Short-Term Shrinkage and Creep of Perlite Concrete Reinforced with Hybrid Fibers

Shrinkage and Creep, especially in light-weight concrete, are recognized as complicated phenomena that significantly impact the serviceability of concrete. This may be attributed to the significant influence of the surface layer's behavior at the interfacial transition zone (ITZ) between the aggregate and the surrounding cement paste on shrinkage and creep phenomena. In this article, the short-term creep and shrinkage of structural lightweight aggregate (LWA) concrete up to 90 days were studied. The concrete was made with a combined coarse and fine perlite aggregate, and the water cement ratio (W/C) was 0.4. Two types of fibers were used: polypropylene and recycled copper wire. Additionally, metakaolin was used as a pozzolanic material. Results indicated that the creep and shrinkage of reinforced concrete is lower than that of lightweight concrete without fiber. The total shrinkage of the MF mix was (1098.5×10-6), comparable to (1229×10-6) of the reference mix (RM) after three months. However, the total creep was (1991×10-6) of the fiber mix (FM) equivalent to (2596×10-6) of the RM after three months. The elevated creep and shrinkage values of the lightweight concrete (LWC) mixtures resulted from the increased porosity of the (LWA) used and the release of moisture retained inside the particles owing to their prewetting during the mixing process.