Concrete spalling sensitivity versus microstructure: Preliminary results on the effect of polypropylene fibers

Rossino, Chiara; Monte, Francesco Lo; Cangiano, S.; Felicetti, Roberto; Gambarova, Pietro G.

doi:10.1051/matecconf/20130602002

Cited by 14 publications

(11 citation statements)

References 6 publications

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“…Four concrete mixes differing only for fibre type have been studied. Cement type CEM I -42.5 R has been used in combination with Ground Granulated Blastfurnace Slag (GGBS), as shown in Table 1 (see also [29,30]).…”

Section: Design and Test Setupmentioning

confidence: 99%

Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading

2019

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Explosive spalling of concrete exposed to fire consists in the violent expulsion of shards from the hot surface due to the interaction between cracking and pore pressure build-up. Fire spalling relevantly increases the overall thermal damage of a structure exposed to fire, thus leading to much higher costs in the repair intervention, and in some cases it can even jeopardize the structural stability due to loss of reinforcement protection and reduction of the bearing cross-sections. High-performance concrete is particularly sensitive to spalling phenomenon due to inherent material features, such as the unstable fracture behaviour and the low permeability (favouring high values of pore pressure). In this context, an experimental campaign has been carried out on high-performance concrete (f c & 60 MPa with silico-calcareous aggregate), without or with one of three different fibre types (steel fibre, monofilament or fibrillated polypropylene fibres). Tests were performed by means of a special test setup developed at Politecnico di Milano, based on slabs (800 9 800 9 100 mm) subjected to Standard Fire at the bottom and to biaxial compressive loading in the mid-plane, while monitoring pore pressure, temperature and deflection. Explosive spalling was observed in both plain concrete slabs and in one of the two slabs with steel fibre, this casting some doubts on the use of steel fibre alone against spalling. No detachment was observed when polypropylene fibre was added to the mix.

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Section: Design and Test Setupmentioning

confidence: 99%

Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading

2019

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“…Fibres. An aspect that has to be considered, when determining the concrete diffusivity containing PP fibres, is the microcracking that appears around the void channels once the fibres evaporate [20]. The cracks, being a mechanical response of the cement paste due to a local stiffness variation, cause a void increment, so reducing the internal concrete pressure after the peak and causing a variation in hydraulic diffusivity.…”

Section: Microcracking Related To Ppmentioning

confidence: 99%

Fire Spalling Prevention via Polypropylene Fibres: A Meso- and Macroscale Approach

Mazzucco

Xotta

2016

Modelling and Simulation in Engineering

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A deep understanding of concrete at the mesoscale level is essential for a better comprehension of several concrete phenomena, such as creep, damage, and spalling. The latter one specifically corresponds to the separation of pieces of concrete from the surface of a structural element when it is exposed to high and rapidly rising temperatures; for this phenomenon a mesoscopic approach is fundamental since aggregates performance and their thermal properties play a crucial role. To reduce the risk of spalling of a concrete material under fire condition, the inclusion of a low dosage of polypropylene fibres in the mix design of concrete is largely recognized. PP fibres in fact evaporate above certain temperatures, thus increasing the porosity and reducing the internal pressure in the material by an increase of the voids connectivity in the cement paste. In this work, the contribution of polypropylene fibres on concrete behaviour, if subjected to elevated thermal ranges, has been numerically investigated thanks to a coupled hygrothermomechanical finite element formulation. Numerical analyses at the macro-and mesoscale levels have been performed.

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“…Mixes M45, M70 and M95 consist of silico-calcareous aggregate (d a ≤ 16 mm), 400 kg/m 3 of cement for Mixes M45 and M75 and 480 kg/m 3 for Mix M95, and water to cement ratio = 0.56, 0.36 and 0.24 for M45, M70 and M95, respectively (see [8]). …”

Section: Design Casting and Curingmentioning

confidence: 99%

“…This first test series allowed to ascertain the role of fiber content and heating rate on the peak values of pore pressure and the consequent decrease of the apparent tensile strength. The second experimental campaign, recently launched at the Politecnico di Milano, is focused on the influence of concrete grade and mix design (see [8]):…”

Section: Introductionmentioning

confidence: 99%

Concrete spalling: Interaction between tensile behaviour and pore pressure during heating

Felicetti

Monte

2013

MATEC Web of Conferences

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Abstract. Explosive spalling is generally considered to be caused by concrete fracturing due to the interaction of (a) the pore pressure induced by moisture transport and vaporization and (b) the stress induced by thermal gradients and external loads. In order to investigate the first point, a special setup has been designed and an experimental campaign has been recently launched at the Politecnico di Milano, regarding ten different concrete mixes, characterized by different compressive strength, aggregate and fiber types.

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Concrete spalling sensitivity versus microstructure: Preliminary results on the effect of polypropylene fibers

Cited by 14 publications

References 6 publications

Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading

Fire spalling sensitivity of high-performance concrete in heated slabs under biaxial compressive loading

Fire Spalling Prevention via Polypropylene Fibres: A Meso- and Macroscale Approach

Concrete spalling: Interaction between tensile behaviour and pore pressure during heating

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