This from Kent in Cambodia:
As you mentioned, Mr. Cumnoo from Poipet has been using your machine. I have not talked directly with him, but did sit down with his foreman (I forgot his name, so I’ll call him “Mr A”) for breakfast a few weeks ago in order to pick his brains. He seemed quite well-versed in all that went on during the building phase of Mr. Cumnoo’s projects. He seemed to like the work and was hoping we’d take him on as a worker if we went down this path. He mentioned some significant drawbacks about the system, however, that made me almost abandon considering this option. I thought, though, that if I asked you about these matters that there might be some simple explanations that he may have overlooked or not understood. Besides, to the best of my understanding, Mr. Cumnoo never received formal training from you – and, thus, his work crew may have been less well-versed in the particulars of your system. Do you mind if I ask you about these concerns? Perhaps you can put them to rest for us:
1) According to Mr. A, the lever action machine alone is not satisfactory for making strong bricks; that the hand operated lever action was not adequate to satisfactorily compress the blocks. In fact, he said they were rather fragile and not fit to build with. Mr Cumnoo apparently talked with some other builders who had tried this method and solved it in the same way that they did – he purchased a $10,000 ?compressor? that exerted enough pressure to really make stout blocks. Can you comment on this? The price you and I talked about for the hand compressor + training was in the neighborhood of $3,000, right? If we would have to purchase an additional machine for $10,000 in order to ensure strong blocks, that would wipe out the savings we hoped to achieve by using to your method.
2) Mr A was convinced that the economics of using the compressed earth block system, in lieu of the standard building methods used in Cambodia, really did not add up. He was convinced that no Cambodian could realistically make a living producing the earth blocks. Rather, he seemed certain that it was just another of those clever ideas that big NGO’s with lots of cash could sink money into. He seemed to think that it worked great for bringing in short term mission teams and getting them involved, but that it would be a big money loser in the long run.
So, Geoffrey, that is what I heard, but that may not be correct. You are quite familiar with all the particulars, so it’d be great if you could help us think this through and answer these questions. Here’s what’s stirring some of our interest in your system:
1) Seems like we could cut costs on future building projects, assuming we didn’t have to buy that additional machine. Our mission is pretty money conscious, and they don’t like us spending big money. So, maybe your system could help us with that matter.
2) We could use local resources.
3) We could use our own unskilled Christian men in making the blocks and building projects.
4) As we gain more and more experience, we may be able to help others in our region with their building projects.
5) We have an interested colleague from the Khmer mountains who is quite interested in how your system may be used to help the mountain people with their building projects. Bricks and building blocks are VERY expensive up there.
It seems that your system could be a huge help to our work here in northwestern Cambodia. But we need to get those two matters, mentioned above, resolved. Would you mind helping us with some information regarding that? Please also comment on whether the Thai two story buildings you showed in your presentation were built with just the hand-operated compressor, or whether they were built with compressed blocks made by another method.
Good questions Kent.
The strength of a block is related to it's compression and it's cement content. That said, consistency is more important than high compression.
To ensure adequate compression of blocks we use a simple hand-held penetrometer to get 5kg/cm^2. At the CVBT our blocks use a mix ratioof 1:13 and pass 20ksc wet compressive strength after 1 week of solar high-humidity curing. Mr. Cuomnoo purchased a penetrometer from us but, as you say, he did not receive training from us.
Using too much force/compression with a manual press will damage it, make blocks that are stronger than needed and require more energy to make (the workers will have to work harder).
I don't like hydraulic presses because they are noisy, dangerous and require highly skilled maintenance. Also, we are able to hold height tolerances closer with manual presses.
We do offer a compression tester for 18,500 baht but I don't think that it is necessary for most small producers. Our BP6 block press is now 54,000 baht and SP6 pulverizer 30,500 baht. 10-day training here is 17,000 per group not including food and lodging (3 groups minimum). I can also do on-site training.
Building Contractors in Thailand that make and build with the blocks say they save 1/3 on construction costs. Success in construction (or any project) depends on good management. It is my understanding that several hundred block producers attended a national conference about 4 years ago (They filled an auditorium as large as the one at the ECHO conference). I think that few, if any, know about NGOs and development projects; they are private entrepreneurs. If there are too many producers and they lower their prices too much in competition then everyone will lose.
The reasons you like the interlocking block system are respectable. I like earth blocks because they make beautiful strong buildings.
The 2-story health center shown in an appendix of the manual you purchased was built with hand pressed blocks made on site in a rural mountain area. My 2-story home (which Ian, from the ECHO conference stopped by to see last week) is made from hand-pressed blocks from our center.
Thanks for your questions.