To make cement, workers mix raw materials, then heat and cool them. Chemical processes create marble-sized aggregates called clinker, which a machine then grinds and mixes with gypsum and other additives to create the final cement powder.
From laying small concrete blocks to pouring massive dams, cement is crucial to the modern world’s construction projects. In fact, most areas have concrete sidewalks, building walls, bridges or other structures that require cement.
However, just because it’s widespread doesn’t mean it’s well understood. Keep reading for a step-by-step guide to how cement is made and a sneak peek at the future of cement.
Table of Contents
- Step 1: Extracting Raw Materials
- Step 2: Creating Raw Meal
- Step 3: Producing Clinker
- Step 4: Grinding and Preparing the Cement
- Step 5: Packaging, Storing and Transporting
- The Future of the Cement Industry
- FAQ About How Cement Is Made
Step 1: Extracting Raw Materials
The first step in making cement is extracting the raw materials. Some materials, like limestone, shale, and marl, come from quarries. There, workers use blasting or heavy machinery to loosen and transport materials from the Earth. Other materials, like iron ore and gypsum, come from mines.
Throughout the cement-making process, these raw materials undergo chemical transformations that ultimately result in the main ingredients of cement. For example, shale contains silica and alumina. Limestone provides calcium oxide (lime).
Step 2: Creating Raw Meal
After extracting the raw materials, heavy equipment transports them to a machine called a crusher for processing. The crusher grinds the materials down to the size of gravel. After crushing, the materials go to a mixing bay, where they become a uniform blend.
Quality control experts test the mixture to ensure it has the correct proportions of each raw material. After passing quality control, this mixture, now called raw meal, is ready to move on to the next step in the cement production process.
Step 3: Producing Clinker
Trucks transport the raw meal to a production facility where it’s heated in a kiln. Temperatures can exceed 2,642° Fahrenheit (1,450° Celsius) — hotter than most lava. Under these temperatures, the raw materials liquefy and undergo complex chemical reactions. After cooling, the result is a marble-like aggregate called clinker.
The newly formed clinker has unique chemical properties that impact the cement’s strength and other key properties.
Step 4: Grinding and Preparing the Cement
After the production of the clinker, the next step is preparing the cement powder. Grinders break down the clinker into a fine powder. Workers then add gypsum to the clinker powder, which helps control the pace of the setting cement. Depending on what qualities workers want the cement to have, they may also use other additives such as fly ash, slag or pozzuolana.
The mixture undergoes more rounds of quality control testing. After passing, the finished mixture is the final cement powder ready for packaging, storing and transporting.
Step 5: Packaging, Storing and Transporting
Silos store large quantities of the final cement powder until it’s ready for processing. At processing plants, machines package the cement powder in large paper bags. Workers then group bags together on pallets where they’re shrink wrapped to protect against the weather. These pallets can then ship out to construction sites whenever an order comes through.
The Future of the Cement Industry
Today, the cement industry represents one of the largest industries in the modern world. In fact, modern buildings and infrastructure have made cement the second-most used substance on Earth after water. Because today’s cement-making process uses limestone, which consists of 50% CO2, the industry unfortunately also creates massive amounts of carbon emissions — about as much as our cars.
The future of cement is calling for more sustainable practices, and one California startup, Brimstone Energy, believes it has the answer. Brimstone Energy has patented technology that replaces the limestone in the cement-making process with a calcium silicate rock with no CO2 — and, therefore, no carbon emissions.
The resulting cement is chemically similar to ordinary Portland cement, so this more sustainable alternative shouldn’t create construction safety concerns or delay building processes. While Brimstone Energy is still a new company, it offers renewed hope in a future of more sustainable building practices.
FAQ About How Cement Is Made
Have other questions about how cement is made? Check out the answers to some commonly asked questions.
What’s the Difference Between Cement and Concrete?
While people sometimes say cement and concrete interchangeably, they aren’t the same thing. Cement is the sticky binding agent that’s mixed with aggregates like sand and rock to create concrete. So, if concrete is like bread, cement would be akin to flour.
How Is Portland Cement Made?
Portland cement is the most widely used basic component of concrete, made by heating and cooling raw materials into a marble-sized aggregate called clinker. Next, machinery grinds the clinker into dust, which then mixes with gypsum.
For a detailed breakdown of each of these steps, check out the step-by-step guide above.
Who Invented Cement?
Modern-day Portland cement was invented in 1824 by Joseph Aspdin, a British bricklayer. Aspdin heated limestone and clay until the mixture calcined and then ground it to dust. This is largely the same process cement factories use today.
While Portland cement didn’t come around until 1824, the history of concrete shows other precursor methods used in ancient structures. For example, The Great Wall of China was built using sticky rice mortar.
How Is Fiber Cement Siding Made?
To create fiber cement siding, workers first create a slurry by mixing wood fibers, Portland cement, sand and other additives. Machinery then presses the slurry through a film, leaving thin sheets of fiber cement slurry coating the surface.
Workers then dry the sheets of fiber cement slurry and press them together to form boards. Finally, they bake the fiber cement boards in high-pressure ovens called autoclaves that harden and cure the cement.
From making cement to mixing and disposing of concrete, the right equipment can make the process faster and easier.
Find equipment rentals for your project today.
