Answer: Cement (sometime referred to as Portland Cement or hydraulic cement) is one component of concrete. Cement is to concrete what flour is to a loaf of bread. Concrete is basically a mixture of 2 components: aggregates and paste. The paste, comprised of cement and water, binds the aggregates (sand and stone or grael) into a rocklike mass as the paste hardens because of the chemical reaction of the cement and water. This reaction is called hydration.

Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is basically a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement. Concrete gets stronger as it gets older. 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 (sometime referred to as Portland cement or hydraulic cement) is one component of concrete. Cement is to concrete what flour is to a loaf of bread. Concrete is basically a mixture of 2 components: aggregates and paste. The paste, comprised of cement and water, binds the aggregates (sand and stone or gravel) into a rocklike mass as the paste hardens because of the chemical reaction of the cement and water. This reaction is called hydration.

Answer: The Setting time of Cement is the time required by concrete to harden and set itself according to the formwork in which it has been placed. The amount of time taken by concrete to set is 7 hours to 10 hours depending on the conditions under which the concrete is placed in the formwork. But this does not mean that the formwork may be removed after 7 hours.

Answer: The water cement ratio is very important with regards to the strength of concrete. The strength of concrete is inversely proportional to the water cement ratio i.e. with teh increase in water content the compressive strength of concrete decreases and vice versa.

Cement is an ingredient found in both mortar and concrete. So it is important that we know whether you are working with concrete or mortar. Concrete is a mixture of cement, sand, stone and water. You may purchase concrete at your local home center or hardware store in pre-mixed bags that only require water. This method is common when small amounts of concrete are needed (around fence posts, cylinder footings for deck posts or small pads).

The invention of portland cement is credited to an English stone mason named Joseph Aspdin. He obtained a patent for portland cement 1824. He called his new product Portland Cement because when hardened, it resembled the color of natural stone quarried on the Isle of Portland in the English Channel. Concrete was used on a very limited basis from its inception through the late 1800's.

Generally walls will require 3000 psi concrete or as specified by your engineer or code. Maximum aggregate size is 3/4" and placed at a 5-6" slump.

Concrete can be placed using any one of several methods: concrete pump, conveyer belt, crane and bucket or by a chute directly from the truck. A boom pump is far and away the easiest method using a 3" or 2.5" reducer in the hose to reduce the concrete velocity. Question: What kind of vibrator should be used? An electric vibrator with a 1-inch to 1.25 inch head and a 12-14 foot shaft.

There is an excellent guide from Concrete Construction magazine that answers that. Click here to view.

Answer: Gypsum is added to control the "Setting of cement". If not added, the cement will set immediately after mixing of water leaving no time for placing.

Answer: Setting is the stiffening of the cement paste after water is mixed. Broadly it refers to change of fluid to solid state.

Answer: The rate of hydration of cement depends on the fineness of cement and for a rapid development of strength high fineness is necessary.