My Messy Adventure with Amazonian Concrete
Alright, so I got totally sucked into this idea of making my own “Amazonian” concrete mix. You know, the stuff they talk about online for being super tough? Sounded perfect for fixing my crumbling garden shed base. Honestly, I just wanted to see if it was actually faster or better like some folks claim.
First step was actually getting the stuff. I drove out to the big building supply place downtown. Took me longer than expected because, surprise surprise, the specific volcanic ash some guides mentioned? Yeah, no luck. Zero. Nada. The guy just shrugged at me. So, I grabbed some standard Portland cement, the roughest construction sand I could find in their yard, and a bag of extra gravel – figured more rock couldn’t hurt for “Amazonian” toughness. Also snagged some plasticiser because folks said it helps it flow better when wet.
Got back home, dust flying everywhere from the sand in my truck bed. Mixing day was… a workout. I used my beat-up old wheelbarrow. Started eyeballing ratios – honestly, most guides were vague. Poured in like 3 parts sand to 1 part cement, threw in maybe 4 parts gravel? Then slowly added water and that plasticiser goo while my neighbor Bill stirred. It looked nothing like the pictures online. Kinda lumpy and way stiffer. Added more water. Then it got way too wet! Added a bit more cement. Kept staring at it thinking, “Is this right?” It was like trying to make some weird, gluey concrete soup.
I finally just decided to dump it into the forms I’d set up for the shed base patch. Shoveled it in, trying to poke out air bubbles with a stick. The mix felt super thick and heavy. Like, my arms were shaking trying to smooth the top roughly with a board. It definitely didn’t pour easily like the nice stuff I see pros use. By the end, I was sweaty, covered in grey splotches, and honestly questioning my life choices.
And then… the waiting game started. The big question: How Long Until It’s Solid? Online forums and videos gave me wildly different answers. Some guys swore you could walk on it in 24 hours. Others said to wait 48 hours minimum before even touching it. One dude on a blog talked about waiting a full week for “Amazonian” strength.
My own experience? I poked it cautiously at 24 hours. It was definitely hard on top, like a crust, but pressing my finger in near the edge left a tiny dent. No way I was putting weight on it. Felt too risky. At 48 hours, the dent was way smaller, almost gone. I gently tapped it with a hammer handle – it made a dull thonk, not the sharp crack of totally soft concrete. I decided to rip off the wooden forms carefully. The sides looked okay, kinda rough but holding together. The edges felt strong.
I finally braved standing on it around the 72-hour mark. Three whole days! I stood on the edge, ready to leap off. It held! Solid. No cracks, no movement. But I still didn’t trust it fully. I waited a full 7 days before putting the shed corner back down onto it. And even then, I put the lightest corner on first. Now, months later, it’s solid as anything. Did it actually set faster than normal concrete? Honestly? Not really. The guys who say 24 hours? Maybe with perfect lab conditions, super precise mix, and magic vibes. In my messy backyard reality with my guesstimate mix? Forget it. Plan for at least 2-3 days before it handles weight, and honestly give it a full week for your mind to relax. The promise of “super-fast setting” didn’t really pan out for my backyard trial.
Why do I know this mix is such a pain? Because my brother tried using it last year for a stupid little patio extension and his contractor totally screwed him over. Promised the moon – “fast-drying,” “stronger than regular,” “easy peasy.” Total garbage. The guy showed up late, mixed the stuff even worse than I did – looked like mud pies. Then he demanded payment upfront before it was even set hard! My brother, being too trusting, paid. Big mistake. Three days later, the stupid patio was still soft enough to leave footprints in one spot, and the contractor just ghosted him. Phone disconnected, fake address given, the whole thing. Left my brother holding the bag, literally stuck with this weird, half-set, lumpy concrete mess. Took weeks to hire someone else to rip it out and start fresh. Never trust a contractor pushing mysterious special mixes too hard, especially if they start demanding cash under the table. Those guys turn into jerks real quick once they get paid.