Cement
The binding powder in concrete and mortar, not the finished material itself.
Quick Answer
Cement is the fine powder that binds concrete, mortar and grout. Mixed with water it forms a paste that hardens around sand and stone. Concrete is the finished mix of cement, water, sand and aggregate, so cement is an ingredient, not the same thing as concrete. Estimators rarely take off cement itself.
The Full Picture
The search intent behind cement is almost always the same question: what is the difference between cement, concrete and mortar? Cement is a manufactured powder. Concrete is cement, water, fine aggregate and coarse aggregate. Mortar is cement, water and sand (usually with lime or another additive), used to bond masonry units. Cement is the glue in all of them, and by itself it is not poured or laid.
Portland cement is the standard type in the US. The Portland Cement Association describes how limestone, clay and sand are heated in a kiln to about 2,700 degrees Fahrenheit to form clinker, which is then ground with gypsum into powder. Common types are classified under ASTM C150, with variations for general use, moderate sulfate resistance, high early strength and others. The structural engineer's concrete spec calls out cement and cementitious material requirements, usually in Division 03.
In a typical mix cement is a modest share of the volume. PCA gives a range of 7% to 15% cement by volume for a typical mix, with aggregate making up most of the rest. Estimators therefore do not take cement off from drawings. They take off concrete in CY and price a delivered mix, where the cement content is a design variable behind the price. Cement itself appears as a takeoff line only in specific cases, such as cement-treated base, soil stabilization, or when the contractor batches or mixes material on site, with bagged cement counted by weight or bag.
Pricing problems usually come from confusing the terms. A bid for cement supply is not a bid for concrete work. Cement price swings pass through to ready-mix prices, which is why many suppliers add surcharges or time-limit quotes. USGS publishes national cement supply and price statistics. The estimator should confirm whether a quote includes delivery, admixtures, supplementary cementitious materials such as fly ash or slag, and how long the price holds.
Real Examples
Common Misconceptions
People assume: Cement and concrete are the same thing.
Actually: Cement is an ingredient. Cement binds sand and rock into concrete, and its share of a typical mix is only a fraction of the volume.
People assume: A sidewalk is a cement sidewalk.
Actually: It is a concrete sidewalk. The phrase is common in speech, but on a bid or a spec, writing cement when concrete is meant can cause a quote for the wrong material.
Frequently Asked Questions
What is the difference between cement and concrete?
Cement is the binding powder. Concrete is the finished material made from cement, water, sand and stone. Cement is only one ingredient and a minority of the volume.
What is the difference between cement and mortar?
Mortar is a mix of cement, sand and water (often with lime) used to bond masonry units. Cement is the binder inside it, and mortar contains no coarse aggregate.
How much does a bag of cement weigh?
A standard US bag of portland cement is 94 pounds. Check the product label, since some masonry and blended cements are packaged differently.
Do estimators take off cement?
Rarely. Concrete is taken off in CY and priced as a delivered mix. Cement is measured separately only for items such as cement-treated base or site-batched work.