Proficiency Testing for Soil Laboratories: A Case Study in Addis Ababa

Abstract

This project assesses the performance level of soil laboratories using proficiency study. Proficiency study is a determination of laboratory testing performance by means of inter laboratory test comparisons, using similar items by two or more laboratories and evaluating the results. The main goal in this study is to show degree of consistency for construction material laboratories in the case study area and evaluate their performance level using Interlaboratory evaluations. There are seven study participants who performed Atterberg limit and sieve analysis on two different soil samples. The study is observational descriptive and since measurements are taken only once through out the study its going to be cross-sectional type. Study participants name has been changed to code names for confidentiality purpose. Once soil lab results were collected from all laboratories, we have calculated sample mean and Standard deviation for all samples. Any result beyond +2Sx is deemed to be an outlier results assuming 95% confidence interval in normal distribution. Two out of seven participants have given one or more outlier results. The overall lab results were found to be highly inconsistent, specifically for Lab-004 in which 35% of its results were found to be inconsistent with other laboratories. This project has clearly shown the need for practice of proficiency studies on a national level and also for development and use of one standard manual for methodologies used in construction material laboratories nation wide to produce a more consistent results. This project also calls for the academic community to do more research in the area of construction material testing in order to understand the underlying problem and give solution.