COMPARATIVE RELIABILITY ESTIMATES OF COMPACTION CHARACTERISTICS OF SAMPLE RE-USE (SR) AND FRESH SAMPLE (FS) COMPACTION OF LATERITIC SOIL AS ROAD PAVEMENT MATERIAL

• Published in: Annals of Faculty Engineering Hunedoara 2021-02, Vol.19 (1), p.91-100
• Main Authors: Yohanna, Paul, Nwaiwu, Charles Malachy Okechukwu
• Format: Article
• Language: English
• Subjects: Approximation; Clay soils; Coefficient of variation; Compacted soils; Dependent variables; Design; Dry density; Energy levels; Engineering; Flexible pavements; Independent variables; Laboratories; Mathematical models; Moisture content; Pavement materials; Random variables; Regression; Reliability; Roads & highways; Soil compaction; Soil moisture; Soil properties; Specific gravity; Standard deviation
• ISSN: 1584-2665; 2601-2332

A first-order reliability program (FORM) incorporated in FORTRAN program was employed to investigate the influence of sample re-use (SR) and fresh sample (FS) compaction of lateritic soil as pavement material compacted at the energy level of British Standard Light (BSL), and centred on regression equations established from laboratory results. The numerical properties of re-use (SR) and fresh sample (FS) compaction properties of lateritic soil were related with those from which the regression equations were formed. By means of regression equations for re-use and fresh sample compaction characteristics, for the related soil properties, reliability index (RI) were computed bearing in mind re-use and fresh sample compaction characteristics (Maximum Dry Density, MDD and Optimum Moisture Content, OMC) as dependent variables and the soil properties (gravel content, clay content, silt content, sand content and specific gravity) as independent variables. The results indicated that in the laboratory developed model, RI is dependent on variations in all the soil parameters. Generally, Observed trend showed that lower RI values for MDD sample re-use was recorded over the MDD fresh sample compaction. In the case of OMCs, higher RI values were observed for sample re-use compaction over fresh sample compaction. Although lower RI values for MDD sample re-use was recorded over MDD fresh sample compaction. However, OMCs of re-use sample compaction with higher RI must be strictly controlled in compacted lateritic soil as road pavement sub-base material. Stochastically, BSL compactive efforts did not produced tolerable safety index of 1.0 as recommended by the Nordic Committee on Building Regulation. Therefore higher energy level compacted using sample re-use compaction method is commended to model compaction properties of lateritic soil use as material for road sub-base of flexible pavement at Coefficient of Variation(COV) of 10-100 % range.