Experimental and Statistical Optimization of Engineered Cementitious Composites for Underwater Concrete

Zainab M. Al-Selmi, College of Civil Engineering, University of Technology, Baghdad 10066, IraqFollow
Basil S. Al-Shathr, College of Civil Engineering, University of Technology, Baghdad 10066, IraqFollow

Keywords

Anti-washout admixture, Polyvinyl alcohol fibers, Underwater casting, Washout resistance, Strain-hardening behavior, Mixture optimization

Document Type

Article

Abstract

The performance of concrete placed in underwater environments is often compromised by washout, reduced workability, and inadequate mechanical properties, while the application of engineered cementitious composites under underwater casting conditions has not yet been systematically investigated. This study addresses this research gap through an experimental and statistical evaluation of engineered cementitious composites for underwater concrete, focusing on the combined effects of anti-washout admixture and polyvinyl alcohol fibers. Six mixtures were tested under submerged conditions with anti-washout admixture dosages ranging from 0.7% to 1.1% and fiber contents between 1.5% and 1.75%. The experimental program evaluated fresh-state properties, including slump flow and washout loss, as well as mechanical performance in terms of compressive, flexural, and direct tensile behavior monitored up to 360 days. The results showed that increasing anti-washout admixture content enhanced underwater stability and reduced washout loss; however, excessive viscosity adversely affected strength and ductility. In contrast, increasing fiber content significantly improved crack-bridging capacity, strain-hardening behavior, and long-term mechanical performance. The optimum mixture, containing 0.7% anti-washout admixture and 1.75% fiber content, demonstrated superior overall performance, achieving compressive strength of approximately 99.6 MPa, flexural strength of about 10.9 MPa, tensile strength of around 4.4 MPa, and an ultimate tensile strain of nearly 3.75% at 360 days. Statistical modeling using Response Surface Methodology confirmed high model significance (p < 0.005) and strong predictive reliability (R² > 0.93). The novelty of this study lies in integrating experimental testing with statistically validated optimization to establish a rational and predictive design framework for high-ductility engineered cementitious composites suitable for underwater concrete applications.

Recommended Citation

Al-Selmi, Zainab M. and Al-Shathr, Basil S. (2026) "Experimental and Statistical Optimization of Engineered Cementitious Composites for Underwater Concrete," Engineering and Technology Journal: Vol. 44: Iss. 5, Article 3.
DOI: https://doi.org/10.30684/2412-0758.1543

DOI

10.30684/2412-0758.1543

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