Microscopic examination of a new mechanism for accelerated degradation of synthetic fibre reinforced marine concrete

Abstract

This research presents an exploratory study into the mechanical biodeterioration of synthetic fibre rein- forced marine concrete. Light and inverted microscopy, scanning electron microscopy (SEM) with energy dispersive X-ray analyser (EDX) of site specimens were used to observe colonisation at the fibre cement interface, enabling the further understanding of this interaction. Algal fronds have been observed grow- ing between fibre and cement. Colonisation has been observed, entangled with, and adhered to fibres. This new mechanism occurs when the material bond is weakened as a direct result of the physical activ- ity of an organism, such as its growth. Loss of surface material, either through biodeterioration or through other mechanical means, such as power washing, is not the primary cause of degradation, but may exac- erbate the condition. A holistic model is presented, detailing the degradation process of macro and micro- synthetic fibres. Microscopic investigation of site concrete revetment armour units was used to validate the model. This multidisciplinary study is the first to report the composition of microbial assemblages fouling and degrading synthetic fibres within marine concrete in the United Kingdom, laying the founda- tion for more study into this new phenomenon.