The Pros and Cons of Shotcrete

Part of being a skilled concrete contractor is knowing all the different types of applications for concrete and the different kinds of concrete itself. This helps your business in a few notable ways. For one thing, the more options you can offer, the more clients you can service. In addition, the more expertise that you have, the better the suggestions that you can make for clients. Shotcrete, compared to say, recycled concrete or limecrete, is more about the process than the material.

What Is Shotcrete?

The start of the process eventually led to shotcrete started in taxidermy, where a professor sprayed plaster on a wireframe for taxidermy purposes. The dry material was pushed through a nozzle, so it got wet as it flew onto the frame, creating a thick and robust coating that stayed set. The tech then was applied to worn concrete as gunite, before changing to shotcrete after pressure tanks were used to force mortar through a hose.

So, moving away from the history lesson, what exactly is shotcrete? Essentially, shotcrete uses concrete or mortar propelled at high velocity onto a surface for construction. Two main processes apply to shotcrete: the wet and dry process.

Dry shotcrete involves putting in materials (pre-blended or semi-dampened) into a delivery hose. Compressed air forces the material to the nozzle where water comes in. The material is then sprayed onto the surface from the hose, where it creates the final shotcrete. The main benefits of taking this route are that it is easy to set up and full control of the materials on site. You can also reach distances of up to 1000 feet horizontally, adding additional versatility.

The other option on hand is the wet shotcrete process. This entails first properly mixing all ingredients, water included, into the equipment. The material is then pumped to the nozzle, and compressed air is introduced there. This creates placing at a high velocity on the planned surface. You see this technique is commonly applied to ready-made concrete. This generally requires minimal formwork and is more cost-effective. If you are working on an irregular surface, the wet process is preferred as well.

Standard Applications of Shotcrete

  • -Bridge restoration
  • -Dams
  • -Sewers
  • -Marine structures
  • -Mining
  • -Tunneling
  • -Architectural landscaping
  • -Ground stabilization
  • -Foundation
  • -Tanks 
  • -Domes

A lot of this is due to some of the unique traits that shotcrete has that make it far easier to implement the conventional pour-and-fill strategy.

Photo By Vadim Ratnikov

Benefits And Drawbacks

So, what are some of the benefits of using shotcrete over conventional concrete options? Here’s a look at some of the key benefits:

Speed of application:

Whether you go with a dry or wet process, shotcrete dramatically cuts down on the amount of time you would otherwise spend building and keeping up traditional concrete forms. Something else that doesn’t get discussed enough is that those same forms also consume many wood and other materials. In that regard, you could consider shotcrete an eco-friendly take on concrete. Even after you apply the shotcrete, you’ll also reach your next objectives quicker, including achieving structural levels of strength.

Reaching difficult areas:

Moving concrete equipment to certain areas can be difficult, but shotcrete avoids the problem altogether. You don’t need to move equipment right next to the pour site, as a skilled professional can place concrete up to hundreds of feet away from the source of the materials. This includes both underground and overhead.

Reduced costs:

Of course, many people wonder about the bottom line when it comes to shotcrete. While there are some added considerations we will discuss in a moment, going for shotcrete can save you money in a few notable ways. For example, buying a combination mixer/pump can greatly reduce your equipment costs in terms of concrete. This applies both to the initial equipment purchase costs and upkeep since you are only working on one piece of equipment rather than two. This saves on labor costs since you can set things up faster and not need as many people to operate the machine. 

With this said, there are some drawbacks to using shotcrete as well. For example, while you may save money in terms of labor and equipment, you’re probably going to pay more regarding production costs for the shotcrete materials. As a result, any contractor thinking of implementing shotcrete needs a holistic look at all the different associated costs to make sure it’s still a financial fit for their needs. There are also concerns about dust and concrete wastage when using shotcrete compared to some more precise methods. In addition, aesthetically, it’s hard for shotcrete to match some of the other options out there. Compared to gunite, you also need to apply it right away, not starting and stopping.

Photo By Andy Dean Photography

Implementing shotcrete construction can sound like an appealing idea for concrete contractors. After all, you get a new method appealing to certain clients and could mean more profit for you. However, integrating any new practice into your business comes with an opportunity cost. As far as shotcrete cost goes, this means the time cost of onboarding your team to use it properly and potentially to buy new materials and equipment to provide this service. 

This puts concrete contractors in a bit of a bind. Is it worth it for their business to take this on? To figure this out, you need to use project management software like eSub. The ability to compare bids with actuals is essential to make sure that you fully understand the cost of this new option. In addition, added efficiency measures like tracking employees and equipment will help you avoid wasted money or time on your shotcrete jobs.

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