All materials deteriorate in some measure from the ravages of time, the effects of wear and tear, and exposure to the elements or chemicals. An important factor for the designer's consideration in selecting a material is its repairability. Concrete lends itself far better than most other materials to rehabilitation. Reconstitution and renovation of concrete seldom require replacement of units, perhaps the most common method of repairing structures made of other materials.
It is a unique distinction of concrete structures that they are rarely beyond repair. A building in Fargo, North Dakota, thought at first to be beyond repair, was instead restored to a higher than original strength by polymer impregnation at only 5 « percent of the cost of demolishing and replacing. A veritable arsenal of repair materials and techniques is available for dealing with every imaginable type of deterioration and it is even possible to repair concrete under unfavorable temperature conditions or in remote, almost inaccessible locations. For example, when necessary concrete can be repaired with magnesium phosphate cements or epoxies at temperatures lower than 0 degrees F or in ovens at temperatures of 120 degrees F, thus disrupting manufacturing or traffic operations minimally. Repairs can be made at higher temperatures by shotcreting with magnesium phosphate or high alumina cements. In locations that humans cannot readily reach, Portland cement grout, mortars or concrete can be pumped in.
This article also discusses repair materials, surface problems, repairing cracks, repairing large-scale damage, structural repair, and waterproofing, dampproofing, and protecting.