PRO: Advancing Productivity Day (ACI Fall 2023, Boston, MA) There are several highly productive specialized concrete formwork systems that will enhance construction productivity. Learn how to unlock these productivity gains through design.

Integration of Experiments & Modeling (ACI Fall 2023, Boston, MA) Shrinkage mitigating strategies have been successfully used to prevent concrete cracking. Numerous studies have demonstrated the efficiency of expansive agent (EA), shrinkage reducing admixture (SRA), and superabsorbent polymer (SAP) on reducing shrinkage and cracking; however, few studies have optimized the content of these materials for special construction purposes. This study investigated the effect of CaO-based EA, SRA, and SAP on compressive strength development, fiber pull-out strength, and shrinkage of fiber-reinforced mortar (FRM) mixtures. Advanced microstructural characterization techniques were employed to explore the mechanism underlying the effect of shrinkage mitigating strategies on the mechanical properties and shrinkage of FRM mixtures and to identify the optimum mixtures for repair application. The results were analyzed statistically, and statistical modeling indicated that FRM made with coupled systems of shrinkage mitigating strategies limited to 5% EA, 1% SRA, and 0.25% SAP were preferred. The preferable combination considering compressive strength, fiber pull-out strength, and shrinkage was the coupled system made of EA and SRA. High heat of hydration obtained using 10% EA resulted in excessive portlandite formation and high expansion, which adversely affected the mechanical properties. The use of 0.5% SAP with additional internal curing water contributed to the excessive expansion of SAP particles and creation of voids into the matrix, which reduced compressive strength and fiber matrix bonding. Statistical analysis of the experimental data revealed that the individual use of 7.5% EA and coupled use of 5% EA either with 0.5% SRA or 0.125% SAP can result in producing flowable, high strength, and low shrinkage FRM mixtures applicable to repair.