keywords: Concrete, Makuba, additive, acid, aggressive environment, curing
This paper presents findings on the use of powdered locust beans pod (makuba) as an additive in concrete cured in normal and aggressive medium. Makuba is an air dried powdery substance obtained from the pod of the locust bean tree (parkia folicoidea). Makuba in concrete grades of 20 and 30 N/mm2 were investigated to determine its suitability as an additive in the concrete mixes in normal and aggressive environment. To each grade of Concrete, Makuba was added in varying concentration of 0, 2.5, 5.0 and 10% cured in 0, 5 and 10% concentration of acid of Tetraoxsulphate (vi), TrioxoNitrate (v) and Hyrochloric acids, and tested for compressive strength after a period of 7, 28 and 56 days, respectively. Results on the compressive strength of the concrete revealed generally a decrease in strength for every increase in Makuba and concentration of acid. However, for cubes cured in normal water (0% of acid), there have been progressive increase in the trend of the strength up to 56 days. For cubes cured in 5 and 10% of acid, there was an increase in strength up to 28 days and a decrease after then up to the 56 days.