| Summary: | Large concrete structures are being built for the production, storage and transportation of oil. The effects of crude oil on the properties of concrete are not well known and little data is available in the published literature. The present investigation is divided into three parts: 1) A study of the mechanical properties of oil saturated hardened cement paste, mortar and concrete. 2) A study of the effect of absorbed oil on the average bond stress, and the bond stress distribution between reinforcing bar and concrete. 3) A study of the changes in the dynamic modulus and logarithmic decrement of concrete soaked in oil for different periods. All the specimens were oven dried to increase the permeability of concrete to oil and to increase the degree of oil saturation. The results were compared with those of similar specimens soaked in water or sealed in polythene bags as control specimens. The mechanical properties. of HCPs, mortar, and concrete studied here were adversely affected by oil saturation. The compressive strength and elastic modulus were reduced by amounts depending on the amount of oil absorbed. The tensile strength was also reduced due to soaking in oil but the reduction was less than that of the companion specimens sealed as a reference. It appears that the oil mainly affects the aggregate-cement bond strength. - i - The average bond strength between steel and concrete, for both plain and deformed bars, decreases with an increase in the amount of absorbed oil. The reduction. for the plain bar was between 1.8-2.3 times greater than that for the deformed bar. The study of the bond stress distribution showed that at the maximum applied-load, the local bond stress at the embedded end of the oil saturated specimens was about six times greater than that at the loaded end. The dynamic modulus of elasticity increased by 12-14% after soaking the concrete in oil for 580 days compared to the oven dried specimens. The increase w~s about 37% less than that of similar water soaked specimens. The studies of logarithmic decrement indicate that the loss of moisture is the most important factor influencing damping capacity.
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