Block size: Block Prasaan vs. Thai Standard

Submitted by laurence on Fri, 12/10/2012 - 14:50

I need some advice Geoffrey, regarding Interlocking Soil Stabilized
bricks/blocks. I wonder if you can shed some light on the topic.

I know there are bricks in Thailand that are called Block Prasaan and
the Thai Standard is 25*12.5*10cm.

Then there are some other presses around that are 30*15*10cm.

I do not care who invented what/when, and what patents are pending over
what design and/or who made the first press to any of these dimensions,
after all they are all advanced redesigns of a CINVA Ram press.

My question is this. What benefits or drawbacks do you see with one vs.
the other?

Block Prasaan teachers claim that the benefit of using 25cm blocks is
that most plans have dimensions that are measurements like 1.25m or
3.75m or more simply 3m, 6m etc. Using a 25cm brick means it is pretty
easy to figure out how many bricks in a meter and no cutting of any bricks.

But then there are a LOT of people around the world making
bricks/equipment that are around 30cm bricks, yourself included.

What are your thoughts?


Submitted by geoffrey on Fri, 12/10/2012 - 14:53


Dear Laurence,

You have asked a good question.

Basically: The smaller blocks are easier for Asians to handle. The larger blocks make a
stronger wall.

Looking deeper we see that many of the small blocks in Thailand do not have a large hole for
steel reinforcement. Many of the small blocks also can not completely block driving rain from
entering a building because the dowels and grout holes do not touch. By masonry standards the
large block can build a higher wall. If I recall correctly standard practice says that a wall can be
no higher than 20 times the width of the wall (or block for a single wythe). So a 15 cm wide
block can build a 3 meter high wall while a 12.5 cm wide block can build a 2.5 meter high wall.
The larger block appears to be to an international standard size. For single story buildings the
smaller blocks are fine. Feel free to ask further questions.

A constructor or builder can easily figure out a 15 or 30 cm grid for floor plan layout. A 30 cm
block has the advantage of being almost exactly 12"

Geoffrey Wheeler, CVBT, Thailand