混合腐蚀环境下改性混凝土的力学性能

Mechanical Properties of Modified Concrete Exposed to Composite Corrosive Environment

分别配制包含SO24-,Cl-,NH+和Mg2+,Cl-,NH+的两组高浓度混合腐蚀溶液,对普通混凝土、掺粉煤灰混凝土、掺聚丙烯纤维混凝土和双掺(聚丙烯纤维和粉煤灰)混凝土试件进行快速腐蚀试验,得到了30,60,90,150d下各类混凝土的抗压强度、劈拉强度与弹性模量的变化规律.结果表明:硫酸根混合溶液中腐蚀离子之间呈现相互削弱的关系,延缓了混凝土的损伤过程;而镁离子混合溶液中腐蚀介质则表现出相互叠加的效应,加速了混凝土的侵蚀进程.在混凝土中掺入粉煤灰和聚丙烯纤维进行改性能够显著提高混凝土的抗腐蚀性能,其腐蚀后劈拉强度可以提高25%～57%.改性混凝土成功应用于城市污水处理厂改造工程中,防腐性能优良,经济效益显著.

Accelerated corroding experiments of ordinary concrete and modified concrete（fly ash concrete, polypropylene fibre concrete and concrete mixed with fly ash and polypropylene fibre） immersed in two group of high concentrated mixed corrosive solutions were carried out. The two mixed corrosive solutions consist of SO- , C1- , NH＋ and Mg2＋ , C1- , NH＋ respectively. Change tendency of compressive strength, splitting tensile strength and elastic modulus of modified concrete varying with corrosive age（30, 60, 90 and 150 d） were obtained. The results show that corrosive effects of ions weaken each other in sulfate mixed solution and alleviate the damage process of concrete. On the contrary, they will aggravate in mag- nesium mixed solution and accelerate the erosion process. Resisting corrosion property of concrete is im- proved markedly by means of mixed in fly ash and polypropylene fibre, which results in 25%- 57% increase of corroded splitting tensile strength compared to ordinary concrete. The modified concrete was successfully applied in renovation project of municipal sewage plant with excellent anti-corrosion performance and significant economic benefit.