SYMPOSIA PAPER Published: 01 January 1990

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


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.

Author Information

Cady, PD
Weyers, RE
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Developed by Committee: C09
Pages: 182–193
DOI: 10.1520/STP23461S
ISBN-EB: 978-0-8031-5122-2
ISBN-13: 978-0-8031-1452-4