Issue 48

V. P. Berardi et alii, Frattura ed Integrità Strutturale, 48 (2019) 222-229; DOI: 10.3221/IGF-ESIS.48.23 224  a testing device to apply load;  a data acquisition system. A still anchoring device mounted on the laboratory modular basement was realized to fix the reinforced specimen (Fig. 1). Load is applied using a 20-kN servo-hydraulic actuator mounted on the laboratory modular basement (Fig. 2). The data acquisition system includes:  actuator load cell and LVDT;  industrial 5 Mpixel camera;  strain gauges bonded to external surface of the specimens;  database management system. The equipment can automatically record the data at fixed time steps. Figure 2 : Testing Device. A preliminary debonding test was performed on a concrete specimen reinforced with GFRP composite laminate. The tested prismatic concrete block (150x150x400 mm 3 ) is one of a series of specimens manufactured using low strength concrete to best simulate the interface behavior of strengthened existing structures. Composite reinforcement was made of a pultruded E glass/polyester fiber reinforced polymer with a thickness of 1.6 mm. The E-glass fiber volume fraction was equal to 35%. A two component epoxy resin was used for bonding. A controlled thickness of 1.6 mm was imposed to the adhesive layer. The specimens were cured at 30 °C for 72 hours. First, five cubic samples (150x150x150 mm 3 ) made of the same concrete mixture of the prismatic specimens were prepared and tested, according to ISO 1920-4 standard, in order to evaluate the mean compressive strengths, respectively cubic R cm and cylindrical f cm . Second, tensile tests, according to ASTM D3039M standard, were performed to obtain the mean Young’s modulus E GFRP and ultimate tensile stress f GFRP along fiber direction of the pultruded GFRP composite. The experimental mechanical properties of concrete and GFRP laminate, together with the nominal Young’s modulus Er and tensile strength f r of resin, according to the manufacturer technical datasheet, are listed in Tab. 1. R cm [MPa] f cm [MPa] E GFRP [MPa] f GFRP [MPa] E r [MPa] f r [MPa] 24.54 20.37 48000 800 11200 25-30 Table 1 : Mechanical properties of specimens’ materials.