Rapidcem Case Study

CASE STUDY 1: Rapidcem used in UTCRCP trial on N12

The Lafarge Cement business line provided product and technical service solutions that contributed to the upgrading of Section 19, between the Rietfontein and Tom Jones interchanges of the N12 freeway on the eastern side of Johannesburg. The SANRAL project was pioneering in its extensive use of Ultra Thin Continuously Reinforced Concrete Paving (UTCRCP), an extremely high strength, specialised concrete application many consider to be the future for South Africa’s roads.

Our innovative RapidCem CEM II/A-V 52,5N was used for the 5 500mÑ of 50mm and 75mms

UTCRCP sections. RapidCem met the important requirement in UTCRCP concrete for high quality raw materials and minimum product variability. It was the first of its strength class in South Africa to offer high early and ultimate strength, while incorporating fly ash in the formulation. In addition, Lafarge’s inclusion of a special strength enhancer meant it could be extended even further with fly ash. (We also supplied Powercrete Plus for 30 000mÑ of concrete mix used for the ‘standard’ 200mm Continuously Reinforced Concrete Pavement.)

For the UTCRCP concrete mix, it was imperative that the proportion of extender in the cement was absolutely uniform. The rigorous ‘Usage Quality’ control procedures on Lafarge South Africa’s cement products enabled us to guarantee the consistency of the Rapidcem formulation. Each tanker load leaving our Lichtenburg Cement Works was subjected to the control procedures, included the XRF determination of the fly ash content. UTCRCP is a concept that is being developed to cater for our climate and conditions by the CSIR, SANRAL and the University of Pretoria. It is a complex formulation to produce a very strong concrete

– in excess of 90MPa – that can easily withstand the heavy axle loads and turning forces of today’s heavy haulage vehicles. The product has very good flexural and bounce properties, and prevents degradation of the sub-base layer. A key feature is the long-term economies it offers with low maintenance and a life expectancy of plus/minus forty years.

Lafarge Quality Department Southern Africa laboratory gave excellent technical support by providing a wide-ranging independent quality control service. This was not limited to Lafarge’s cement but also covered the different mix components from third parties such as aggregates, fibres and admixtures.

This is a valuable backup service in view of the importance of the pioneering UTCRCP project.