Cinva-Ram Block Making Tips

This is a compilation of the e-mails I've sent out during the last part of the project to assist you in completing the work.


There is now a cement mixer downstairs. You'll recognize it by its stunning appearance. It's outside. Please treat it with respect and clean it out when you're through using it.

The CinvaRam is working smoothly. I've also moved it outside. Please clean up around it after you're through using it.

I want to emphasize the importance of documenting your work for the final blocks.You need to put together a package on the development of the blocks, and give the rationale for the decisions you made, including background material, like sketches, calculations, formulas, etc. Someone reading you stuff should be able to duplicate your blocks. Graphic presentation of that work is important.


Some people have started to use the equipment downstairs to test blocks.

A few tips:

1. The concrete mixer appears to work. Don't put too much in it, though, or it doesn't work as effectively. Remember that there is approximately 6 quarts of mix in one block. Don't attempt to make enough mix for more than 2 blocks in one shot.

2. Find the optimum rate at which to turn the drum so you get an effective mix. Can't go too fast.

3. CLEAN IT OUT when you're done. Come to me if you find it full of dried stuff, and the team that had control of it before you will be sorry. The schedule on the wall will govern who is responsible.

3a. Woe be unto you who breaks the cement mixer.

4. Water: base the amount of water you use on the FEEL of the mix, not on the quantities we found in testing. Ultimately, you need to base your decisions on what you know and feel is right, not on a numerical function.

5. There is a plywood plate in the bottom of the machine. (Thanks to Sean Talley for making this) It is tapered to account for the out-of-squareness of the machine. Make sure it is in the machine correctly, and don't lose it.

6. There is no more lubricant for the inside of the machine downstairs. If you want to use lubricant, supply it yourself.

7. Remember that red sand makes for a more workable, moldable mix (due to natural clay content). Don't simply adopt the normal, strong concrete mix and expect it to work. You are making blocks that need to be molded in a cinva-ram, delivered and transferred. Your mix needs to accommodate this criteria.

8. When we did our first test blocks, we slid the finished blocks off the machine onto a plastering hawk. The hawk is no longer down there. You will have to supply whatever you are going to use to deliver the blocks, and move them to wherever they are going to dry. The more you move them the greater chance of damage you have. [If I were you, I'd get some pieces of masonite, or something similar (very thick cardboard maybe?). I'd deliver the blocks onto those pieces and set the whole thing aside to dry, without touching the block anymore. I would label the piece of masonite with my name and the mix recipe.]

9. CURING. These things are going to take up a good bit of space. There is probably not enough room in the immediate area. You want to put them somewhere they won't get damaged. Find a place where they will be safe from harm. [If I were you, I'd probably use the studio for the first 24 hours or so, when the blocks are most vulnerable.]

9. The documentation of your work will be a VERY big part of your grade. Someone else should be able to reproduce your work, based on your documentation. Like I have with all of the other sections of this lab series, I will be photographing these new blocks and posting them to the web. I see all of this work as a line of research that could be useful to us or someone else in the future. Documentation of the work is critical.

10. If you haven't noticed, I feel strongly about the documentation of our work and process (as in the web stuff I've posted). While you are doing this, if you make any observations about technique that should be shared with the whole class, e-mail them to me and I will forward to the whole list. Building the knowledge base is important.


A couple other things I've observed:

1. The Cinva-Ram is a little sticky on the start of the ejection stroke. It appears to be from friction between the sides of the block and the sides of the box. Also, there is some friction between the bottom plate and the sides of the box. I would say that lubrication of the inside of the box is essential. It made a big difference in the ejection stroke. Also, if it is still feeling sticky, it helps for one person to lift the bottom up on the ends (sort of like I was doing on that day in class), while the other person works the lever, to get the stroke started.

2. Figure out the optimum amount of mix so that you get full compression with the handle brought down to horizontal. That's the only way you can guarantee that all the blocks you make will have the same dimension. You want the bottom of the box to come all the way up.


Patrick Smith points out to me that I had a typo in my link to the Virginia Tech block experiment page.

That has been corrected. It is As I look at that site again, I notice that it is pretty good at explaining their process for selecting soils, mixing, etc. It would be worth a look if you have yet to make any of your blocks.