Placing the Rip-Rap

Over my career, I helped place thousands of square yards of poured in place concrete rip-rap on header banks, and other slopes. You've seen them; concrete on the slopes around the sides of overpass slopes. They keep the soil in place, which prevents the earth from washing away. 

After the slope was graded, we'd place forms, which consisted of 2 x 4's turned flat, so some wet concrete could spill under the forms. The forms were set about 10 feet apart, and the same amount of space was between each set of forms. This allowed the sections to be finished by finishers on each side. Multiple sections would be poured during the day. If the concrete set enough, the forms were stripped, and the sections in between would be poured. We called it "checkerboarding". After all the concrete was poured, the rip-rap would extend from the abutment to the toe of the slope.

At the bottom of the slope, a toe-wall was hand dug to keep the rip-rap from sliding. At set locations up the slope, trenches were excavated by hand, loose gravel was placed, and PVC pipes were placed with screen on the backside to keep the rock from leaving. These "weeps" allowed ground water under the concrete to drain, and keep the slope from failing.

We always poured from the top to the bottom. The concrete was batched very dry, and little water was ever added. Gravity helped with placing the concrete, and the excess concrete screeded wouldn't pile in front of the screed, which would usually cause the screeded concrete to slide down the slope. Pouring from the bottom to the top could be done, but the work was much harder, and having a section of fresh screeded concrete slide down the slope was the usual result. 

Finishing didn't require the most beautiful of concrete. Finishers (which I was during a pour) used wood hand floats and knee boards made from plywood with multiple nails driven through to keep the finisher from sliding down the slope. A rudimentary handle was made with pieces of 2x4 ripped down the middle. With the pours only 10 feet wide, finishers on each side could finish half without having to creep across the entire width on knee boards. 

Finishing required most all motions to be uphill. The wood floats worked up enough grout to leave a mostly smooth surface. A finishing broom dragged across the wet concrete was the final finish. Trying to finish with a magnesium, or steel, hand float caused the concrete to slump, and slide downhill. 

After the concrete was finished, we sprayed curing compound on it, and either called it a day, or moved on to another section. 

The work was hard. With many of the sections, the slope was a one-to-one slope, and spending a day working on the slope would separate the men from the boys. Those that stayed learned something useful, but I never found anyone that relished the task. If you stayed long enough, and learned all there was to learn, you moved from working in front of the screed to finishing. It didn't take me long to know that's were I wanted to be, even though it was just as hard to finish. The more I learned, the more valuable my knowledge became, and eventually I was entrusted with making it happen by pushing a crew.

Could I still do it? No, but I could teach someone, if they were willing to work hard.