Best Cement Types for Countertops
Queston:
What’s the difference between Type I, Type II and Type III cements, and what is the best type to use in concrete countertops?
Answer:
Portland cement comes in a variety of different types. In the United States, they are classified as Type I, II, III, IV or V. Only Types I and III are appropriate for use in concrete countertops.
Type I is ordinary portland cement suitable for general-purpose use and is the most common type. It is available in white or gray and meets ASTM C150 standard specifications for portland cement. White Type I portland cement contains very small amounts of iron and magnesium oxides, the chemical components that give gray cement its darker color. White cement is used primarily for architectural purposes. Because it is ground slightly finer than gray cement, it tends to react a bit faster and gain strength earlier.
Type III is a high-early-strength cement. It is ground finer and reacts faster than Type I cement, so the early strength gains are greater. However, the ultimate strength is no higher than Type I. Thus concrete made with Type I or Type III cement will have very similar 28-day strengths, all else being equal. Type III is also available in white or gray varieties, but white Type III is difficult to order in small quantities (less than a pallet). So for small projects, such as countertops, it often must be special ordered.
The other cement types possess special properties that are irrelevant for countertops. Type II is a moderate sulfate-resistant cement, important when concrete is cast against soil that has moderate sulfate levels. Some cement manufacturers produce a Type I/II cement that meets the requirements of Type II. Type IV and V are often used in special construction applications where a low heat of hydration is required or high sulfate resistance is important.
What’s the difference between Type I, Type II and Type III cements, and what is the best type to use in concrete countertops?
Answer:
Portland cement comes in a variety of different types. In the United States, they are classified as Type I, II, III, IV or V. Only Types I and III are appropriate for use in concrete countertops.
Type I is ordinary portland cement suitable for general-purpose use and is the most common type. It is available in white or gray and meets ASTM C150 standard specifications for portland cement. White Type I portland cement contains very small amounts of iron and magnesium oxides, the chemical components that give gray cement its darker color. White cement is used primarily for architectural purposes. Because it is ground slightly finer than gray cement, it tends to react a bit faster and gain strength earlier.
Type III is a high-early-strength cement. It is ground finer and reacts faster than Type I cement, so the early strength gains are greater. However, the ultimate strength is no higher than Type I. Thus concrete made with Type I or Type III cement will have very similar 28-day strengths, all else being equal. Type III is also available in white or gray varieties, but white Type III is difficult to order in small quantities (less than a pallet). So for small projects, such as countertops, it often must be special ordered.
The other cement types possess special properties that are irrelevant for countertops. Type II is a moderate sulfate-resistant cement, important when concrete is cast against soil that has moderate sulfate levels. Some cement manufacturers produce a Type I/II cement that meets the requirements of Type II. Type IV and V are often used in special construction applications where a low heat of hydration is required or high sulfate resistance is important.
posted by Jeff Girard
at
12:57 PM
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