Ethyl silicate for surface treatment of concrete - Part II: Characteristics and performance

In this study, several aspects of the surface treatment of concrete with ethyl silicate were investigated. After the treatment, two different types of concrete (w/c 0.45 and 0.65) showed a dramatic decrease in capillary suction, chloride diffusion coefficient and carbonation depth. A penetration depth into the concrete of about 3-5 mm was assessed. Microstructural investigations showed evidence of a chemical interaction of the amorphous silica gel within the concrete forming calcium silica gel and a selective distribution of silica gel, which was mainly deposited in the small pores. In addition, the brightness and colour changes of the concrete surfaces after the treatment were analyzed quantitatively, finding limited differences, further decreasing over time. This last aspect is relevant for architectural applications of concrete, for example façades of residential buildings, where the architects may be interested in using the texture of concrete but are concerned by possible colour changes related to surface treatments application.     

Ethyl silicate for surface protection of concrete: Performance in comparison with other inorganic surface treatments

The protection of concrete surface from environmental aggressions is often a basic issue for the enhancement of its durability. Due to the unsatisfactory long-term performance of many organic products and the subsequent need for frequent re-application, growing interest has been recently addressed toward inorganic materials. In the present study, ethyl silicate, widely used for the consolidation of weathered stones in architectural restoration and recently investigated for surface treatment of reinforced concrete structures, is compared with some inorganic products based on sodium silicate and nanosilica, generally used for the protection of concrete floors. Performance and effectiveness of the treatments are investigated in terms of morphology and microstructure; water absorption rate; water contact angle; chloride, carbonation and abrasion resistances. The results obtained highlight ethyl silicate, among the products investigated, as the most effective protection treatment for reinforced concrete structural elements.     

Intelligent Condition Monitoring of Aerospace Composites: Part I - Nano Reinforced Surfaces & Interfaces

This study is part of a major research program concerning intelligent condition monitoring of aerospace composites. Specifically, it evaluates the influence of nanofillers on the reinforcement of adhesively bonded layer under mode-I fracture toughness using multiscale modelling. In this novel approach, we couple coarse–grain molecular dynamics with continuum mechanics. The molecular dynamics domain and the finite element domain are overlapped in a handshaking subdomain, The implementation of coarse–grain molecular dynamics radically reduces the size of the problem. An explicit algorithm coupling the two methodologies was developed and used to determine the energy release rates of cohesive cracks in adhesively bonded composite joints with varying amount of nano-reinforcement in the adhesive layer. Both the quality of the prediction of the multiscale model and the influence of the nanofillers are evaluated and discussed.