Q: Can you tell me whether the high pH of curing portland cement (typically ~12.4) might have any impact on the long-term performance of geogrids?
A: It depends on the geogrid and its formulation. There are three categories of geogrid: (1) punched and drawn (polyethylene [PE] uniaxial, polypropylene [PP] biaxial and triaxial), (2) strap (polyvinyl alcohol [PVA]), and (3) woven, coated polyethylene terephthalate (PET). There are ramifications of high pH on geogrids only with the woven, coated PET over long-term exposure. Please consult the following references for more details:
DiMaggio, J. A. (1989). “Geosynthetics: How long will they perform?” Proc., GRI-2, Durability and Aging of Geosynthetics, Elsevier Applied Science, London, U.K., and New York, 1–5.
Koerner, G. R., Hsuan, G. Y., and Koerner, R. M. (2002). “Field measurements of alkalinity (pH) levels behind segmental retaining walls, or SRWs.” Proc., 7th International Conf. on Geosynthetics, A. A. Balkema, Lisse, The Netherlands, 1443–46.