Mix Design Tips- Shotcrete

Shotcrete, is the process of pneumatically placed concrete. It is one of the material and an application. Here, the requirements for shotcrete materials are mainly based on the chemical and physical properties. The following materials are used in the Shotcrete

• Portland Cement -> Type I, Type II and Type III.
Cement is exhibit a tendency towards flash setting to be avoided and it is supported by different exposure requirements and strengths.

• Aggregate
The Aggregate gravity should not less than 2.50. It is the best security procedure to screen all used particles. In Coarser Sand is used to increase the re bound and reduce the particle over sizes. Aggregate should be hard and sound.

• Water
Clean Water depending upon the Short Crete mixing.

• Reinforcing Steel
This is applicable requirements of section 03 20 00 concrete reinforcing.

• Admixtures
It is specifically helpful for Shotcrete work. There are four types available such as Set Controllers, Air-Entraining Agents, Mineral Admixtures and Water Reducer.
Water reducing properties are mainly used for the improvements in strength and cohesiveness.

It consist of two mixing process,
1. Dry-Mix Process
2. Wet-Mix Process

The mix process contains a 70 percent aggregate and sand and 30 percent cement material. The Dry mix proportions that will best suited ranges of 1 part cement to 3 to 4 ½ parts sand. The sand dump in the dry mix should be damped and the nozzle man has a critical time managing acceptable slump and uniformity of the shotcrete in place. Test panel used to determining the physical properties like water tightness, shrinkage and strength. The sand particles must be coating with cement. The Wet-Mix process permits best control and more accurate than the dry –mix. Four types of admixtures can be used and mix proportion is same as to the dry mix. The slump is normal use in the range from 0 to 4 inches and proper control of water mixing.

Tagged as: Coarser Sand, Mineral Admixtures, Portland Cement, Reinforcing steel