Date of Publication

5-5-2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Subject Categories

Civil and Environmental Engineering | Civil Engineering | 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. Reinforced concrete 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 product which is called rust is typically 3 to 6 times the original volume of steel reinforcement, which cause stress to the concrete resulting to cracks. The rate of corrosion is affected by the permeability of concrete and of concrete. This means that improving the concrete’s permeability and cracking resistance will improve its corrosion resistance. Self-compacting concrete (SCC) is known to have low porosity and permeability due to its low water content. It has higher cement factor than conventional concrete, which increases the alkalinity and improve the passivation of rebar. In order to improve the durability, hooked-end steel fiber is added to SCC. The addition of steel fiber decreases the crack severity and width. According to literatures, some of the steel fibers attached in the reinforcement redirects the flow of current and becomes sacrificial anode. Central composite design was used to determine the required design mixes and response surface methodology was used to develop the models. 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=0.679), 5-day corrosion (R2=0.998), 15-day corrosion (R2=0.626). The cement ratio has been the leading factor that affects the slump flow, gtm, 5-day corrosion and 15-day corrosion with p value >0.05. Steel fiber has also been significant to passing ability and both 5- and 15-dayscorrosion levels with p values less than 0.05. With the use of SCC and the addition of steel fiber, the corrosion level is reduced 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 maximized, and the corrosion level should be minimized. Seventy different design mixes were produced by the software. These design mixes were sorted into three categories, highest desirability, lowest cement content and lowest corrosion level. Top five design mixes for each category were included in the report. All design mixes obtained an acceptable rheological properties and compressive strength.

Abstract Format

html

Language

English

Format

Electronic

Keywords

Fiber-reinforced concrete; Self-consolidating concrete

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Embargo Period

5-4-2023

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