PREPARATION,APPLICATION, AND EFFECT OF MAGNESIUM CARBOXYLATES FROM HURA CREPITANS SEED OIL ON CONCRETE’S HYDROPHOBICITY

Abstract

Studies have shown that there are problems of water capillary movement in buildings erected in water logged areas and this always affects the lifespan of buidings. This research work was therefore carried out to find solution to the problem using metal soap of long fatty acids. Oil extracted from the seed of Huracrepitans using hexane in a soxhlet extractor, analysed for fatty acid composition, and some physicochemical properties using standard methods. Magnesium carboxylate was later produced from the oil using a two stage synthesis. The first stage involves saponification of the oil to yield sodium carboxylates(soap), the second stage involved metathesis, in which sodium was replaced with magnesium, thus yielding the desired magnesium carboxylates. Concrete formulations based on (0.2, 0.4, 0.6, 0.8 and 1% w/w) of magnesium carboxylates from Huracrepitans seed oil were prepared, cast into identical and regular cuboids dimensions of (10.5 x 5.00 x 2.5mm). Blank casts were also made without magnesium carboxylate. All casted concrete were allowed to cure for 28 days. They were subsequently oven-dried at 90oc for 24 hours. Water absorptivity tests were later performed. The dominant fatty acid in the oil was oleic, while the iodine value , saponification value, viscosity, specific gravity, and free fatty acid were 170.432mg/I2/g, 242.0mg/kOH/g, 0.91g/m and 2.21 respectively. The performance of water absorptivity tests showed that the magnesium carboxylate produced from Huracrepitans seed oil reduced the capillary absorption. Concrete formulation based on 0.4% magnesium carboxylate presented the least sorptivities. Application of magnesium carboxylate at this concentration to concrete will therefore extend the service life of concrete strenghths built in aggressive areas.