Steel fiber reinforced geopolymer matrix (S-FRGM) composites applied to reinforced concrete structures for strengthening applications: A preliminary study

Steel fiber reinforced geopolymer matrix (S-FRGM) composites are explored as a new tool in strengthening applications of reinforced concrete (RC) structures. The suitability of fly ash geopolymers as the matrix employed in S-FRGMs is investigated in this paper. Geopolymer matrix is used to embed galvanized steel fibers and bond the composite to a concrete substrate. By varying the molar concentration of the NaOH activating solution, three different geopolymer matrices are obtained and the influence of the alkaline environment on the bond behavior between fibers and matrix is examined. Physical, mechanical, and microstructural properties of the three matrices are measured and related to the interfacial bond behavior of S-FRGM-concrete joints. Results show that the decrease of the molar concentration of the NaOH activating solution leads to an increase of the interfacial bond behavior between matrix and fibers, which in turn improves the effectiveness of the composite action of the strengthening system.