Construction materials supplier AfriSam has launched a new specialist product, Roadstab Cement, for road stabilisation applications.

The new cement has been undergoing research, development and testing for the past three years.

“This product has been developed to achieve superior stability across a range of road material types. It offers enhanced performance, even with soils with a high plasticity index,” says AfriSam product manager Mike McDonald.

He adds that the cement will offer civil engineers a good alternative for road design.

The construction materials supplier reports good results from tests conducted on the higher-clay-containing soils found in the Free State. The product was used in road stabilisation trial projects on the N8, in Tweespruit, the N1 from Fonteintjie to Wurasoord, the N6 at Smithfield and the N5 from Bethlehem to Kestell.

Consistently good outcomes were achieved, states AfriSam.

“The same excellent results have been demonstrated on projects in Gauteng. These include the Kaalfontein road, in Midrand, the R21 between Boksburg and OR Tambo Inter-national Airport and on runways at Lanseria Airport,” the supplier adds.

Stabilisation using cement improves the engineering properties of granular materials. When cementitious material is mixed with granular material in predetermined portions and adequately compacted and cured, a bound material with significant strength forms.

AfriSam states that cement with extended setting times, such as Roadstab Cement in the 32.5 strength class, is more suitable for soil stabilisation applications, because of the longer working times required to place and compact the material.

McDonald says a minimum of 2% cementitious material is required to ensure a uniform distribution of the stabilising agent throughout the stabilised layer, as cement content lower than this may result in the required strengths not being achieved, even though prior laboratory tests have indicated otherwise.

The selection of the cement type influences the time between the placing and the compaction of the stabilised layer.

“Cement starts hydrating as soon as it comes into contact with moisture. If most of the hydration has occurred by the time the material is compacted, the chemical bonds that have been formed between the cement and the soil will be broken down by the compaction process and further chemical bonding will be limited,” notes McDonald.

The release of Roadstab Cement follows AfriSam’s recent revision of its entire cement product portfolio.

“The upgrade of our cement product range forms part of our strategic vision and [the aim is] to position AfriSam as a company committed to sustainable inno- vation,” says AfriSam CEO Stephan Olivier.

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