An investigation into the hydraulic properties of needle-punched nonwovens for application in wet-press concrete casting Part I: Wet-press concrete casting

A study was made of the hydraulic performance of polypropylene nonwoven fabrics employed as absorbent form-liners in the production of wet-press concrete flags. Cellulose paper is traditionally used. It was found that, during pressing of the concrete mix, the expressed water was discharged from the mould through the nonwoven fabrics by contra-directional flow, whereas the paper liners effected unidirectional flow. When used only once, the paper, owing to its smaller pore size, gave a lower particle content of the filtrate than did the nonwovens. However, with repeated use of the paper liner, the particle content of the filtrate and the particle contamination of the paper rapidly exceeded that for repeated use of the nonwovens.