Performance of concrete with fly ash and recycled HDPE plastic aggregates after fire exposure

Date of Publication

2018

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Civil Engineering with Specialization in Structural Engineering

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Adviser

Mary Ann Q. Adajar

Joenel G. Galupino

Defense Panel Chair

Andres Winston Oreta

Defense Panel Member

Richard M. De Jesus

Abstract/Summary

Due to the amount of energy required and emissions produced in the production of its components, concrete can have negative impacts to the environment and society. With the hope of advancing sustainable concrete production, the study sought to explore waste materials, namely HDPE and fly ash, as concrete constituents.

The alternative concrete specimens were made by partially replacing sand with HDPE pellets at 5%, 10%, 15% by volume of fine aggregates, and cement with fly ash at 30% and 60-% by weight of binder. To assess the feasibility of the alternative concrete, the study investigated the compressive strength (FC'), post-fire relative residual strength (RRS) and fire resistance rating (FRR). The study focused on the mechanical and fire performance, because given the inevitability of fire, the proposed alternative material should not only be strong enough for structural use but also safe enough to withstand fire. The results of the tests were then used to form response surface model equations to find the optimum amount of HDPE and fly ash substitution.

The compressive strength tests were done on 100-mm by 200-mm cylindrical specimens at varying curing periods (7, 24, 28, and 120 days), while the fire performance test were done on 50 mm-cubes cured for 28 days. The cubes were fired on one side until the temperature on the unexposed surface reached 139°C above the initial temperature. This duration is taken as the FRR. The fired cubes were then subjected to compressive strength tests to obtain the RRS.

The results show that HDPE slightly increased or did not have a significant effect on the 28th-day compressive strength, whereas fly ash generally decreased the strength. Due to the delayed pozzolonic action, the fly ash mixes still showed an increase in strength after curing beyond 28 days.

As with the fire performance, replacement of up to 5% HDPE increased the RRS. Fly ash generally decreased the RRS except for 10% HDPE samples which increased with 30% fly ash. The more the HDPE content, the less fly ash was more beneficial for the RRS. In the other hand, the FRR was at the highest at 60% fly ash. It was found that fly ash improved the FRR of samples with 5% and 10% HDPE.

Using response surface method, the optimum percent substitution to maximize the compressive strength and fire performance was found to be 11.46% fly ash and 12.71% HDPE. This proportion is predicted to yield a 28th-day compressive strength of 30.80 MPa, RRS of 73.45% and FRR of 9.96 min.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU21558

Shelf Location

Archives, The Learning Commons, 12F, Henry Sy Sr. Hall

Physical Description

xvi, 167 leaves ; 30 cm.

Keywords

Fly ash; Concrete

This document is currently not available here.

Share

COinS