How to produce concrete hollow blocks?

It is mainly produced by a concrete brick making machine. First, the raw materials are mixed in a certain proportion. The raw materials are transported to the mold of the brick machine, vibrated by the vibrating platform, the upper mold is pressed down, and formed in the mold.

Hollow bricks made by concrete brick making machine have large output, high efficiency, save manpower and save raw materials. Moreover, the produced hollow block has high strength and accurate size.

According to the different output, we can choose different types of brick making machines to produce concrete hollow bricks.

What hollow bricks can your brick machine produce?

First, all concrete block machines can produce hollow bricks of all sizes.

The usual size is 8’ hollow blocks, 6’ hollow bricks, 5’ hollow blocks, 4-inch hollow blocks. A set of brick machine can be equipped with different molds, and different molds can make concrete bricks of different sizes.

concrete hollow blocks

The main features of concrete hollow blocks

Concrete hollow blocks have several characteristics, such as light weight, fire prevention, sound insulation, heat preservation, impermeability, earthquake resistance, and durability, and are pollution-free, energy-saving and consumption-reducing.

They are just green and environmentally friendly building materials needed in the contemporary era.


Concrete hollow brick has become an important part of contemporary new wall materials and has broad development space and development prospects.

Hollow bricks are often used in non-load-bearing parts. The porosity rate is equal to or greater than 35%. Bricks with large empty spaces and a small number are called hollow bricks.

Hollow brick is the main wall material commonly used in the construction industry.

Due to its advantages of light weight and low consumption of raw materials, it has become the first recommended product by the national construction department.

Grade standard and marking of hollow brick

According to its size deviation, the appearance quality is divided into: excellent products (A), first-class products (B), qualified products (C).

According to its intensity level: MU3.5, MU5.0, MU7.5, MU10.0, MU15.0, MU20.0

Mark in the order of product name (codename NHB), strength level, appearance quality level and standard number.

Examples of tags:

The block with strength grade MU7.5 and appearance quality of excellent product (A) is marked as:

NHB MU7.5A GB8239

Technical requirements of concrete hollow brick

The main size is 390mm × 90mm × 190mm, other sizes can be customized according to customer needs.

The minimum outer wall thickness should not be less than 30mm, and the interval between holes should not be less than 25mm. The hollowness should not be less than 25%.

Size tolerance(mm)







Length ±2 ±3 ±3
Width ±2 ±3 ±3
Height ±2 ±3 +3


Strength Class ( MPa)

Strength Class Compressive strength of hollow block
The average value is not less than The minimum value of a single block is not less than


















Relative water content (%)

Application area Humid Medium Dry
Relative water content is not greater than 45 40 35
Remarks: Humidity-refers to areas where the average relative humidity is greater than 75%

Moderate-refers to areas with an average relative humidity of 50%-75%

Dry-refers to areas where the average relative humidity is less than 50%

The Raw material standards

Cement: Cement complying with GB / T 175, GB / T 1344 and GB 12958 should be used.

Fine aggregate: It should meet the requirements of GB / T 14684.

Coarse aggregates: crushed stones, pebbles and heavy slag can be used. The crushed stones and pebbles should comply with the provisions of GB / T 14685, and the heavy slag should comply with the provisions of YBJ 20584, with a maximum particle size of 10mm. If broken stones such as stone chips are used, the content of fine stone powder smaller than 0.15mm should not be greater than 20%.

Admixture: should meet the requirements of GB 8076.

Construction requirements of concrete hollow brick

Materials to be prepared: hollow bricks that meet the requirements,

Required raw materials for mortar: cement, sand, water.

Admixture: Lime, the purpose of adding lime is to increase the adhesion between the brick and the setting material.

What is the ratio of mortar?

When you use mortar strength M7.5, cement strength 32.5, the ratio of mortar and cement is:

Weight ratio:

Cement: Water: Sand = 1: 0.9: 6.72

Amount per cubic meter = 250kg of cement, 220kg of water, sand: 1680kg

When you use mortar strength M10 cement strength 32.5 mortar and cement ratio is:

Weight ratio

Cement: Water: Sand = 1: 1.07: 6.35

Dosage per cubic meter = cement 260kg, water 280kg, sand: 1650kg

In addition to the strength calculation requirements, the materials used for general masonry should meet the following requirements:

① For the masonry below the indoor floor, small blocks of ordinary concrete and cement mortar not less than M5 should be used.

②The bottom wall of civil buildings with five floors and above should use small blocks not less than MU5 and M5 masonry mortar.

The concrete hollow block wall should be double-painted, and the outdoor feet should be painted with cement mortar.

For light-weight aggregate concrete small block walls in a humid environment, effective moisture-proof measures such as plastering with cement mortar should be used for the walls.

In the northern cold regions, when the outer wall of the house is made of light aggregate concrete small blocks, light aggregate concrete or other effective thermal insulation construction measures should be adopted in the places where the thermal insulation performance of the ring beams, lintels, core columns and other external walls is weakened.

hollow concrete blocks

chao zhang

Author: Chao Zhang

I am Chao Zhang, I have been working in the brick making industry for over 10 years. I have a deep understanding and research on various models of block making machines, especially automatic brick machines, concrete block machines, compressed earth block machines, clay brick machines, cement brick machines. I have a special understanding of this industry. I can help my clients choose the suitable brick machine and assist them in designing and building a brick production factory. If you want to know everything about brick making machines, please contact me. I am happy to help you.