Supplementary Cementitious Materials, of SCMs for concrete, are unique additives used in tandem with or to replace a portion of traditional Portland cement or blended cement. SCMs for concrete are used to help enhance or provide additional performance benefits such as protection against plastic shrinkage cracking, structural support, or durability improvements for specific applications. Often, SCMs are created through separate industrial-producing processes and were once case-off materials. Valuable SCMs for concrete such as silica fume, fly ash, and ground blast furnace slag, are some examples of industrial byproducts that have found relevance in the concrete enhancement industry. However, there are some SCMs for concrete, such as metakaolin, that have been specifically produced and formulated with the intent of being used as an SCM. This article will provide more detail on available SCMs for concrete, their specific usages, and working with R-E-D Industrial Products to source these beneficial materials.
Most Common SCMs for Concrete
The use of SCMs in a cement mixture may be needed for several different reasons and to produce specific outcomes, such as to improve strength and durability, while others may be used to lessen alkali reactivity, decrease permeability, and increase hardening properties through either hydraulic or pozzolanic activity, or both. Considering the wide range of benefits provided by supplementary cementitious materials, it is important to look at the composition of each and the potential benefits offered for specific applications.
Silica Fume
Silica fume is an ultrafine powdery byproduct created through the production of silicon metal or ferrosilicon alloys. Also known as micro silica, silica fume particles are roughly 100 to 150 times smaller than a particle of cement. Silica fume possesses incredible pozzolanic properties and reacts with calcium hydroxide to form strengthening compounds and enhance the resilience and durability of poured concrete. As an SCM for different concrete applications, silica fume is available in densified, semi-densified, and undensified variants which simply refers to the amount of fume per cubic foot. Concrete enhanced with silica fume has several unique applications including structural or construction applications, down-hole oil and gas well development projects, and refractory applications that require enhanced performance at elevated temperatures.
Ground Granulated Blast Furnace Slag (GGBFS)
This unique SCM for concrete is commonly referred to as slag and is a byproduct of pig iron production in blast furnaces. The chemical composition of GGBFS is primarily amorphous (glass) silicate and aluminosilicate. When added to concrete, ground granulated blast furnace slag helps to improve the durability and sustainability of concrete while making meaningful improvements to strength and resistance to thermal cracking. R-E-D Industrial Products has developed a proprietary slag replacement product from the Re-Act 4™ ground glass pozzolan. Ground granulated blast furnace slag can be used as an SCM for concrete in ready-mix concrete designs, precast projects, high-strength dams or building foundations, and high-volume mortar applications or paving projects.
Metakaolin
R-E-D Industrial Products is a leading supplier of Dynapoz metakaolin, widely considered throughout the industry to be a premium SCM for concrete. Metakaolin is an anhydrous calcined structure of the aluminosilicate naturally occurring clay mineral kaolinite. Once added to concrete, metakaolin enhances the pozzolanic reactivity and, once cured, improves the resistance to chemical attacks and structural integrity. Dynapoz metakaolin is an ultra-fine material and meets all technical specifications for ASTM C-618, AASHTO M295-11, and all Class N pozzolan specifications that guarantee reliable performance and consistent quality.
Fly Ash
Fly ash is a pozzolanic material harvested from the electrostatic precipitators in coal-fired thermal power plants and subsequently utilized as a beneficial SCM for concrete applications. Fly ash is spherically shaped and has a rich composition made from silica (glass) and alumina. When added to Portland cement and adequately hydrated, fly ash reacts with the free lime (calcium hydroxide) particles to form an additional resilient binder known as calcium silicate hydrate. The shape of fly ash also helps reduce the volume of water required to hydrate the mixture, making it ideal for projects with sustainability concerns or in drought-stricken areas of the country. Fly ash is predominately used as a partial replacement for concrete and improves workability, durability, and works exceptionally well in heavily sloped or high-temperature applications.
Crushed Glass Pozzolans
Crushed glass pozzolans are specifically designed to generate a superior cementitious material for concrete with a low-carbon footprint and a wide range of construction applications from architectural pre-cast concrete to ready-mix and UHPC. R-E-D Industrial Products Re-Act 4™ is a fine, white-colored, amorphous glass powder manufactured from 100% recycled glass. Crushed glass pozzolans are environmentally safe and sustainable as an SCM for concrete and conform to all ASTM C1866/CSA A3000-21 specifications. Crushed glass pozzolans are quickly becoming a leading option throughout the concrete industry due to their sustainability features and are more readily available than other byproduct SCMs like fly ash or silica fume.
SCMs for Concrete & ASTM Standards
Since SCMs can drastically improve performance characteristics in concrete, SCMs are required to meet particular specifications to ensure safety. Currently, slag cement must conform to ASTM C989/C989M. Whereas supplementary cementitious materials like metakaolin, natural pozzolans, and fly ash all must meet ASTM C618, and silica fume to ASTM C1240, glass pozzolans must conform to ASTM 1866 M.
Depending on the chemical composition needed to achieve a specific type of concrete, a binary blend or ternary blend of cement mixture may be needed. A binary blend is when there is one supplementary cementitious material added to Portland cement, and a ternary blend is when two SCMs are added to Portland cement. These unique blends are specifically formulated and developed to significantly improve the performance of the concrete based on the end application, exposure to certain chemicals, strength requirements, or sustainability metrics detailed in the project outline.
Get a Quote for SCMs for Concrete from R-E-D Industrial
R-E-D Industrial Products has over forty years of combined experience in the SCMs for the concrete industry and offers the highest quality products at competitive prices and expedited delivery times. From silica fume to metakaolin and ground glass pozzolans, companies that choose to work with the professional team at R-E-D Industrial Products will immediately improve their concrete mix to meet whatever challenges the end application presents. The benefits of SCMs for concrete can help address early or late-stage cracking, help resist chemical attacks or environmental conditions, and even improve structural strength or longevity. If you are interested in learning more about SCMs for concrete from R-E-D Industrial Products, please contact a member of our team and share more about your upcoming project so we can recommend the ideal supplementary cementitious materials for your application.