Development of a reduced specification for surfacing aggregate on low traffic roads in Botswana

The paper discusses the results of a surface dressing road trial constructed in the UK to assess the performance of aggregates from Botswana that do not meet the specifications but may be usable. The aggregates are duricrust materials (calcrete and silcrete) which are very variable in quality; the main reason in seeking to utilise them is to reduce the cost of road construction in the remoter regions of Botswana. The results indicate that the aggregates are certainly suitable for use as surface dressing aggregate under low traffic conditions and also under higher traffic conditions depending on their composition. Amendment of the Botswana standards is proposed.