Let’s discuss about something that might seem pretty basic but is crucial in the construction world: concrete blocks! Sometimes called cement bricks or concrete masonry units (CMU), these blocks are the building blocks—literally—of walls in construction projects. They’re precast, meaning they’re formed and hardened before they get to the job site. Interesting, right?

These concrete blocks can come in different designs, featuring solid, hollow and cellular. These have may have either smooth sides all around. Once stacked together with concrete mortar, they create solid walls that stand the test of time.

Did you know that the Romans were the first to use concrete mortar way back in 200 B.C.? They used it to bind stone structures together. Fast forward a bit, during the reign of Emperor Caligula from 37-41 A.D., small blocks of concrete were used for construction in what is now Naples, Italy. However, much of that advanced concrete tech was lost after the Roman Empire fell in the fifth century. It wasn’t until 1824 that an English stonemason named Joseph Aspdin invented Portland cement, which we still use today.

Then, in 1890, Harmon S. Palmer designed the first hollow concrete block in the U.S. After a decade of experimentation, he patented his creation in 1900. His blocks were quite hefty, measuring 8 x 10 x 30 inches! Back in those days, a single person could only craft about 10 blocks by hand. Compare that to modern machines that can produce up to 2,000 blocks per hour—talk about progress!

What Goes Into Making These Blocks?

Making concrete blocks involves a mix of powdered  cement, water, sand, and gravel. When combined, these materials create a light grey block known for its fine texture and impressive strength. A regular concrete block weighs between 34 to 19 kg. The recipe generally has sand, gravel and water, resulting in a dry, stiff mix that maintains its shape when demoulded.

The Design Matters

Most concrete blocks come in standardized shapes and sizes for easy construction. The most common size in India is 200*200*200 (8”), 200*200*150 (6”), 200*200*100 (4”) inches. But don’t worry! There are variations out there to meet different aesthetic and functional needs. Some manufacturers even create blocks designed specifically to resist water infiltration, while others offer split-faced blocks that have a rough, stone-like texture on one side for added visual appeal.

How Are These Blocks Made?

So, how do we actually make these concrete blocks? The process involves four main steps: mixing, moulding, curing, and cubing.

1. Mixing

First up is mixing! Sand and gravel are stored in silos and transferred via conveyor belts as needed while the cement is kept safe in silos to prevent moisture. The raw materials are weighed and then blended together in mixers. There are two main types of mixers: the planetary mixer and the horizontal drum mixer. Once mixed,  water is added to create the perfect consistency.

2. Moulding

After mixing, the concrete is poured into the mould of the block making machine. A sufficient amount of vibration is given to allow the material to blend together and give it its optimal strength. Depending on the machine, you can mould anywhere from 5 to 20 blocks at once! The moulds are compressed, often using hydraulic pressure and vibrations, ensuring the concrete sets properly.

3. Curing

Once moulded, the blocks are placed onto pallets and rolled into a curing kiln. Here, they’re either cured at room temperature with gradual steam heating or  just the regular water curing. This process takes about 24 hours, giving the blocks their strength.

4. Cubing

Finally, the cured blocks are rolled out after curing  for a minimum of 21 days and are ready for delivery.

Keeping Quality in Check

Manufacturing concrete blocks requires constant monitoring to ensure quality. Every batch of raw materials is weighed accurately, and water content is checked to maintain consistency. Once the blocks come out of the machines, their dimensions and curing conditions are carefully monitored to ensure they meet standards.

And there you have it! From ancient Roman innovations to today’s advanced production, concrete blocks are a fascinating and vital component of modern construction. If you have any questions about these building blocks, feel free to ask!

At Apco, we’re committed to excellence in the construction industry. As a leading manufacturer, we provide versatile and durable concrete blocks that adhere to the highest standards. Trust us for quality materials that empower your building projects, ensuring strength and reliability every step of the way. Choose Apco for a solid foundation!