Single-lap shear bond tests on Steel Reinforced Geopolymeric Matrix-concrete joints

Abstract

Nowadays Fiber Reinforced Polymers (FRPs) represent a well-established technique for rehabilitation of Reinforced Concrete (RC) and masonry structures. However, the severe degradation of mechanical properties of FRP under high temperature and fire as well as poor sustainability represents major weak points of organic-based systems. The use of eco-friendly inorganic geopolymeric matrices, alternative to the polymeric resins, would be highly desirable to overcome these issues. The present work aims to investigate the bond characteristic of a novel Steel Reinforced Geopolymeric Matrix (SRGM) strengthening system externally bonded to a concrete substrate having low mechanical properties. SRGM composite material consists of stainless steel cords embedded into a fireproof geopolymeric matrix. Single-lap shear tests by varying the bonded length were carried out. The main failure mode observed of SRGM-concrete joints was debonding at the fiber-matrix interface. Test results also suggest the effective bond length. On the basis of the experimental results, a cohesive bond-slip law was proposed.

Bond Behavior of Fabric-Reinforced Geopolymeric Matrix System – A Pilot Study

“…This is because of the fact that there is an effective bond length, beyond which, no significant increase in the maximum load occurs. The effective bond length is typically in the range of 150 to 250 mm [5][6][7]15]. As such, it would be misleading to calculate values of the bond strength (max) based on results of specimens with a bonded length greater than the effective bond length.…”

“…The use of inorganic alkali-activated geopolymeric matrices with ground industrial waste materials, alternative to the polymeric resins and cementitious mortars, would offer a sustainable and eco-friendly strengthening solution. Few studies focused on studying the structural behavior of concrete elements strengthened with fabric-reinforced geopolymeric matrix (FRGM) strengthening systems [13][14][15]. Vasconcelos et al [13] employed metakaolin-based geopolymer mortar as a sustainable alternative to commercial mortars.…”

“…Due to its limited fluidity, the geopolymer matrix was unable to penetrate into the carbon fiber filament yarns and transfer the load to the carbon fiber reinforcement. Bencardino et al [15] examined the bond behavior of steel-reinforced geopolymeric matrix-concrete joints in single-lap shear bond tests. An effective bond length of 200 mm was required to develop the maximum bond strength.…”

Experimental Investigation and Numerical Analysis of Bond Behavior in SRG-Strengthened Masonry Prisms Using UHTSS and Stainless-Steel Fibers

“…Using combining composite textiles and inorganic matrices, resulting in what is related to with various names: textile-reinforced concrete (TRC), textile-reinforced mortar (TRM), fabric/fiber reinforced cementitious matrix (FRCM), steel reinforced grout (SRG) and others. Reinforcing fabrics/fibers could be made of steel [2], basalt [3], polyparaphenylene-benzobisoxazole (PBO) [4], carbon [5], aramid or glass [6] and basalt. Many experimental works are available in the literature on FRCM/SRG-concrete bond tests [2][3][4][5][6], flexural strengthening using traditional [7] and innovative eco-friendly [8] technique and on axial behavior of confined masonry columns [9].…”

Cohesive fracture in composite systems: experimental setup and first results

“…With reference to FRP-concrete end debonding, it is well-known that the corresponding mechanical behavior can be modeled via a cohesive law, that allows also the prediction of the mode II fracture mechanism experimentally observed in failure of strengthened systems [16][17][18][19][20]. Several researchers are being studied this local failure mechanism by proposing different test setups, generally based on either linear variable displacement transducers (LVDTs) or laser meter devices installed on composite plate and located at the beginning of bonded area, as well as on strain gauges, positioned along longitudinal direction [21][22][23]. Some recent studies have introduced a non-contact optical technique, digital image correlation (DIC), to obtain the FRPconcrete slip on extended areas of tested specimen rather than only on the beginning of bonded area [24][25][26][27][28][29][30][31][32].…”