Effect of paste content on the properties of high-strength concrete pavements

摘要

Ultra-thin continuously reinforced concrete pavement (UTCRCP) is an innovative pavement typethat has the potential to fulfil South Africa’s pavement repair strategy requirements. Prematurefailure in UTCRCP is linked to the formation of cracks that allow water ingress into supportinglayers. Environmental conditions, as well as concrete properties, determine the concretecracking tendency. Concrete properties are a function of the mixture proportions, and unlikeenvironmental conditions, mixture proportions are controllable. The effect of mixture proportionson 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 propertiesof HSC used in UTCRCP. Two sets of concrete were tested. The paste content of the firstset was varied from 23% to 37% by mass, using multivariable analysis in conjunction withsuperplasticiser (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 contentinfluenced early-age properties, but not long-term properties. Through variation of the pastecontent over a wider range during the second set it was found that paste content does influenceboth the early-age and long-term properties of HSC. From the results it could be seen thatincreasing the paste content of HSC generally has a detrimental effect. The paste content of HSCused in UTCRCP should be minimised, while maintaining a reasonable workability.