Q.: Our company supplied concrete for some flatwork from which 15 cubic yards had to be torn out and replaced because of low test strengths. We are not convinced that the low strength measurements were valid. How can we determine who should pay the cost of removing and replacing this concretes

A.: In ASTM C 94, Specification for Ready-Mixed Concrete, Section 17 deals with such problems. It suggests that if the manufacturer and purchaser cannot agree, a panel be formed of three qualified engineers to adjudicate the controversy. One of these engineers is designated by the manufacturer, a second by the purchaser, and the third by the other two members of the panel. By prior agreement their decision is binding.

A useful six-step procedure for adjudicating such disputes is described in the document, "In-Place Concrete Strength Evaluation A Recommended Practice," NRMCA Publication Number 133-79, National Ready Mixed Concrete Association, 900 Spring Street, Silver Spring, Maryland 20910; members $2, others $4.