What Is White Cement? Is It Good To Use?
White cement, also known as white Portland cement, is a type of cement that is similar to ordinary gray Portland cement in most aspects except for its high degree of whiteness. The color of white cement is achieved through modifications made to the manufacturing process, which minimizes the presence of coloring elements such as chromium, manganese, iron, copper, vanadium, nickel, and titanium.
These elements are responsible for the characteristic greenish-gray to brown color of ordinary Portland cement. By reducing their presence, white cement achieves a higher level of whiteness. However, this modification makes white cement more expensive than gray cement .
Here are some key points about white cement:
- Raw mix formulation: The raw mix formulation for white cement involves minimizing the presence of coloring elements like chromium, manganese, and iron. This is achieved by using raw materials with lower levels of these elements.
For example, limestone used in gray cement manufacture usually contains higher levels of iron oxide (Fe2O3) compared to limestone used in white cement production. Kaolin, which is low in SiO2, is often used as a replacement for conventional clays in gray cement production. Additionally, sand is usually included in the mix to achieve the desired particle size .
- Uses: White Portland cement is commonly used in combination with white aggregates to produce white concrete for prestige construction projects and decorative work. It is often used for pre-cast cladding panels and can be used in combination with inorganic pigments to produce brightly colored concretes and mortars.
Compared to ordinary cement, white cement allows for the production of brighter and more vibrant colors. The pigments can be added at the concrete mixer, or manufacturers may supply ready-blended colored cement using white cement as a base. To be considered “white,” the powdered material must have a reflectance value (“L value”) over 85% .
- Clinker grinding and handling: After the clinker is produced, it is next ground to cement, often after a drying stage. Calcium sulfate, in the form of a high-purity grade of gypsum or anhydrite, is added to control the set of the cement.
In some cases, a small amount of titanium dioxide may be added to improve reflectance. Care must be taken to avoid contamination with colored materials at all stages of grinding and handling .
- Specifications: White Portland cement meets standard specifications such as ASTM C 150 and EN 197. It has essentially the same setting behavior and strength development as gray cement. However, due to its use in pre-cast concrete products, it is often made to a high-early strength specification such as ASTM C 150 Type III.
Manufacturers also guarantee the whiteness of the product, typically measured using a reflectance measurement such as Lab L-value or tristimulus. Simply specifying a low iron content does not guarantee good whiteness, as the color of white cement depends on the “bleaching” and “quenching” operations during manufacturing .
In addition to the information provided in the search results, it is worth noting that white cement has various advantages and disadvantages:
- White cement provides walls with more adhesive strength due to the presence of iron and magnesium, making it suitable for applications before painting.
- Whitewashing with white cement gives walls a great final look and eliminates the need for a priming coat before painting.
- The low absorption rate of white cement reduces the amount of paint needed to cover the surface.
- When combined with color pigments, white cement allows for striking visual effects without compromising the structural integrity of the building .
Disadvantages of White Cement:
- White cement is more expensive than regular gray cement, costing about four times as much.
- It has less strength than regular gray cement and Pozzolana Portland cement, limiting its use in concrete applications.
- White cement has a rapid setting period, which requires masons to work quickly .
In conclusion, white cement is a type of cement that is similar to gray cement in most aspects except for its high degree of whiteness. It is used in combination with white aggregates and inorganic pigments to produce white concrete for prestige construction projects and decorative work. White cement has its advantages and disadvantages, and its use is more common in applications where visual appearance is important.