The key property of white concrete that differentiates it from gray concrete is its white color. The whiteness of concrete comes from the color and purity of raw materials it contains. Therefore, the source, shape, purity, and color of raw materials used in white concrete affect its whiteness degree. In addition to providing aesthetic and decorative advantages due to its white color, white concrete also exhibits high performance in terms of strength and durability properties. In this article, we will address subjects such as what white concrete is, its areas of use and points to take into consideration.
What is White Concrete?
Concrete is a construction material which is obtained by mixing aggregate, cement, water, and certain additives when required. Main difference of white concrete from gray concrete is its white color. Therefore, white concrete is a concrete type which consists of white aggregate, white cement, water and, when necessary, white chemical and mineral additives in harmony with its color. Any change in the properties of raw materials would lead to changes in the appearance and color of the concrete.
Materials and Properties of White Concrete
Materials and properties of white concrete;
- White Cement: Raw materials used in the production contain minor amounts of metal oxide (especially iron oxides). Therefore, it is very purse and highly white. In addition, pure raw material usage, fine grinding and usage of advanced technologies also improve other chemical, mineralogical and mechanical properties of white cement. High calcium silicate content and high level of fineness ensure high levels of both early strengths and final strengths. White cement generally contains low amounts of alkali. Therefore, white concretes have high resistance to alkali-aggregate reactions as well. You can check out our post titled Everything About White Cement for more detailed information.
- Aggregate: Approximately 75% of concrete is made up of aggregates. Therefore, aggregate properties have major influence on the performance of the concrete. White colored aggregates are used in the production of white concrete. Marble aggregates and white dolomites are preferred due to their color in the production of white concrete.
- Water: The properties of concrete are influenced by the mixture used in the production and the quality of curing water. Therefore, potable water, clean mixture and curing water should be used in white concrete production.
- Chemical Additives: Chemical additives may be preferred to improve concrete properties. The whiteness of these additives significantly affects the color of white concrete. Therefore, white, or transparent chemical additives should be used.
- Mineral Additives: In addition, artificial pozzolanas such as white silica fume, metakaolin, granulated blast furnace slag or natural white pozzolanas such as pumice powder and perlite powder may be used during the production in order to improve performance properties of white concrete.
- Pigments: High whiteness of white cement allows the use of different color pigments. Thanks to this, concrete of all colors with the vividness found in nature can be produced using different pigments. Pigments used during colored concrete production should be inorganic in origin. In addition, they should not exceed 6% of the weight of the white cement used inside of material in order to prevent them to negatively impact concrete strength.
These materials making up white concrete should be procured and stocked in a controlled manner. Thus, the cleanliness of all equipment used in the process of white concrete production, from transportation to placement, is particularly important for the final color’s whiteness.
What are the Areas of Use of White Concrete?
White concrete can be used in all reinforced concrete structures. In addition, it is frequently preferred in decorative rack, precast construction elements and restoration projects due to its aesthetic appearance and high strength. It is successfully used in developed countries for reinforced concrete structures, particularly in conference, art, and culture centers in addition to metro and train station, communications towers, stadium and sport venues, housing complexes and residential constructions, bridges and overpasses as well as retaining walls.
Image 1. Usage of White Concrete in Architecture (Valencia Science and Art Museum)
What are the Areas of Use of White Concrete?
In general concrete is required to have the following properties;
• It should have the minimum concrete strength targeted for any age.
• It should be adequately impermeable.
• It should be adequately durable for the service period. In other words, it should have the quality of being resistant to freeze-thaw, wetting-drying, heating-cooling, abrasion, acids, sulphates, and chemical reactions such as alkali-aggregate reaction.
• It should have the adequate volume constancy; in other words, it should not exhibit shrinkage or expansion to the extent of causing cracks.
White concrete provides several advantages to be used in many areas by having all the main properties of conventional concrete as well as having aesthetic properties and providing a beautiful appearance.
Points to Take into Consideration in White Concrete
In contrast to the conventional gray concretes, there are certain points to take into consideration during concrete design, concrete mixing, handling, placing, compressing, and leveling as well as in terms of molding, fitting, and casting conditions in order for the white concrete to exhibit the required performance properties. The main ones are as follows;
• In order to obtain the desired whiteness degree; white aggregates with the properties and granulometry complaint to TS 706 should be used in white concrete mix designs. Because the main factor that determines the color of white concrete is the white cement and the fine white aggregate used.
• Concrete and mortar additives to be used in white concrete mix designs should be transparent in color.
• All materials to be added in the concrete should be stored hygienically.
• Attention should be paid to the fittings to be used in reinforced concrete to be free of rust and dirt.
• Attention should be paid for the molds to be used to be clean and for the cement paste not to leak out of the mold during vibration in order to prevent dirt.
• Since the surface is expected to be smooth and void-free in exposed concrete applications, preparation and placement of the concrete should be done correctly.
• More attention should be paid to curing white concrete compared to conventional concrete.
Why Should You Use White Concrete?
White concrete applications are becoming increasingly popular in today’s construction sector thanks to the color of concrete as well as the mentioned properties and advantages of use. White concrete is used in the production of many construction materials and construction elements. Applications such as stairs, urban furniture and buildings, art structures, restoration works, bridges and overpasses are among these. The points to take into consideration in white concrete are mainly due to it providing the desired performance properties and high whiteness. White concrete is frequently preferred in reinforced concrete structures with its high performance in terms of high strength and durability properties in addition to its aesthetic and decorative properties. In conclusion, white concrete has many areas of application in modern settlements.
References:
- White Cement Concrete Handbook, PCA Bookstore.
- Erdoğan, T.Y., Beton, ODTÜ Geliştirme Vakfı Yay. ve İletişim A.Ş., Ankara, 2003.
