An Alternative Method to the West African Compaction (WAC) Test Procedure

Abstract

It had been suggested to use the West African Compaction Test Procedure since the early 1950’s so as to determine the CBR of gravel lateritic soils in West African countries [1]. This test procedure called West African Compaction (WAC) [2] is largely used in road construction in West African countries and had the particularity to be long and use a large amount of material. This note is the result of several comparisons between test procedures taken to determine the CBR from the WAC method to the standardized laboratory test commonly used to determine the CBR

Grain Size Influence on the Compaction Aptitude and the Bearing Strength of the Gravel Lateritic Soils

“…It gradually changes from a loose to a dense state. Air void between the coarse grains tends to be reduced and filled by fine particles generated by the breaks material [27]. As it is shown that between the five classes, the well graded by its coefficient of uniformity contain more fines, and can get the best CBR index, it is that of 0/31.5 mm diameters.…”

“…But the CBR is sensitive to water [20]. CBR is an important parameter in pavement design [27] to assess the durability and the load strength. Figure 6.…”

“…Nevertheless, the required conditions concern only the 0/20 mm granular class on which are applied the standard procedures of the modified Proctor and the CBR tests. After immersion the CBR decrease considerably and this is more important for the first three day [20], from which it is important to consider the 4 days soaked CBR, to anticipate on the flood hazard.…”

“…Hence, the Maximum Dry Density is the Y coordinate of the vertex and the Optimum Moisture Content is its X coordinate. CBR test is performed with various compaction energies (10, 25 and 56 blows by free fall from a height of 457 mm of a hammer of 4.5 kg weigh, compacting a material by five layers into a mold of 152 mm diameter and 116 mm high) andputted in to soak for 96 hours[20].…”