Concrete Vs Cement
Cement is often confused with concrete, and it is a common misconception that cement and concrete are interchangeable terms.
Knowing the basic fundamentals of each, including history, composition, and differences, will help you gain more knowledge when talking to construction experts.
Below, we will take a closer look at cement and concrete, including the main differences and uses.
Cement can be made from a variety of materials, but it cannot be used alone. In fact, Roman cement was crushed with burnt lime, volcanic ash, and brick supplements.
Today, Portland cement is the most common cement used and is one of the lowest cost materials in the world due to the wide availability of limestone and shale.
Also, read: Difference Between 33, 43 and 53 Grade Cement
There Are Five Types of Portland Cement with the Following Features:
- Type I cement is good for general purposes, where special properties are not required.
- Type II has moderate resistance to sulfate and makes up the majority of cement sold in North America.
- Type III cement has a relatively high initial strength, meaning it gains strength more quickly than type I, allowing companies to be removed earlier.
- Type IV has a low heat of hydration and is used in large construction projects. It develops resistance at a slower rate than other types of cement.
- Type V cement is used only for severe sulfate resistance, as it develops resistance at a slower rate than other types of cement.
The first step in cement making is to extract limestone (and other materials) from a quarry by blasting.
The materials are reduced in size and then transported to a plant for processing.
Then, other materials, such as sand, clay, shale, iron ore, plaster, and minerals, are ground with limestone to produce raw flour, of uniform size and chemistry.
The raw meal is then processed in an oven that exceeds 2,642 degrees Fahrenheit or 1,450 degrees Celsius (hotter than molten lava when it erupts from a volcano!).
A rotary cement kiln, responsible for more than 95% of the world’s cement production, is essentially a long tube with 12 feet in diameter and more than 300 feet in length, depending on the production capacity of the plant.
The processing of raw flour in the oven allows various structural changes and chemical reactions to occur and the formation of new compounds that contribute to the strength of the cement.
The white pieces that emerge from the oven are called “clinker” and are cooled by air. The “clinker” is crushed in a mill to the desired size and strength.
A laboratory collects samples and checks the fineness, consistency, strength, and heat of hydration, among other attributes.
Due to the high temperature required in the oven, coal, natural gas, fuel oil, and petroleum coke are often used for burning.
However, with efforts towards more sustainable manufacturing, plant operators are adding more recycled materials to the fuel, such as landfill overflow, slaughterhouse waste, plastics and more.
Another example of tires that can be difficult to discard otherwise.
Now that the “clinker” has cooled and has been ground into fine cement powder, it is sold in bulk, bagged or transported to a plant where it is mixed with other ingredients to form concrete or mortar.
Concrete is the final product resulting from mixing cement, aggregates (including sand), water and mixtures. It is initially malleable in its “wet” state and solidifies over time, gaining strength and durability.
The first use of concrete was by the Roman Empire. Although there is some indication that earlier civilizations used a distant form of concrete, the Romans used a mixture of quick lime, pozzolana, and a pumice aggregate.
The Pantheon is the largest unreinforced concrete dome in the world, built-in 120 A.D.
Concrete mixtures vary according to strength, appearance, and local requirements. As mentioned above, it is usually made up of four main ingredients that are mixed in a specific proportion based on the application:
- Cement: This is the binder used to join other materials.
- Aggregates: coarse aggregates (greater than 3/8 “in diameter) and fine aggregates (sand).
- Water: Water is the most important element in the quality of concrete manufacturing and is necessary for two purposes:
- Hydration to create a chemical reaction with cement.
- To help workability (water/cement ratio).
- Admixtures: are ingredients other than cement, water, and aggregates that are added to the mixture just before or during mixing. Examples include chemical retardants, accelerators, water reducers, and superplasticizers; mineral fly ash, silica smoke, and slag.
Prefabricated spread test, depending on the application, there are several types of concrete that can meet your needs.
An example is a self-compacting concrete (SCC) that is highly flowable and can spread quickly in place without separating.
The water-cement ratio in self-compacting concrete is about 0.32 instead of 0.48 in conventional concrete. The flowable aspect of SCC makes it ideal for precast concrete.
Another example is polymeric concrete, which uses a catalyst to join aggregates. It is pressed instead of spilled and used in applications where greater resistance to corrosion is required (for example, sanitary
sewer boxes). Other types of concrete include high-performance concrete, permeable concrete, and shotcrete.
Pre-mixed concrete is manufactured at a batch plant and delivered to the project site with water added to a barrel truck.
Often, various mixtures are used to provide optimal results in different climatic conditions.
An example includes accelerators such as calcium chloride or non-chloride accelerators that increase the rate at which the hydration reaction occurs.
Concrete: A Sustainable Option
With sustainable and ecological construction methods highlighted, it is important to understand the role that concrete plays in the environment.
Concrete can remain for thousands of years and gain strength as it ages, whereas other building materials can rot, rust and burn.
The concrete of old buildings and demolished bridges, as examples, can be crushed, reduced and incorporated into new lots as an aggregate component.
It can also be used as rip rap and new road bases. Concrete is a building material with high energy efficiency, due to its inherent thermal mass and ability to absorb heat.
In addition, recycled materials – such as post-consumer glass and slag cement – can be incorporated into concrete for masonry units that can contribute to green and sustainable design.