Calcium chloride dihydrate is a versatile inorganic salt compound derived from calcium and chlorine, typically appearing as a white, crystalline solid in flakes or granules. It is highly valued across numerous industries because it is extremely soluble in water and strongly hygroscopic. This means the compound readily attracts and absorbs water molecules from the surrounding environment. Its ability to dissolve easily in water, often releasing heat, makes it an excellent chemical agent for controlling various physical environments, from preserving food to maintaining structural integrity in construction materials.
Moisture Absorption and Humidity Control
The compound’s strong hygroscopic nature establishes its primary function as an effective desiccant. When exposed to humid air, calcium chloride dihydrate actively pulls water vapor out of the atmosphere. This absorption continues until the solid material dissolves completely, forming a liquid solution in a process known as deliquescence.
This mechanism is widely utilized in non-mechanical dehumidifiers for enclosed spaces like basements, closets, and garages. The solid flakes collect airborne moisture, which is then captured as a brine in a collection receptacle.
Desiccant properties are also crucial in industrial settings for drying air, gases, and liquids, preventing corrosion or degradation of sensitive materials. The electronics and pharmaceutical sectors rely on this compound to maintain low-moisture environments for manufacturing and storage, protecting packaging from humidity-induced damage.
De-Icing and Brine Solutions
Calcium chloride dihydrate is highly effective for managing ice and snow on roads, sidewalks, and parking lots in cold climates. Its effectiveness stems from its ability to lower the freezing point of water through freezing point depression. When applied to an icy surface, the substance dissolves, creating a brine solution with a freezing point significantly below that of pure water. This allows it to melt ice at temperatures as low as -25°F (-32°C), where rock salt (sodium chloride) becomes ineffective.
Furthermore, its dissolution is an exothermic reaction, releasing heat upon contact. This heat accelerates the melting process and helps the compound penetrate the ice layer more rapidly.
Beyond de-icing, the compound is integral to industrial temperature control systems as a stable brine solution. Concentrated solutions are used in refrigeration plants and industrial cooling loops as a heat transfer fluid, circulating efficiently without freezing even at very low temperatures.
Applications in Food Processing
The food industry utilizes calcium chloride dihydrate extensively as a multi-functional additive, recognized as Generally Recognized as Safe (GRAS).
One of its primary roles is as a firming agent to maintain the structural integrity of processed foods. In canned fruits and vegetables, the calcium ions react with pectin substances in the cell walls, which helps the produce retain its crisp texture and shape through the canning process.
This compound is also routinely added to milk in the cheesemaking process to improve the efficiency of curd formation. The addition restores calcium lost during pasteurization, which is necessary for the milk proteins (casein) to properly coagulate when a rennet is introduced. This results in a firmer curd and higher cheese yield.
In the beverage industry, the compound serves to adjust the mineral content of water, particularly in brewing beer, where specific ion concentrations are needed to enhance flavor profiles and support yeast function during fermentation. It is also used as an electrolyte and taste enhancer in bottled drinking water. Additionally, it can be used to reduce the sodium content in pickled products by replacing sodium chloride while preserving the salty flavor and firmness of the pickles.
Roles in Construction and Manufacturing
The compound has specific applications in large-scale industrial and construction environments, leveraging its chemical reactivity and moisture-attracting properties.
Concrete Accelerator
In concrete construction, it functions as an accelerator, which speeds up the setting time and early strength gain of the cement mixture. This is particularly beneficial for cold-weather concreting, where low temperatures naturally slow the hydration process, allowing builders to begin finishing work earlier. The acceleration effect is achieved because the calcium chloride increases the rate of the cement’s hydration reactions, resulting in a faster development of strength. When added to the mix, a two percent concentration by mass of cement can reduce the final set time by up to two-thirds compared to plain concrete.
Dust Control and Drilling Fluids
A separate, extensive use is for dust control on unpaved roadways and construction sites. When applied to dirt or gravel roads, the highly hygroscopic nature of the compound causes it to attract and retain atmospheric moisture, which keeps the road surface damp. This retained moisture effectively binds fine dust particles together, preventing them from becoming airborne when vehicles pass over the surface. In the oil and gas industry, the compound is incorporated into drilling and completion fluids to control the density and viscosity of the brines used in the wellbore.