The following is a summary from a Concrete Expert Witness Report of a Claim against a Concrete Contractor regarding defects alleged in concrete materials and workmanship, including damage to concrete, post tensioning strands, attachments and related materials and installation. A full Concrete Forensic Analysis and Investigation was performed.
The on-site conditions show that most of the concrete are mildly to heavily scaled
which is directly exposed to irrigation (precipitation is low) water draining over
concrete surfaces, or includes areas of concrete exposed to freezing and thawing
cycles, and which experience extreme weathering, but to little direct moisture.
Coarse aggregates in the concrete appear to be expansive, or are otherwise breaking
down as well. ASTM C 33 has detailed requirements and discussion regarding
aggregate soundness, friability, durability, and alkali aggregate reactivity. This includes
exterior horizontal flatwork and the vertical edge of PT slabs as well. (The exterior
concrete does not “show” well.) Cracking of the PT portion of the concrete is low and
generally acceptable, though some cracking of exterior flatwork may be excessive and
due to expansive soils. While the structural integrity of the PT Slab and Foundation
System appears unaffected by site conditions, and the foundations appear to be
designed and functioning properly, Plaintiff offers evidence which may lead a trier-of-
fact to believe that the soils have caused cracking and distortion to the foundations
and thus distress to the walls and other parts of the structure.
It is likely that invasive sampling and testing would largely confirm that the concrete improvements installed by Southern Building and Concrete, Inc. satisfied contractual requirements, except possibly for the aggregate materials supplied as an ingredient to the concrete itself.
Furthermore, it is highly likely that the following conditions would be demonstrated by such an Invasive Testing Program:
• The slab thickness meets the requirements of the plans;
• The present concrete strength in garage, interior, and footing samples greatly exceeds the requirements of the plans;
• The original concrete strength met the requirements of the plans;
• The post-tensioning tendons are not corroded as plaintiffs’ experts imply, and its strength today meets the requirements of the plans for the PT tendon strength originally required;
• Visquene is present as required, and its thickness meets the requirements of the plans;
• The granular base above the visquene is present as required, and its thickness meets the requirements of the plans;
• The depth of the edge footing meets the requirements of the plans;
• The soils are as expansive or very much more expansive than expected;
Allegations of sulfate attack (the environment destroying the concrete itself because the concrete was not designed and installed to resist it) and chloride corrosion (corrosion is damaging the steel which was intended to strengthen the foundation system, and was allowed to penetrate the concrete because it was defectively installed) coupled with the observable condition of much of the exterior concrete constitute a very aggressive and powerful claim by plaintiffs. They offer fairly credible evidence of various types to support the claims of defective concrete, though the concrete is substantially more durable than they admit.
They assert that but for the defective materials and workmanship of Southern Building and Concrete, Inc., the concrete would be more durable and resistant to its environment and would not cause the consequential damage of rusting to the embedded metallic materials, or have its insufficient resistance to sulfates.