STP1061

    Petrographic Examinations Aid in Establishing the Causes of Deterioration of Precast Concrete Sewer Manhole Sections

    Published: Jan 1990


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    Abstract

    This paper describes a forensic investigation to establish the causes for very severe, early deterioration of precast concrete sewer manhole sections. Petrographic examinations played a major role in determining the causes of the deterioration. Early on, it was established that the entrained air-void systems were severely inadequate in the affected sections. However, many manhole sections that were located well below the frost line still showed severe deterioration. In addition, crack patterns characteristic of expansive reactions (map cracking) were present along with the typical fracture planes parallel to exposed surfaces commonly associated with freezing and thawing attack. Petrographic examinations revealed that the MgO content of the portland cement in those sections was 3 1/2 times that of the unaffected sections and, at 9.1%, was more than 50% higher than is permitted in ASTM C-150.

    Keywords:

    magnesia reactivity, freezing and thawing deterioration, precast manholes, air-entrainment


    Author Information:

    Cady, PD
    professor of civil engineeringassociate professor of civil engineering, Penn State UniversityVirginia Polytechnic Institute and State University, University ParkBlacksburg, PAVA

    Weyers, RE
    professor of civil engineeringassociate professor of civil engineering, Penn State UniversityVirginia Polytechnic Institute and State University, University ParkBlacksburg, PAVA


    Paper ID: STP23461S

    Committee/Subcommittee: C09.65

    DOI: 10.1520/STP23461S


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