Sessions & Events

Fire Performance of Ultra-High-Performance Concrete

Wednesday, October 29, 2025  11:00 AM - 1:00 PM, H - Holiday 2

Ultra-high performance concrete (UHPC) is a novel class of concrete that has superior mechanical properties and durability characteristics. Although UHPC exhibits exceptional performance at room temperature, the behavior of UHPC under fire conditions can be of concern due to faster degradation of strength and modulus properties with temperature, as well as its high susceptibility to fire-induced spalling. Since UHPC is a new construction material, there is limited information on its fire performance. This session will invite research and industry groups to share information on the fire performance of UHPC with students, faculty, researchers, and practitioners. Attendees will learn about the current fire problems in UHPC, recognize knowledge gaps and research needs, and practical solutions for improving UHPC fire performance.

Learning Objectives:
(1) Assess fire testing of UHPC at material and structural levels, including intermediate, and full-scale evaluations;
(2) Explain the behavior of UHPC under elevated temperatures, including changes in mechanical and thermal properties, and assess the potential for post-fire strength recovery;
(3) Evaluate the effects of fiber type and dosage on the fire performance of UHPC, focusing on spalling resistance and strength retention at high temperatures;
(4) Apply optimization strategies to enhance fire resistance of UHPC, including adjustments to mixture composition, curing regimes, and structural detailing for future design guidelines.

Guidelines for Fire Design of Ultra-High Performance Concrete Beam

Presented By: Venkatesh Kumar Kodur
Affiliation: Michigan State University
Description: Ultra-high performance concrete (UHPC) is increasingly gaining attention for structural applications, with structural fire safety being a key design factor. It is evident from recent research that UHPC structural members are prone to fire-induced spalling and have lower fire resistance than traditional concrete members. Currently, there are no specific guidelines for the fire design of UHPC members, and extending existing fire design provisions developed for conventional concrete members may not be appropriate considering the unique challenges posed by UHPC. This paper outlines the critical factors contributing to the lower fire performance of UHPC structural members, discussing these factors in detail using data from both numerical and experimental studies. Based on the results from parametric studies, as well as observations from published data, a set of design guidelines for mitigating spalling and enhancing fire resistance of UHPC beams is proposed.

Fire Performance of Ultra High Performance Concrete (UHPC) Double with Insulated (DWI) Wall Panels

Presented By: Mark Green
Affiliation: Queen's University
Description: The growing applications of Ultra High Performance Concrete (UHPC) in structures, particularly high-rise buildings, have prompted recent developments in Double Wythe Insulated (DWI) panels. These panels incorporate UHPC wythes and an insulating core, such as expanded polystyrene. While promising research on UHPC materials at high temperatures has been conducted, intermediate-scale and full-scale fire testing is necessary for further assessment of the full DWI panels. The two main objectives of this research are to quantify the thermal properties at high temperatures of small-scale UHPC specimens reinforced with various types of fibres and to conduct fire tests which experimentally assess the performance of UHPC DWI panels in fire conditions. Intermediate and full-scale panels have been developed for fire testing against the ASTM E119 and CAN ULC S101 temperature time heating curve. Information stemming from this test series will allow for a way forward for this system, which could include recommendations for refinement (e.g. to the mix design to reduce concrete spalling, or to the shear connectors to enhance composite action), contributing to its development and application in North American construction.

Understanding Chemical Degradation and Residual Strength of UHPFRC at 100–900°C

Presented By: Kay Wille
Affiliation: University of Connecticut
Description: This presentation explores how chemical degradation affects the residual mechanical properties of ultrahigh performance fiber-reinforced concrete (UHPFRC) after exposure to temperatures ranging from 100°C to 900°C. The study focuses on isolating the influence of chemical changes by employing a long drying period and a slow heating rate to minimize pore pressure buildup from water evaporation. Differential scanning calorimetry and thermogravimetric analysis were used to identify critical stages of chemical degradation. These findings were then correlated with existing research to develop a simplified model for predicting the temperature-dependent stress–strain behavior of UHPFRC. The presentation will highlight key insights from this work and offers discussion about the implications of designing UHPFRC structures exposed to extreme thermal conditions.

Effect of Autogenous Self-healing on Post-fire Cured Ultra High-performance Concrete

Presented By: Liberato Ferrara
Affiliation: Politecnico di Milano
Description: Mechanical properties of Ultra High-Performance Concrete (UHPC) degrade when exposed to elevated temperatures, even more than ordinary concretes due to its dense microstructure. Concerning, in particular, the special application of nuclear power plants, in which UHPC can find a promising use, concrete can be subjected to moderately high temperature (usually lower than 400°C) along the working life, this making of interest the study on the influence and persistence of UHPC's innate self-healing capabilities over the thermal degradation. In this context, the paper focuses on an experimental study of UHPC recovery ability by autogenous self-healing after being exposed to high temperatures. The UHPC specimens have been made with hybrid fibres, that is, polypropylene and steel fibres, and have been pre-cracked up to a cumulative crack width of 0.3 mm under 4-point flexural test. The pre-cracked specimens have been exposed to a temperature of 200 °C or 400 °C, with an heating rate of 1 °C / minute from room temperature and kept at the target temperature for two hours, with a following slow cooling at a rate of <1 °C / minute. The specimens have been kept in the lab environment for 24 hours after reaching room temperature. Then they have been tested for residual flexural capacity or allowed to self-heal under water immersion for six months. The damage and healing evolution have been monitored periodically using ultra-sonic pulse velocity survey and digital microscope inspection. Nevertheless, the thermal degradation, during the healing period, UHPC showed a significant recovery in terms of strength assessed by ultra-sonic pulse velocity tests.