GEOTECHNICAL PROPERTIES AND AGGREGATE QUALITY ASSESSMENT OF MARL DEPOSIT IN AFIKPO AREA, SOUTHEASTERN NIGERIA.

Abstract

Purpose: Marl is an impure limestone that is generally not good for cement production because of its low calcium carbonate content. Aggregates derived from marl deposit in Afikpo Area, Southeastern Nigeria, are currently being used in construction of concrete structures and highway pavements by construction companies and individuals. There is no published information on the suitability of the aggregates for such uses. The purpose of this study was to determine the suitability of the aggregates as components of concrete and highway pavements in terms of satisfying the non-swelling and acceptable strength characteristics / requirements. Methodology: Geotechnical tests including Atterberg limits (liquid limit, plastic limits and plasticity index), linear shrinkage and free swell were used to evaluate the swelling characteristics; while physico- mechanical tests including specific gravity, water absorption. Aggregate Crushing Values (ACV), Aggregate Impact Value (AIV) and Los Angele Abrasion Value (LAAV) were used to evaluate the strength characteristics. The field studies indicate that the marl deposit is associated with Ezeaku Formation of Lower Benue Trough. Results: Results of geotechnical tests indicate liquid limit, plasticity index, linear shrinkage and free swell values of 29.50%, 4.60%, 0.36% and 10.00%, respectively. Similarly, results of physico-mechanical tests indicate specific gravity, water absorption, ACV, AIV and LAAV values of 2.58%, 1.90%. 23.50% 29.45% and 42.70%, respectively. Unique contribution to theory, practice and policy: Since the results satisfy the non-swelling characteristics (plasticity index < 12%, linear shrinkage < 8% and free swell < 50%) and acceptable strength characteristics (water absorption < 3%, ACV < 30%, AIV < 30% and LAAV < 45%) requirements for good concrete and highway pavement aggregates, aggregates derived from marl deposit in Afikpo Area, Southeastern Nigeria, are strongly recommended to be used as aggregates in concrete and highway pavement construction