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Smoke Production
Published in John A. Conkling, Christopher J. Mocella, Chemistry of Pyrotechnics, 2019
John A. Conkling, Christopher J. Mocella
Calcium stearate, a type of soap and lubricant, was used as a burning rate modifier that also helped lubricate mixing of the composition, increasing particle packing and density. This has the effect of obstructing hot gasses from moving through the unreacted material, which would normally speed the burn rate (undesired in smoke production, since increased burn rates can lead to “flame-ups” instead of smoke production). Potassium chloride was added as a diluent, meaning is generally pyrotechnically inert and was also reported to reduce incandescence of the composition (recalling boron carbide as a potential “green” green-light emitter); since obstruction of sight and not illumination is the ultimate goal, this is a beneficial effect. However, KCl was also found to produce solid products (slag), detrimental to smoke production, so an appropriate balance between reducing incandescence and not generating too much solid products had to be evaluated.
Effect of surface free energy on water absorption of roller-compacted concrete pavement containing calcium stearate powder
Published in Road Materials and Pavement Design, 2023
Ali Mohammad Lotphi, Amir Modarres
Type II Portland cement was used based on the specifications specified by ASTM C150 (2012). In this study, calcium stearate powder was employed to make the concrete hydrophobic. To produce hydrophobic concrete, hydrophobic cement can be used in a cement plant by blending stearic fatty substances during clinker milling. Due to limitations in hydrophobic cement production in cement plants, hydrophobic additives are usually used that are directly added to the mixture during the production process. Calcium stearate is a powder easily mixed with cement and achieves a homogeneous dry mixture. In addition to making the concrete hydrophobic, calcium stearate powder improves the concrete workability (Nemati Chari et al., 2019). This product is one metallic soap of stearic acid obtained by replacing calcium ions with hydrogen acid ions. This material is used in various industries such as paper, plastics, chemical dyes and pharmaceuticals and is widely available. One kilogram of calcium stearate is about one US dollar. For 1.5% calcium stearate by weight of cement, about 4 kg of calcium stearate is needed per cubic metre, which increases the production costs by $ 4 per ton of concrete.