Recycled Poly(Vinyl Butyral) Used as a Barrier to Prevent Mortar Carbonation

Abstract

The paper deals with testing of CO2 diffusivity through poly (vinyl butyral) (PVB) layers and their efficiency to serve as barriers against cement mortar carbonation. Two different types of PVB were tested; PVB sheet made from original extruded PVB polymer and PVB sheet made from PVB dispersion obtained from recycled windshields. The first part of the work was focused on testing CO2 diffusion when polymer sheets were exposed to a CO2 atmosphere (10% v/v CO2) with 0% RH. The excellent barrier capability against CO2 permeability of both types of polymer layers was observed. In the second part, mortar specimens were exposed for 23 days to two different carbonation regimes (laboratory conditions and chamber with CO2 atmosphere (1% v/v CO2) and 60% RH), having been coated or not with recycled PVB dispersion. Compressive strength tests, carbonation depth measurements and acoustic measurements (impact-echo method) were performed. The results showed the alternation of the compressive strength values depending on whether PVB coating was used or not. Both phenolphthalein test and impact-echo method confirmed the protective effect of PVB layer against mortar carbonation.