INFLUENCE OF SEAWATER ON THE STRENGTH OF RC BEAMS AND CORROSION BEHAVIOR OF STEEL

Abstract

The effects of seawater on the strength performance of reinforced concrete (RC) beams were
investigated. Four RC beams measuring 150 x 200 x 800 mm were constructed. Two beams were constructed
with concrete mixed with freshwater and the other two were constructed with seawater. Center point loading
test was conducted on the beams specimens. Load, deflection, and strain of each beam were monitored and
recorded. It was found that the difference between the strength test values obtained by using freshwater and
seawater were minimal. However, formation of rust in steel when seawater was used was very evident.
Hence, the effects of seawater on the corrosion behavior of steel were investigated. Mortar specimens with
cold-joint were used as medium to facilitate the investigation of corrosion. Ordinary Portland cement (OPC)
Type 1 was used as binder for the mortar and was partially replaced with fly ash at 30% and 50%.
Rectangular prism specimens of dimensions 40mm by 40mm by 160mm were cast for macrocell corrosion
measurements and compressive strength determination. From the test results, the following were observed:
(a) Specimens with fly ash were observed to have lower corrosion rates compared with the ones without fly
ash; (b) Specimens mixed with freshwater resulted to the higher strength both at 7th-day age and 28th-day
age; (c) Regardless of the type of water used in making the mortar, specimens cured in seawater achieved
higher later strength values.