Treatment of recycled concrete aggregates using silica fume impregnation and its influence on the properties of concrete

Date of Publication

2017

Document Type

Bachelor's Thesis

Degree Name

Bachelor of Science in Civil Engineering with Specialization in Structural Engineering

Subject Categories

Civil Engineering

College

Gokongwei College of Engineering

Department/Unit

Civil Engineering

Thesis Adviser

Richard M. De Jesus

Defense Panel Chair

Daniel Nichol R. Valerio

Defense Panel Member

Jonathan R. Dungca
Maria Emilia P. Sevilla

Abstract/Summary

Recycled concrete aggregates (RCA) are aggregates sourced form construction demolition and debris. As such, the use of RCA as coarse aggregate often results in weaker concrete in comparison to concrete utilizing natural aggregates. The factor that significantly affects this is the adhered mortar, that is present in RCA. It is necessary to target this old mortar in order to treat and enhance the properties of RCA. Two treatments were conducted in this study: sulfuric acid bath (SA) treatment, and silica fume impregnation (SF) treatment. SA treatment utilizes a sulfuric acid solution with a 0.5 molarity and reacts with the old cement mortar which dissolve and remove adhered mortar on the RCA. SF treatment utilizes silica fume to penetrate the void spaces and irregular spaces along the surface of RCA. Silica fume also reacts with cement during the hydration process which produces additional C-S-H, creating a stronger layer of cement around RCA. A combination of these two treatments were also conducted. The treatments resulted in insignificant changes in the physical properties of RCA. SA treatment was found to have a detrimental effect on the surface of RCA, which developed a weaker layer of adhered mortar on the RCA surface thus by causing a reduction in the mechanical strength of the concrete. SF treatment resulted in improved compressive strength in comparison to untreated, SA, and combined treatment RCA concrete. It was also found that a value of 50% replacement of RCA in all treatment samples was the optimal in maximizing the strength of RCA concrete.

Abstract Format

html

Language

English

Format

Print

Accession Number

TU21632

Shelf Location

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

Physical Description

105 leaves, illustrations (some color), 30 cm.

Keywords

Aggregates (Building materials); Strength of materials

Embargo Period

5-13-2021

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