17 - Bi-component polyolefin fibers used for concrete and shotcrete applications

Abstract

Cement and concrete are relatively strong when subjected to compressive forces, but are not able to take much stress or strain in tension. The obvious method to improve the tensile properties is to incorporate fibers. This paper describes the research program on the development of Bi-Component Polyolefin fibers, which covers the choice of a fiber type based on the interfacial bond, design of the optimum core and sheath combination, including surface plasma treatment. The most successful fiber was chosen from the varied tests performed and field tests were conducted in order to test their performance in concrete and shotcrete. The field tests and research proved to be very successful for industrial applications and the technology was bought by the company Brugg Contec AG in Switzerland. The bi-component fiber developed called Fibrofor is now marketed as Concrix by Brugg Contec AG. For this purpose a bi-component fiber with a core consisting of a low melt flow rate polymer and narrow molecular weight distribution and a sheath consisting of a polymer with a higher melt flow rate and a broader molecular weight distribution were manufactured.