Published by Hemant in Industrial Flooring · 10 November 2022
Tags: fm2flooring, warehouse, flooring, laser, flooring, laser, screed
Tags: fm2flooring, warehouse, flooring, laser, flooring, laser, screed
Industrial Flooring Guidelines for a New Concrete Flooring
Namaste & Ram Ram
Dear Reader this article has been written for the end users, who would like to cut through the jargons of latest methods in industrial flooring using Laser Screeds and FM2 Terminologies.
The 10 minutes needed to read this article will help you be prepare for your next meeting with a flooring contractor or a flooring consultant.
I have tried to make it as simple as possible to help you get the basics clear in the field of Industrial Floorings.
First lets understand what type of load stresses a warehouse floor is exposed to !
As an industrial floor has to face multiple types of loading , an awareness of following factors is important when executing an industrial flooring project.
A Concrete Slab has to effectively face the following during its service life
- External actions – loads, static, dynamic.
- Thermal and Shrinkage
Sub-Base Preparation for an Industrial / Warehouse Flooring
Subgrade - structural integrity is of vital importance to the long-term bearing capacity and serviceability of the floor
- The sub-base should be a compacted soil surface that has been a vibro-roller compacted surface.
- Proctor Density Test be performed to check the quality of soil to check for performance of the subgrade to avoid any future settlement issues due to plasticity of soil. A compaction of 95% of expansive soil is to be achieved.
- Care to be taken with soil compaction that no abnormal shrinkage and swelling there to disallow non-uniform base. For soft spots granular material or GSB is used to prepare a stable surface.
- A sub-grade finalized with two layers of compacted 75mm GSB - Graded Stone base is suggested.
- A plate load test is recommended to be carried out to check for any variation in load bearing capacity of the subgrade.
A typical finalized Sub-base with GSB/WMM using grader to finalize levelness
Why is PCC not a suitable sub-base for the main floor ?
- PCC is a non reinforced, brittle srata with low grades of compressive strength between M-10 to M-15 and very less flexural strength!
- This reduces PCC’s performance to transfer loads and it cracks, directly transferring those cracks to the main floor / grade slab
- PCC has an uneven level profile with variance of level going between 20 to 45 mm or even more leading to further reduction in load transfer performance of the main floor to sub-base thus creating chances for cracks and long term performance issues.
A well Compacted soil and Sub-base with GSB/WMM compacted and dressing within a tolerance of +/- 5 to 10mm is the best performing sub-base for modern industrial grade slabs.
Why Use Slip Membrane.?
- Application of a high tensile plastic sheet that is tear resistant allows the floor to move easily for its shrinkage stress release.
- Low quality sheets degrade over time and affect the performance of slab movement in future.
- Also the sheet layer has to withstand Transit Mixer movement and minimize tear occurrences.
Thickness of Grade Slab ?
A minimum thickness of 150mm has to be maintained for a light to medium duty industrial floor. More thickness of 175-200mm or more is recommended for a long service life of the floor based on usages and future heavier duty uses.
Flatness & Levelness Selection , FM2 or regular flooring ?
- If the storage height on the floor goes above 10-12 meters and regular material shifting happens by MHE, a flooring of FM2 level is recommended.
- Using modern automated Laser Guided Flooring systems high quality of tolerances are achievable.
- FM2 criteria is nowadays considered with certifications for high stacking/storage warehouse use floors.
- Areas where the floor is used for robotic movement can go for FM1 or Superflat flooring specifications or DM category for very high MHE movement areas.
“The figure on right shows the effect of unevenness for high storage / racking material movement while picking material from high storage.” >>>
Use of Steel / Macro fibers instead of Regular Steel Reinforcement
- Steel Fibre Reinforced Concrete (SFRC) is a concrete that has a homogenous distribution of randomly oriented discontinuous steel fibers. Steel fibers are introduced in the concrete mix during the mixing of concrete.
- Main benefit is that Steel fibers add ductility to an otherwise brittle concrete and this reduces crack development in the slab
- As the concrete cracks, the fibers transfer tension across the crack, bridging it and thereby guaranteeing a post crack load carrying capacity.
- Steel Fibers Reinforcement allows redcues steel rebar installation time along with allowing placement of Larger Grade Slabs in a Single Go. This helps with the tigh timelines generally associated with the flooring projects.
Aso the regular steel rebar is laid with spacers, but practically in large flooring sites, these spacers will not stay as intended and the profile of the rebar in grade slab does not set as expected. Thus leading to ineffective performance of reinforcement.
- Increase concrete toughness
- Post crack flexural strength
- Resistance to chipping and spalling
- Impact resistance
- Resist crack propagation
- Shear strength
- Energy Propogation
- Fatigue resistance
- Recommended Dosage for a medium duty flooring would be 15 to 20 Kg of steel fiber per cum of concrete. Higher Dosages of Steel Fiber as per design allows bigger saw cut joint sizes increasinig the service life of the floor.
- For creating jointless panels a dosage of Steel Fiber can be planned of even up-to 35-40 kg per cum saw cut joints are minimal and a seamless flooring can be attained.
Regular Reinforcement With 20Kg SF With 30 Kg SF.
Above figures denote how steel fibers can help reduce the number of saw cut joints as compared to a regular rebar reinforced grade slab. This is also advantageous when the floor has to be upgraded to synthetic toppings in future like Epoxy or PU floorings.
Other Important Factors to consider - Panel JointsLoad Transfer Mechanism / Options for Panel Joints
Use of Dowel Plates for Panel Joints / Day Joint for Load Transfer. The placement of the Dowel Plates has been designed as per requirement.
Use of Armored Joints for high MHE traffic area to increase life of floor panel joints drastically and avoid costly breakdowns
Various Type of Armoured Joints are available, above is a pic of a Parallel Type.
Casting Methods - Laser Screeding / Laser Guided Screeding Works
- Laser Guided Systems like Automatic Boom Screed, Ride on Laser allow large pours to be done in a single day. We can now achieve 500 to 1500 per day, with support of RMC vendors based on critical timely supply of RMC at site as per specification without any variation in RMC batches.
- Having fewer panel joints directly makes the flooring more durable as compared to now obsolete VDF/ Tremix / VDC methods.
- The controlled batching of RMC by the plant itself makes the entire flooring project of defined quality and as per planned specifications
Isolation of the Grade SlabThe grade slab has to be isolated by all vertical interactions for natural stresses to be relieved.
- The8/10 mm PU moisture insensitive board has to be used on all corners, walls and foundations.
- Steel isolation rebars has to be designed around columns and corners to prevent stress cracks
Sealing of Saw Cut Joints
- Joints are created to release stressed in concrete floor.
- These joints shoould be sealed wirth a durable sealant with a good service life under the exposure or warehouse wear and tear.
- Some of the materials to seal these are
- PU Sealant 1K
- PU Sealant 2K
- Polysulphide Sealant ( Old system, Outdated)
- Semi Rigid Sealnts based on Epoxy ( Most Durable for Warehouse Use)
The joints have to be sealed properly, as the wear and tear damage starts from the joints first. A proper specification in this help to increase the service life a long way.
Surface Treatment with Dry-Shake Hardener and Densification Treatment In-Situ to achieve following
- High Abrasion resistance for topping by using minimum 3 to 4 kg of Dry Shake Hardener per Sqm minimum.
- This dosage can be increased upto 10kgs based of heavier duty requirements
- Enhanced Hydration of Cementitious material for increasing the strength of the top surface by using Liquid Nano Silica Densifier Cum Hardener Systems at the time of casting itself.
- Densification and Dustproofnig using Nano Silica treatment helps by Neutralizing non-reacted free lime and making the top surface dust free and closing the pores for further enhancing the final finished properties of the floor achieving reflective properties.
- (Note This is a Technical Requirement)
- Industrial use floors can be left unpolished or slightly polished to achieve a clean mild reflective surface or it can be grinded and polished to the following high reflective look. With 6/8 step polishing.
- ( Note: -6/8 Step is a cosmetic Requirment for Large Markets & Wholesale Distribution Centers)
- A reflective, easy to clean floor, with dust free properties improve the workspace environment for enhanced productivity.
This brings an end to this article. Hope you were able to understand modern flooring methods with practical aspects as presented. Feel free to comment or send us your query. We would be happy to clear any doubts.
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