Susceptibility of the concrete tank of the sewage treatment plant at MDC 100 to sulfate attack

Date

2011

Degree

Bachelor of Science in Civil Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

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Abstract

The site where the study was conducted is the MDC 100. It is a four-billion peso high rise building owned by the Mercury Drug Corporation and located at E. Rodriguez Jr. Avenue corner Eastwood Avenue, Barangay Bagumbayan, Quezon City. Placed under the slab of Basement 5 of the building is a sewage treatment plant (STP) designed to treat the wastewater coming from kitchen wastes, rainwater and water from flushing.

Structures generally experience chemical attacks due to the compounds existing in their service environment. Sulfate attack, one the most common chemical attacks, typically occurs when dissolved sulfate in water penetrates the concrete.

Organic compounds produce hydrogen sulfide (H2S) which reacts with water to become sulfuric acid (H2SO4). The sulfuric acid reacts with the cement paste and forms calcium sulfate causing a combined acid-sulfate attack. This may lead to extensive cracking, expansion or loss of bond between the cement paste and aggregate.

Since the permeability of the concrete tank of STP solely depends on the concrete itself and wastewater contains decomposing organic compounds, the tank of STP is very much prone to sulfate attack.

In this study, the susceptibility of the tank of the sewage treatment plant in MDC 100 to sulfate attack was analyzed through exposure of concrete samples to a sulfate-induced environment. Six samples simulated from the mixture used at the site were made and tested for 28 days using the recommended methodology of ASTM C1012-95.

The initial results of the study proved that the concrete mixture used for the STP is not durable enough to withstand sulfate attack throughout its service life. It was confirmed by evidences such as change in appearance and length expansion after a short period of exposure.

Language

English

LC Subject

Concrete tanks--Design and construction, Sewage disposal plants.

Location

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

Call Number

LG 993 2011 E63 D48

Document Type

Thesis

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