Materials and Structures

, 52:14 | Cite as

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

  • Francesco Lo MonteEmail author
  • Roberto Felicetti
  • Chiara Rossino
Original Article


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 (fc ≈ 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 × 800 × 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.


Biaxial loading Explosive spalling Fibre Fire Deflection High-performance concrete High temperature Pore pressure Slab 



The Authors are grateful to Italcementi S.p.A.—HeidelbergCement Group, Global Product Innovation Department (Bergamo, Italy) for the design of the concrete mixes and the useful contribution in preparing the specimens. Fondazione Lombardi Ingegneria (Minusio, Switzerland) is thanked for the financial support given to this research project. The logistic and technical support of LPM (Laboratory of Material and Structural Testing) at Politecnico di Milano is also acknowledged. Finally, the authors wish to thank Alessandra Piovan, Gabriele Scaciga and Haibin Zhi, who actively contributed to this study in partial fulfilment of their MS degree requirements at Politecnico di Milano.

Compliance with ethical standards

Conflict of interest

The first two authors are members of RILEM Committee TC 256-SPF “Spalling of concrete due to fire: testing and modelling”.


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Copyright information

© RILEM 2019

Authors and Affiliations

  1. 1.Department of Civil and Environmental EngineeringPolitecnico di MilanoMilanItaly
  2. 2.Global Product Innovation DepartmentItalcementi S.p.A. - HeidelbergCement GroupBergamoItaly

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