Humankind has adopted numerous technologies throughout the history of its civilization. One of the most significant achievements has been building homes that protect us from environmental hazards. In the early days, humans used naturally found substances like wood, stones, or clay to make their safe abode. However, with the progress of technology, humans have been able to invent concrete. Concrete is the most consumed manmade substance in the world. Its usage in construction work has remarkably changed the whole sector. Concrete has made it possible for us to build megastructures that we could never imagine.

Moreover, concrete has also evolved through certain stages in its lifetime. There was a time when site-mixed concrete was the only option. Currently, Ready-Mix Concrete is rapidly taking place as it offers better quality, design, workability, and efficiency. It is an ideal product for constructing high-rise buildings, mega bridges, flyovers, schools, hospitals, shopping malls, low-maintenance roads, etc.

Even though concrete has a history older than 5000 years, Ready-Mix Concrete is only slightly over a century old. The developed nations have an established network of Ready-Mix Concrete factories that run a successful chain of deliveries in all corners of the country. The developing nations are still trying to install more batching plants to deliver Ready-Mix Concrete on demand. The manufacturing process of Ready-Mix Concrete is composed of several sophisticated tasks. Only the best manufacturers can maintain a consistent and international quality of concrete.

How is Ready-Mix Concrete Made?

Contrary to the conventional method of concrete mixing, Ready-Mix Concrete is manufactured offsite to meet customers’ specific needs and then supplied in a particular vehicle. It is the customer’s first choice for both commercial and domestic projects. The offsite production allows for better quality assurance and a faster turnaround. The batching plants are designed and computerized to maintain given protocols with excellent accuracy. Ready-Mix Concrete is made with a combination of cement, water, and various aggregates like sand, crushed stone, or gravel.

Different Types of Ready-Mix Concrete

With the increasing popularity of Ready-Mix Concrete globally, different types of Ready-Mix Concrete have appeared in the market. Furthermore, other manufacturers adhere to specific guidelines for preparing their concrete mix.

Usually, there are three different types of Ready-Mix Concrete available. These are

1.   Transit Mixed Concrete
2.   Shrink Mixed Concrete
3.   Central Mixed Concrete

Transit or truck mixed concrete is mixed on route to the job site. The ingredients for preparing concrete are loaded into the mixer truck, mixed until a uniform consistency is produced, and delivered to the job site.

Shrink mixed concrete is partially mixed at the batching plant. It enables the reduction or shrinkage of the total volume of the concrete mixture. It allows for a controlled measurement of the concrete. The final mixing is usually done on the route or at the job site.

Central mixed concrete is thoroughly mixed at the batching plant and then transported to the job site in a concrete mixer truck.

The Manufacturing Process of Ready-Mix Concrete in Bangladesh

Concrete manufacturers follow certain protocols to produce the best quality concrete globally and in Bangladesh. However, there might be slight differences in quality due to concrete mix design, product quality, customer requirements, weather conditions etc. The following section discusses how manufacturers make Ready-Mix Concrete in batching plants.

Concrete Mix Design

An effective concrete mix design is essential to prepare a batch of concrete that is both economically viable and robust in nature. In order to achieve this goal, manufacturers determine the workability, strength, and durability of concrete, depending on the project’s requirements. After that, a mixed design is prepared to fulfill the desired conditions.

Materials required for preparing Ready-Mix Concrete mainly consist of fine and coarse aggregate, cement, and water. Sometimes admixtures are used to enhance some other properties of the concrete chemically. Different concrete mix designs are available for specific weather and workability conditions.

In Bangladesh, Ready-Mix Concrete manufacturers start with choosing slump value, which is critical for easily placing and complying with Ready-Mix Concrete without segregation in a fresh state. Forms and reinforcement are taken into account to determine the maximum grain size of coarse aggregate. The cement to water ratio is crucial for establishing the compressive strength of the mixture. So, the amount of water and air content are estimated accordingly. Coarse aggregate and acceptable aggregate ratios are fixed for the highest possible volume. Finally, moisture control is monitored to finish the concrete mix design. Based on the formula, manufacturers prepare a trial batch of Ready-Mix Concrete. Then they perform various tests on the batch to ensure everything is up to perfection. If the trial batch passes all the tests, the mix design is finalized and ready to be prepared in bulk.

High-quality concrete relies on the correct proportions of raw materials. Using too much or too little of something will never bring the best results. Besides, it can make the product less useful with incorrect ratios of materials. A standard concrete mix should contain around 10% – 15% of cement, 15% – 20% of water, and 60% – 75% of aggregates. Other admixtures can be mixed with the formula to enhance the strength and durability or speed up or delay the concrete setting time. These additives will vary depending on the job’s requirements.

Source: Doncaster Quickmix

Production and Transportation

Production of Ready-Mix Concrete involves several processes. The batching and mixing techniques are most significant where materials are being measured and introduced into the mixture to prepare a paste of uniform consistency. The dry elements are brought together in specific quantities in modern manufacturing plants with automatic computers. So, there is no chance of error in the slightest of margins, which is very common in traditional concrete mixing practices. Desired quantities of cement, water, and aggregate are transferred simultaneously to the mixer according to the concrete mix design. The container has rotating blades that mix the formula until it becomes entirely homogeneous, uniform in color, and consistent. The batch mixer continually rotates until it achieves the desired consistency.

Ready-Mix Concrete production can be done in two different types of batching plants. Batching plants are nothing but advanced machines that produce Ready-Mix Concrete by mixing the desired quantity of raw materials. The two types of batching plants include Dry Mix Plants and Wet Mix Plants. In dry mix batching plants, all concrete ingredients are mixed in preferred quantities except water. Then the mixture is kept in a Ready-Mix truck.

Source: RMS Concrete 

After the Ready-Mix Concrete is prepared and mixed in a batch plant, it is transported in a transit mixer to the site and delivered to the customer in a fresh state. Transportation of concrete is challenging as the mixture tends to harden as cement and water start reacting immediately to enable hydration. Hence, specialized trucks with rotating drums transport the Ready-Mix Concrete product to job sites to control hardening or loss of consistency.

Placing and Compacting

Ready-Mix Concrete is transported to job sites to be placed into the molds as near as possible to its final position. Required substantial quantities should be precisely calculated to fill the formworks. Cold joints will occur if there is any interruption in the filling process. It can severely hamper the bonding of concrete. Generally, formworks are cleaned and lubricated before filling in with concrete to get the best results. Specialized trucks are used to pour concrete into the molds. In some cases, Ready-Mix Concrete is placed using mobile and stationary pumps. Transit mixers can directly place the concrete in the molds also.

Concrete placing is achieved in horizontal layers of similar thickness. Each layer must be compacted before placing the next one. If any voids remain, they can trap air, which will cause high permeability and low strength and durability in the hardened state of Ready-Mix Concrete. The entrapped air or void is eliminated by compaction, which is generally achieved by vibration. Vibration can reduce friction between the particles so that concrete can flow into the edges and fill up any space.

Ready-Mix Concrete is getting very popular in Bangladesh in recent years. Contractors are slowly learning the advantages of using Ready-Mix Concrete, and customers demand it over traditional methods.

Finishing

Finishing is done after placing and compacting Ready-Mix Concrete. It is applied in two stages, screeding and floating. A flat wood or metal plate is used to remove any remaining imperfections. Sometimes, machines are used to smoothen the surface in slabs and large concrete areas.

Curing of Concrete

Curing is the final stage of finishing concrete work. Curing is the process of keeping concrete moist and warm to facilitate proper hydration of the concrete. Continuous water is sprayed on the surface to keep the concrete wet and prevent evaporation. There are different concrete curing methods that can be applied depending on the work.

Summary

Ready-Mix Concrete is the most efficient and cost-effective solution. Developed nations rely heavily on Ready-Mix Concrete to build domestic, commercial, and megaprojects. Developing countries like Bangladesh are increasing their reliance on the Ready-Mix Concrete products, which is an excellent sign for Bangladesh’s industry and overall construction. Not only does it offer an affordable solution, but also better quality and workability. Several Ready-Mix Concrete manufacturers in Bangladesh follow international standards to produce the best quality concrete. More and more contractors are now leaning toward using Ready-Mix Concrete instead of traditional site-mixed concrete. It is an excellent sign for the Ready-Mix Concrete market in our country.

Frequently Asked Questions (FAQs)

What is the difference between Ready-Mix Concrete and Cement?

Ans: Cement is a dry powder that works as a binding material. Concrete, on the other hand, is a combination of cement, aggregates, and water.

Why is Ready-Mix Concrete used instead of site-mixed concrete?

Ans: Ready-Mix Concrete offers a multitude of benefits over traditional site-mixed concrete, like cost efficiency, better workability, no storage hassle, and better quality. That’s why Ready-Mix Concrete is used.

Which cement is used to prepare Ready-Mix Concrete?

Ans: Manufacturers use good quality Portland Cement to prepare Ready-Mix Concrete.

What is the most challenging part of manufacturing Ready-Mix Concrete?

Ans: The most challenging part of manufacturing Ready-Mix Concrete is sourcing good quality raw materials and transporting the finished product within a definite time to job sites.

How much Ready-Mix Concrete a standard truck can carry?

Ans: A standard Ready-Mix Concrete truck can carry around six cubic meters of concrete.