Calcium oxide

About: Calcium oxide is a research topic. Over the lifetime, 7600 publications have been published within this topic receiving 66104 citations. The topic is also known as: caustic lime & quicklime.

Role of curing temperature in progress of lime-soil reactions

Abstract: An expansive black cotton soil was used to assess if ambient temperature influences the progress of lime-soil reactions Lime-soil mixes containing lime additions above the Lime Modification Optimum (or Initial Consumption of Lime value) of the expansive black cotton soil was cured for periods ranging from 1 hour to 400 days at 25°C The curing temperature of 25°C is representative of mean temperatures occurring in semi-arid regions of Karnataka, India The in situ progress of lime treatment was monitored by the use of electrical conductivity and pH measurements The trend of decrease in conductivity and pH of the 4 and 7 lime-soil mixes suggested that pozzolanic activity commenced after 1 day of curing at 25°C Comparatively, an earlier study by other researchers had reported that pozzolanic activity does not commence before 7 days of curing at 115°C for lime additions above the Lime Modification Optimum value of swelling clay Combining the results of studies at 25°C and 115°C, it appears that higher ambient temperatures do accelerate the progress of lime-soil reactions

Engineering Behavior of a Remolded Expansive Clay Blended with Lime, Calcium Chloride, and Rice-Husk Ash

Abstract: This paper presents experimental results obtained from tests conducted on remolded expansive soil specimens blended with rice-husk ash (RHA) and stabilized with lime and calcium chloride. The amounts of RHA, lime, and calcium chloride were varied from 0 to 16%, 0 to 5%, and 0 to 2%, respectively, by dry weight of the soil. The effect of additives on unconfined compressive strength (UCS) and California bearing ratio (CBR) is reported. It was found that the stress-strain behavior of expansive clay improved upon the addition of up to 5% lime or up to 1% calcium chloride. A maximum improvement in failure stress of 225 and 328% was observed at 4% lime and 1% calcium chloride, respectively. A RHA content of 12% was found to be the optimum with regard to both UCS and CBR in the presence of either lime or calcium chloride. An optimum content of 4% in the case of lime and 1% in the case of calcium chloride was observed even in clay-RHA mixes.

Development of an Inert Anode for Electrowinning in Calcium Chloride–Calcium Oxide Melts

Abstract: Studies were performed investigating the anodic testing of calcium ruthenate for electrowinning in calcium chloride–calcium oxide melts. The results showed that calcium ruthenate may be suitable as an inert anode in calcium chloride containing melts as it exhibited a low rate of corrosion in melts containing a small amount of calcium oxide, capable of producing oxygen on its surface, and did not contaminate the melt. To reduce the amount of ruthenium in the anode, solid solutions of calcium ruthenate in calcium titanate were investigated. At low concentrations, the solid solution is a semiconductor with a relatively low conductivity at room temperature, but at the temperature of operation, 1173 K, the material is an excellent electronic conductor. The other way of reducing the amount of ruthenium is to coat the solid solution onto a substrate. In this way, the substrate would give the mechanical strength while the coating would give the electrical conductivity and corrosion protection. Calcium ruthenate-based anodes can endure long-term use in the laboratory under an applied electrical field with oxygen being liberated on the anode indicating that these materials are candidates for the electrowining in calcium chloride–calcium oxide melts.

Destructive adsorption of chlorinated hydrocarbons on ultrafine (nanoscale) particles of calcium oxide. 2

Abstract: As a one-step approach to the safe destruction of chlorocarbons, the reaction of carbon tetrachloride with ultrafine particles of calcium oxide to give calcium chloride and carbon dioxide (CCl4(g) + 2CaO(s) → CO2(g) + 2CaCl2(s)) has been studied in detail. Calcium oxide prepared by an aerogel/hypercrytical drying method (AP−CaO) is superior to a conventionally prepared (CP−CaO) sample, and both are vastly superior to commercial CaO (CM−CaO). Optimum temperature for this gas−solid reaction is 450 °C, although AP−CaO reacted with reasonably high capacity as low as 300 °C. The effects of surface −OH, added water, CCl4 pressure, and a wide range of temperatures are discussed. Conditions for the suppression of byproducts C2Cl4 and Cl2CO are presented. Morphological changes in the particles after CCl4 reaction were studied by atomic force microscopy. A wide range of other techniques have been applied toward complete characterization of the process and products, including FT-IR, pulsed U-tube reaction studies, g...