It is rare that one can point to any one thing as the complete cause of poor performance in concrete. Although the problems in hardened concrete, which will be discussed in this and the concluding installment of the series, usually appear as the result of action by external influences, the preventive measures often deal with practices in concrete mix design and in handling, placing and curing procedures. Scaling is the surface deterioration of concrete caused by the action of de-icing agents and /or freeze-thaw cycles. Scaling usually occurs on horizontal surfaces. To avoid scaling: order concrete with optimum air content; make sure that aggregates conform to ASTM C33; do not add more water at the jobsite; continue curing until design strength is attained; and apply a protective coating. Random cracking occurs when no provision is made for the changes in volume which are bound to occur with concrete masses of any appreciable volume or area. If joints are not provided for such movement, random cracking will occur rather than the more desirable controlled cracks at predetermined joints. To minimize cracking it is necessary to attack the problem from a number of directions including structural design, mix design, placing and curing practices, and the use to which the concrete is to be put. The term spalling refers to sloughing off of concrete as a result of mechanical abrasion and impact, as opposed to scaling caused by internal expansive forces and chemical reactions. To avoid spalling: use small radius jointing tools; use proven joint details; align dowels to a true horizontal with the subgrade and center line; keep joints clear of debris; and use well designed form ties. In addition, this article discusses the problems of dusting, alkali-aggregate reaction, and popouts and provides suggestions for correction.