Assessment of Durability of Reactive Powder Concrete Using Oxygen Permeability Index
-Durability of concrete is very important parameter for using natural resources effectively and reducing the cost of reconstruction, maintenance and repair of structure. This paper focuses on need of much of the need for concrete repair can be eliminated, if sufficient consideration and attention is given to control of surface quality of concrete at the construction stage. A South African approach is used to measure the oxygen permeability index testing and concluded that the method is applicable to actual project and is durability index is a parameter to evaluate the durability of RPC and cover zone concrete. RPC shows a good OPI value indicating impermeable concrete and its use can be justified for special purpose.
Performance-based durability testing, design and specification in South Africa: latest developments
Over the last decade, an approach to improving the durability of reinforced concrete construction has been developed in SouthAfrica. The philosophy involves the understanding that durability will be improved onlywhenunambiguousmeasurements of appropriate cover concrete properties canbemade. Suchmeasurements must reflect the in situ properties of concrete, influenced by the dual aspects ofmaterial potential and construction quality. Key stages in formulating this approach were developing suitable test methods, characterising a range of concretes using these tests, studying in-situ concrete performance, and applying the results to practical construction. The paper discusses the latest developments in durability specification practice in South Africa and attempts to show a sensible way forward for practical application of the DI approach. The approach is an integrated one in that it links durability index parameters, service life prediction models, and performance specifications. As improved service life models become available, they can be implemented directly into the specifications. Concrete quality is characterised in-situ and/or on laboratory specimens by use of durability index tests, covering oxygen permeation, water absorption, and chloride conduction. The service life models in turn are based on the relevant DI parameter, depending on whether the design accounts for carbonation-induced or chloride-induced corrosion. Designers and constructors can use the approach to optimise the balance between required concrete quality and cover thickness for a given environment and binder system.
Durability Predictions Using Early-Age Durability Index Testing
Durability of reinforced concrete structures is often dependent on the corrosion of reinforcement due to ingress of aggressive ions and fluids. Using the premise that the potential durability of concrete is determined by the protection provided by the cover concrete to the embedded steel, the resistance may be defined in terms of transport properties such as absorption, permeation and diffusion. A suite of durability index tests was developed to characterize the earlyage resistance of concrete to transport of fluids and ions that affect corrosion of reinforcement. These tests were found to produce reasonable predictions of durability performance for reinforced concrete structures. Early-age laboratory characterization testing is discussed together with field data regarding carbonation rates and chloride ingress into concrete. Findings suggest that the approach may be usefully applied as performance specifications where durability of reinforced concrete structures must be guaranteed.