N. B. Singh

Hydration of bagasse ash-blended portland cement

Hydration of bagasse ash (BA)-blended portland cement has been studied by employing a number of experimental techniques. It is found that in presence of BA setting times are increased and free lime is decreased. The compressive strength values increased with hydration time in the presence of BA and the values were found to be higher than that of control. The blended cement was found to be more resistant in an aggressive environment.

Effect of polyvinyl alcohol on the hydration of cement with rice husk ash

Effect of 3.0-wt.% polyvinyl alcohol (PVA) was studied on the hydration of ordinary Portland cement in the presence and absence of 10% rice husk ash (RHA) by employing different techniques. The results have shown that PVA increases the strength and decreases the porosity. The increase in strength is due to the interaction of PVA with cement, forming some new compounds that fill the pores or improve the bond between the cement. The two cements behave in a similar way, and hence, replacement of cement by 10-wt.% RHA is beneficial.

Effect of citric acid on the hydration of portland cement

Abstract Effect of lactic acid on the hydration of portland cement has been studied by employing various experimental techniques. Results indicate that lactic acid accelerates the hydration contrary to other α-hydroxy carboxylic acids which act as retarder. Electrical conductivity measurements give an indication that lactic acid forms a salt of calcium lactate during the interaction with calcium hydroxide. Zeta potential measurements give negative test regarding the adsorption of lactic acid portland cement surfaces. SEM photographs show that probably lactic acid accelerates the hydration by increasing the crystalline character of calcium hydroxide, which in turn accelerates the nucleation and growth of the hydration products.

Effect of lignosulfonate, calcium chloride and their mixture on the hydration of RHA-blended portland cement

Abstract Hydration of 10 wt.% rice husk ash (RHA)-blended Portland cement has been studied in the presence of 2 wt.% CaCl 2 , 1 wt.% lignosulfonate (LS) and a mixture of the two admixtures by using different methods. Free lime determinations and differential thermal analysis have shown that CaCl 2 accelerates the pozzolanic reaction of Ca(OH) 2 and RHA. In the presence of mixture of two admixtures, lower amount of water is required for consistency of the paste. IR spectral studies have supported that the mixture of the two admixtures act as a strong accelerator for cement hydration. The compressive strength is highest in the presence of a mixture of the two admixtures at 28 days of hydration. The admixtures did not prevent the deterioration of the blended cement in corrosive atmosphere.

Effect of superplasticizer on the hydration of a mixture of white portland cement and fly ash

Abstract Hydration of a mixture of white portland cement with 25 wt. % fly ash in the presence and absence of 1% lomar-D has been investigated. Both fly ash and the superplasticizer act as a water reducer and increase the setting time. The compressive strength of white portland cement at 28 days is increased with the addition of fly ash. The strength is futher increased in the presence of a superplasticizer. Porosity measurements indicate that increase in strength is a result of decrease in porosity. It is found that after 7 days of hydration the reaction between CH and fly ash increases; however, the extent of this reaction is lower in the presence of a superplasticizer. The superplasticizer is probably adsorbed at the cement and fly ash surfaces.

Preparation of metal oxides and chemistry of oxides ions in nitrate eutectic melt

Nitrate eutectic melts have been used as a nonaqueous solvent for many reactions. Some of the metal salts when heated in nitrate eutectic melt are converted to corresponding oxides comparatively at a much lower temperature. The reactions may be homogeneous or heterogeneous. Metal oxides obtained in this manner are expected to have lower surface area and hence may act as a better catalyst.

Polymer Nanocomposites and Cr(VI) Removal from Water

The progress in nanocomposites is varied and used in many industries. Nanocomposites can be made with a variety of enhanced physical, thermal and other unique properties. They have properties that are superior to conventional microscale composites and can be synthesized using simple and inexpensive techniques. The addition of small amounts of nanoparticles to polymers has been able to enable new properties for the composite materials. In recent years polymer nanocomposites have received significant attention because of their importance both from academic and industrial point of view. Composites, Nanocomposites in general and Polymer nanocomposites in particular have been discussed. Different type of nanocomposites and their preparations have been reviewed in brief. Application of polymer nanocomposites for the removal of Cr(VI) from aqueous solution has been described taking the examples from the literature as well as our own results. It is found that nanocomposites can be used in an effective manner for the removal of Cr(VI), a highly toxic metal ion.

Hydration of composite cement

Abstract Hydration of OPC + GBFS + RHA composite cement has been studied by using consistency, setting time and compressive strength measurements. It is found that composite cement hydrated for 28 days has the highest strength.

Crystallization behavior of biochemicals: morphologies and kinetics of complex multinary organics

Drug delivery is a very complex phenomenon. Most of the drugs are soluble in the water and flow easily in the body. However, drugs consisted of complex organics crystallize in different morphologies such as needles, plates, dendrites and organized lamellars. We have observed that 3.methoxy 4-hydroxybenzaldehyde also known as “vanillin” forms needles and plate morphologies in very small difference of pH or organic impurities and can crystallize in different forms. We have performed extensive studies to understand the crystallization of binary and ternary complex organic materials systems to understand the crystallization and morphologies. We will present the results of non-water-soluble organics using melt methods and discuss the mechanism of formation of different morphologies. More specifically results of 3.methoxy 4-hydroxybenzaldehyde-m.dinitrobenzene and 8- hydroxyquinoline-succinonitrile, systems will be discussed.

Prosthodontic Management of Fibrous Ridges-A Twin Case Report

Fibrous’ or ‘flabby’ alveolar ridges pose significant problems for the provision of stable and retentive dental prosthesis for affected patients. In particular, problems arise during the act of impression making, when forces cause the mobile denture bearing tissues to become distorted. Many approaches have been reported, to manage hyperplastic and movable tissues. This twin case report depicts application of various approaches to manage the flabby ridges in treatment of complete denture.