If there’s one skill you need to know to build a pedestrian bridge in Nicaragua, it’s mixing concrete by hand. It takes literally thousands upon thousands of pounds of concrete and mortar to hold the tiers, towers and anchors of the bridge together, and there’s no way we could get a cement truck to site to mix it for us. That means it’s all volcano method, all day, every day!
So to give ourselves a little primer for what is soon to come, Continental Crossings held a concrete mixing workshop at the Iowa City Ready Mix plant just south of Iowa City. Manager Duane Tack was a fantastic help. He provided all the tools and donated all the materials as well as his own personal time. Not to mention, the sweet shirts he decked us out in!
In case you haven’t been exposed to the “volcano method” before, which I hope you haven’t, here’s a rundown of what it is. That way when we complain about how often we have to do it in our updates from Nicaragua, you’ll know exactly what we’re talking about.
[tabtext]Step 1[/tabtext][tabtext]Step 2[/tabtext][tabtext]Step 3[/tabtext][tabtext]Step 4[/tabtext][tabtext]Step 5[/tabtext][tabtext]Step 6[/tabtext]
Measure out all your dry materials (sand, gravel, cement) using a uniform measuring device. 5-gallon buckets are perfect.
Pour it all together into one pile. Mix all the dry ingredients together by working your way around the perimeter and scooping from the edges back up to the top of the pile.
Then “send” the pile. This means moving it all from one location to another to make sure you get the stuff under the bottom of the pile that might have been missed.
Once all the dry ingredients are thoroughly mixed, form it back into a nice pile and then make a crater in the top like a volcano. Pour water into the crater.
Repeat the same mixing process as before until a uniform mix is achieved. We also took some samples that we will test later to see how strong our concrete is.
Make sure to clean all the tools off so the concrete doesn’t dry on them and make them weight 50 pounds. Then you’re done!