Thermo‐mechanical response of concrete sandwich panels reinforced with glass fiber reinforced polymer bars

Abstract

The thermo-mechanical behavior of sandwich panels was experimentally investigated. The panels featured two external concrete layers reinforced with glass fiber reinforced polymer rebars (GFRP) and an internal expanded polystyrene insulation layer. These are typical for low load bearing and thermally insulated panels in façade claddings. To assess the suitability of the internal GFRP reinforcement, the heating condition was such that rebars in one concrete layer were exposed to temperatures higher than the glass transition temperature of the resins. Such extreme condition allowed verifying the retention of the mechanical behavior, in terms of deformability and load-carrying capacity, with bending tests of unheated and heated panels. As main outcome, the elevated temperature produced significant modification of the insulation layer, considerable reduction of global stiffness and load-carrying capacity, while GFRP bars were not apparently modified.concrete, glass fiber bars, mechanical testing, sandwich panels, thermomechanical loading | INTRODUCTIONIn the last two decades, several investigations showed the advantages and disadvantages of replacing the steel reinforcement with FRP (fiber reinforced polymers) rebars in structural concrete components. 1 Many investigations and applications were focused on the GFRP (glass fiber reinforced polymer) rebars for their non-corrosive and nonconductive characteristics as well as their high strength, low weight, and durability. 2-4 One important field of application of GFRP reinforcement is slender concrete structures. The lack of corrosion allows to reduce the bar protection decreasing the concrete covers and, as consequence, the thickness of concrete members. Slender layers of reinforced concrete are frequently adopted as the load-carrying members of sandwich panels used, in the construction industry, as façade panels or slabs for pavements. External cladding sandwich panels made of pre-cast concrete usually consist of three layers: thin load-carrying concrete layer, the thermal insulation, and a thin facing concrete layer. Sandwich panels are frequently adopted in buildings to exploit their structural and thermal efficiency. Nowadays, they play an important role in the building industry that aims to improve the energy efficiency and increase the durability of building constructions.Several efforts were dedicated to the understanding and optimization of the mechanical behavior of sandwich panels with different reinforcements: steel rebars and connectors (see, e.g., Reference 5); steel rebars and GFRP connectors (see, e.g., Reference 6); steel fiber reinforced selfcompacting concrete and GFRP connectors (see, e.g., Reference 7). Some investigations were devoted to the mechanical response of steel-free sandwich panels having both reinforcement and connectors made of GFRP (see, e.g., Reference 8).In spite of the interest in constructions industry on steelfree sandwich panels, their durability and in particular their

Experimental and microstructural study of the compressive strength of concrete samples containing low volumes of expanded polystyrene beads

“…The first set of samples was so designed to make it possible to evaluate the effect of low volumes of EPS beads on the slump and uniaxial compressive strength of concrete, yet, samples containing higher EPS contents were also prepared for the sake of comprehensiveness. Accordingly, the four W/C ratios of 45, 50, 55, 60% and the 15 EPS volume contents of 0, 1, 2, 3, 4, 5, 6,7,8,9,10,15,20,30, and 40% were chosen. The EPS concrete mixes of this set of samples were prepared by the partial replacement of coarse aggregates with EPS beads.…”

“…Ultra-lightweight closed-cell EPS beads can be effectively employed to produce concretes with promising strength to weight ratio, attractive sound, and heat insulation characteristics, and exemplary crushing and energy absorbing capacities. [1][2][3][4][5][6][7][8][9][10][11] Accordingly, mush research have been conducted in the past two decades to characterize the mechanical properties of EPS concrete from which a big portion is related to its compressive strength. 7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] A closer look to this part of literature reveals that only the compressive strength of samples containing considerable volume contents of EPS beads (more than 10%) are addressed with a common finding stating that compressive strength is an ever decreasing function of EPS volume content.…”

Konstruktion und Bemessung selbsttätiger Hochwassersperren aus Hochleistungsbeton

“…An der TU Kaiserslautern wird seit 15 Jahren daran gearbeitet, das Trag-und Verformungsverhalten von Konstruktionen aus Hochleistungsbeton zu erforschen [11][12][13][14] und dabei auch die Vorteile von Sandwichkonstruktionen nutzbar zu machen [15,16].…”

Numerical modeling of the interaction between reinforcement and concrete at early age—A comparison between glass fiber reinforced polymer and steel rebars

“…Recently, Salah‐Eddine et al 35 developed an analytical study to predict the axial‐ and flexural‐load capacity of the GFRP‐reinforced HSC. Recently, Schmitt et al 36 developed an experimental study which deals with the thermomechanical response of concrete sandwich panels reinforced with GFRP rebars. He deduces from his experimental study that when the temperature in the concrete achieves the 292°C, the GFRP rebar keeps a good adhesion with the concrete.…”