R. Jeyalakshmi

Greener durable concretes through geopolymerisation of blast furnace slag

The eco-friendliness of concrete is quantified by parameters such as embodied energy (EE) and embodied CO2 emission (ECO2e), besides duration of designed service life. It may be noted that ECO2e is also referred as carbon footprint (CF) in the literature. Geopolymer (GP) is an inorganic polymeric gel, a type of amorphous alumino-silicate product, which can be synthesised by polycondensation reactions. The concrete reported in this paper was prepared using industrial wastes in the form of blast furnace slag, fly ash as geopolymeric source materials and sodium silicate and sodium hydroxide as activators. Many mechanical properties such as compressive strength, chloride diffusion, steel corrosion, rapid chloride permeability test and rapid migration test are compared with Portland cement.

A novel proton conducting polymer electrolyte membrane for fuel cell applications

A series of phenolphthalein-based sulfonated poly(ether ether sulfone) (SPEES) membranes were synthesized by aromatic nucleophilic polymerization reaction. The degree of sulfonation was controlled by direct synthesis of sulfonated polymer, which leads to high thermal stability. The physicochemical properties of the SPEES membranes were studied in order to evaluate the suitability of these membranes in fuel cell applications. The ion-exchange capacity of the synthesized SPEES membranes was found in the range between 2.19 mequiv. g−1 and 2.35 mequiv. g−1. The morphology of the membranes was investigated with high-resolution scanning electron microscopy and confirmed the presence of hydrophilic domains that impart good proton conductivity. The membrane electrode assembly of SPEES-30 and SPEES-50 membranes has been successfully fabricated, where SPEES-50 produced a maximum peak power density of 643 mW cm−2 while applying in hydrogen–oxygen fuel cell.

Studies on Physio Chemical Properties of Fly Ash for their Effective Alkali Activation

SEM: Scanning Electron Microscopy; XRD X-Ray Diffraction; EDAX: Energy Dispersive X-Ray Spectroscopy; EDXRF Energy Dispersive X-Ray Fluorescence; FT-IR: Fourier Transform-Infra Red Spectroscopy ; SP: Super Plasticizer; AAS: Alkali Activator Solution; ASTM: American Society for Testing and Materials; FA: Fly Ash; CTM: Compression Testing Machine; GSM: Geo polymer Source Materials; FAGP: Fly Ash Based Geo polymer

Studies on Effect of Refractory Chemicals on Cement Mortar

Concrete has remarkable fire resistance properties. In the case of fire, it is found that the concrete affected by fire depends to a great extent on the intensity and duration of fire. Previous experience has shown that concrete structures are likely to have a good fire rating than structures made of other materials. Nevertheless, concrete undergoes important chemical and physical changes, starting at 400°C - 500°C. As calcium hydroxide and other hydration products start to decompose, concrete tends to lose its strength, typically around 600°C - 700°C. In order to improve the high temperature properties of concrete, admixtures can be used in concrete. In the following, a study on the effects of different admixtures on the properties of concrete at high temperature is presented.