Moisture "transmission" is the needed common "proof" in claims of damage by sulfate attack and moisture penetration. Thus, attorneys argue the moisture or water vapor damaged the structure and/or contents above the concrete, especially the flooring. (I will address the flooring issue in a future column.)
This is not to say there are not legitimate claims of defective concrete. There are. I have investigated, for example, instances where the use of certain packaged materials have resulted in defective products and installations. And I have seen instances of serious defects caused simply by poor workmanship.
However, many of my investigations concern allegations that have been shown to be based on theories that do not hold up when they are examined by accepted scientific principles and methods.
For example, in a number of cases, expert witnesses have argued that scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM/EDX) methods are valid as stand-alone tools when analyzing concrete. However, when shown SEM images of a number of predominately carbon-based compounds, under oath one expert could not distinguish between a diamond and a graphite pencil lead or a lump of coal. In another instance, an expert concluded that, because of the peak ratio of calcium to silica and the rest of the EDX spectra, the material was likely hydrated cement, possibly undergoing sulfate attack. In fact, the sample was a Tums antacid tablet!
Unscientific methods are used to support claims of high moisture content and unacceptable levels of vapor emissions from hardened concrete. The oft-cited vapor emissions test recommended by the flooring industry, for example, is unreliable in predicting or preventing flooring distress. But to be refuted in a court of law, such claims require costly investigations.
What precautionary measures may be appropriate for concrete suppliers, contractors and design professionals to address their potential exposure to litigation and reduce their risk? One method may include installing concrete with a 0.45 w/cm ratio using Type V cement and 4,500 psi concrete, since plaintiffs argue this is a "bright line" codified standard. But the only residences built to this claimed specification are those built in response to litigation claiming sulfate attack. I don't recommend this for a variety of reasons: It will increase the cost of the foundation, waste cement, may be environmentally backward and in my opinion is just wasted money and resources.
One sure way to avoid expensive concrete litigation is to get out of the concrete business. Barring that draconian measure, buy insurance, if you can get it, then read the policy carefully and diligently address and shift risks regarding all duties or responsibilities associated with flooring standards. Nowadays, contractors frequently can't obtain insurance, and self-insure, sometimes citing this as an advantage with respect to spurious litigation.
Also, since flooring standards are being imposed on the concrete contractor, some choose to limit liability by writing a letter to the general contractor saying they cannot be responsible for flooring standards or flooring failures, and that the concrete will be installed per the specs given.
Good luck and best wishes for 2009.
Geoffrey D. Hichborn, Sr., PE, is a civil engineer with nearly 30 years of experience in forensic evaluation of cement and concrete materials and related construction. He provides consulting services to manufacturers, developers and design professionals, and also serves as Senior Consultant at Concrete Insights Corp., a forensic and consulting firm, ConcreteInsights.com. CIC investigates the design, installation, performance and repair of concrete and related materials of construction, providing expert testimony in construction litigation and specialized consultation for concrete evaluations, repairs, standards and specifications. CIC investigators are known as "The Concrete Detectives."