Forensic Investigation of Failed Reinforced Concrete

There are many ways for concrete to fail. It cracks, delaminates, spalls, becomes discolored, and dusts prematurely. M+P Labs can help you determine why these failures have occurred and assess if the damage is cosmetic or structural and should be replaced.

Through materials testing, we can answer the following questions:

  • Did the materials used match the concrete mix design?
  • Were there any compatibility issues between the materials or environment?
  • What was the water/cement ratio?
  • Was the concrete placed properly?
  • Was it finished properly?
  • Did it cure properly?

Listed below are some of the techniques we use to answer these questions.

  • Unit weight and absorption (ASTM C642). Measurements obtained will be compared against the mix design specifications.    
  • Water-soluble chlorides (ASTM C1152). Measurements taken at two depths in four cores to assess chloride penetration:  0-1.5” below the surface and 2-3” below.  Chlorides promote the corrosion of reinforcement and may induce concrete to crack or spall.
  • Air Void Analysis (ASTM C457). Performed on polished core cross-sections using calibrated image analysis software. This analysis will provide detailed information about the percent composition and distribution of the constituents in the concrete, including coarse and fine aggregate, cement paste, entrained and entrapped air.  We also use this technique to estimate of the water:cement ratio. 
  • Aggregate analysis (ASTM C856). Petrographic analysis of the aggregates in a concrete core to identify the predominant minerals in the coarse and fine aggregate, and to determine if any deleterious reactive minerals are present. 
  • Petrographic analysis (ASTM C856). A microstructural examination by optical and scanning electron microscopy (SEM) of the paste and aggregate on a polished depth profile of a core to look for features such as cracks, compatibility issues, evidence of detrimental reactions, breakdown of aggregate, etc.This also includes a microstructural examination of the near-surface of each core to determine if bleed channels and other characteristic features are present to assess if proper finishing and cure of the concrete occurred. We recommend selecting two cores from “good” areas and three cores from “bad” areas.

The results of all testing are documented in detailed written report with high-quality photographs and photo micrographs depicting features. The report will include an assessment of the concrete based on the information provided by the client, laboratory testing and site visit (optional).  Recommendations for repair techniques will also be included if desired.

For clients local to our Schenectady, NY laboratory, we also offer:

  • Delamination survey
  • Covermeter survey
  • Half-cell potential survey
  • Coring Services

 
All testing at M+P Labs is performed in compliance with the following three quality systems: ISO 17025, Nadcap (aerospace & defense industry) and 10 CFR 50 Appendix B (nuclear utility industry).  These quality requirements are applied to each and every job we perform,  regardless of whether it requires conformance to any of these accreditations.  The accuracy of the results produced by our staff of highly-experienced analysts allows our clients to make critical decisions based on precise and reliable information.

March, 2011