摘要
为改善粉煤灰混凝土的耐久性,以粉煤灰混凝土为对象,分析不同碱性激发剂掺量(0%、5%、8%、10%)对粉煤灰混凝土质量损失率、相对动弹性模量和抗压强度的影响.采用扫描电镜SEM和EDS光谱衍射图对粉煤灰混凝土碱激发过程进行微观分析.结果表明,随着碱性激发剂掺量的增加,不同养护时间碱激发粉煤灰混凝土的抗压强度均呈先增加后减小的趋势.4种碱性激发剂掺量的粉煤灰混凝土的质量损失率均随冻融循环次数的增加而增加,碱性激发剂掺量为8%时粉煤灰混凝土的质量损失率最小;4种碱性激发剂掺量的粉煤灰混凝土的相对动弹性模量均随冻融循环次数的增加而减小,碱性激发剂掺量为8%时粉煤灰混凝土的相对动弹性模量减小幅度最小;4种碱性激发剂掺量的粉煤灰混凝土抗压强度均随冻融循环次数的增加而减小,碱性激发剂掺量为8%时粉煤灰混凝土抗压强度最高、抗压强度减小幅度最小.2种碱性激发剂掺量(0%、8%)下粉煤灰混凝土的主要元素均为Ca、O、C、Si、S.碱性激发剂掺量为8%时可以有效促进粉煤灰混凝土的水化反应,增加胶凝材料的水化产物含量,改善粉煤灰混凝土的力学性能和耐久性能.
Abstract
To improve the durability of fly ash concrete,fly ash concrete was used as the object to analyze the effects of different alka-line activator dosages(0%,5%,8%,and 10%)on the quality loss rate,relative dynamic elastic modulus,and compressive strength of fly ash concrete.Microscopic analysis of the alkali excitation process in fly ash concrete was conducted using scanning electron mi-croscopy(SEM)and EDS spectroscopic diffraction patterns.The results showed that with the increase of alkaline activator dosage,the compressive strength of alkali activated fly ash concrete at different curing times showed a trend of first increasing and then decreasing.The quality loss rate of fly ash concrete with four different alkaline activator dosages increased with the increase of freeze-thaw cycles,and the quality loss rate of fly ash concrete was the smallest when the alkaline activator dosage was 8%;the relative dynamic elastic modulus of fly ash concrete with four different alkaline activator dosages decreased with the increase of freeze-thaw cycles,and the de-crease in relative dynamic elastic modulus of fly ash concrete was the smallest when the alkaline activator dosage was 8%;the compres-sive strength of fly ash concrete with four different alkaline activator dosages decreased with the increase of freeze-thaw cycles.When the alkaline activator dosage was 8%,the compressive strength of fly ash concrete was the highest and the decrease in compressive strength was the smallest.The main elements of fly ash concrete with two alkaline activators(0%,8%)were Ca,O,C,Si,and S.When the dosage of the alkaline activator was 8%,it could effectively promote the hydration reaction of fly ash concrete,increase the hydration product content of cementitious materials,and improve the mechanical and durability properties of fly ash concrete.
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