Date of Publication

5-15-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Subject Categories

Civil Engineering

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Advisor

Jason Maximino C. Ongpeng

Defense Panel Chair

Bernardo A. Lejano

Defense Panel Member

Andres Winston C. Oreta
Lessandro Estelito O. Garciano
Rodolfo P. Mendoza, Jr.
Michael Angelo B. Promentilla
Lea B. Bronuela-Ambrocio

Abstract/Summary

Corrosion has been the leading cause of reinforced concrete structure degradation. Structures in marine environments are susceptible to accelerated corrosion due to the presence of chloride. Corrosion due to chloride attack is known to be fast and severe. Corrosion products are typically 3 to 6 times the volume of steel reinforcement, which can induce stress that will cause cracks. The rate of corrosion is affected by the permeability of concrete and its durability to prevent or at least delay the cracks. These ideas were capitalized on in improving the concrete's corrosion resistance. Self-compacting concrete was used as a reference because of its established advantages, such as low porosity and permeability due to its low water content and high cement factor, which improves the passivation of rebar. In order to improve the durability, steel fiber is added to the developed concrete. The addition of steel fiber improves the cracking resistance of concrete, and some of the steel fiber can be attached to the rebar, which redirects the flow of current and serves as a sacrificial anode in reference to the literature. Models derived based on material constituents (cement, w/c, SP, and steel fiber) predict the following responses, slump flow (R2=0.847), l-box (R2=0.626), gtm (R2=0.727), fc’ (R2=0.432), 5-day corrosion (R2=0.998), 15-day corrosion (R2=0.626). The cement ratio has been the leading factor that affects the responses with p-values of >0.05, 0.276, >0.05, 0.33, >0.05, and >0.05, respectively. Steel fiber has also been significant to most responses, including the corrosion level. The P-values calculated for each response were, 0.944, >0.05, 0.235, 0.0669, >0.05, and >0.05. The corrosion level of SFRSCC is lower by 45.41% by average as compared to SFRC design mixes. This research also successfully developed charts that can used as a substitute for the troubleshooting guide for design mix of SFRSCC. The optimal design mix was calculated using the derived models. Several criteria were set, such as, the mixture should yield acceptable rheological properties in accordance with EFNARC, the compressive strength should be greater than 28Mpa, and the corrosion level should be minimized. The optimum design mix has a projected 15-day corrosion level of 6.8%, which is lower than the lowest corrosion level from the data used. The derived optimum design mix has cement (469.76kg), w/c (0.4), SP (0.734%) and steel fiber (30%).

Abstract Format

html

Language

English

Format

Electronic

Keywords

Self-consolidating concrete; Reinforced concrete—Corrosion

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Embargo Period

5-4-2025

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Available for download on Sunday, May 04, 2025

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