Comparison Between AAC Blocks and CLC Blocks

Comparison Between AAC Blocks and CLC Blocks

To answer the most common question people ask me, “should I manufacture AAC* blocks or CLC^ blocks?” here I am with the promised guide about comparison between AAC blocks and CLC blocks. I hope it helps my audience to decide the right product for them. I have tried to compare both products on various parameters. This by no means is an exhaustive list, but it might help to guide your decision making process in right direction. I’ll include some more parameters soon. Kindly go through it and let me know your views. I would be glad if this guide helps you decide on the right kind of lightweight block. So here is first episode in comparison between AAC blocks vs CLC blocks.

Note: Kindly post your CLC related queries on our discussion forum. I have set up a dedicated topic to deal with CLC blocks and related queries. This would be like one stop solution for anybody looking for information related to CLC blocks.

1. Production capacity

Generally production capacity of CLC blocks ranges from 20 to 80 m3/day. This relatively small capacity is result of various factors which I have discussed below. In case you want to ramp up production, then there is very little you can do other than replicating the manufacturing line.

Production capacity of AAC blocks starts from 160 m3/day and goes all the way up to 1500 m3/day depending on client requirement. But most of the plants in India have production capacity in range of 500-1000 m3/day. For those who want to set up their first AAC plant, I would recommend 350-500 m3/day as initial capacity. Of course it can be scaled up later on without much hassle and little bit of extra investment. Going for capacity smaller than 350 m3/day is not advisable as there is very small difference in terms of investment since except for extra autoclaves; rest of the equipment stays the same.

So, if you are looking for a expandable project with bigger volumes, then AAC blocks manufacturing is the one for you.

2. Scalability

As most of the CLC equipment is available in lower capacities, ramping up production would require setting up a parallel line. In addition to investment, it would also call for more manpower. Moreover like other cement products, CLC requires a total curing time of 28 days, more space would be required to accommodate increased production. Since CLC blocks require such long curing time, they can’t be stacked up unlike AAC blocks to save space.

It is possible to increase production capacity of AAC plant just by installing more autoclaves and some extra molds. As a matter of fact most of the equipment for plant capacity from 160 m3/day to 800 m3/day is same except for number of autoclaves and molds. These factors work in favour of AAC as production capacity can be increased with much lower investment. AAC is the clear winner in this section.

3. Land requirement

CLC equipment requires very less space due to compact size and smaller production capacity. A CLC production facility requires around 350 m2 of covered space (depending on automation levels) for protecting CLC equipment from the elements. But much more space is required for curing CLC blocks. As mentioned earlier, total curing time for CLC blocks is 28 days. Out of this, wet curing is required for minimum 14 days. Moreover since ‘green’ CLC blocks can’t be stacked above each other beyond a certain limit, lot of space is required. E.g. A CLC plant producing 50 m3/day would require minimum space of 1400 m2 to accommodate 28 days worth of blocks arranged in stacks of 1 m3 (1 m x 1 m x 1 m) each. Similarly if production is increased by 25 m3/day, space requirement would increase by 700 m2.

On the other hand, AAC factory with production capacity of 500 m3/day requires around 5 acre (20,000 m2) of land. AAC blocks are ready to be used once they are steam cured inside autoclaves. Due to this AAC blocks can be stacked on top of each other without worrying about any damage. This way no additional space is required for finished goods storage even after capacity expansion. Even while expanding the capacity of an AAC plant land required does not increase drastically. E.g. scaling up from 160 m3/day to 240 m3/day requires less than 400 m2 of space.

A fresh batch of AAC blocks fed to autoclave for steam curing

A fresh batch of AAC blocks entering autoclave for steam curing

4. Investment

CLC equipment with production capacity of 20 m3/day ranges between Rs. 2-5 million depending on the supplier and level of automation. Project cost for a 20 m3/day plant would come to around Rs. 3.5-7 million excluding land. Since total production and hence sale of a CLC plant is lower, working capital requirement is smaller.

Equipment cost for AAC plant of 500 m3/day would range from Rs. 50-80 million for Chinese equipment depending on the supplier and level of automation. Similar capacity equipment from European vendors would cost anywhere between Rs. 400-700 million. Most of the AAC machines in India are of Chinese origin, so we’ll continue keeping that in mind. Project cost for a 500 m3/day plant would come to around Rs. 130-200 million excluding land. In addition to high project cost, working capital required for AAC plants is much higher due to bigger production capacity.

In terms of investment, AAC is clearly the most capital intensive project and recommended for those with strong funding sources. While for those entrepreneurs who want to make smaller investment and test waters, CLC is the way to go.

5. Manpower

A medium capacity CLC plant of 40 m3/day would require 6-10 workers in a shift (8 hours), bringing total manpower requirement to 18-30 workers per day.

An AAC plant of 500 m3/day would require 12-15 workers in a shift (8 hours) with total manpower requirement to 36-45 workers daily.

/* Please note that this guide is not complete. I’ll amend some more parameters for comparing AAC blocks vs CLC blocks soon. */

Difference between AAC blocks and CLC blocks (…contd…)

 * - Autoclaved Aerated Concrete blocks
 ^ - Cellular Lightweigh Concrete blocks also called Foam Concrete blocks

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