Frequently Asked Questions

Soil Stabiliser and Compaction Aid

Engineers engaged in road construction and other major earth moving and construction projects such as airstrips, dams and industrial hardstandings, easily understand the cost and other advantages of using Roadbond. Technical reports and technical support is available from the product supplier. However many non-technical individuals are often placed in the position of having to take the decision as to whether or not Roadbond is to be specified for use in projects in which they are responsible for the provision of finance and have difficulty in understanding how precious funding can be saved by using Roadbond.

The following non-technical answers to frequently asked questions, we trust, will assist decision makers to take positive decisions with confidence regarding the specification and use of Roadbond in projects under their control.

What is Roadbond?
Is Roadbond a dangerous product?
How is Roadbond applied?
What strength improvement is possible?
Are there any other improvements to Roadbond treated material?
Does Roadbond reduce the cost of road construction?
Can maintenance costs be reduced using Roadbond?
Where is Roadbond manufactured?
How is Roadbond packaged and delivered?
How much Roadbond is required to treat a kilometre of road?
Does the Roadbond manufacturer / supplier provide technical support?
Is Roadbond a new and untried product?
What is the history and background of Roadbond?

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Q. What is Roadbond?

Roadbond is a proprietary mix of liquid chemicals which when diluted with water and applied to most soil and gravel materials, prior to compaction, substantially increases their strength and compactibility enabling poor or unsuitable materials, which would normally be rejected, to be used in the construction process. Acceptable material is also improved by Roadbond®.

Q. Is Roadbond a dangerous product

No. Roadbond, supplied as a concentrate, is an acid and is classified, for the purpose of transporting it by air, sea and road, as mildly corrosive. In its concentrated form it is 99% biodegradable, non-flammable and safe to handle with minimum protective clothing

When diluted for use, it is non-corrosive, environmentally friendly and not hazardous to humans, animals, bird life or vegetation. Health, safety and handling information is supplied with the product.

Q. How is Roadbond applied?

Earthworks, such as in roads, are constructed in layers of 15 – 30 cm. The soil or gravel material for the layers is placed where required and is then sprayed with water, which is then mixed uniformly with the material to aid the compaction process. Roadbond is simply added in controlled amounts to the water in the water tanker prior to the spraying process, so that it is applied uniformly to the material in the layer prior to the mixing and compaction process. No special equipment is required.

Q. What strength improvement is possible?

This varies with the type of material, but an average improvement in the load bearing strength of the Roadbond treated material, after compaction, is in the region of 80 -100%. Strength increases above 300% have been recorded.

Q. Are there any other improvements to Roadbond treated material?

Yes. Many materials contain clay particles which are strong when dry, but rapidly weaken when wet. Clay particles attract water (hydrophillic). When treated with Roadbond the clay particles repel water (hydrphobic) and the material retains its strength in wet conditions. The change in the clay particles is permanent and cannot be reversed. The material is also able to be compacted to higher densities, increasing its strength and resistance to penetration by water.

Where the material contains little or no clay particles the compaction agent in Roadbond enables higher compaction densities to be obtained with less compactive effort and a consequent saving in cost.

Q. Does Roadbond reduce the cost of road construction?

Yes, cost savings can be obtained in several ways.
As previously stated roads are constructed in layers, the topmost layer needs to have the greatest strength to carry the weight of the traffic which is directly imposed upon it. This load is dissipated through the lower layers which successively require less strength as the layers distance themselves from the surface. The design strength of each layer is specified to meet the traffic loading for which the road is designed. Should the material in the road alignment and adjacent to it not meet the strength specified, it needs to be excavated, removed from site and replaced by imported material at considerable cost.

However, if Roadbond can increase the strength of the available in situ material to the specified design strength, the cost of its removal and replacement is saved. Where available material is useable but of low strength it is often necessary to increase the thickness of the layers or to increase the number of structural layers to meet specified design requirements.

By using Roadbond to increase the strength of the material, the thickness or number of layers can be reduced. If the design, using the available untreated material, requires four structural layers and can be reduced to three layers of lesser thickness, a saving of around 25% or more can be made.

Q. Can maintenance costs be reduced using Roadbond?

Yes. In the case of an unsurfaced road, World Bank studies have shown that pot-holing, tracking, wash-boarding and dust generation are all reduced and periodic maintenance (re-gravelling etc.) can be extended from the usual 3 years to 4 year intervals, reducing overall maintenance costs by 20 – 25%.

In South Africa, as well as other countries by using Roadbond it has been possible to build a surfaced road at less cost than that of an untreated gravel road of traditional construction. The savings indicated are calculated after including the cost of Roadbond in the cost of construction.

Q. What rate of construction can be achieved using Roadbond?

In Russia it is claimed that a rate of construction, of one kilometre per day, for roads, has been achieved. In South Africa a more conservative figure of 400 – 500 metres / day per construction unit is the norm.

Q. Where is Roadbond manufactured?

All Roadbond products are manufactured in South Africa and production capacity is more than sufficient to satisfy international requirements. Consideration is being given to establishing an additional facility in Europe.

Q. How is Roadbond packaged and delivered?

Roadbond has an advantage over any other SPP stabiliser in as much as it can be super concentrated to reduce shipping, storage and handling costs. The concentrate (RBX25) can be delivered by sea or by air cargo in 25 litre plastic drums containing the equivalent of 625 litres of Roadbond (commercial strength) and is easily diluted on site prior to use.

Q. How much Roadbond is required to treat a kilometre of road?

The answer to this question depends on two essential pieces of information:-

• How many cubic metres of material are required to be treated and

• What is the optimum dosage of Roadbond required to treat 1 x cubic metre of material

If for instance 2 x 15 cm layers are to be stabilised in a road 6.5 metres wide, it is a simple mathematical calculation to determine that a rounded off figure of 2,000 cubic metres per kilometre is to be treated with Roadbond.

The amount of Roadbond required to treat a cubic metre of material varies to suit the type of material to be treated and as a general rule the more clay particles the material contains, the higher will be the dosage of Roadbond for best results. Dosages can vary from as little as 75 millilitres / cubic metre (ml / M3) to as high as 250 ml / M3.

The required dosage for a particular material is determined by simple tests in a soils laboratory.

At a typical, laboratory determined dosage of 150 ml / M3 and material to be treated per kilometre of 2,000 M3, the amount required would be 300 litres of Roadbond (12 litres of super concentrate RBX25).

Q. Does the Roadbond manufacturer / supplier provide technical support?

The manufacturer provides adequate technical instructions for correct use and application of Roadbond, including instructions for laboratory testing. Where required by the client the services of experienced consultants and technicians are available to assist in road design, laboratory testing and support on site during construction. Such services are usually charged on a reasonable cost plus basis.

Q. Is Roadbond a new and untried product?

No. Roadbond has been used successfully to construct roads since 1994 in widely varying soils and climatic conditions. In Siberia excellent roads have been constructed where temperatures vary from as much as - 50ºC in winter to + 50ºC in summer. In South Africa Roadbond treated roads have survived heavy rainfall and flooding without damage. In all, Roadbond has been used successfully to construct more than 7,000 kilometres of road internationally.

Q. What is the history and background of Roadbond?

J. W. MacBain, by profession an architect, became involved in innovative technology when he participated in the design of a new mine prop for deep level gold mining. In conjunction with an Anglo American subsidiary, the product was developed, extensively tested and became standard equipment in South African gold mines.

After selling the business and retiring, a specific road construction problem came to his attention; the stabilisation of the underlying soil upon which roads were built.

J. W. MacBain, with his extensive knowledge of structures, started a research programme, carried out at a UK university, two South African universities and the Department of Transport in KwaZulu Natal in South Africa.

The product Roadbond was born. Further research led to the super-concentration of the product into RBX25 which had not been achieved by any other manufacturer of a road stabilisation product.

The first successful laboratory and field trials were carried out in 1994 and Roadbond stabilised roads have been in existence since then. Roadbond has been used on more than 7000 kilometers to date.