Unearthing Earth Blocks

Mud blocks have been a matter of concern to anyone I discuss the project with. This is a new concept, at least not as conventional as concrete and bricks. Thus, it comes with a lot of questions and misconceptions. So here is what I know about the blocks:

• Are you building with mud? What about heavy rains?

Yes, this is mud - but unlike conventional buildings where the building blocks of the structure are burnt bricks, here it is replaced with unburnt bricks. However, it's the same cement-sand mortar that is used to bind the blocks together. The block, however, is more than just mud; it is stabilized using up to 7-10% cement and made by compression. This is also left to cure for up to 28 days to let the cement attain its complete strength. This prevents the block from washing away in heavy rains.

• But why? Why not just bricks? Aren't you back to cement and sand?

I believe this is going to be more sustainable compared to regular buildings as it is going to save some cement in plastering. The blocks can be left exposed as they have accurate finishing and chiselled ends.

They breathe - However, pouring in cement mortar to pack them is going to reduce their breathability, but I have chosen to leave them without waterproofing to retain their porous nature to the best possible limit.

• Wait, so you need waterproofing? What's the whole point of breathing bricks then?

Waterproofing is just additional support. If you want the bricks to let air pass through them, they are also going to let water pass through them. So for buildings that are going to be exposed to water all through the year, it might be better to waterproof them (at the cost of sacrificing the breathing property of the brick). But my plan has Mangalore tile roofing that would extend to about 3 ft outside the walls, and I hope that would prevent direct rains on the wall. Repeating point 1 - water is not an enemy to CSEB as it has cement; it's just that they can pass through it.

• Now, how strong is it?

To answer this, I think it's important to clarify a few other matters. CSEB is a concept and not any particular type of brick. It is the process of making unburnt blocks by compressing soil stabilized with a little cement, and they are left to cure for about 28 days before putting them to use. Now, these can be made in various shapes for various purposes. They can be hand-made or machine-made.

They can be circular for circular pillars or square and hollow and interlocking, as the manufacturer wishes to do.

Blocks that are made interlocking have grooves in them. The manufacturer from whom I bought them makes them with three grooves to allow for easy electrical and plumbing works in them. They lock one on top of the other like Lego blocks, and cement-sand slurry - a lean mortar - is poured into them.

They could also be made like normal blocks without grooves in preferred sizes and built with mortar itself. Since all these are made in moulds, they would again be perfect and accurate, and with just pointing done, I am sure they can be left exposed and would do great aesthetically.

Answering the question, the interlocking blocks that I am using are said to perform great as load-bearing for up to G+1 structures.

• What if I am not going to use them in a framed structure and not as load-bearing?

That should be totally fine, and the number of stories is not going to matter anymore as it would be the columns and the beams carrying the load to the foundation. It would just be important to consider the weight of the CSEB block when designing the beams and columns as they are heavier than any normal brick. And building multistory buildings with such heavy blocks might not be cost-effective in my opinion.

• What about the maintenance, since we are also not plastering this?

Well, that I might have to see on the go in the years to come. But the corners are to be dealt with carefully; the damage you do to the blocks' appearance cannot be easily rectified with plaster.

• How about electrical and plumbing?

This is crucial in fact. The entire plumbing and electrical had to be planned in advance since there is going to be no chipping off at the end. The block you stack today is the block you would see for years to come. So the electrical lines were planned along with the foundation, and the electrical team worked alongside the concreting members to make sure the lines were aligned correctly.

• What about half-size or smaller blocks?

The dimensions of this block (from this particular manufacturer) are 6” x 12” x 3.5”. I have also not used a double layer of bricks anywhere. The partition walls and the main walls are all of the same 6” thickness. In case the blocks need to be of smaller size or even half size, they can be cut and sized with machines and blades specifically designed for stone cutting.

This, I hope, clarifies the basics of CSEB and gives a brief idea of how it is to build with them. There's more to talk about building with them - the intricacies, challenges, and fun when working with them - that I hope to cover in the next blog!

As always, thanks for reading through. Drop a comment if there's anything to say 😊