Ultra-thin continuously reinforced concrete pavement (UTCRCP) is an innovative pavement type
that has the potential to fulfil South Africa’s pavement repair strategy requirements. Premature
failure in UTCRCP is linked to the formation of cracks that allow water ingress into supporting
layers. Environmental conditions, as well as concrete properties, determine the concrete
cracking tendency. Concrete properties are a function of the mixture proportions, and unlike
environmental conditions, mixture proportions are controllable. The effect of mixture proportions
on the properties of high-strength concrete (HSC) used in UTCRCP should be investigated.
The objective of this research was to study the influence of paste content on the properties
of HSC used in UTCRCP. Two sets of concrete were tested. The paste content of the first
set was varied from 23% to 37% by mass, using multivariable analysis in conjunction with
superplasticiser (SP) dosage. The paste content of the second set was varied from 25% to 60%
by mass, only varying SP dosage to control the workability.
The multivariable analysis revealed that, within the parameter range tested, paste content
influenced early-age properties, but not long-term properties. Through variation of the paste
content over a wider range during the second set it was found that paste content does influence
both the early-age and long-term properties of HSC. From the results it could be seen that
increasing the paste content of HSC generally has a detrimental effect. The paste content of HSC
used in UTCRCP should be minimised, while maintaining a reasonable workability.