Test method development for evaluating the freeze-thaw performance of segmental retaining wall blocks

摘要

Segmental retaining walls (SRW), typically constructed along highways, havegrown in popularity over the past decade. Manufacturers of SRW blocks have estimatedthe service life of a properly constructed wall to be approximately 75 years. However,there have been reports of SRW systems failing after only five years in service.Suspected causes of the SRW failures are freeze-thaw damage while exposed to deicingsalts sprayed by snow plows from highways.The current standard test method used for evaluating the freeze-thaw durability ofSRW blocks has several drawbacks and does not accurately replicate environmentalexposure field conditions. The objective of this research is to develop and assess a newstandard test method for evaluating the freeze-thaw durability of SRW blocks that obtainsreproducible results and offers sufficient information on the freeze-thaw performance forSRW block manufacturers and state highway agencies (SHAs).The research completed a preliminary proof of concept test for the new freezethawtest method developed using small, commercially available SRW blocks to mitigatepotential problems and establish appropriate test parameters. The testing producedresults of freeze-thaw degradation that followed the same modes of failure that has beendiscovered during field evaluations.After the proof of concept test was completed, a series of freeze-thaw tests wereconducted using sets of SHA approved and non-SHA approved SRW blocks. Three different manufacturers?????? SRW blocks were evaluated. There was no significant freezethawdegradation of any of the blocks after 200 freeze-thaw cycles, so for two blocks,experiments were extended to 400 cycles using a twelve-hour freeze-thaw cycle. Themodification of the test did not result in more rapid deterioration of the SRW blocks.The researchers found that the freeze-thaw durability test method developedherein is beneficial for determining the freeze-thaw performance of the lower qualityspecified blocks. The test method gives realistic results, which match typicaldeterioration modes that are common in field settings, in a timely manner. However, thetest method for testing SHA quality SRW blocks takes longer times and may not be areasonable test for such products.