Concrete Sandblasting for the Perfect Surface Finish

Sandblasting, commonly referred to as abrasive blasting, is a method of smoothing, shaping, and cleaning hard surfaces by forcing solid particles at high speeds across the surface. An American soldier and inventor, Benjamin Chew Tilghman, invented a sandblasting method.

This process is comparable to sandpaper, but it offers a more consistent finish without any issues in hard-to-reach areas and corners. Sandblasting can happen both naturally and artificially. In the natural sense, it is through aeolian erosion caused by windblown particles, and artificial erosion is caused by using compressed air.

What is Sandblasted Concrete Finish?

Sandblasting is the perfect way to get a non-slip and coating-free solution for restoring your concrete. It’s highly effective and cleans stones, metal, and other solid surfaces. Sandblasting can reveal the stones buried under cement. This process creates a rough texture using high-velocity materials that create friction during operation. Sandblasting concrete is effective for removing dirt and achieving a perfect surface, but not all surfaces require the same treatment. Some areas may only require minor cleaning, while others need deep cutting to achieve the desired texture for the customer. But remember, industrial sandblasting equipment is necessary for this process.

In the past, sandblasting used to take place in open-air environments, which put operators at risk of injury from harmful or toxic materials. Silica dust is especially dangerous if inhaled. However, in 1918, the sandblasting enclosure became a safety measure. This enclosure protects the worker with a viewing screen that revolves around the workpiece.

Advantages of Sandblasting Concrete

The following are the advantages of sandblasting:

• Sandblasting is an easy, simple, time-saving and efficient method.
• Sandblasting requires less machinery for the process.
• Sandblasting is easy to perform and uses sand as an abrasive material which is readily available in various parts across the globe.
• It is particularly effective at reaching corners and intricate geometrical areas without requiring much effort.
• This powerful method can even remove hard layers of concrete, highly adhered paint colours and slag from welded materials.
• Except for sand, other abrasive materials can also be used, depending on the situation. They may be steel grit, dry ice, walnut and coconut shells, crushed glass, etc.

Disadvantages of Sandblasting Concrete

The following are the disadvantages of sandblasting:

• Sandblasting makes a lot of noise and air pollution, which can be disturbing for the surroundings.
• Sandblasting is not effective on smooth surfaces.
• The operator must wear a respirator, or they can suffer from airborne diseases like lung cancer (silicosis) and breathing problems.
• You can suffer from choking if an enclosed area under work is not ventilated.
• The abrasive material, or powder, cannot be reused.
• You can suffer from skin diseases if you do not wear the uniform with a hood during work. Glass powder and small steel particles can be harmful to bare skin.

Application of Sandblasting Concrete

The following are the applications of sandblasting:

• Sandblasting can be used by woodworkers, machinists, auto mechanics, and many more in their work area.
• It can be used on huge buildings, large machines and small tools such as screwdrivers, wrenches, hammers, and other different metal tools. The process cleans dirty surfaces, or tools and it is a way to remove burs, tags and excess material.
• Sandblasting can be used for industrial and mechanical purposes, but other people, like artists, can use sandblasters on different surfaces to complete art, like making statues or signs, etc.
• Abrasive blasting is also used for achieving clean streets, walkways, and other concrete surfaces.

Different Types of Sandblasting Process

01. Water Sandblasting

Water sandblasting, also known as wet sandblasting, uses a mixture of water and abrasive materials to clean and prepare surfaces. This method is safer and more environmentally-friendly than traditional dry sandblasting, as it greatly reduces the amount of dust and debris created during the process.

The process of water sandblasting involves using a pressure washer fitted with a special sandblasting nozzle. The nozzle mixes water and abrasive materials, such as sand, together as they propel out of the nozzle at high speeds. The water in the mixture acts as a lubricant and a coolant, reducing the amount of dust created and protecting the surface from heat damage.

Water sandblasting is typically used to remove paint, rust, and other unwanted materials from a variety of surfaces, including metal, concrete, and brick. It prepares surfaces for painting or coating, as well as to create a rough surface texture for decorative or safety purposes.

Water sandblasting requires more equipment than dry sandblasting, such as a pressure washer and a special sandblasting nozzle. This special equipment can be expensive and require maintenance. Additionally, the water used in the process can create additional cleanup and disposal costs.

02. Air Sandblasting

Air sandblasting also known as dry sandblasting, uses compressed air to forcefully propel abrasive materials, such as sand, at high speeds against a surface to clean and prepare it. This method is commonly used to remove paint, rust, and other unwanted materials from a variety of surfaces, including metal, concrete, and brick. It is also used to create a rough surface texture for decorative or safety purposes. It is mostly used for metal surfaces to prevent moisture buildup and avoid water intrusion on the surface.

The process of air sandblasting involves using a sandblaster, which is a machine that uses compressed air to propel the abrasive materials at high speeds. The operator aims the nozzle of the sandblaster at the surface and controls the flow of abrasive materials and compressed air.

Air sandblasting creates a large amount of dust and debris during the process. This can be hazardous to both the operator and the environment, and it requires a significant amount of cleanup. Additionally, air sandblasting can cause heat damage to the surface. The high-speed abrasive materials can generate a lot of heat, which can cause warping or other damage to the surface. This can be particularly problematic when cleaning delicate surfaces.

03. Vapour Blasting

Vapour blasting is a type of wet blasting in which the compressed air is added to water in the nozzle, producing a mist called Vapour. Wheel blasting is a wheel machine of high power and good efficiency.

04. Micro-Abrasive Blasting

Micro-abrasive blasting is a dry abrasive blasting method which uses small nozzles. It helps to deliver a good stream of abrasive to a small part or small area on a larger part. It is also known as pencil blasting.

05. Automated Blasting

Automated blasting prepares and coats application. Automated blasting uses automated equipment and technology to control and perform the sandblasting process. This can include using robotic systems to control the movement of the blasting nozzle and the flow of abrasive materials, as well as using computer-controlled systems to monitor and adjust the blasting parameters.

06. Dry-ice Blasting

The dry-ice blasting process uses dry ice and air. Dry ice is a soft material and as less destructive, and the force of frozen carbon dioxide helps to remove the surface contamination.

Different Types of Sandblasting Materials

1. Abrasive Media: Grit Size 80 Grit Around 0.007
2. Sand: Produces Free Silica
3. Aluminium Oxide: Lasts 30-40 X over sand
4. Silicon Carbide: Lasts at least 40-50X over sand
5. Garnet, Glass Beads, Black Magic Coal Slag, Walnut Shells and Plastic Pellets

Sandblasting Concrete Equipment

Sandblasting required the following equipment:

1. Compressor: A compressor is the most essential piece of equipment needed for sandblasting concrete. It generates the compressed air that propels the abrasive materials at high speeds. The size of the compressor required will depend on the size of the project and the type of abrasive materials used.
2. Sandblaster: A sandblaster is a machine that uses compressed air to propel the abrasive materials at high speeds. It has a nozzle that the operator aims at the surface, and it controls the flow of abrasive materials and compressed air.
3. Abrasive Materials: Abrasive materials, such as sand, clean and prepare the concrete surface. Different types of abrasive materials, such as aluminium oxide, silicon carbide, and glass beads, are used depending on the type of surface and the level of surface preparation required.
4. Protective Gear: Sandblasting creates a lot of dust and debris, so it is important to wear protective gear, such as a respirator, goggles, and gloves, to protect the operator from inhaling dust and debris.
5. Hose: A hose connects the compressor to the sandblaster. It is important to use a hose that is of the correct size and is made of durable material to withstand high pressure and abrasive materials.
6. Nozzle: The nozzle is the part of the sandblaster that the operator aims at the surface. Different types of nozzles can be used, depending on the type of surface and the level of surface preparation required.
7. Hose and Nozzle Clamps: Hose and nozzle clamps secure the hose and nozzle to the sandblaster.
8. Surface Preparation Materials: You may need surface preparation materials, such as a paint stripper and degreaser, to prepare the surface for sandblasting.
9. Lighting: Adequate lighting is important to ensure that the operator can see the surface.
10. Backup Equipment: Backup equipment, such as an extra nozzle, hose, and abrasive materials, should be on hand in case of equipment failure or if the project requires it.

What is the Mechanism of Sandblasting?

The mechanism is very simple; the compacted air sets the abrasive material in motion at a high speed, which helps to remove the oxide layer or material. After the work, the quality of the cleaned surface increases in a short time. Ae per the research paper, ASTM A516 Grade 70 Steel plate is widely used for service in welded pressure vessels. It helps to improve toughness, which is very useful in pressure vessels and industrial boilers. Some research shows us the effects of the sandblasting process on ASTM A516 Grade 70. It helps in improving the mechanical properties and fatigue life of the material.

Precautions to be Taken While Sandblasting Concrete

While following the procedure of sandblasting, you should know about the process and keep in mind the following protective measures:

• To prevent damage during sandblasting, remove all extra items. It is also necessary to cover unmovable objects, like windows, doors, and surfaces. It helps to protect the other areas and keep them clean.
• If sandblasting is being carried out in enclosed places, then ensure that the place is ventilated. Wear safety gears, like safety glasses, a helmet or hood, ear muffs or ear plugs, etc. The most important thing for the worker is a respirator, which would help prevent inhaling dust particles while working.
• Use stencils before beginning sandblasting to get the desired texture.
• Once the tank is filled with available material or sand, switch on the compressor, maintaining the pressure points between 40 and 100 pounds PSI. The sandblaster for concrete must be in a low-pressure setting.
• The nozzle should be facing towards the concrete, but 20 cm to 40 cm away from the body of the worker who is operating the machine. The operator must know the perfect nozzle position to get the perfect surface finish.
• After sandblasting the concrete, clean the surface with compressed air. The worker can increase the pressure to get a clean surface.

On a Final Note, sandblasting concrete is a process that uses compressed air to forcefully propel abrasive materials, such as sand, at high speeds, against a concrete surface to remove old paint, stains, or other unwanted materials from the surface of the concrete. It can also create a rough texture on the surface of the concrete to improve traction or create a decorative effect. But always remember to wear protective clothing, glasses, earplugs, and a hood when using a sandblaster. Hire a professional or experienced worker for sandblasting because if the sandblaster is not used properly, then it can damage the concrete surface. Work with patience and time to get the desired surface. You can get a smooth surface with little effort and time.

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Author Bio

Aditya Bhople – Aditya Bhople is a Technical Content writer and has done his Diploma in civil engineering and currently pursuing B.tech in Civil Engineering from Vishwakarma Institute of Information technology, Pune. He has 3 years of experience in Content development especially in the construction niche and works as a content writer with various websites and companies. He is passionate about research in Innovative Topics in civil engineering. You can reach him on Linkedin and Instagram.