Manual of carbonate sedimentology, a lexicographical approach

Abstract

The effect on compactibility of incorporating peat into four Trinidadian agricultural soils before compaction was investigated in a laboratory experiment. A factorial experiment was used to study the effect of peat applied at four levels (0, 4, 8 and 12% by mass) on the maximum dry bulk density (MDBD) and optimum moisture content (OMC) of the four soils (two sandy loams, clay loam and clay) compacted using 5, 15 and 25 Proctor hammer blows. The compaction tests were carried out at different moisture contents which varied according to the values of the plastic limits of the soils.Results showed that while the mean values of MDBD of the soils declined significantly (p = 0.001) from 1·51 to 0·92 Mg m-3 with increasing peat content, the mean values of OMC increased from 24·2 to 42·6%. While MDBD increased, OMC decreased with increasing compaction levels. This applied to all the soils tested. The clay soils had significantly lower values of MDBD and greater values of OMC than the sandy loam soils. There were significant interaction effects between soil type and level of added peat and between compaction level and level of added peat. These interactions were used to describe the effect of peat on soil compactibility. Multiple linear regression equations based on compactive effort, sand content, clay content and percentage peat content, were generated for predicting values of MDBD and those of OMC of compaction of the soils used in this study. There was reasonable agreement between the equation for predicting MDBD and a similar equation derived for Nigerian soils in previous work. A good negative relationship obtained between MDBD and OMC is also similar to the one derived from previous research.