Composites durability

Despite improvements in composite durability with certain eement replaeements, little is known as to the mechanism of improved durability. That is, does the eement pore solution play a significant role, or does the permeability of the eomposite Or are durability improvements based on a combination of the two Also, how is eement hydration altered by lowering the pore solution pH These questions must be answered before establishing any criteria or recommendations for improving pulp fiber-eement eomposite durability. 

V Alstadt, R W Lang and A Neu, The influence of resin, fibre and interface on delamination fatigue crack growth of composites . Durability of Polymer-based Composite Systems for Structural Applications, ed. A H Cardon and G Verchery, London, Elsevier Applied Science, 1991, p 180. 

Major studies are currently being undertaken into composites durability. One of these programmes, the Composites Durability Study, is being carried out in the USA by the Civil Engineering Research Foundation and the Society of the Plastics Industry s Composites Institute Market Development Alliance, for the benefit of the design and construction industry and the civil engineering profession. It is said that particular concerns include... 

The duration and quality of cure of the fresh mix determine the hydration progress and the volume of hydration products, which may eventually fill up the capillary pores and reduce their permeability. For reduced w c and prolonged cure the pore size distribution diagrams are shifted towards smaller sizes, with decreasing total volume. The saturation of capillary pores plays an important role in the composite durability if the material is exposed to freeze-thaw cycles. Damage is more probable when the critical value of the saturation is attained and the increasing volume of ice cannot be accommodated without additional stresses. The hardened paste density is also important to ensure resistance against all other external attacks. 

J.K. Christie, A. Tilocca, Aluminosilicate glasses As Yttrium vectors for in situ radiotherapy understanding composition-durability effects through molecular dynamics simulations. Chem. Mater. 22(12), 3725-3734 (2010)... 

Ninety-five distinguished scientists attended the symposium including 21 scientists from 11 countries and 50 technical presentations. Each day was divided into a morning session devoted to service life prediction and an afternoon session involving a discussion of UL 746. Sessions near the end of the week were focused on the NSF composite durability workshop. 

Accelerated Testing Methodology for Polymer Composite Durability... 

Chapter 18 Accelerated Testing for Polymer Composite Durability 3.3 Master Curve for the CSR Strength... 

W.R. Sharman and B.P. Vautier, Accelerated durability testing of autoclaved wood-fibre reinforced cement-sheet composites . Durability of Budding Mater. 3, 1986,... 

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