We get asked questions all the time on building concrete quarterpipes, so here it is. A step by step on building a quarter on an existing concrete slab. We did this for a city project four year ago. I am sure there are better ways to do it, but this is what worked for us. In this situation, we hand stacked the concrete as opposed to using a pump.
Step 1: First we stacked the cinder blocks. As you notice in these photos the cinder blocks are offset and grouted. We ran rebar through the cinder block which are drilled into the concrete slab. The steel coping is welded to the rebar. On the far left side you will also notice the wooden tranny template we drilled into the concrete using Tapcon screws. Last but not least, we cut out a section of the existing concrete where the front of the quarter meets the slab. We went about 2 inches down and a foot across. This is to prevent chipping and make a smoother transition into the quarter.
Step 2: The next step was using fill. We used rocks, sand, dirt and whatever we could fill the sand bags with. Always make sure whatever you used as fill is properly compacted. After that we installed the rebar. We drilled holes in the ground, installed the rebar and bent the rebar 90 degrees to start forming the cage. We used 3/8″ rebar. Also notice how the side forms are built. All the side forms are secured to the ground with Tapcon screws. It is very important you have extra support when pouring concrete into a wooden form. You do not want a blow out.
Step 3: We truck poured the quarterpipe filling the forms and the cinder blocks. The next step is to vibrate the forms to eliminate voids in the concrete. We did this hammer using a hammer drill on a metal plate. Once the concrete is placed you want to begin screeding the concrete using the wooden transition forms and getting a level surface. In this situation, we used a 12′ 2×4 to from end to end working our way up the transition. After you have screeded the concrete the next step is to start scrubbing. This is the process of getting the rocks down and bringing up the cement. The process of scrubbing takes a lot of time and attention to detail. The only way you will get good at it is practice. We used a magnesium float for this process.
Step 4: The last step is to finish the concrete using a steel pool trowel. This is the process of ‘burning’ the concrete to get a smooth finish. You need to wait for the concrete to cure some before hitting it with a trowel. If the concrete is too wet you will have to wait before it gets hard enough to finish. If the concrete dries too quick it’s even worse and you can end up with a rough surface. If you are using steel coping like we are you want to make sure you have one guy dedicate to edging underneath the coping. It is very important that the area around the steel coping is edged on the deck and beneath the coping. This will prevent future chipping.
Step 5: Give the concrete a good 24hrs minimum to cure before you start to skate it. If the concrete is too green you can easily damage the concrete by skating it too soon. Give it some time, then it’s time to shred!!!