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Pavements, Trenches and Pipes

Steel fibre reinforced concrete slabs/pavements on grade

Research student: Stuart Arnold

Supervisors: Simon Austin, Paul Fleming, Peter Robins

Funder: Loughborough University EPSRC Studentship

Start date: 1 October 2000

Context and Background:
There is very little understanding on the use and characteristics of steel fibre reinforced concrete in internal slabs, external roads and hard-standings. The increase in loads that have occurred in storage and traffic over the last few years have created the need for a better appreciation of the pavements behaviour when in service.

Many of the current design methods and specifications are based on un-reinforced or traditionally reinforced slabs that fail to fully take into account the additional effects that steel fibres and varying sub-bases/grades can provide. The incorporation of fibres into the concrete mix can create an increase in the flexural strength (post initial cracking), and can enhance the durability and loading capacity of the concrete under cyclic loading. There is of yet very little information available to industry that enables an economic design with the degree of certainty that is available in other structural elements of the building. Until this is freely accessible to industry the thickness, and therefore amount of concrete used in the slab construction, will remain as it would in un-reinforced sections.

Aims and Objective:
The specific aims and objectives of the project include:

• Development of a computer model to predict slab behaviour.
• Develop a better understanding on the effects of various loading types.
• Determine the type and extent of crack control possible in various situations.
• Develop a better understanding of joint behaviour in external slabs.

Method and Current Status:
At the present time a thorough literature review is taking place as to the current state of the art. There have been meetings with consultants and societies to select the important issues that are relevant to the construction industry and give direction to the project as a whole. Over the next six months it is expected that an understanding of a finite element model will be completed and initial development of this to incorporate further loading and design situations will be undertaken. In the long-term it is expected that laboratory tests will be carried out on a number of specimens to determine their behaviour under different loading and climate conditions. It is also hoped that continuation of previously installed instrumentation into operational sites will be completed, as well as the possibility new sites being examined.

Benefits/Expected Outcomes:
It is expected that the project will enable a much better understanding of fibre reinforced concrete when used as a floor slab or rigid pavement. This will provide the possibility of reducing slab thickness, meaning a reduction in concrete usage, which will both save the client money and reduce any damaging effects on the environment. Durability will also be better understood with regard to loading fatigue. This information could provide a reduction in repairs that need to be undertaken during its working life, reducing the whole life cycle cost of the slab.