Macro synthetic

fibre

reinforced Concrete

Peter Hughes

BSc Building Surveying

University of Central Lancashire

2008

Properties of Macro synthetic fibres and their composites

Outline experimental programme and discussion of results and conclusions

Applications

Agenda

Local and central Government have committed £800 million in 2010

Our vision of the future of concrete should be on its longevity

Concrete can perform even under very severe conditions

DURABILITY

Background

Aspect ratio

Fibre characteristics

PolypropylenePolypropylene is durable, stiffer than

some other plastics, good resistance to fatigue, so that most plastic hinges, such as those on flip-top bottles, are made from this material.

PolyethyleneThe first proposed application was in

submarine telecommunication cables. One of the advantages of polyethylene fibre is that it can be produced with a relatively high modulus of elasticity.

Fibre Properties

Positive effect on drying shrinkage cracking Positive effect on plastic shrinkage cracking Improves residual flexural strength in

excess of 30% Increased toughness, impact and abrasion

resistance Some MSF may be used as secondary

reinforcement Eliminating steel fabric removes the risk of

chloride induced corrosion of reinforcement in marine applications.

Benefits

Capillary Absorption/Vacuum saturation Surface hardness

Ultrasonic pulse velocity Compressive strength

S.E.M

Experiments

The durability of concrete is one of the most important properties and the focus of

attention in my paper. The essence of my work was to discover the effects of adding the synthetic macro fibres

and there effect on durability.

Durability

Durability of concrete largely depends on the ease with which fluids, both liquids and

gases, can enter into, and move through, the concrete.

Cracks must be avoided or controlled and minimized because they impair the durability and structural integrity.

Permeability

Results

Results

Sorptivity results suggest that the near-surface concrete was far more resistant to

fluid ingress in the MSF mix than in the corresponding reference mixes.

The impermeability of the MSF demonstrated in the experiment, indicates good resistance

to infiltration of solutions. This being an important property to achieve, especially in

coastal structures when trying to limit chloride ingress.

Summary of main findings

The rebound values for the MSF mix of a mean 30, are surprisingly low for a C40/50

mix.

The conversion curve on the hammer and Bungey imply a rebound number in the region of 30 indicates around 30MPa.

The compression test gives 50Mpa for the MSF at 56 days suggesting a r number of

40+, yet the number remains constant. This may be a result from the fact that the MSF

are acting as impulse absorbers.

UPV tests were most favourable in the OPC design mix. The MSF showed a much lower value. This may be due to the fibre content (dosages of 3.5kg/m3) and its effect on the pulse path being distracted in the sample.

Blackpool Sea Defences Brighton Sea Defences Bristol Ave Recycling plant

Applications

Brighton sea defences

Bristol Ave, Recycling depot

Conclusions

Concrete durability is significantly affected by its permeability, and the penetration of the aggressive liquids, frost action, and steel

corrosion are all influenced by the concrete’s permeability. These problems

have been decreased by reducing the permeability of the concrete sample.

This research presents the development and evaluation of MSF, and their favourable

effect on the durability of concrete.

Due to its high residual strength, it is the first synthetic additive truly capable of replacing its steel counterparts in terms of increasing the impact and fatigue qualities of concrete.

From Sulphate attack, Freeze/thaw damage, to salt crystallization, salt scaling, abrasion

and marine growth, these chemical and physical predators will test the sea walls and concrete structures of our country to

their limits.

Future research

Discussion contributions on this presentationcan be made via

http://myspace.com/peterphd PHughes1@uclan.ac.uk

Thankyou