Electrical resistivity of type IP cement concrete containing crystalline rice husk ash as supplementary cementing material

Date

4-2011

Degree

Bachelor of Science in Civil Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Marish S. Madlangbayan

Committee Member

Ginghis Maranan, Perlie P. Velasco

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Abstract

This study investigated the behavior of the direct current electrical resistivity, a key durability parameter, of concrete mixes with the addition of crystalline rice husk ash (RHA). Electrical resistivity is the resistance of a material to passage of electric current – high electrical resistivity indicates high durability of concrete. Electrical resistivity tests were done on concrete samples containing 10%, 15%, and 20% RHA (by mass of total binding material) and results were compared with a control mix containing 100% Type IP Portland cement. Electrical resistivities were determined after the concrete samples were cured for 28 and 56 days. It was found out that at 28 days curing period, electrical resistivities of 10% and 15% RHA concretes were relatively equal with the control concrete; lower electrical resistivity was observed from the concrete with 20% RHA. However at 56 days curing period, higher contents of RHA resulted in higher electrical resistivity. This improved electrical resistivity can be ascribed to the development of the aggregate-cement interface, called interfacial transition zone, of the concrete pore structure due to the pozzolanic reaction of crystalline RHA. Pozzolanic reaction converts calcium hydroxide, a product of the hydration of cement, to a less porous product known as calcium silicate hydrate, resulting in a less porous concrete microstructure and thus making conduction of electric current less efficient. Since crystalline RHA is a slow reacting material, a highly developed concrete pore structure can only be achieved with longer curing period (e.g. 56 days). Moreover, a colorimetric test was done on selected specimens and test results had validated the electrical resistivity data.

Language

English

Location

UPLB College of Engineering and Agro-Industrial Technology (CEAT)

Call Number

LG 993.5 2011 E63 L33

Document Type

Thesis

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