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Replacing or servicing corroded reinforced concrete structures requires careful consideration of the rate of corrosion of the embedded rebar. Corrosion rates are usually measured using monitoring techniques, but these techniques may not always give reliable results due to the effect of factors called rate influencers. Though the consideration of rate influencers does not entirely alleviate the problem, monitoring them during measurements will significantly reduce the probable error. Hence, this paper compares the experimental results of prior studies with an effort to draw out the best corrosive environment for the efficient working of a few widely used monitoring techniques and presents a list of some major rate influencers that need concern for the accurate evaluation of corrosion. A literature review is performed to achieve the above objectives. The Monitoring techniques considered in this study are linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS), galvanostatic pulse technique (GPT), and half-cell potential (HCP).

Induced Draft Cooling Towers (IDCT) are an important industrial structures, which removes the heat absorbed in the circulating cooling water systems of thermal power plants. The cooling tower in general comprises of RCC members’ viz. Column, Beam, Slab, Wall, Louvers, Fanstack Shell etc. The process of operation is itself an important factor which affects the durability of members of IDCTs, due to which the RCC members of IDCT are subjected to varying exposure condition, some members are continuous under water, some are partially submerged, some have alternate drying & wetting and some are completely dry. Due to different exposure conditions of RCC members of these structures generally shows very contrasting states of distress i.e. varying from apparently un-distressed to highly distressed state. Apart from process of operation of IDCTs, the other important factors that affect the durability of these RCC structures are presence of Chloride in water being cooled & Chloride in concrete present during the construction and carbonation due to aging of concrete. The RCC structures were assessed by various Non-Destructive evaluation techniques and deterioration mechanisms were established. The present paper highlights the findings of condition assessment studies of selected IDCTs located in different climatic regions of India.

Sedimentary rocks being a historical building stone are formed by deposition of sediments & further cementation of organic & mineral particles at the earth's surface. These rocks comprise of grains predominantly with quartz content besides Plagioclase-albite, Feldspar, lithic fragments. In this research work, sandstone cutting waste was explored from the Bayana basin (Bharatpur), Rajasthan (India) and utilized in cement concrete by replacing natural sand to further evaluate its effect on the microstructure of concrete. These sandstone cutting wastes were utilized in concrete by opting 0.40 water-cement ratio, after evaluating its chemical & physical properties and the same concrete samples were studied by using scanning electron microscopy, thermogravimetric analysis and optical microscope besides the mercury intrusion porosimetry. Microstructure study of concrete consisting of sandstone cutting waste investigates its influence on physical & mechanical properties. The microscopic evaluation disclosed the formation of interconnecting voids in the concrete comprises sandstone cutting waste beyond its 30% substitution in concrete. The Optical microscope studies indicate the homogenous distribution of aggregates up to 30% sandstone cutting waste in concrete. Better thermal resistance was observed for concrete samples comprises of sandstone cutting waste at elevated temperatures. Effective use of sandstone cutting waste not only reduces the burden of waste in the mining region but also enhance sustainability in cement concrete construction.