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Cinder Blocks and Concrete Blocks

Cinder Block Vs Concrete Block

Cinder blocks are made from concrete by mixing it with fly ash or coal cinders. Concrete blocks on the other hand are made from cement (although both these terms are used interchangeably). Even the terms cinder and concrete blocks are thought to be the same.

Let’s break down the differences between these two by keeping in mind that cinder blocks are made from concrete while concrete blocks are made from cement.

What are Cinder Blocks?

As we said, cinder blocks are made from coal cinders (fly ash) and concrete. The meaning of cinder blocks is bricks made from cinder. The ingredients are mixed, molded, and cured into a hollow rectangular structure. Because there are no strong binding elements used in its construction, cinder blocks are brittle and are used only for small projects. This also makes these blocks super light in weight with negligible tensile strength. Its mass production has stopped since the end of World War II bringing newer technology and better elements into the civil business.

The construction of cinder blocks involves the following ingredients:

  • Volcanic cinders or granulated coal
  • Water
  • Portland cement

This composition gives cinder blocks a dark grey color with a coarse texture on their surface. A typical cinder block weighs around 11.8 to 15 kg.

Coal was a commonly found fuel in most homes back in the 1900s. Places like Bethlehem Steel burned coal 24/7 which means they produced tons of cinders. Ash is the term used for cinders nowadays and we have long graduated to more eco-friendly forms. The reason behind cinder blocks going out of fashion is the advent of more efficient means, one of them being concrete blocks.

Different Sizes of Cinder Blocks

The commonly used sizes of cinder blocks are 8-8-16 inches. Most cinder blocks look similar but if you check the actual size it may differ from what’s stated on the label. More apt dimensions for a cinder block are 7 ⅝ – 7 ⅝ – 15 ⅝. The reason for taking such small measurements is to accommodate the mortar in its 3.8 inches hollow. The two hollows of a cinder block are divided by a 1-inch divider. The extended ends measure about 1 ¼ inch in depth.d

5 Types of Cinder Blocks

Cinder blocks are divided into 5 classifications based on their purpose in constructing a structure.

1.  Hollow Blocks

Cinder blocks are hollow blocks so what makes hollow blocks a subtype? Cinder blocks used in constructing the following structures are generally called hollow cinder blocks:

  • Fences
  • Partitions
  • Basements
  • Foundation of the building
  • Columns
2.  Decorative Blocks

Cinder blocks with a unique coating on their surfaces are called decorative coating and can resemble smooth stones or plastered surfaces. They do tend to absorb moisture so no exterior walls should be built with decorative cinder blocks. If at all it’s being put to that use, make sure to coat it with a waterproof sealant.

3. Partitioning Blocks

Partitioning cinder blocks are used to partition blockhouses. These cinder blocks make it easier to even out interior walls because of their easy installation technique and its lightweight.

4. Foundation Blocks

Apart from hollow cinder blocks, foundation cinder blocks are also used to lay the foundation of a structure. These are super compact blocks that will not collapse under the typical pressure of a high-story building.

5. Ragged and Chipped Blocks

These are the latest addition to the cinder block catalog. Ragged cinder blocks have a decorative surface that resembles crushed bricks. They are the best exterior house design choice and are also found on fences.

What are Concrete Blocks?

Concrete blocks, also called concrete masonry units (CMUs), have one or more hollow cavities that can accept metallic reinforcement. The following materials are commonly used to make concrete blocks:

  • Gravel
  • Sand
  • Water
  • Portland cement

These ingredients give concrete blocks their light grey color and high compressive strength with a fine texture on their surface. Ideally, a concrete block should weigh anywhere between 17.2 to 19.5 kg.

2 Primary Types of Concrete Blocks

There are two primary types of concrete blocks: solid and hollow. Depending on their structure these two types are further classified into

1. Hollow Concrete Blocks

Just as the name suggests, the characteristic feature of a hollow concrete block is a hollow at its center. They come in 3 grades based on whether their densities are higher (Grade C), lower (Grade B), or equal to (Grade A) 1500 kg/㎥. Grades A and B are used for walls with load-bearing capacities while Grade C blocks are used for non-load-bearing walls. Hollow blocks can be further divided into 9 types based on how they are used in construction:

  • Stretcher Blocks
  • Pillar Blocks
  • Lintel Blocks
  • Jamb Blocks
  • Column Blocks
  • Corner Blocks
  • Splitface Blocks
  • Bullnose Block
  • Partition Blocks
2.  Solid Concrete Blocks

Solid concrete blocks are grey bricks with no hollows in them and are used for their heavy tensile strength. They are less expensive than hollow blocks and are huge in size. Solid concrete blocks have 5 subtypes classified according to their use in construction:

  • Fly ash Blocks
  • Autoclaved Aerated Concrete Blocks
  • Paving Blocks
  • Cellular Lightweight Blocks
  • Expanded Clay Aggregate Blocks

Cinder Blocks vs Concrete Blocks

Sl. No. Point of Difference Cinder Block Concrete Block
Main aggregate The aggregate used is fly ash. Only wall units contain fly ash as aggregate.
Other aggregates Cinder blocks are made of cinder and concrete. Concrete blocks are made of cement, wood, or steel.
Weight They are lighter than concrete blocks. Because of sand and stone in it, concrete blocks are heavier.
Withstanding power They cannot withstand too much pressure which is why they are used in small projects like constructing a garden wall. Concrete blocks are brutally strong which means they can be used in all kinds of structures.
Maintenance cost These can easily break which means maintenance cost is high. Concrete blocks can withstand wear and tear for a long time so you don’t need to maintain them now and then.
Structure Cinder blocks have a hollow structure in a rectangular shape. Concrete blocks are flattened structures.

Final Word

Cinder blocks were made using the cinders from volcanic ash or coal. Since we have upgraded to better fuels, we have stopped using coal, and the use and made of cinder blocks have fallen. These are not mass-produced anymore but are still used for small structures like fences or garden walls. Nowadays, concrete blocks made with cement, sand, gravel, and water are used in all kinds of construction. Authorities specifically prohibit the use of cinder blocks in major construction because of their brittle nature. Concrete blocks have the tensile strength to withstand the load from high stories and strong weather which is why their prominence has risen.

Cinder Blocks and Concrete Blocks FAQs

1. What is the difference between a cinder block and a concrete block?

Cinder blocks are rectangular hollow structures made from coal cinders and concrete. Concrete blocks are flat structures made of cement, wood, and steel.

2. Are cinder blocks cheap?

Standard cinder blocks cost 1 to 5 dollars per block on average. This price range includes the following types of blocks:

  • Concrete masonry units (CMU)
  • Slump blocks
  • Half blocks
  • Rounded blocks
  • Hollow concrete blocks
  • 3. How long will the cinder block last?

    Cinder blocks last up to 80 years under proper maintenance. Both concrete and cinder blocks need an extra decorative layer with proper insulation.

    4. When did they stop using cinder blocks?

    Cinder blocks have stopped being mass-produced since 1947 after World War II. The main reason cinder blocks are no longer used to build houses is its high cost of labor, fill, and tools.

    5. Do cinder block walls need rebar?

    Yes, rebar must be placed in all kinds of masonry cores for structural support. The surrounding space of a rebar must be filled with coarse.

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