Hi Marco,
My
answer would be: none.
You are located in Italy - the kingdom of masonry. Someone said that fired brick has advantages of adobe but none of its faults.
If the material has to be specially protected then there is an intrinsic problem with this material.
People were building from adobe and rammed earth in the past, but only because it was the only material available or it was cheaper than stone or fired brick.
Saying all of this - I'm the owner of the CEB home, but I'm in the States where the only masonry option for seismic designs is vulgar
concrete block, even less acceptable (to me) ICF or solid concrete. All cement based.
There do exist structural bricks, but they are extremely expensive here, because they are used in public construction, that has immense financial bloat.
Italy is beautiful and also the tourist attraction (like the rest of Europe), because it was using quality materials to erect beautiful structures that are STILL standing.
In theory unfired material
should be cheaper than fired one, but only in theory. I was trying to make CEBs myself. One major problem that nobody talks much about was the material preparation, before compression. My soil (in dry state) is almost as hard as a brick, but digging it one will extract big crumbled pieces that have to be pulverized first. How? By hand over the sieve was not an option. It was taking 20 minutes to prepare material just for one brick. Then I got engine powered crusher that would still need around 8 minutes per brick and a lot of fuel. On top of that none of my bricks was passing laboratory tests required here when bricks are made on site.
At the end it may be cheap only if you do not value your time. I decided to buy them from the professional. In case of making regular adobes you have advantage of using water. Mixing clay with water is relatively simple and can be easily done in bulk without special equipment.
Regular adobes can be also stabillized, but then they become less of an adobe, but result is visible. My blocks supposedly have 10% of cement, but it can not be true, because if left in the rain, unprotected over the winter they will crumble to nothing. The CEBs I made with actual 10% of cement were laying in the grass for 8 years almost unchanged, but if you have to use so much cement why to bother with such a material? Lime can also be used as stabillization but the soil mix should have pozzolanic properties to react with it.
If I was in Italy and had to build I would use sedimentary stone ashlars first then as the second option Wienerberger type bricks. Stone would not be cheaper, but bricks probably will. They can be easily reinforced if needed to meet the seismic requirements (3S for Livorno).
I just checked Tecnomat in Pizza and they have 20x30x18cm blocks for E2.15 (with included VAT). They would probably deliver them for free on a short distance.
So for example compared to my CEBs that was 20x10x40 cm and cost $3 6 years ago (delivery included) you are getting two times more of a better building material for the same price. Of
course the price of CEBs may be different in Italy, but then you would have to transport them.
If you go the route of making them yourself, please count the time for your work and the laborers. Also for double floor building you will have to build much thicker first floor walls, which I like, but it adds to the construction cost. You could also do 1.5 floors - with attic used for low ceiling sleeping area - it would also make the building to have more beautiful proportions.
I have built a gate and a barn/coop from structural (clay) bricks. What a wonderful material. I did not have to worry to protect from massive rains I got this year, wouldn't have to worry about chipping, tiles adhesion, lime plaster adhesion, etc.
I'm still planning another building from CEBs - a gazebo/summer room, so I will use over 700 bricks I have left from the house.
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