How To Build A Spray-In-Place Concrete Fence - Monolithic

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extremely valid measurement for concrete in the 5, 6 sack range with 3/4 or larger aggregate. Compressive Strength Tests Compressive strengths in the conventional concrete industries are performed by breaking cylinders that have been filled and set aside for that purpose. A good correlation between a series of cylinders is about 20%. Unfortunately shotcrete doesn’t test very well in cylinders unless they are special shotcrete cylinders which are hard to come by. The most valid system for testing shotcrete seems to be the Windsor probe or spraying a 2” thickness that is later cubed and tested. Cubed tests and Windsor Probe tests are generally quite comparable. The Windsor Probe is much easier as it is simply a matter of firing a bolt with a predetermined charge into the concrete and measure the depth of penetration. It is somewhat destructive in that there’s a small hole left with a bolt sticking out of it. Cubed tests are totally nondestructive unless they are taken as cores. The major problem with cubed tests is always the question -- was the concrete cured under exactly the same conditions that are in the facility itself. Concrete Thickness Every endeavor is made to make concrete the proper thickness. This thickness is gauged by the amount of embedment on the steel and by the experience of the nozzleman. It is further checked and corroborated by the calculations of the volumes needed for the project. In general, however, the thickness is less important than properly embedding all of the reinforcing steel. When 1/2 inch to 3/4 inch of concrete covers the rebar on both sides, it is thick enough. The MudSlinger GHP1500 concrete pump is an ideal size for building fences. This is a very simple pump and can be driven by running an air compressor. Safe Operations and Practices The use of appropriate safety equipment is required. This includes face shields, or safety goggles, respiratory protection (as needed) and waterproof gloves. Wet concrete will “burn” unprotected skin. Shoes should be water proof and provide physical protection to the wearer. The first layer of shotcrete should be about 1/2 to 3/4 of one inch. After it is set, a second coat can be applied to bury the rebar. 18
To Mix or Not to Mix The shotcrete is placed in layers. The first layer is left for several hours or overnight to gain strength. Then the second layer can be applied, then, of course, the third layer. By the time the second and third layers are in place the fence will be very strong. Do you want to use ready-mix or mix on-site? In order to use readymix you will need a larger pump and will want to have more of the fence formed. Mixing on-site has advantages, such as ease of pouring the fence posts and convenient scheduling. Obviously, if the job uses thousands of yards of concrete, a ready mix plant is the only way to go for ordering shotcrete. But for the small jobs using the small pumps, we suggest you consider mixing on site. Mixing on-site with small mixers must be well organized. The mixers can be a Porta-mix mounted on a skid loader, or a plaster mixer, or small line concrete mixer. The biggest advantage of on-site mixing is the ability to control the speed and delivery. There is nothing worse than waiting a few hours for the ready-mix truck and then immediately having a breakdown that prevents unloading it. Shown above the first layer of concrete is in place. There are places where some of the concrete sloughed off. These places will be easily filled in with the second layer of concrete. Shotcrete Mix Design Mix Design for 1/3 cubic yard Shotcrete mix design varies from job to job due to different types of materials and other conditions. However, following is a mix design that works well in most areas. Cement — 188 lb. Two sacks of standard Type I or II or I-II Portland cement. This is what the lumber yard will carry. It is not mortar mix. Water — about 80 lbs. (10 gallons.) Water must be clean (potable). 19
Page 1 and 2: How To Build A Spray-In-Place Concr
Page 3 and 4: Step 1 Design the Fence Layout Wher
Page 5 and 6: Well laid-out plan for a zigzag fen
Page 7 and 8: This particular fence starts with t
Page 9 and 10: Step 2 Install Fence Posts The next
Page 11 and 12: Place the forms vertical and two to
Page 13 and 14: (Above) Drill small holes above and
Page 15 and 16: Step 5 Applying the Shotcrete The n
Page 17: tor’s experience. Concrete Streng
Page 21 and 22: After the forms are removed spray a
Page 23 and 24: Final color coat sprayed is on the
Page 25 and 26: Appendix In the past 20+ years, we

How To Build A Spray-In-Place Concrete Fence - Monolithic

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