Q: I have a project where I need to bind small river rock, 1/4-inch minus. I was considering using portland cement and was wondering if I should add a bonding agent. How much water would I add to the mix?
A: There are all sorts of binders for rocks you can use for landscaping projects, including portland cement. You can add just enough water to the cement to make it sticky and coat each rock, or you can go with a slightly wetter mixture that will be more flowable. If you’re going to do a lot of work with portland cement, you’ll want an agent that won’t set up too fast, like Calcium Chloride or a retarder.
Q: I want to pour my own footing forms for my new house. Which type of Portland Cement should I use?
A: For footings and foundations, use a Type N or Type S Portland Cement. These cements are not as strong as Type I and II cements but they offer improved resistance to deterioration in concrete exposed to sulfates in soil or ground water.
The first step in using portland cement is to determine what consistency you need for your application. Portland cements are available in different consistency levels from low to very high, and they can be mixed with water or various other liquids or powders to further adjust the consistency.
When mixing portland cement with water, you want enough water so that the mix will paste, but not too much so that it’s loose and runny. The ideal consistency is to where it will stick to the trowel when lifted. This is called plastic or field consistency. If you add more water to this mix, it becomes a slurry, which is very liquid and easy to pour.
A slurry is like a thin paste – it’s not as thick as mortar but not as thin as concrete. It’s used for crack repair, bonding a finish layer of concrete to an existing slab or patching small holes in a concrete surface. A mortar mix has more sand than a slurry does, so it lays up thicker on surfaces without trickling down slopes like a slurry does. Mortar is used for brick and block laying as well as stucco applications. A concrete mixture has even more sand than mortar does, so it’s usually used for larger projects such as sidewalks
Portland cement is not a brand name, but the generic term for the type of cement used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver. Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and bind the aggregates into a rocklike mass. This hardening process continues for years, though most of it occurs in the first few years. Cement is manufactured by heating raw materials such as limestone, silica, alumina and iron to temperatures approaching 2,700°F in huge rotary kilns. At these high temperatures all water molecules are driven off and chemical reactions take place to form new compounds that give cement its unique properties. In addition to limestone and other aggregates mixed with water, portland cements also contain gypsum. The primary ingredient in portland cement is calcium silicates (alite and belite). A small amount of calcium aluminates is also included to make portland cement set quickly under water.
Cement is not restricted to gray or white; there are many colors available. Some manufacturers color their cements with mineral pigments for decorative effects.
What is Portland Cement?
Portland cement, the basic ingredient of concrete, is a closely controlled chemical combination of calcium, silicon, aluminum, iron and small amounts of other ingredients to which gypsum is added in the final grinding process to regulate the setting time of the concrete. Portland cement is a fine gray powder that hardens when mixed with water. It is manufactured by crushing and heating to high temperatures limestone or marble rock combined with small amounts of sand, iron ore and clay. The resulting “clinker” is then pulverized into a fine powder.
How are different types of Portland Cements manufactured and used?
The type of Portland cement used in a concrete structure determines the time it will take to harden, and also its final strength. Learn more about the types of Portland cement.
What is Concrete?
Concrete is made up of three basic components: water, aggregate (rock, sand, or gravel) and Portland cement. Cement acts as the binder that holds the aggregates together in their solid mass. The aggregates are usually divided into two groups—fine and coarse. Fine aggregates generally consist of natural sand or crushed stone with most particles passing through a 3/8-inch sieve. Coarse aggregates
Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-specialty grout. It was developed from other types of hydraulic lime in England in the mid 19th century, and usually originates from limestone. It is a fine powder, produced by heating limestone and clay minerals in a kiln to form clinker, grinding the clinker, and adding 2 to 3 percent of gypsum. Several types of Portland cement are available. The most common, called ordinary Portland cement (OPC), is grey, but white Portland cement is also available. It is more expensive than grey cement for two reasons: Firstly because it requires more processing (it requires a second calcination step during which iron oxides that would otherwise be present are removed) and secondly because during its production it has to be protected from the air with a layer of aluminium foil to keep it white. From the chemical point of view there are no differences between gray and white OPC.
Portland cement is a basic ingredient of concrete, mortar and most non-specialty grout. The type of Portland cement used in a concrete structure determines the time it will take to harden, and also its final strength. Learn more about this hydraulic cement that’s used in building construction.
Portland cement is not a brand name, but the generic term for the type of cement used in virtually all concrete, just as stainless is a type of steel and sterling a type of silver. Cement comprises from 10 to 15 percent of the concrete mix, by volume. Through a process called hydration, the cement and water harden and bind the aggregates into a rocklike mass. This hardening process continues for years, which is why concrete gets stronger as it gets older.
Portland cement is a basic ingredient of concrete, mortar, and most non-specialty grout. It is a fine powder produced by grinding Portland cement clinker, a limited amount of calcium sulfate and other compounds. It is widely used in the production of Portland cement clinker.
Portland cement clinker is made from limestone and clay or shale and a small amount of iron ore and gypsum. These raw materials are ground into a fine powder, mixed together in predetermined proportions, burned in a rotary kiln at temperatures up to 2,640 degrees Fahrenheit (1,450 degrees Celsius) to form clinker “cakes” or nodules, and ground into Portland cement.
Typically CEM I 52.5 N has the following properties:
Specific gravity (kg/m3 at 20°C): 3120
Bulk density (kg/m3): 1750 to 1850
Blaine fineness (cm2/g): 2500 to 4500
Standard consistency: 32% ± 1%