An investigation on the mechanical properties of concrete mixed with crumb rubber and fly ash after exposure to elevated temperature

Date of Publication

2018

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Civil Engineering with Spec in Construction Technology & Management

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Adviser

Mary Ann Q. Adajar

Defense Panel Chair

Jason Maximino C. Ongpeng

Defense Panel Member

Maria Emilia P. Sevilla

Ronaldo S. Gallardo

Abstract/Summary

The increasing amount of waste rubber tires has brought detrimental effects to the environment and various health risks. Thus, there is a necessity of finding ways to reuse them in order to reduce waste. The objective of the study is to determine the compressive, tensile, and flexural strength of concrete with 20% fly ash replacement cement while incorporating crumb rubber as partial replacement to fine aggregates after exposure to elevated temperature. The samples were comprised of 0%, 5%, 10%, 15%, and 20% crumb rubber replacement. Other properties determined were the slump, air content and unit weight, as well as the modes of failure that occurred to the concrete samples. It was observed that as the percentage of rubber increased, the strength parameters as well as unit weight decreased. Also, as the time of exposure to elevated temperature increased from 1 to 3 hours, the strength parameters decreased. Based on the results of the samples containing rubber, the samples with 5% rubber replacement to sand obtained the highest compressive, tensile and flexural strength whereas the samples containing 20% rubber obtained the least compressive, tensile and flexural strength. The optimum mix is 5% replacement of crumb rubber to fine aggregates, and 20% replacement of fly ash to cement, as its strength properties may be acceptable for structural use up to 1 hour exposure to elevated temperature. The concrete sample with 20% rubber replacement exposed to 3 hour elevated temperature is not a recommended mix as the samples experienced explosive spalling. It can be noted that the incorporation of rubber caused a decrease in workability, wherein the mix incorporating 20% rubber caused the cement, fly ash, water, sand, and rubber clumped up together forming ball-like shapes. The modes of failure that occurred to the cylinders tested for compressive strength showed mostly type 5 failure, which implies that the strength is relatively high, as the failure only occurred at the outermost tips of the specimen.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU21576

Shelf Location

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

Physical Description

xv, 152 leaves : illustrations (some color) ; 30 cm.

Keywords

Fly ash; Concrete; Cement; Crumb rubber

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