受硫酸盐侵蚀的再生混凝土耐久性研究

为研究再生粗骨料取代率对再生混凝土抗硫酸盐溶液侵蚀性能的影响规律,进行干湿循环和硫酸盐溶液的耦合试验,探究了随着干湿循环龄期的增长,再生粗骨料取代率对再生混凝土的质量损失率、伸长率、相对动弹性模量、硫酸根离子扩散深度的影响。试验结果表明:再生粗骨料掺量为100%的再生混凝土的质量损失率最大,达到了0.35%;试件的相对动弹性模量下降速度变化较复杂,分为匀速下降期、缓慢过渡期、加速下降期;试件伸长率随着侵蚀龄期的增长逐渐增大,且增幅越来越大;试验过程中,硫酸根离子逐渐向试件内部扩散,侵蚀破坏逐渐向深层移动,且再生粗骨料掺量越多的试件内部破坏得越快、越明显。研究结果可为实际工程中再生粗骨料的掺量选择提供参考。

Durability of Recycled Concrete Subjected to Sulphate Erosion

In an attempt to understand the influence of recycled coarse aggregate on the properties of recycled concrete subjected to sulphate erosion, we probed into the changes in mass loss rate, elongation rate, relative dynamic elastic modulus, and sulfate ion diffusion depth of recycled concrete under the combined actions of drying-wetting cycles and sulphate erosion. Research findings demonstrated that the mass loss rate of recycled concrete with 100% recycled coarse aggregate was the largest, reaching 0.35%. The decline of relative dynamic elastic modulus can be divided into three stages: uniform decline stage, slow transition stage, and accelerated falling stage. The elongation of the specimen increased gradually with the increase of erosion age, and such increment accelerated. During the test, sulfate ions gradually diffused into the specimen, and as the content of recycled coarse aggregate increased, the erosion damage became faster and more apparent.The research findings offer reference for determining the dosage of recycled coarse aggregate in practical engineering.