Title:
Does PVC Tubing Release Chlorides When used in Concrete?
Author(s):
Mohamad Nagi
Publication:
Concrete International
Volume:
16
Issue:
11
Appears on pages(s):
46-48
Keywords:
concretes; chloride; corrosion; polyvinyl chloride; rigid conduit; tubing; Materials Research
DOI:
Date:
11/1/1994
Abstract:
A laboratory study was conducted to determine if polyvinyl chloride (PVC) conduit and tubing introduce harmful levels of chloride ions when used in reinforced concrete. This investigation was performed in two phases. In both phases, 1-in.-diameter rigid nonmetallic conduit and 1-in.-diameter electrical nonmetallic tubing were used. In the first phase, PVC conduit shavings were placed in an environment that is chemically similar to that of concrete to measure the amount of chloride ions that enter into the solution. In the second phase, concrete blocks containing reinforcing steel and tubing/conduit were constructed to determine the potential for corrosion of the steel in the presence of PVC. To accelerate the diffusion of chloride, concrete blocks were kept in humid and warm conditions for 5 days, followed by 2 days in normal dry conditions every week. Corrosion activity was monitored each week. Powder samples were taken from blocks to measure the chloride content at the end of the test and compared to a control block containing no PVC tubes and kept under the same environmental conditions. Test results showed that PVC tubing and conduit did not release measurable amount of chlorides when kept in a chemically simulated concrete environment. Chloride contents in concrete blocks containing PVC were the same as control specimens. No signs of corrosion were observed on steel reinforcement when the steel reinforcement was removed at the end of the test.