Experiment 06

In experiment  06, I made 10 specimens from 5 different mixes to find the right proportion. I used the small mixer for better control of the process.
After 1 week I removed the forms and examined the specimens:
– Specimens 33 and 34 were a bit watery but they had a smooth surface and the mix looked homogeneous.
– Specimens 35-38 which had big proportion of paper pulp in the mix, were too wattery and were damaged while removing the forms.
– Specimens 39 and 40 seem to have the best water proportion but they were too brittle.
– Specimens with sand in the mix were heavier that the ones which had only paper and cement.
I will make10  new specimens -experiment 07- with the proportions of specimens 33 and 34 and the water content of specimens 39 and 40.

New mixer used

Experiment 06: 10 speciment - 5 different mixes

Specimens without the forms. Five of them where damaged while removing the forms

Cleaning the forms




About Menelaos Kokkinos

Menelaos Kokkinos TU Delft mgkokkinos@gmail.com
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2 Responses to Experiment 06

  1. Jay Hawk says:


    I’m very interested in watching your experiments and results.

    It is difficult to tell from your photographs, but it appears that you are lining your forms with plastic or other non-permeable linings. This may be partially causing your water issues.

    I have often reminded people that papercrete is NOT a concrete masonry product. This is essentially a cementitious wood composite. Using the same thoughts and practices that are standard best practice for concrete will often cause problems. Almost everyone that begins working with papercrete must change their mindset and think of it as wood before they understand and have success working with it.

    My experience in working with papercrete is that watery mixes often work out to be some of the best ones (as long as it is not an extreme excess of water). I suspect that the extra water allows the paper to more easily be broken down into individual fibers instead of chunks. The key to making watery mixes practical is to use formwork that will ALLOW EXCESS WATER TO DRAIN.

    When most papercrete builders make building blocks they will usually use a bottomless form set on a bed of sand and/or set on some perforated landscape fabric. This will allow excess water to drain out of the mix. If you are lining your forms with plastic, you may be trapping the water inside and that is working against you. Having a bottomless form also allows the builder to remove the form just minutes after pouring. Instead of lifting the entire sample and inverting it for removal, they can simply but gently lift the form off the blocks and leave the very damp papercrete sitting on the ground without damaging them. Wet/uncured papercrete is always extremely fragile. The less you handle your wet samples the better off you will be.

    I suggest you try using forms that will drain if you are not already doing so. (Perhaps you are. I simply can’t tell for sure from your photos.) You will find that your blocks will dry MUCH faster. For your experiment, you may want to capture this runoff water. You’ll find that most of the water will drain out fairly clean, indicating that most of the cement is remaining in the papercrete, and not leeching out. The paper fibers tend to act like a filter and trap the vast majority of the cement.

    I’m sure you already know this, but sometimes in a science experiment it is easy to overlook and neglect to record and control some obvious variables. Humidity, temperature, and movement of the air greatly impact drying times. Obviously the more humid your weather, the colder, and the more stagnant the air is around your samples, the slower they will dry. The less humid, warmer, and better air circulated, the faster your samples will dry. I’m sure you know all of this, but since you are measuring drying times, it’s important to document the enviroment in which your samples are drying if another scientist wants to try to replicate your results some day.

    Another possible area for your investigation would be to create samples by compressing the damp slurry into your forms after an initial draining period of a few minutes. You will discover that the final dry product is dramatically stronger. Not only will it be more dense, have higher compressive strength, be less elastic, and have less shrinkage, but you’ll also discover that compressing the damp slurry will INCREASE the R-Value, not decrease it. This may seem counterintuitive, but my experiments at home have consistently shown that unless the mineral content of the mix is extremely high, that compressing the damp slurry into the form dramatically decreases air infiltration through the material improving insulating properties. (search the Papercreters message archives for “calorimeter”)

    Don’t hesitate to post questions to the Yahoo Group. While the people there may lack in technical and scientific knowledge, they have an abundance of practical EXPERIENCE working with this product. They know how to mix it and handle it well. Most will be happy to share what they have learned and will support your efforts as best they possibly can. Take advantage of their experience. Many there have made many tonnes of papercrete. While they may not have scientifically tested it, they do understand a lot about it. Also keep in mind that like any open internet forum there are also a great many people who are new or inexperienced as well. I’m sure you are smart enough to tell them apart and will treat their answers accordingly.

    I hope you find my comments helpful. I offer them as personal insights and encouragement. Please do not misinterpret them as criticism. You are doing excellent work which I’m confident will be much appreciated by the papercrete community. You are obviously free to conduct your experiements in whatever manner you deem appropriate. I’m not trying to interfere. Feel free to use or ignore my comments at your discretion.

    Keep up the great work.

    (Primary moderator of the Papercreters Yahoo Group)

    • Dear Jay,
      Thank you for your helpful comments and forgive my late reply. I was really busy with a presentation that I didnt have any time to reply or upload new information in the blog. Presentation went good -I am graduating in a month- and now I have more free time.
      I believe tat the water problem is partially caused of the plastic forms, the different climate etc. but I believe the main problem is the process I use to make the paper pulp. (drill with x shaped head). Comparing to the normal concrete mix I use 10 times more water. Excess water afferct the strength of the mix.
      The problem with the pressed specimens is that that I have big deviations in the values and the increase in the properties is not that big. Today I will upload some results with different reinforcement ways.
      I would like to make more experiments but as I said its only a graduation project and it is about to end, that why I tried to make the most nessesery experiments. I would like to continue the research but finding funding is really difficult.
      Thank you again for you comments, please fell free to contact me again about the new posts.

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