica fume≤20%) and silica fume (silica fume≤10%) can promote the hydration reaction of AASC and the denser microstructures.
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Key words:
- alkali-activated slag-based concrete /
- fly ash /
- silica fume /
- mechanical property /
- microstructures
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表 1 胶凝材料的主要化学成分
Table 1. Main chemical compositions of cementitious materials
% 胶凝材料 CaO SiO2 Al2O3 MgO SO3 K2O Na2O MnO Fe2O3 TiO2 矿渣 36.82 26.75 19.66 11.10 2.65 0.29 0.84 0.37 0.32 0.94 粉煤灰 5.60 45.10 24.20 2.10 0.85 0.85 硅灰 0.12 96.65 0.31 0.11 0.97 0.07 表 2 胶凝材料的主要物理性能
Table 2. Main physical properties of cementitious materials
胶凝材料 密度/
(g·cm−3)比表面积/
(m2·kg−4)需水量
比/%流动度
比/%矿渣 2.80 455 105 95 粉煤灰 2.20 330 95 120 硅灰 2.17 19000 120 表 3 AASC配合比设计
Table 3. Mix proportion design of AASC
kg/m3 试件编号 矿渣 粉煤灰 硅灰 细骨料 粗骨料 水玻璃 NaOH 水 减水剂 AASC-P 417.00 0 0 724.00 1085.00 161.80 3.60 84.00 3.30 AASC-FA10 375.30 41.70 0 AASC-FA20 333.60 83.40 0 AASC-FA30 291.90 125.10 0 AASC-FA40 250.20 166.80 0 AASC-FA60 166.80 250.20 0 AASC-SF5 396.20 0 20.85 AASC-SF10 375.30 0 41.70 AASC-SF15 354.50 0 62.55 -
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