High performance concrete (HPC) bridge decks are prone to premature cracking if movement is restrained. Internal curing (IC) can reduce shrinkage cracking in concrete structures, thus improving their performance and service life. However, there is very limited information available in the literature on the possible extension of service life due to internal curing. This paper addresses this ques...

plastic shrinkage is one of the most important parameter which must be considered in hot weather concreting. if plastic shrinkage is not prevented, cracking will be significant, especialy if silica fume is used in the mix. in this paper, the effect of silica fume in bleeding and evaporation was investigated in laboratory. the results showed that in restrained shrinkage, beside relative humidity...

In situ transmission electron microscopy study of electric field-induced cracking has been conducted on ^001& oriented 0.65Pb~Mg1/3Nb2/3!O3 – 0.35PbTiO3 crystal. Fracture of the 90° domain boundary was directly observed in the tetragonal area under both static and alternating electric fields. The field strength required to induce domain boundary cracking was lower for alternating electric field...

A coupled reactor/furnace simulation has been conducted for a 100 kt/a SL-II naphtha cracking furnace containing both long-flame and radiation burners. The computational fluid dynamics approach was used to simulate the flow, combustion and radiative heat transfer in the furnace. The software packages COILSIM1D and SimCO were used to account for the cracking process in the reactor coils. The sim...

The Developmental Path of Internship Program within the Iranian System of Teacher Training   Gh. Ahmadi, Ph.D.* S. Maleki** M. Mehrmohammadi, Ph.D.*** S.M.R. EmaamJom’eh, Ph.D.****   Theoretically, internship programs can utilize any one of the three known approaches: craft model, applied science model, and reflective model. The purpose of the current paper has been to show the developme...