It is well known that ﬁber and matrix type largely inﬂuence the overall mechanical properties of a composite. However, the end properties of a composite produced from these materials are also a function of the way in which the materials are prepared and processed. For most commercial repair systems available for civil infrastructure applications, themanufacturers provide both the ﬁbers in the sheet or fabric form and the matrix. The ﬁbers are normally treated with coatings that provide good wetting for the chosen matrix. They also provide polymers for pre-treatment of surfaces and cover coats. In most cases, the sheets or fabrics are saturated with the matrix and applied to the prepared surface (manual lay-up), then allowed to cure. Preparation includes cleaning, ﬁlling of voids and application of prime coat on the parent material (substrate). After the matrix cures, a topcoat is applied for protection and aesthetics. In some cases, ﬁreproof coatings are used to improve the ﬁre resistance of the repair. The composites are also available in preformed, pre-cured sheets. These laminates, made of unidirectional carbon ﬁbers, have much higher tensile strength because of better alignment and factory processing. These thin laminates are attached to the concrete surface using polymers. Here again, the manufacturers supply compatible primer and adhesives.