make Perlite Concrete Garden Boxes PART 3.5 – Lightweight Perlite with CSA and Portland Cement

make Perlite Concrete Garden Boxes PART 3.5 – Lightweight Perlite with CSA and Portland Cement

Hi it’s Kent from MAN about TOOLS and this
is a follow up video to Part 3 of my series of making garden box panels from lightweight
concrete. These reinforced concrete panels link together
to make long lasting rot proof garden boxes. In part three I experimented with some concrete
mixes looking for a good alternative to gravel-based concrete that was light and durable. In that part I looked at three blends. As that was more than enough to cover in one
video. The vermiculite blend was my favourite but,
I also wanted to try perlite as an aggregate. So that’s the focus of this video. And to also add some colour to the concrete. Perlite is a hard, highly porous material
made by super-heating volcanic glass. Some viewers thought that perlite would be
superior to vermiculite as perlite does not absorb as much water. I’ll show the mixing, pouring, and unmolding,
then look at the weight and durability results as compared to regular gravel-based concrete. If you haven’t seen part 1 or part 2 of this
series then you might get more from this video if you watch them first. Link in the upper right or the description
below. I’ll be using the forms I built in part 2
of the series. I have plans available on my website, I also have a full blog post for this video
with all the ingredients and ratios for the perlite mixes. There’s a lot to cover here so let’s get started. This lightweight concrete blend is made from
portland cement, perlite, and sand. To some of the batches I’ll add a small amount
of glass fibre for extra reinforcement. You add about one pound of this fiber per
cubic yard of concrete. So when I calculated how much I needed per
batch it came down to a third of an ounce per 48 inch panel. Here’s the proportions I used for the first
attempt at perlite concrete: one part portland cement, two parts perlite, and one part sand. These proportions are by volume. I didn’t realize how dusty the perlite would
be so I was glad I was working outside. A mask would have been better. And I did wear one later on. I add the perlite and sand to my wheelbarrow
first. And add a little water to wet the mix. Once it’s well blended, I add the Portland
cement. And continue to add water a little at a time. When I saw that the mix ratio was looking
good and the wet perlite concrete blended smoothly, I added half as much more of the
ingredients, in the same proportions, to increase the batch size so I’d have enough to fill
my 48 inch form. I add a few shovel fulls to the form and push
the perlite mix around the pipes with a small trowel. I used a reciprocating saw, without the blade,
to vibrate the form and settle the concrete mix. Then I laid in a section of reinforcing wire
mesh. This galvanized wire mesh is cut from a large
hog panel fence I bought from my local farm supply store. I used small bolt cutters to cut a piece of
this heavy 4 gauge panel to fit the form. Then I topped up the rest of this and vibrated
it some more. I use a trowel to smooth the surface. I liked the consistency of this first blend
so, I decided to make another batch with the same proportions as the first. But this time I’d add some glass fibre for
more reinforcement. Perlite is very light and it’s easy to mix
in a wheelbarrow. And for these tests I like this method as
I can really see how it’s blending. And how much water I need without over doing
it. This second batch went well. Like the first, half fill the form, vibrate
the mix to settle it and bring bubbles to the surface, add the wire grid, then top up,
settle, and finish with a trowel. And I’ll round off the sides when it sets
up. It was the end of the day so I covered the
forms with plastic and left them to harden. The next morning I set up to make two more
batches. This time in the 36 inch forms. This third batch used the same proportions
as the first two but, for this one I’ll add some red colour. I add two ounces to the mix in the wheelbarrow. And I’ll add some glass fibre again. I start as before, blending the perlite and
sand. I then dilute the red colour in water and
add it to the wheelbarrow. And wow, it was very red! Then I add some fibre. And finally the portland cement. There were a few chunks of portland so I broke
them up by hand. Now it’s a matter of slowly adding water for
just the right consistency. You can see the sheen of the vegetable oil
spray I use on the forms before filling them. Pam cooking spray works very well. I cover the wires that wrap around the pipes
to keep the oil off them while spraying. And like before, I filled the forms half away,
settled it a bit with the reciprocating saw, add the mesh, and then top it up. And smooth any bubbles with a trowel. The red colour looked to be pretty uniform
throughout the mix. I think the key is to add it to water first. And to add it early in the blending. I was getting a pretty good feeling that the
perlite blend would be a good lightweight alternative, similar to the vermiculite blend
from Part 3 of the series. So, for the 4th form I decided to change things
up with the proportions AND the type of cement. This blend then uses CSA cement, perlite,
sand, and glass fibre. And I’ll add some black colour this time. I didn’t have pure CSA cement but a mix called
Cement ALL. It already has some fine sand in the blend
so I modified my proportions to accommodate for that. The CSA based cement is stronger than portland
so I figured I could use more perlite because of that. And with the Cement All having sand in it
already, I reduced the amount of sand I would add to this blend. And hope that it would work. I used one part Cement ALL, 3 parts perlite,
half a part sand, a pinch of fibre, and two ounces of the liquid pigment. With a greater ratio of perlite, I found this
mix felt dryer and not as smooth and sticky like the previous three. Cement ALL is fast setting so I worked quickly. Blending the sand and perlite with water first,
then adding the Cement ALL and more water. It didn’t seem to settle as well with the
recip saw so, I also tapped the form with a wooden mallet. In about 45 minutes the CSA concrete was hardened,
warm to the touch, and a white haze was forming as it was drying. I cured it for one hour by sprinkling it with
water every 10 minutes or so. The next day I removed the form sides, and
ends, and these castings came out fairly easily. I first stripped the 48″ panels. Removing the screws and gently wiggling the
sides, then rocking the ends. Then tipping the panel up and prying off the
base with the help of a paint scraper. Both 48″ forms looked identical and time would
tell if the addition of the glass fibre would make any difference. Next, I stripped the 36″ red coloured panel. It too looked good and I didn’t see any issues. Right out of the form it kinda looks like
red clay brick. And finally ,I stripped the black dyed CSA
concrete panel. It felt harder and that’s to be expected as
it cures quicker than portland. To help all the panels cure to their maximum
strength, I completely submerged them in water in an old bathtub. After a few weeks I removed them to dry slowly
in my shop before weighing. Then I could test them for durability. As in Part 3 of this series I lined up panels
on the lawn and ran an edge trimmer against them. The line trimmer didn’t damage the perlite
concrete at all. Like the vermiculite, the perlite-based concrete
mixed easily and was noticeably lighter. And this made it easy to fill the forms. It settled well with vibration and has a smooth
texture while troweling and edging. It came out of the forms easily and has a
nice smooth finish. It passed the weed eater test so I think,
all in all, perlite concrete in these proportions makes a good lightweight alternative for these
garden panels. The panels weighed, on average, 34 percent
lighter than regular concrete. And this was a bit lighter than the similar
vermiculite panels from part three. The CSA perlite panel was 45 percent lighter. Since CSA concrete is stronger than Portland
I was able to use more perlite in the mix. The drawback is the CSA cement is more expensive
and sometimes harder to find. And, the portland ones appear to be strong
enough, and light enough. The colours worked well and blended evenly. I think I could have used less of the red
as it came out deeper than I expected. The black looks pretty good though and I’d
use that again. And maybe even more. I’m happy with perlite and it makes a light,
strong, and durable panel for these garden boxes. I wouldn’t hesitate putting them in my garden
if weight was an issue for me. So I hope that was helpful and interesting. If you have any questions then please add
them to the comment below. I try to answer as many as I can. Especially in the first week of posting a
video. If you like what you see here then please
give this video a thumbs up and subscribe if you haven’t already. In the next episode I’m going back to look
at aircrete. I’ve worked on some new blends and got really
good results. So that’s coming right up. This is Kent from MAN about TOOLS. Thank you for watching and we’ll see you soon.

Comments (51)

  1. Does the porous aggregate substitutions affect long term durability of seasonal freeze-thaw cycles?

  2. Terrific update! As a reinforced concrete special inspector, I appreciate your attention towards consolidation and curing. Can’t wait for the next update

  3. Perfectly!
    And what can you say about the two-layer block of foam concrete and the upper layer of more durable concrete for protection surface?

  4. Great video! Good job! 👍👍

  5. I don’t know what type of weight issues you would have using them but little advice never tell the customer you don’t use your own product and don’t put in their minds of any problems like as of weight. Maybe I’m wrong I don’t know. If I was an older person and if you said weight issue they might think they’re too heavy for me to work with you can always have somebody install them. I don’t know maybe I’m right maybe I’m wrong. ??? But they look nice and they come out good if I were to use something like that I would build them Myself but I don’t do raise garden. 👍

  6. Really good stuff! Very good video. One comment: I'd try to mix the color with most of the water you plan to use to get a most even color distribution. e.g.: If you expect to use 20L of water for a batch of concrete, I'd mix the required amount of color with 18L of water first, then mix that into the dry mix. Just a thought!

  7. Excellent video as always. I plan to build these using this perlite mix. Thank you.

  8. I plan to start building raised garden beds this winter and I really like your design! I had planned to get a small, electric concrete mixer and am now curious -May I ask why you mix everything in a wheelbarrow instead of a concrete mixer?

  9. Brilliant! Ty for the research. Presented so well. I didn't have much luck with aircrete, so I'm interested in your findings.

  10. great video, at 71 I have made 36 4 ft panels with concrete they are heavy, how do the light ones compare in over all durability.

  11. Love you attention to detail. Any destructive tests for strength?

  12. thanks for sharing the updates looking forward to more.

  13. Thanks for using my suggestion about using perlite

  14. These are really cool.

  15. I'm considering a garden on the top of shipping container. The load bearing is on the rim only.
    So reducing the weight on the center of container is very important .
    I don't want to build a new roof at the same time don't want to collapse the center.
    A waterproof membrane will go on 1st. So no contact between concrete and steel . Then beds and light weight soil blend. Around the rim with a center walk . Also a safety fence/ trellis around the outside rim. The center walk will have a trellis coverage.
    We are near the coast of NC with zone 8 hot dry summers it is very important that the inside of the container stay cool.
    The sides will be covered with vines/ tall sunflowers
    As shade.
    Any ideas?

  16. Awesome video! I look forward to your Aircrete video.

  17. Always enjoy these videos!

  18. I was amazed with part 1 it just keeps getting better and better 🐓

  19. A great replacement for aggregate are fired clay pebbles or "hydroton" with is commonly used in hydroponic growing and is becoming a mainstay in the construction industry due to is non compacting nature along with light weight and strength

    Keep up the good work

  20. The red is my favorite! And I don’t normally prefer red bricks but this was a much lighter Adobe like appearance… stunning! Now I’d like to see lime without cement in your forms🤞🏼Lime floors are finally getting some acknowledgement as truly environmentally friendly, and can be reused unlike concrete/cement or today’s versions of an old traditional version of Rome’s concrete formerly known as Lime concrete. Besides the fact Lime gets stronger with time and moisture it’s also cooler to the touch when the sun has been bearing down on it making it perfect to be poured around pools and as back door patios. I’m curious if Lime has to be slaked at home “quicklime” or if hydrated or hydraulic lime (box store version) would function just as well? I’ve read arguments both supporting hydraulic lime and arguments that it needs to be freshly slaked… I have no idea, nor do I know what formula would make a strong block or brick for paving with hydraulic or hydrated lime. Yes ppl sometimes mix in cement/concrete but that ruins the water permeable/breathability nature of LimeCrete so I’d hate to use modern cement with lime. Seeing perlite used in this demonstration reminds me of a demonstration using powdered lime with volcanic ash as aggregate but also sand and pebbles may be necessary to make a brick/block. Anyways curious, hoping someone will take on the lime brick challenge, it’s not very popular because it’s not well known of its amazing properties and the fact that it is environmentally safe, reusable, etc. and grows in strength for 100’s and thousands of years.

  21. Where do you source your perlite?


  22. so professional! I am simply impressed!

    And yeah: I crave the new aircrete-receipts, as I was in fear, you dropped this completely, as you could not like the warping in the older samples.


  23. A plasticizer would help with the workablity and mixing of the CSA mix.

  24. Have you thought about testing any stains, patterns, etc?

  25. You talk about a mask and don't use one.
    As an old man, (I'll tell you now).
    In about 4 to five years from now, you will most likely be on oxygen (and) or have COPD.

  26. Do you think this moulding process would be ok to border/retain a pathway running across a slope? Maybe to a max. Height of 18 inches exposed, maybe 2 foot overall deep? I was intending to form up, but this method maybe less work and do the trick?

  27. If you were going to sell a set of these, how much do you think they would sell for on places like Marketplace and CL?

  28. Please tell me about your experience after using all of these panels
    Which combination would you recommend to everyone considering all it’s aspects
    Makings expense, strength , expected life & easy process
    Thank you

  29. I like that red color it does look like that red brick give me ideas I can make my own bricks like that

  30. Excellent video and super useful project

  31. Perhaps Black Blasting Sand could make the black panels blacker. The sand is black, as the name says. Usually found at home improvement stores.

  32. Oh boy! Kent's at it again. Yeah, glad you did this, well done.

  33. Looking forward to seeing your aircrete tests …Thanks Mike

  34. I fell in love with linseedoil decades ago and resently cooked linseedoil. It is very cheap to get 1kg bags of ironpigment here in Austria, dont know how it is in your area? On the other hand there is supposed to have strange reactions of iron and csa … and if you throw "loads" of read colour in the mixture, it is not unlikely ironpigment.

    So if you dunk or spray your panels (after totaly drying!) in cooked linseed oil (and if you want the colour, adding this ironpigment), you would even maybe have a good protection of the concrete against any water or acids from f.e. a compost …. ? What you think about that?
    The linseed-oil never dries but has some interesting polymerisation-reaction with the oxygen n the air – but this takes many days. On the other hand you could pour the linseed-ironoxide-mixture (Norwegians red houses) over your salad and it would have maybe some health benefits 😉 – not that somebody should do so, but if you spill something in nature, it will be compleetely harmless. And it lasts for decades on f.e. would, as it does not peel of and let's the would breathe in some way.

    In Germany in church- and castels renovation it is now – for goods sake – forbidden to use any other colour than linseed oil, as all the other new plastic-colour-stuff destroyed old wood tht lasted for centuries in just a few years.

    By the way: When painting smooth surface Iron with this mixture I experienced, that the colour disapeares completely after just half an hour, but comes back if you touch or brush it again just after some time before it gets stiffer, so that you still get a nice dark-red colour, that does not annoy in the garden. When mixing in the ironoxide, just take a few of the oil first, rub a paste and than gradually put in the ret of the oil. This is like they did it for centuries. This and the special recipes in the lime mortar-mixtures where passed on inside mason families from generation to generation as secrets.

    Sorry for my bad English and the long text, but maybe you have a minute to answer, as I would like to know, what you think about my lines here?

  35. Hi. Your videos, as usual, are a great source of inspiration. I'm placing this aside as I will definitely build some of these for my garden following your guidance. Thank you so much!

  36. Thanks for all your diligence and hard work on this series Kent. I love it!

  37. Are your panels 1 1/2” thick?

  38. Only thing missing is costs. If you're counting pennies which blend?

  39. Love the pannels & plans. Please help me modify the plans to allow the panels to be mounted at angles other than 90 Deg, like 45 & 60 Deg angles.

  40. I wonder how well something like this would work for making your own drive way blocks. I wonder how thick they would need to be.

  41. Very nice project. As a perlite manufacturer, I greatly appreciate it. This could be an excellent business opportunity for someone. If anyone was wondering about other mix ratios and strength ratings here a link to two brochures that has many details.

  42. how about 'hybrid/laminated' panels? do the outer section of the panel (first half-fill) with standard or light mix and inner with aircrete. you should have significant weight reduction as well as front hard face to stand up to the edger?

  43. Love from Algeria sorry for my english , Hope a panel as Hardy … For build house thks

  44. Hey Kent! How are you?

  45. Interesting. Thank you.

  46. Great job, thank you sir.

  47. An excellent presentation 👍😎🇦🇺🌏

  48. Have you looked into aircrete?
    Honey do carpenter has some good videos on aircrete.

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