Among the various possibilities of fibers, FIDIA S.r.l. - Technical Global Services supplies, for the design of structural restoration, different kind of fiber sheets, such as carbon, glass or aramid fiber sheets, impregnated in situ using an epoxy resin whose job is to protect fibers from external damages, assure a good fibers alignment and guarantee a good strain distribution among them. Mechanical properties of a FRP (Fiber Reinforced Polymer) composite material depend on the correct arrangement and mixture of the above-mentioned fibers and resin. Among the several types of fiber sheets available on the market, FIDIA S.r.l. supplies only thermojointed sheets. The uniqueness of such sheet is that during installation it does not unwind making it easier to labor workmenship.
Concerning the strengthening of RC and PC structures, FIDIA S.r.l. promotes the use of high strength or high modulus carbon fibers, according to the problem to deal with; on the other hand, in case of masonry structures, both carbon and glass fibers are mostly commonly used. Aramid fibers are applied mostly as mechanical anchorages for strengthening solutions that implemented carbon and glass fiber sheets, since they show a higher shear and impact strength.
According to the CNR-DT 200/2004 design guidelines, "Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Existing Structures" FRP composite materials supplied byFIDIA S.r.l. have the following nomenclature:

• FIDCARBON, FIDGLASS, FIDARAMID indicating the fibers typology (carbon, glass or aramid);
• UNI, BID, QUADRI corrisponding to the direction of fibers arrangement (unidirectional, bidirectional and quadriaxial);
• the number following the above-mentioned name (200, 300, 320, 400 etc.) explains the sheet weight, generally expressed in g/mq;
• the nomenclature HM or HT represent the acronyme of High Modulus and High Tenacity, that are two typical properties of composite materials;
• the last number (100, 240, 390, etc.) corresponds to the elastic modulus of the composite material and is expressed in GPa.