Studying 5 items of the most important aspects of roller compacted concrete and its main admixtures

Concrete is one of the most commonly used materials in the construction industry. Generally, sand, water, and cement are mixed to make the concrete; in fact, the presence of water and cement leads to an increase in sand cohesion and consistency. Sometimes other materials are used instead of water in the concrete mixture which makes it bond to different surfaces. Accordingly, there is another type of concrete in which sand, gravel, and cement are compacted by a roller and implemented on the desired surface under high pressure which is called Roller Compacted Concrete.

RCC Technology

This technology which has been well-known by the name of RCC has been approved at the international level by companies active in the field of producing concrete formulation. Using this mixing method in different projects requires acquaintance with the advantages and uses of compacted concrete and its main properties which will be studied in the following. 

The introduction of RCC based on the definitions of global organizations

The American Concrete Institute (ACI) professionally uses this definition of Roll-Crete which the RCC is compacted before the hardening process and sticks to the desired surface by moving the device. According to the slump test, this type of concrete has zero consistency which indicates its complete dryness and special machinery is used to compact it.

This type of concrete does not differ from conventional concrete after it reaches the desired compaction. When implementing this type of concrete in different structures, first the material is poured on the surface by trucks and special bulldozers disperse the material on the surfaces and finally, it is compacted by vibrating rollers. 

The efficiency of this method is the same as conventional concrete casting, but it reduces the expenses of implementation by up to 50% due to its special technology.

The ingredients of RCC

The main material used in the RCC includes 35% fine aggregates, 10% cement, 40.5% coarse aggregate, 13% water, and 1.5% air. These values can change depending on the condition. Other materials may be required in the project when using concrete. In this condition, fly ash or other pozzolanic material is used to reduce the heat of hydration.

But the concrete may need microbubbles to improve its properties inside its ingredients. The air-entraining CapcoAir SLA will have a very efficient performance in this condition.

Especially, in environments with colder weather, the existence of air bubbles maintains some controlled bubbles of the same size inside the concrete and protects the concrete in re-freezing or re-thawing conditions.

The main 4 properties of RCC

The RCC has special properties which make it different from conventional concrete. Each of the properties is formed under a specific percentage of concrete admixtures and may reduce or increase.

Checking strength value: Different tensile and compressive strengths have been developed in the RCC based on the material used in the concrete such as cement, aggregate, sand, etc. which are similar to the conventional concrete and may differ up to 7% to 13 %.

• The consistency: the type of aggregate used in the ingredients, the amount of sand and water, and the mixing time lead to a different level of consistency in the RCC. Using the CapcoCrete SPC251 increases the consistency of concrete. Moreover, an increase in the compressive strength, a reduction in the elastic modulus, and using fine aggregates increase the consistency.
• Thermal properties: The temperature is the same in the RCC and conventional concrete and the reduction or increase in the temperature is changeable based on the type of cement and its amount in the main ingredient.
• Checking elasticity and Poisson: the elasticity ratio is low in the compacted concrete and the hydration heat is developed based on this ratio. The value of Poisson changes between 0.15 to 0.20 and reduces water supply heat.

Special properties of RCC

The RCC has special properties that make it different from conventional concrete. Using materials like Silica Fume in the ingredients increases the overall properties of the substance. This powder is like fly ash or Portland cement that are supplied with grey color in the market.

• Very high capacity of RCC: the concrete should be able to withstand high weights of the compaction process. Therefore, the efficiency of this type of concrete is preserved after setting due to its high capacity.
• The gap between RCC particles: This only happens in some projects due to the reduction in the cement used in the RCC and particles with bigger diameters lead to early separation of concrete particles.  
• No bleeding: The very little amount of water is used in this concrete and bleeding occurs in very small percentages of water.
• Specific volume increase: Reducing the used water leads to using more raw materials to increase compaction therefore, the mass of RCC material increases compared to the conventional concrete.
• Very high compressive and tensile strength: the durability and strength of the compacted concrete vary depending on the place. 
• The elasticity modulus: This property is much more in the compacted specimen and leads to an increase in compressive strength.

The advantages of using RCC:

Using some materials increases the advantages of RCC for the user. The Hamgerayan Production Company (Capco) does widespread activities in the field of producing new materials for RCC which are as follows:

• The amount of cement used in this method is very little due to the thickness of the concrete.
• The temperature of concrete reduces in this method and there is no need to use a cooler.
• The concrete is compacted by a device in this method and there is no need to use mold.
• The displacement, distribution, and compaction of concrete are cost-effective.
• The high strength of RCC against compression and vibration
• This type of RCC has a long life and long-term usage.
• It has highly resistant to water and other liquids
• It has high implementation speed and does not need reinforcement when implementing
• The temperature does not soften this type of concrete due to its special properties.
• The maintenance of this concrete is cost-effective

RCC usages

This type of compacted concrete has widespread uses in the fields of constructing special roads for heavy machinery, paths suitable for bicycles, railways, power plant floors, the place of airplane repair, dam construction, street construction, military institution, pavement, etc.

The most important use of the RCC is the construction of gravity dams in which the materials are compacted in horizontal layers through special devices and the cement used is of lower content. Therefore, the final cost is very low. Other common uses of RCC include pavement of different surfaces which is accomplished in 3 different parts.

Finer aggregates and cement with higher content are used in this type of concrete and in return a high-strength pavement is implemented on the surface.

Conclusion

Today, concrete is one of the most important materials that is used in the construction industry and has widespread uses. The variety of this product was increased over time by adding special materials and the RCC and compacted concrete was supplied to the market competing for the conventional concrete.

Currently, this product has drawn different industrial activities’ attention to itself due to its special properties and advantages and became the most commonly used building raw materials. Many users around the country intend to use this product in their structures and look for providing RCC raw materials.

You can purchase building chemical admixtures and concrete plasticizers through Capco Company or call 021-89331 to contact the experts of the company. The products of the company are of very high quality and provided with first-class materials to have a positive effect on your work.