Influence of High Temperature on the Fracture Properties of Polyolefin Fibre Reinforced Concrete

Abstract

Concrete has become the most common construction material, showing, among other advantages, good behaviour when subjected to high temperatures. Nevertheless, concrete is usually reinforced with elements of other materials such as steel in the form of rebars or fibres. Thus, the behaviour under high temperatures of these other materials can be critical for structural elements. In addition, concrete spalling occurs when concrete is subjected to high temperature due to internal pressures. Micro polypropylene fibres (PP) have shown to be effective for reducing such spalling, although this type of fibres barely improves any of the mechanical properties of the element. Hence, a combination of PP with steel rebars or fibres can be effective for the structural design of elements exposed to high temperatures. New polyolefin fibres (PF) have become an alternative to steel fibres. PF meet the requirements of the standards to consider the contributions of the fibres in the structural design. However, there is a lack of evidence about the behaviour of PF and elements made of polyolefin fibre reinforced concrete (PFRC) subjected to high temperatures. Given that these polymer fibres would be melt above 250 °C, the behaviour in the intermediate temperatures was assessed in this study. Uni-axial tests on individual fibres and three-point bending tests of PFRC specimens were performed. The results have shown that the residual load-bearing capacity of the material is gradually lost up to 200 °C, though the PFRC showed structural performance up to 185 °C.

Bactericidal Properties of Low-Density Polyethylene (LDPE) Modified with Commercial Additives Used for Food Protection in the Food Industry

“…Among the above-mentioned, LDPE is used to make most film packaging [9]. Interest in conventional plastics is related to well-known methods of processing these materials [10,11]. Materials intended for packaging must have appropriate processability, good durability, barrier properties and the possibility of creating multi-layer materials or additional active properties, including biocidal and biostatic [7].…”

Residual Tensile Properties and Explosive Spalling of High-Performance Fiber-Reinforced Cementitious Composites Exposed to Thermal Damage

“…It was reported that the volume fraction of the steel fiber (20%) used in this study could effectively suppress the explosive spalling induced by high temperatures, and the cross-section loss of steel fibers increased with an increase in the thermal damage. Alberti et al [15] investigated the residual fracture energy and strength of polyolefin fiber reinforced concrete (PFRC) by adopting a three-point bending test after exposure to fire at temperature ranging from 20 • C to 200 • C. Polyolefin macro fibers (PF) are known to be a viable alternative to steel fiber for structural reinforcement in specific applications. It was revealed that the degradation of the mechanical properties of PFRC occurred between 150 • C and 200 • C, and the specimens showed no structural capacity at 200 • C because most of the fibers were found to be melted.…”

Experimental Study of Chloride Resistance of Polypropylene Fiber Reinforced Concrete with Fly Ash and Modeling

“…Among those fibers, the polypropylene fiber (PF), attributing to the high abrasion and corrosion resistance and low cost, was a promising reinforcing material using in the alkaline environment where the concrete holds [ 15 , 16 , 17 ]. The PF was effectively in curbing spalling caused by internal pressure of concrete under high temperature and is beneficial for structural design of elements [ 18 ]. Owing to the high tensile strength of PF, the tensile strength and the toughness of concrete can be elevated while the plastic shrinkage and the brittleness are reduced.…”