Effects of three different types of fibers and dosage on the properties of alkali-activated copper slag-slag cementitious materials.

The use of copper slag instead of part of the slag to prepare alkali-activated cementitious materials can achieve the resource utilisation of copper slag, but alkali-activated copper slag-slag composite cementitious materials have the disadvantages of high shrinkage and low flexural strength, which limit their application in practical engineering. In order to improve its performance, this study used glass fiber, polypropylene fiber, steel fiber at 0.2%, 0.4%, 0.6%, 0.8%, 1.0% by volume admixture into alkali-activated copper slag-slag composite cementitious materials, respectively, to explore the effect of fiber on the drying shrinkage and mechanical properties of alkali-activated copper slag-slag composite cementitious materials. The test results show that the addition of fibers can compensate the drying shrinkage of AAMs and improve their mechanical properties. 1.0% of GF and SF can compensate the drying shrinkage of 17.5% and 27.3%, and PPF can also inhibit the drying shrinkage of the material, but the drying shrinkage will be exacerbated when the dosage is more than 0.8%. The addition of fibers does not have a significant effect on the compressive strength, but significantly improves the flexural strength of the material. When the dosage of GF, PPF and SF reaches 0.6%, 0.8% and 1.0% respectively, the flexural strength of the specimen at 28d is increased by 7.9%, 19.86% and 61.66% compared with that of the blank control group, respectively. Through microstructural analysis, it was found that the fibers formed a mesh structure in the material, which effectively inhibited the development of cracks and improved the toughness of the material. This study provides a theoretical basis and practical guidance for the optimization of the properties of alkali-activated copper slag-slag composite cementitious materials.