CSEB (Compressed Stabilized Earth Blocks) are used to build premises, but can be used also for roads. An experiment was made in Auroville, on the Kindergarten road, on 100 meters length, with around 800 blocks.
The blocks are 24 x 24 x 8 cm. The mix proportion is the same of all the blocks:
- 200 liters of Auroville soil
- 30 liters of sand
- 30 liters of chips gravel
- 1 bag of cement (50 liters) = 13%
- 1/4 bag of lime (10 liters) = 2.61%
Chips gravel was added to increase the load bearing strength but more importantly to increase the resistance to abrasion.
After one month of curing, some blocks have been treated with Zycosoil product, in order to give them a better waterproof resistance. Zycosoil SG nanotechnology has been developed to prepare in-situ waterproofed soil layer, to act like a nano membrane on the compacted soil layer during pavement construction.
The blocks have been differentiated in 3 types:
- Blocks diluted 1/100 of solution Zycosoil - 503 Blocks
- Blocks diluted 1/50 of solution Zycosoil - 196 Blocks
- Blocks without solution - 139 blocks
We tested the waterproofing of the Zycosoil product, comparing block with 1/100 solution and block without solution. Below are the results:
Comparison graph of one block with 1/100 Zycosoil solution and one block without solution
The block treated with the Zycosoil product has absorbed more water (5.81% of his weight) than the block that has not been treated (4.63% of his weight). This should have been the opposite and therefore, it seems that the product is not very useful. Nevertheless, the experience has been made only with one block of each type and should have been done at least with 3 blocks. Furthermore, it is possible that a mistake has been done by the workers in the protocol during the immersion of the blocks.
The blocks have been put in place in the road the 6th of October 2010.
1" of sand has been spread on the road and the road service passed the road tamper, so as to level nicely the blocks and allow sand to fill in the joints. Some fine sand has been kept on the road so that the rain and the motorbikes sent it in the joints. Borders were done with concrete. The space between the border and the blocks has been filled with cement mortar, as CSEB should not move.
Kindergarten road experiment, after 1 year
After the Kindergarten road success, the Auroville road service decided to do one more piece of road with our blocks.
Blocks were 24 x 24 x 8 cm. This time, we did not add any chemical, and the mix composition was:
- 130 Liters of Auroville soil
- 40 Liters of sand
- 40 liters of chips gravel
- 1 cement bag = 14% by weight
More than 11 000 blocks 240-4/4-8 were produced during April and May 2011. Blocks have been tested after two months Falcon Industrial Testing Laboratory and gave a compressive strength of 9.6 MPa as an average.