By the way, do the users of Rhino blocks usually plaster their wall? 70% of them plaster their wall or what is the breakdown? Can you leave the walls unplastered for unstabilized blocks? What are the effects of non plastering walls. Plastering is a labor intensive process.
Good questions Sujorno.
"Rhino blocks" are another name for Interlocking Compressed Earth Blocks. One of their labor saving advantages is that they don't need plastering. Except, for the first 2 or 3 layers on the outside of a building. They do need a 'good hat and good boots.' That is, a roof overhang that prevents direct rain fall on the top of the blocks (this is especially important for fence walls). And, a good damp-proof layer to prevent the wall from sucking up water from the ground through the footing. Interior walls of unstabilized soil blocks can do well without plaster. The soil will rub off a bit. So, plastering helps keep the house clean. There are also other materials (other than a cement sand render) that can be used for "rendering". GATE/GTZ published a nice booklet on this. If outside non-stabilized block walls are not protected they will erode. There is a city in Africa made of unstabilized earth walls. They maintain their walls every year. If walls are protected they can last a very long time. White-washed (lime) adobe walls on Mission churches in California have been there for over 400 years.