Go for soil cement blocks
They are quite strong and also add character to a building
Simple: The construction process with soil cement blocks is like building with any other block, except taking care of joints and corners
With reference to mud buildings, though rammed earth has a greater history behind it, building a stabilised mud block (SMB) or soil cement block (SCB) wall is much easier and convincing to a new client. Commonly, mud blocks measure 9”x9”x6” with minor size variations, edge profile and cornice decoration options, as may be required for the project.
The soil is prepared the same way as for ramming, but here it is packed into the molds within a small machine. The machine comes with a pressing lid, operated by two workers throwing their weight on it, so the soil gets adequately compacted. After compacting, the fresh blocks are lifted out of the machine and kept in the open outside for drying under the sun. All this can be managed within a 60×40 site or even smaller sites if the road sides can be used.
All the three major institutes, viz. ASTRA, Auroville and DA, have developed their own versions of the block making/pressing machine, with the ASTRA model being popular in Bangalore. It is advisable to have three labourers as a team to start making blocks few weeks before the wall construction, get the blocks sun dried and stock up at site. Ideally, the soil dug up from the site itself should be used for blocks, to save on transporting mud from outside.
There are testing labs such as Mrinmayee which can study the sample soil to give advice about the water content and quantity of cement and stone quarry dust to be added to stabilise the soil. However, in case the soil is unfit for blocks or it is in short supply, blocks may have to be ordered from outside.
The construction process is like building with any other block, except for care for joints and corners. Unlike what many people fear about, the SMB wall is not a weaker option! While a normal brick can be cut by the mason using his ‘karni,’ here we need a cutting machine. Even electrical grooves cannot be done by a small chisel and hammer, but once again demand machines. No water can seep through the block, as such external pointing is important only to ensure water-proof joints. The joints with stabilised mud mortar can take any number of nails, a routine household requirement. Of course the joint lines, both horizontal and vertical, are visible in the building, adding a character to it.
Alternately, the wall can be mud-plastered if an even surface without joint break is desirable. It can also be painted with any colour, if the mud looks need to changed. It is interesting to note that a mud building offers the option to completely conceal the mud looks or celebrate the earthy looks, once again scoring over other choices. However, we need not highlight the intentions of using mud construction and what option most owners choose!