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.
Aging live Antarctic fur seals and southern elephant seals
This study describes a method for extracting post-canine or incisor teeth from live antarctic fur seals (Arctocephalus gazella) and southern elephant seals (Mirounga leonina) respectively and their use to determine age in a field situation. Dental elevators were used to loosen the teeth from the alveolus and periodental ligament. Most teeth were removed within l-2 min and a total of 214 and 81 teeth were collected by this method from antarctic fur seals and southern elephant seals respectively. No seal recaptured at intervals up to a year after a tooth was extracted showed signs of infection or distress related to removal of the tooth. Teeth were thin-sectioned for the purpose of aging. In both species cementum growth layer groups were a more satisfactory indicator of age than dentinal growth layer groups. Estimates of age from cementum growth layers were confirmed for Antarctic fur seals using seals which had been tagged as pups up to 16 yr before sampling.