（1 内蒙古科技大学土木工程学院， 包头 014010； 2 莱芜城市发展集团有限公司， 莱芜 271100）

［摘要］通过在含有100%再生粗骨料的混凝土中同时掺入20%的矿渣和0%，15%，30%掺量的粉煤灰，并进行碳化、冻融和冻融碳化耦合试验，研究冻融和碳化环境对再生混凝土耐久性的影响，对比分析试件抗压强度、质量损失率、相对动弹性模量、碳化深度的变化规律，建立冻融-碳化耦合作用下矿渣-粉煤灰再生混凝土抗压强度模型。结果表明：粉煤灰掺量为15%时，再生混凝土的抗冻性能最好，当冻融次数大于100次后，粉煤灰对再生混凝土抗冻性能的促进作用开始减弱；粉煤灰掺量越多，再生混凝土的抗碳化性能越弱，当粉煤灰掺量为30%时，其碳化深度是粉煤灰掺量为0试件的2倍以上；在冻融-碳化耦合环境中，冻融作用促进了碳化深度的增长，碳化作用加剧了矿渣-粉煤灰再生混凝土的冻融破坏；建立的矿渣-粉煤灰再生混凝土冻融-碳化耦合抗压强度模型能较好地反应冻融-碳化耦合环境下的抗压强度退化规律。

［关键词］冻融循环； 碳化； 粉煤灰掺量； 再生粗骨料； 冻融-碳化耦合作用； 耐久性； 抗压强度模型

中图分类号：TU528文献标识码：A文章编号：1002-848X(2020)15-0085-06

Experimental study on slag-fly ash recycled concrete under the action of  freeze-thaw-carbonation coupling

WANG Chenxia1, LIU Jun1, CAO Fubo1, WANG Zhe2

(1 School of Civil Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, China;2 Laiwu City Development Group Co., Ltd., Laiwu 271100, China)

Abstract:In order to research the durability of recycled concrete mixed with slag-fly ash in the freeze-thaw and carbonation environment, 20% slag and 0%, 15%, 30% fly ash were simultaneously blended in the recycled concrete containing 100%   recycled coarse aggregate, and carbonation, freeze-thaw and freeze-thaw-carbonation coupling test were carried out. The degradation law of specimen compressive strength, mass loss rate, relative dynamic elastic modulus and carbonation depth changes was analyzed. The compressive strength model of slag-fly ash recycled concrete under the action of freeze-thaw-carbonation coupling was established. The results show that the frost resistance of recycled concrete is best, when the content of fly ash is 15% in recycled concrete, at the same time, the promoting effect of fly ash on the frost resistance of recycled concrete begins to weaken, when the freeze-thaw cycles are more than 100 times. The more fly ash content, the weaker the anti-carbonization performance of recycled concrete, and the carbonization depth is twice as much as that of recycled concrete without fly ash when the fly ash content is 30%. In the regenerated coarse aggregate coupling compressive strength environment, the freeze-thaw effect promotes the growth of carbonation depth, and the carbonization accelerates the freeze-thaw damage of slag-fly ash recycled concrete. The established slag-fly ash recycled concrete freeze-thaw-carbonization coupling compressive strength model can better reflect the degradation law of compressive strength under the freeze-thaw-carbonization coupling environment.

Keywords:freeze-thaw cycle; carbonization; content of  fly ash; recycled coarse aggregate;  freeze-thaw-carbonization coupling effect; durability; compressive strength model

*国家自然科学基金项目(51868061）;内蒙古自然科学基金项目（2020MS05071）。

作者简介：王晨霞，博士，副教授，Email: wangchenxia77 @qq.com; 通讯作者：曹芙波，博士，教授，Email：caofubo@139.com。