The Shotcrete : Properties , Types ,Procedure , Uses , Advantages and Disadvantages


 In this 21st Century on the Planet Earth every Human Being is Running Over the Shortcuts and Everybody wants to complete their work or anything else as Early as Possible and the most of it is a True thing to be done to Survive in this New World and Similarly in the Field of Construction and Engineering the Developers and Researchers are moving Along to Discover a New Type of Concrete Every Day and Shotcrete is one of the Development and Improved Version of Concrete when we are in Hurry of Completing the Concreting.

These days at the place where our cranes , human crew and Lifts are not able to access , the Shotcrete is used and Shotcrete is nothing but a finest Form of concrete and we know that during concreting these tasks are done - Batching , mixing , transporting , placing , compacting , finishing and curing , But in the case of shotcrete these 3 steps ( placing , compacting as well as finishing ) are done at the same time which is the most important difference between normal concrete and a shotcrete. Today in this Article we will discuss about the various things Related to Shotcrete as well as we will discuss some important points such as its Types , Uses , Benefits , Shortcomings , Applications based on Shotcrete.

What are the Properties of Shotcrete ?

The Shotcrete is sometimes also called as Blastcrete , Blowcrete , Guncrete and jetcete and more of that are their in different countries . Their are a Lot of Properties Shotcrete which are Enlisted as Follows :

  1. Aggregate Size - Maximum Small
  2. Cement Content - High than Conventional
  3. Air Voids - Lesser than Normal Concrete 
  4. Bond Between Steel Bar and Concrete - Strong
  5. Water to Cement ratio - More

What Equipment are used in Shotcrete ?

Their are Various Equipment being used in Shotcrete and which differs according to the method we are using to apply the Shotcrete , For example the Shotcrete can be done both manpower as well as machinery , The Manpower Method comes under Semi Machinery Method . So the Equipment used are Presented in the List Below :

  • Spraying Arm
  • Concrete Pump
  • Robust Chassis ( for Underground Shotcrete )
  • Control System
  • Additive Pump ( for Hardening Admixture dose )
  • On Board Compressor

What are the Types of Shotcrete ?

Mainly their are no Type of Shotcrete , as Discussed in the Properties of Shotcrete , Every time during the Batching of shotcrete the same Material is used and only quantity of that materials differs accordingly as well as the Difference between Types of Concrete is Sometime Variable due to the Place of Application such as Tunnels , Underground , Retaining Walls and more of that , Sometimes it also Depends on the Formwork and Reinforcement as well as the Surface on which we are Applying the Shotcrete. So, The Types of Shotcrete are :

  1. Dry Mix Shotcrete ( In case of Lightweight Concrete )
  2. Wet Mix Shotcrete ( In Dry Conditions and where we want more Slump )
  3. Air Entrained Shotcrete ( If the Surface of Application is Permeable to Water )
  4. Steel Fibrous Shotcrete ( To Improve Ductility )
  5. Refractory Shotcrete ( To use at High Temperature )

How the Batching of Shotcrete is Done ?

During the Batching of Shotcrete we are having two Options with us whether to make it in Pug Mill or Order it from Some Nearby Renowned Concrete Batching Plant and In the Case of On site Batching to make Shotcrete use the Following Composition :

  • One Part to Cement
  • Four Parts of Aggregates ( Fine + Small Coarse )
  • Water - 7% and Vary According to Site Conditions
  • Admixtures - Rapid Hardening Admixture
  • Superplasticizer - According to Need
  • Crushed Ice - According to Temperature

How to Prepare the Surface Before Shotcrete ?

Before Starting to Apply the Shotcrete Some of things are Important to Keep in Mind . The Shotcrete is Applied in Various Construction Projects such as Dams , Retaining Walls , Tunnels , Plaster So, Before Anything you have to Prepare the Surface on which the shotcrete has to apply as well as Make sure About the Following Terms :

  • Do Not Apply Shotcrete on a Frozen Surface 
  • If Shotcrete is going to apply on rocky surface make sure to clean all the mud
  • The Surface should be Compacted and Trimmed in a Proper Line
  • Chipping should be Done to Remove the Undulations
  • All the Edges of the Surface should be Tapered
  • Sand Blasting is Essential ** If Not banned in your Country
  • Clean the Surface with Air Water Jet Before Application of Shotcrete.

What is Procedure for Applying the Shotcrete ?

Their are Multiple Procedures in case of Shotcrete According to the Method and Type of Shotcrete . But in the Following Lines we are Going to Discuss the Normal Shotcrete Procedure as follows :

  1. First of All Prepare the Surface on which shotcrete has to be applied according to the Instructions Given in the Above Paragraph as well as Make Sure that the Surface is Neat and Clean and Free of Undulation and In the Proper Line .
  2. The Second task that needed to be done is the Preparation of the Form work , Normally In the case of Shotcrete Wooden Formwork is used and In this Formwork Make Sure All the Dimensions and the Most Important Thickness is True as well as Check the Formwork from and  Leakage , If any Leakage is there than Apply a Part Foam there.
  3. The Third Step in this Procedure is the Placement of Reinforcement or Steel Bar Mesh Inside the Formwork with the Help of Crane But Before that Check the Reinforcement Completely by Checking that all the Bars are Tied Properly as well Check for the Spacing and the Cover Blocks if Needed .
  4. The Fourth Step is the Important One it is Essential to do Perfectly Because if the Reinforcement is not Perfect we can Re-Install that and If the Formwork is Disturbed we can Balance done but if the Shotcrete is Incorrect then the Project may Fail So Before Application of Shotcrete Check the Flow of it as well as the Temperature .Now Start Applying the Shotcrete in Thin Layers so that as sudden Bulging is not there .
  5. The Final Step is to Check Whether Final Finishing is Needed or Not . In some cases Finishing is Automatically done by Shotcrete Gun But Sometimes you have to Do that But make sure that the whole layer of shotcrete is settled and their is no chances of fall. 

What are the Uses of Shotcrete ?

Their are a Lot of Uses or Applications of Shotcrete in the Modern World which are enlisted as Below :

  • It is used in Canal Lining
  • It is used for Fast Plastering of walls
  • It is used in Retaining walls where the access for manpower in not there
  • It is used in Tunnels
  • It is used in Underground Structures
  • It is used in the Construction of Swimming Pools and Pounds
  • It is used in Artificial Rock Layering

What are the Advantages of Shotcrete ?

The Benefits of Shotcrete is Discussed as Follows :

  • Very Less Manpower is Needed 
  • It Saves a Lot of Time
  • It is Economic
  • Concreting is Now Possible with shotcrete in such areas where human cannot go 
  • The Repair of Layer is Easy
  • The Water Cement Ratio can be Controlled Easily
  • It is Resistant to Weather and Chemicals
  • It Turns Up High Compressive Strength
  • The 28 Days Strength can be Achieved Early
  • It is Less Permeable than Conventional Concrete
  • No Extra Compaction and Vibration Equipment are Needed
  • Bond Strength Between Steel Bar and Shotcrete is Stronger than Normal Concrete
  • Less Form Work is needed

What are the Disadvantages of Shotcrete ?

As we know that If their are Benefits of Something their are some Consequences of the same and the Shortcomings of Shotcrete is as Follows :

  • High Amount of Electricity is Needed to Create such a Large Pressure 
  • It Consumes High Amount of Cement
  • Their is Big Problem with Dusting
  • During Second Layer some Concrete is Wasted in the Process of Rebounding
  • A Smooth Finish can't be Expected using Shotcrete
  • A Skilled Manpower is needed
Now , I think each Term Related to Shotcrete has been Discussed , If you have any doubt in Any Section then you can Contact us through the Comment Section or Simply Fill the Contact Form.

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