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.
Permeability and Sorptivity Response of Concretes to Variations in Early-Age Curing
For the majority of reinforced concrete structures, active curing during early ages primarily serves to enhance the long-term durability of the structure. This is derived from the fact that curing mainly affects the cover concrete zone, which is the first line of defence against the ingress of aggressive agents into the concrete.
Design of reinforced concrete lining in pressure tunnels, considering thermal effects and jointed rockmass
Abstract Jaeger's theory (Jaeger, Rock Mechanics and Rock Engineering , Cambridge University Press, 1972) of the design of the lining for a pressure tunnel applies to a tunnel located in an isotropic, homogeneous and elastic medium. The theory is derived from the elasticity equations for the plane stress condition. In this paper, Jaeger's theory is extended to a plane strain situation. Also included is a discussion of the effects of a uniform increase (or decrease) in the lining temperature, jointed rockmass, cracking of the tunnel lining, and cracking of the rockmass around the opening. Tables are presented for the modulus of subgrade reaction for various rockmass conditions and for rock sharing pressures for various lining conditions. The reduction factor to include the effect of joints in rockmass is derived by the analysis of a numerical model of the lined tunnel by the finite-infinite-interface element method.