Unit for Construction Materials
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Fibre Reinforced Concrete

Fibre reinforced concrete (FRC) is becoming a more popular construction material due to the positive contribution it makes to concrete. Fibres can be divided into two general geometric categories, namely micro fibres (length typically less than 15 mm) and macro fibres (lengths at least 30 mm). Fibres can also be manufactured from different materials, most common being steel, polypropylene, glass and PVA. Natural fibres can also be used. The greatest advantage of adding fibres to concrete is the improved post cracking behaviour of concrete in tension and flexure. Micro fibres are often used for the reduction of the risk of plastic shrinkage cracking, or increasing the ductility of concrete in the case of Strain Hardening Cement-based Composite (SHCC). UCM has focused on a large number of aspects of FRC, but most recently the focus has been on the use of macro synthetic fibres and the creep of cracked FRC. ​

Mechanisms of Creep of Cracked Fibre Reinforced Concrete

Postdoctoral Fellow: Dr John Babafemi

Supervisor: Prof WP Boshoff

This postdoctoral fellowship involves ​the investigation of the creep of cracked fibre reinforced concrete, of both synthetic and steel fibres. The focus is more on the mechanisms causing the creep and also possible ways of reducing the creep once the mechanisms are understood. Single fibre pull-out creep tests, micro CT scanning and SEM are included in this investigation. The results will also be modelled to be able to predict the creep behaviour on a structural level. 

Design using Fibre Reinforced Concrete

Student: Fred Mudge (M.Eng)

Supervisor: Prof WP Boshoff

Fibres in concrete have the advantage that they could partially or completely replace traditional reinforcing in concrete structures. Appropriate design guides, which take into account the typical applications, however are lacking. This project involves creating design guidelines for designing fibre reinforced concrete members for specific applications.

Modelling the Creep of Cracked Fibre Reinforced Concrete

Student: Leo Pike (M.Eng)

Supervisor: Prof WP Boshoff

The investigation of the creep of cracked fibre reinforced​ concrete has gained momentum over the past few years, especially after the creation of the Rilem Technical Committee CCF titled: Creep behaviour of cracked sections of fibre reinforced concrete. However, there is still no proposed model of how to include the additional creep caused mostly by fibre pull-out (of steel fibres) in the structural design of FRC structures. This study will propose a model that could be used together with the fib Model Code 2010 to determine the long term deflections of FRC members. 

Fatigue Behaviour of Fibre Reinforced Concrete

Student: Humaira Fataar (M.Eng)

Supervisor: Prof WP Boshoff & Dr R Combrinck

This research investigates the long term fatigue behaviour of steel fibre reinforced concrete due to cyclic loadings. If cracks develop in concrete, fibres help in bridging the gap and reduce the progression of the crack growth. However, research on the crack propagation of fibre reinforced concrete under cyclic loadings is rare. This research aims to fill this knowledge gap by conducting fatigue tests on concrete beams as well as single fibre pull-out fatigue tests.