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Polyvinyl alcohol yarns long term properties characterization and assessments. Part II: Chemical durability

For more than a decade now, High Tenacity Polyvinyl Alcohol (HT-PVAl) yarns have been attracting a lot of interest in the geosynthetic community, particularly for the reinforcement of stabilized ground structures in civil engineering. PVAl interest principally lies in its excellent resistance to strongly alkaline or acidic environments combined with a high stiffness that makes it a serious reinforcement material. Today, several products manufactured with HT-PVAl yarns can be found on the market and their demand is boosted by the increasing use of soil treatments, recycled materials or low-quality fills in extreme pH conditions. Despite this rising attraction for PVAl, its characterization remains an open issue for the scientific community, as well as a challenge for the standardization organization that faces difficulties in specifying this material and assessing its long-term durability. In the second part of this study, we will focus on the chemical degradation mechanism and kinetics of HT-PVAl yarns. This study will be based on a series of aging tests carried out in laboratory at various temperatures and pH values. Physico-chemical and mechanical characterization methods will be proposed in order to define aging tracers allowing the evaluation of the long-term performance of HT-PVAl yarns.