Frequently Asked Questions

There are numerous advantages to using the shotcrete process. The economical sustainability of shotcrete include material, labor, and time savings as well as improved quality. On top of the following "top ten" sustainability advantages of shotcrete, the American Shotcrete Association's Sustainability's page offers the following:

• Formwork savings of 50-100% over conventional cast-in-place construction
• Formwork does not have designed for internal pressures
• Complex shapes require very little, if any, formwork
• Crane and other equipment savings elimination
• Labor savings of at least 50% in repair applications
• New construction speed savings of 33-50%
• Speed of repair reduces or eliminates downtime
• Better bonding to the substrate, which enhances durability
• Adaptability to repair surfaces that are not cost-effective with other processes
• Ability to access restricted space and difficult-to-reach areas, including overhead and underground

Although both wet and dry shotcrete have specific benefits, advancements in both equipment and material have made the applications almost interchangeable. In most applications, the preferred method is determined by:

• Economics
• Availability of material and equipment
• Site access
• The expertise and preference of the contractor

In most concrete, aggregates are generally inert. However, some aggregates react with the alkali hydroxides in concrete. This reaction causes expansion and cracking over a period of many years. This alkali-aggregate reaction has two forms: alkali-silica reaction (ASR) and alkali-carbonate reaction (ACR).

Alkali-silica reaction (ASR) is more serious because aggregates containing reactive silica materials are far more common. Typically, indicators of ASR are random map cracking. However, in advanced cases, you will experience closed joints and attendance spalled concrete.