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All Faq's

1. What is VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring?
VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring is a system for laying high quality concrete floors where the key is Dewatering of Concrete by Vacuum Process wherein surplus water from the concrete is removed immediately after placing and vibration, thereby reducing the water cement ratio to the optimum level.

VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring increases the Compressive Strength, Tensile Strength, and Abrasion Resistance and minimizes the Shrinkage and Floor Wraps. VDF Flooring results in High Strength, Longer Life, Better Finish and Faster Work. This type of floor is suitable for high abrasion & heavy traffic movement.
2. What is the full form of VDF Flooring?
The full form of VDF Flooring is Vacuum Dewatered Flooring.
3. What is the Work Methodology of VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring?
(VDF Flooring Specifications or Flooring Specifications or VDF Flooring Methodology or VDF Flooring Procedure or Vacuum Dewatered Flooring Specification or Vacuum Dewatered Flooring Procedure)

• Tying Line Dori (Threads) as per the slope requirements

• Laying Guide Rails to every 4 meters using MS Channels or as required in straight lines along the Line Dori, taking levels as per the slope and fixing them using concrete also called grouting and left to set for a minimum of 24 hours

• Pouring the concrete in between the channels and spreading using Shovel or Hoe (Kudal/Parah)

• Vibrating the concrete with a poker vibrator especially to the sides of the panels

• Surface Vibration the concrete using Double Beam Screed Vibrator running over the guide rails twice to achieve maximum compaction for RCC with double mats

• Final levelling of the concrete using the Straight Edge/Bull Float/Aluminium Bottom (Fanti/Baddha)

• A system of lower mats & top mat is laid on the green concrete & this is attached to a vacuum pump. This draws out surplus water if any. (We strongly oppose dewatering of RMCs. RMCs have water cement ratio already maintained to its minimum possible level by addition of admixtures. Further dewatering decreases the water cement ratio below the required level thereby causing undulations in the surface, loss in strength and formation of cracks.)

• The concrete is left to stiffen. When the base concrete has stiffened to the point when foot traffic leaves an imprint of about 3-6 mm and any bleed water should now have evaporated, but the concrete should have a wet sheen, Floor Hardener is applied at an even application rate of 3-7 Kg/Sqm or as per the requirement of the floor.

• Application of Power Floater on the surface until the surface is sufficiently compacted & levelled with no major lines appearing any more

• Final finishing using Power Trowel and trowelling until the required finish is achieved. Finish could be any of the Smooth Finish, Sand Finish or Line Finish.
4. What is the cost of VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring?
For the least cost of VDF Flooring, please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com.
5. What is the tolerance for VDF Flooring??
Tolerance of VDF Flooring varies with the kind of machinery used for Screeding and Trowelling:

S. No Machines Used for screeding Tolerance Level
1 Laser Screed <4.5 mm FM1
2 Double Beam Screed Vibrator <8.5 mm FM2
6. Who is the best contractor for Industrial Flooring works in India?
Virsa Corporation is the best contractor for Industrial Flooring works in India like VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring, Laser Screeding, Epoxy Flooring and Groove Cutting works
7. What is the difference between IPS Flooring & VDF Flooring?
An IPS (Indian Patent Stone) Floor is generally used over terraces in general, to achieve an economical and water sloping finish with a decent monolithic appearance....

However the IPS finish may even be used for other interior and semi-interior areas as the need may be, but in areas, where required structural strength by a floor would be more eg. Car Parks, Workshops and Driveways, a similar kind of a multi-layered flooring using lean concrete in a different proportion altogether may be utilised......Unlike IPS, a VDF floor calls for a more skilled labour with almost twice as many man hours over the same stretch..... This system raises the cost as there is machinery required, but appearance wise and strength wise the VDF (Vacuum Dewatered Floor) floor stands out......

The VDF is generally done with a base layer of lean concrete with suitable expansion joints executed with rubber or steel strips... Then a screed vibrator is run over the surface, supported on channel shuttering spaced 4.0 meters apart. The screed vibrator is run twice to achieve optimum compaction & levelling. After this a system of lower mats & top mat is laid on the green concrete & this is attached to a vacuum pump. This draws out excess water.
8. What is Laser Screeding?
(Laser Screed Flooring or Laser Screed Concrete Floors)

Laser Screeding is the modern way to do the concrete flooring. This technique allows us to lay concrete floors in wider bays of any size. It drastically reduces Time, Labor, number of Construction Joints and eventually improves the flatness of floors. With this technique it is possible to lay concrete floors up to 3,000 Sqm per day.

It eliminates the need of fixing guide rails to every 4 meters. Laser screed simultaneously cuts, vibrates and levels the concrete in a single pass. All these operations are controlled by laser transmitter, receivers and computer. So, manual errors are eliminated thereby giving us Zero Level Difference floor (Super Flat).

9. What are the benefits of Laser Screeding or Laser Screed Flooring?
• Reduced form work

• Decreased number of cold joints

• Increases Productivity & Efficiency

• Exceeds specified FF and FL's on projects

• Greater accuracy through Laser Technology

• Reduces labour costs due to faster placing times

• Produces floors of unequalled Flatness & Levelness.
10. What is the Laser Screed Price or the cost of doing Laser Screeding?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com
11. What is the tolerance for Laser Screeding?
Tolerance of Laser Screeding is 1 mm. Tolerance of Laser Screeding followed by Ride on Trowel finish is 2mm.
12. What is Groove Cutting?
Groove Cutting is the technique to provide control joints in Concrete to guide cracks along a predetermined line and to help accommodate the movement of the concrete and avoid Cracking of Concrete and long-term damage.

Concrete expands and contracts constantly with changes in the temperature, the moisture content of the air and due to drying of cement which results in shrinkage. The movements result in stress that can cause cracks in the concrete and destabilization of the base.

Uncontrolled cracking can cause an uneven surface, which is subject to increased wear over time and water seepage, which can damage the substrate. Though formation of cracks is almost impossible to prevent, it can be controlled. The purpose of the Groove Cutting is to weaken the slab along the predetermined line so that the slab cracks there instead of somewhere else.
13. What are the benefits of Groove Cutting?
• Prevents cracking of concrete and increases the life of concrete

• Gives Aesthetic Looks
14. What is the cost of Groove Cutting?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com
15. What is Epoxy Flooring??
Epoxy flooring is Smooth, Monolithic Flooring using multiple layers of Epoxy Resins that is applied to the floor to different thicknesses depending upon the requirements. The epoxies are self levelling by nature, thereby spreading across the floor itself, in a manner so as to minimize the undulations and bring about as level a floor as possible.

Concrete surfaces are porous, making them vulnerable to water, abrasion and chemicals. When applied to concrete, Epoxy Flooring creates a protective layer of protection which enhances aesthetics and hardens the surface. Epoxy systems are exceptionally diverse and can be engineered to meet the unique demands of nearly any facility.

Epoxy flooring is tough, smooth, aesthetic and resistance to Moisture, Chemicals and wear & tear which gives abrasion resistance to surfaces, easy to clean and offers a very glossy look to the surface. Due to these properties this kind of flooring is suitable for Industries like Automobile, Pharmaceuticals, Dairy and other Food grades.

Epoxy is any of various usually thermosetting resins capable of forming tight cross-linked polymer structures characterized by toughness, strong adhesion, and low shrinkage, used for floorings. Epoxy in this case refers to a system that is made up of resins, hardeners, fillers & pigment. The resin and hardener is mixed together where they chemically react to form a rigid plastic material that is strong, resistant to degradation and that bond extremely well to its substrate.
16. What is Vacuum Dewatering Procedure?
• Vacuum dewatering process removes surplus water present in the concrete. This is done using the Vacuum Equipment comprising of Suction Mat Top Cover, Filter pads and Vacuum Pump. The process starts immediately after surface vibration.

• Filter pads are placed on the fresh concrete leaving about 4 inches of fresh concrete exposed on all sides. The Top Cover is then placed on the filter pads and rolled out till it covers the strips of exposed concrete on all sides. The Top Cover is then connected to the vacuum pump through a suction hose and the pump is started.

• Vacuum is immediately created between the filter pads and the top cover. Atmospheric pressure compresses the concrete and the surplus water is squeezed out. This process lowers the water content in the concrete by 15-25%.

• The dewatering operation takes approximately 1.5 - 2 minutes per centimetre thickness of the floor. The dewatered concrete is compacted and dried to such an extent that it is possible to walk on it without leaving any foot prints. This is the indication of concrete being properly dewatered and ready for finishing.
17. What are the benefits of VDF Flooring or Vacuum Dewatered Flooring or Tremix Flooring?
• Increased Compressive strength by more than 50%

• Reduced Cement consumption by more than 30% as no cement is required separately for finishing.

• Increased Abrasion resistance by more than 50%

• Increased wear resistance

• Minimum dusting & crack formation

• Minimum dry and plastic shrinkage and floor wraps

• Uniform homogeneous floor with High flatness accuracy

• Lower water permeability due to increased density.

• High early strength minimizes damage on newly cast floors

• Earlier utilization and Reduced maintenance cost
18. Typical Application Areas of VDF Flooring
• Warehouses, Godowns

• Roads, Sports Courts

• Cellars, Parking Areas

• Production Areas

• Pharmaceutical Companies

• As the base floor for Epoxy & PU Floorings
19. Does Vacuum Dewatered Concrete require curing?
Yes, Vacuum Dewatered Concrete also requires curing for 21 days.
20. What are the serious Concerns of Vacuum Dewatered Flooring or VDF Flooring or Tremix Flooring?
• The withdrawal of water produces settlement of the concrete, possibly up to 3%. This can be topped up with the application of a dry shake but with little bleed water at the surface there is a risk of subsequent delaminating.

• In practice the VDF process produces voids in the concrete and it has been found that with the same water / cement ratio, ordinary concrete has been found to have a somewhat higher strength than VDF concrete.

• VDF concrete stiffens very quickly. This is acceptable in cold climatic conditions but leaves the window of workability very short in hotter climates.

• Some of the finer materials are removed with the VDF process and fine sands and cement contents of greater than 350 Kg/Cum should be avoided.
21. Should we do Vacuum Dewatering when using RMCs?
In RMCs the water-cement ratio is already optimum. By the application of suitable admixtures in concrete water cement ratio is at its minimum specified value. Any further decrease in water cement ratio shall cause lack of sufficient water for the complete curing of cement particles thereby decreasing the strength of concrete and even causing cracks. So, even though as the name suggests, Vacuum Dewatering is the KEY to the whole VDF Flooring Process; this process should not be used when RMC or Ready Mixed Concrete is used.
22. What is a Double Beam Screed Vibrator?
Screed vibrator is used for the levelling as well compaction of concrete it consists of high quality steel bar (4.2 meter) with spacing of 250 MM in between. Special water protective vibrator motor is mounted in the centre which produces 1830 N centrifugal force which is most ideal for compaction of green concrete. They are also available in different sizes from 2 meter to 5.5 meter.
23. What is Vacuum Pump?
This is the core of the system. A continuous discharge vacuum pump is complete self contained unit. The unit is mounted on a transportation trolley. 24Sqmt freshly laid concrete can be De-watered in one single operation with one set mat. The pump is powered by 7.5 H.P. 3 Phase electric motor.
24. What are Filter, Suction and Top Mat?
Suction mat is placed directly on the green concrete after vi bro screed operation is over. A Special high class nylon filter is fixed on plastic mats which acts a filter during the vacuum operation filter mats in different sizes are provided with the system, Top mat is provided the junction box and is De-watering placed on top of filter mat for the purpose of sealing special synthetic cloth is used in the top mat it comes in standard sizes of 4x6 meter.
25. What is a Power Floater?
It is surface grinding equipment powered by 3 H.P. Electric motor through gear box with floating RPM of 130. It grinds the surface to make it wear resistance.
26. What is Power Trowel?
It is surface finishing equipments powered by 3H.P. electric motor through gear box towelling RPM of 135. It polishes the surface after floating operation and 3 to 4 passes are required for giving fine finish to the floor.
27. What is Form Work?
Construction of floor begins with careful preparation. Before casting MS Channel are generally used us form works. They act as a stopper, also as support for pulling the screed board vibrator
28. What is IPS Flooring?
IPS flooring stands for Indian patent stone flooring. It is a basic type of concrete flooring which provides good wearing properties. It is generally used for all types of floors and mix of concrete. Generally used mix for IPS flooring specification is 1:1.5:3 (cement, sand and stone aggregates). It is laid over the concrete base (1:4:8), which is almost 3 to 4 inches thick plain cement concrete (PCC) base.

We can decide the thickness of the IPS flooring as per the requirement of work; in residential floor 75 mm floor thickness is sufficient whereas industrial floor thickness should be kept 150 mm.
29. What is the Full Form of IPS Flooring?/dt>
The full Form of IPS Flooring is Indian Patent Stone Flooring or Indian Pattern Stone Flooring
30. What is the Work Methodology of IPS Flooring?
(IPS Flooring Specifications or Flooring Specifications or IPS Flooring Methodology or IPS Flooring Procedure)

• Making a reference level on the wall and transferring this marking to all locations where flooring is to be done using tube level.

• Flooring thickness level to be marked and dummy level dots provided in every 1 or 2 meter ensuring required slope of flooring.

• Concrete be poured and levelled with a Straight Edge and finished with a wooden float or trowel. Concrete may be placed in panels to minimize shrinkage cracks.

• Glass, aluminium or brass strip are fixed in cement mortar with their tops at proper level according to slope and allowed to harden for minimum 36 hours.

• The final towelling should be done before the concrete has become hard and sufficient pressure is required to make firm impression on the concrete surface.

• If glossy or smooth IPS flooring surface required then neat cement punning, 2 to 3 mm thick is spread over the IPS concrete surface and allowed to soak into the concrete. The surface is finished with metal trowel to give surface a glossy look.

• Concrete is cured by surface ponding or wet Hessian clothes are spread for 21days.
31. What is the cost of IPS Flooring?
(IPS Flooring Rate analysis)

Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com. .
32. What is the example of IPS Flooring?
An IPS Floor is generally used over Terraces, Car Parks, Workshops and Driveways in general, to achieve an economical and water sloping finish with a decent monolithic appearance. IPS finish may even be used for other interior and semi-interior areas as the need may be.
33. Where is Laser Screeding used?
(Typical Application Areas)

• Doubly reinforced slabs

• Metal decks

• Grade slabs with dual slopes

• very large factory floors

• For faster Works

• For Zero Level Floors with no undulations
34. How a Laser Screed Works or what are Laser Screeding Specifications?
(Laser Screeding Methodology or Laser Screeding Procedure or Laser Screeding Flooring Specification or Laser Screeding Flooring Procedure)

• In Laser Screeding concrete is poured on the surface and Laser Screed cuts, vibrates and levels the concrete in a single pass. Laser Screed eliminates the need of fixing guide rails to every 4 meters.

• All the operations are controlled by laser transmitter, receivers and computer. So, manual errors are eliminated thereby producing high strength, dense; durable floors improving floor quality & increasing profits.

• Our Laser Screed being compact, portable, and extremely manoeuvrable, making it easy to gain access to almost any area and can also be used on elevated slabs and rebar floors and covers areas in excess of 3,000Sqm per day thereby decreasing the Labour Cost.

• We are equipped with the Latest Laser Screed and Power Rake providing state of the art concrete placing technology.
35. Do we give Laser Screed Rental Services or provide Laser Screed Operator?
Yes, we do give Laser Screed on Rent.
36. What are Somero Laser Screeds or Bull Laser Screed?
These are the Laser Screeding Machines used by us to do the Laser Screeding..
37. What is the Work Methodology of Groove Cutting?
(Groove Cutting Specifications or Groove Cutting Methodology or Groove Cutting Procedure or Groove Cutting Specification)

• Leaving the concrete surface to get cured for a minimum of 72 hours after casting to avoid chipping off of edges

• Locating the joints and marking on the concrete using Line Dori and Paint exactly along the joints making panels of 4Mtrs X 4Mtrs or as specified

• Cutting the concrete using heavy duty Cutting Machine with diamond cutting wheel of 4mm thickness

• The Minimum thickness of the Grooves should be 4mm and Minimum depth of the Groove should be one fourth of the thickness of the concrete.

• Cleaning the Grooves using air blower and filling with appropriate sealant.
38. What is Epoxy Coating?
Any epoxy floor that is less than one millimetre thick is best referred to as an epoxy floor coating. This is accomplished by application of one coat of Epoxy Primer and Two Coats of Brush/Roller applied Epoxy Paint.
36. What are Somero Laser Screeds or Bull Laser Screed?
These are the Laser Screeding Machines used by us to do the Laser Screeding..
39. What is the difference between Epoxy Flooring & Epoxy Coating?
The difference between Epoxy Flooring and an Epoxy Floor Coating lies in the depth of the epoxy. An epoxy floor must be at least one millimetre thick. Any epoxy floor that is less than one millimetre thick is best referred to as an epoxy floor coating.
40. What is the Work Methodology of Epoxy Flooring?
(Epoxy Flooring Specifications or Epoxy Flooring Methodology or Epoxy Flooring Procedure or Epoxy Flooring Specification)

• Cleaning: The substrate should be made structurally sound, dry and free from loose materials. All the surface contamination, laitance, grease and oil must be removed appropriately while deeper penetration should be removed by mechanical means.

• Surface Preparation: Filling cracks & patches if any with epoxy mortar, while bigger pot holes to be treated with non-shrink repair mortars.

• Priming: Application of one coat of solvent free epoxy resin based primer for better adhesion of the subsequent flooring to the substrate.

• Epoxy Topping: - Resin, Hardener, Filler and pigment are mixed together and laid on the floor to required thickness using notched trowel and finished using spike rollers.
41. What is the Work Methodology of Epoxy Coating or Epoxy Coating Specifications or Epoxy Coating Methodology or Epoxy Coating Procedure or Epoxy Coating Specification?
• Cleaning: The substrate should be made structurally sound, dry and free from loose materials. All the surface contamination, laitance, grease and oil must be removed appropriately while deeper penetration should be removed by mechanical means.

• Surface Preparation: Filling cracks & patches if any with epoxy mortar, while bigger pot holes to be treated with non-shrink repair mortars.

• Priming: Application of one coat of solvent free epoxy resin based primer for better adhesion of the subsequent flooring to the substrate.

• Epoxy Coating: - Resin, Hardener and pigment are mixed together and applied on the floor to required thickness using Brush.
42. What are the types of Epoxy Flooring?
• Food Grade Epoxy Flooring

• Heavy Duty Epoxy Flooring

• Anti Skid Epoxy Flooring

• Anti Static Epoxy Flooring
43. What are the advantages or benefits of Epoxy Flooring?
• Tough, Smooth, Aesthetic, seamless surface finish

• Low Porosity, Moisture and Water resistant

• Dirt & Dust free and thus easy to clean

• Strong Bond Strength to the substrate

• Provides Safe, Cleaner, Healthier & More Pleasant ambience

• Non Inflammable and Anti-skid thus provides safe surface for Industrial use

• Attractive flooring surface with Glossy or Mat finish as required

• Chemical Resistant and thus protects the substrate from chemical degradation

• High Impact Resistance and thus protects the substrate from wear and tear

• Allow for quick and easy application
44. What are the benefits of Epoxy Coating?
• Tough, Smooth, Aesthetic, seamless surface finish

• Low Porosity, Moisture and Water resistant

• Dirt & Dust free and thus easy to clean

• Strong Bond Strength to the substrate

• Provides Safe, Cleaner, Healthier & More Pleasant ambience

• Non Inflammable and Anti-skid thus provides safe surface for Industrial use

• Attractive flooring surface with Glossy or Mat finish as required

• Chemical Resistant and thus protects the substrate from chemical degradation

• High Impact Resistance and thus protects the substrate from wear and tear

• Allow for quick and easy application
45. Typical Application areas of Epoxy Flooring
• Pharmaceuticals Industries,

• Food Processing Industries,

• Automobile Industries,

• Chemical & Fertilizer Industries,

• Garages & Car Parkings

• Ware Houses
46. How long will an epoxy system last
The life of an epoxy flooring system is dependent upon a number of factors:

• Type of flooring system

• Amount and type of traffic

• Exposure to chemicals

• Cleaning procedures
47. Why does an Epoxy Flooring or Epoxy Coating failing or Bubble Formation or Blistering or Debonding?
Epoxy coating systems can fail for a number of reasons including:

• Moisture vapour transmission

• Contamination of substrate

• Poor preparation of surface
48. What is the cost of Epoxy Flooring?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com.
49. What is the cost of Epoxy Coating?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com.
50. What is the difference between Epoxy Flooring and PU Flooring?
Although epoxy flooring systems perform well in a number of environments, epoxies are not recommended for many facilities within the food and beverage industry. Urethane concrete/cementations urethane is the product of choice in these environments due to a number of performance factors:

• Resistance to thermal shock

• Impact resistance

• Withstands hot water and steam cleaning

• Urethane Concrete is formulated to withstand the harsh conditions found in the food and beverage industry.
51. What is the difference between PU Flooring and PU Coating?
Any PU Floor that is less than one millimetre thick is best referred to as PU Floor coating. This is accomplished by application of one coat of PU Primer and Two Coats of Brush/Roller applied PU Paint
52. What is the cost of PU Flooring?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com.
53. What is the cost of PU Coating?
Please call us on 75690 13544 / 96184 14445 or 040-3243 4682 or write to us at pm.virsa@yahoo.com.
54. Can we paint over epoxy paint with new epoxy paint?
We can do Epoxy Paint over existing Epoxy Paint but the existing epoxy paint should be grinded to give a KEY to make the new paint stick to it better.
55. What is Load Transfer Mechanism?
In case of heavy load traffic, a Load Transfer mechanism is used. Load transfer devices prevent the uneven shifting of Concrete Slabs under heavy loads. Shifting can cause uneven slabs and breakdown of the joints.

Dowels, load plates, or slots can be embedded into the concrete to act as load transfer devices. These devices are laid perpendicular to the construction joint, extending into both slabs across the joint. Their purpose is to distribute the load evenly between slabs thereby protecting the concrete along the joints.
56. What are the Reasons of Concrete Cracking?
Concrete expands and contracts constantly with changes in the temperature, the moisture content of the air and due to drying of cement which results in shrinkage. The movements result in stress that can cause cracks in the concrete and destabilization of the base.

Uncontrolled cracking can cause an uneven surface, which is subject to increased wear over time and water seepage, which can damage the substrate.
57. What Is the Meaning of Grouting?
The definition of grouting is filling masonry joints or gaps with a coarse, thin cement or mortar mixture. Masonry projects that incorporate individual tiles or rocks into a pattern on floors, walls or other flat surfaces are typically finished off by grouting.

Grouting is the application where we utilize a mix of cement and sand along with other material (such as epoxy) to fill the spaces that may result during some construction operation. Grouting is mainly used for filling the spaces rather than to hold any main stresses.
58. What is Injection Grouting?
Injection Grouting is specially designed for arresting seepages and dampness using Cementitious grouting admixed with expanding grout admixture or cutting off gushing water of high pressure and speed using Polyurethane Grouting and retrofitting works by using Epoxy resin Grouts.

The grout material, when mixed with a certain amount of accelerator, will react with water or moisture and expand, to form a tough, closed-cell rubber that is essentially unaffected by corrosive environment. Injection Grouting is used for filling up the cracking in structural members, bonding concrete and other members permanently. Developed using modern techniques, Injection Grouting materials possess the following features:
59. Types of Injection Grouting
a. Cementitious Grouting – used for arresting water seepages by filling pores & capillaries

b. Polyurethane Grouting - used for arresting active water leakages where the pressure is high

c. Epoxy Grouting – used for crack repairs & retrofitting
60. How to Patch a Concrete Floor?
• Patches 1 inch or deeper require a concrete mix with coarse, crushed-stone aggregate, which bonds well with existing concrete. Shallower ones need a sand mix using the following steps:

• Use a hammer and a cold chisel to level the bottom of the hole and undercut its sides slightly so the patch can't pop loose. Vacuum, then clean the area with water and a wire brush. Wipe clean.

• Apply the concrete bonding agent

• While the bonding agent is still tacky, mix the concrete with water and scoop some into the patch. Press it into the corners and against the edges with a trowel. Now fill the patches completely, leaving some material mounded on top.

• Level the patch with a straight-edged board at least a foot longer than the width of the hole. Move it back and forth in a sawing motion. This will also push down the aggregate and make the final smoothing easier. When the surface loses its wet sheen and feels firm to the touch, smooth it with a magnesium or wood trowel, which won't interfere with curing.

• Work the trowel in a fanning motion to blend the edges with the existing concrete. Do this several times as the mix cures. To burnish the surface very smooth, use a steel trowel (shown) on the final few passes.
61. What are Joint Sealants?
Joint Fillers and Sealants are hard, semi-rigid materials typically used to fill the construction joints in concrete floors. Being flexible joint sealants expand and contract along with the concrete. Their main purpose is to prevent water, other liquids, and debris from entering the joint. They can also improve the appearance of a floor. Most sealants are available in colours and can make the joints “disappear”.
62. What are Floor Hardeners?
Floor hardeners provide a dense, tough surface capable of withstanding the abrasion and impact loading seen by floor slabs in a wide range of commercial, industrial and manufacturing facilities.
63. What are the Types of Floor Hardeners?
There are two types of Floor Hardeners: -

• Dry shake floor hardeners come in mineral aggregate and metallic varieties. The selection of a dry shake hardener is dependent on the specific solution intended for the particular application.

• Liquid Floor Hardener
64. What are Dry Shake Floor Hardeners?
Dry shake floor hardeners come in mineral aggregate and metallic varieties. The selection of a dry shake hardener is dependent on the specific solution intended for the particular application. Dry shake hardeners provide 2 to 8 times the abrasion resistance of plain, cured concrete. Most manufacturers offer hardeners in a range of colours.
65. What are the Types of Dry Shake Floor Hardeners?
There are two types of Dry Shake Floor Hardeners:

• Metallic Floor Hardeners

• Non-Metallic Floor Hardeners
66. What are Metallic Floor Hardeners?
Metallic floor hardeners are formulated with graded, non-oxidizing or oxidizing metallic aggregate in a high strength cementations binder. Mineral hardeners contain a mixture of well graded, non-metallic aggregates, plasticizer and cement binder. Both are recommended for use in either interior or exterior applications where a hard, long wearing, heavy duty floor is required. Metallic hardeners should not be applied to concrete with intentionally added chloride.
67. Give an example of Non-Metallic Floor Hardeners?
• Fosroc Nitoflor Hardtop Standard

• Dr Fixit Piditop 333

• Sika Chapdur
68. EARTH COMPACTOR
Our Earth Compactors are compact, light weight, self propelled machines having low amplitude, high forces and high frequency based on the principle of reciprocal pressure generation by frequency unidirectional impulse vibrator which causes the ramming and forward movement.

We are capable of compacting thicker layers of non-cohesive and semi-cohesive soils sub grades, manoeuvres close to abutments retaining walls, pilling, ideal for key trenches, cannel embankments, back fill jobs, factory floor, foundations, bridge approaches etc and maximum proctor density (95% to 98%) in less numbers of passes application non-cohesive soil,.
69. What is the alkathane paper which is used for VDF Flooring?
Alkathene Sheets are manufactured from a "new generation" virgin low density polyethylene. It is used as underlay for the VDF Flooring works.
70. Can you paint over epoxy paint with new epoxy paint?
Yes we can. However, the existing epoxy paint should be sanded to "rough" it up to make the new paint stick to it better.
71. Does vacuum dewatered concrete require curing?
Yes, the vacuum dewatered concrete requires curing in order to gain its strength. The concrete is cured for 28 days.
72. What is the Grade of Concrete?
Grade of concrete is the index of the strength of concrete. Minimum grade of concrete used shall be M15 conforming to IS-456. Grade of concrete is decided by the Design Mix but it is affected by Batching, Mixing, Placing, Curing etc.
73. What is Water Cement ratio?
The water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix and has an important influence on the quality of concrete produced. A lower water-cement ratio leads to higher strength and durability, but may make the mix more difficult to place. Placement difficulties can be resolved by using plasticizers or super-plasticizers.

Concrete hardens as a result of the chemical reaction between cement and water (known as hydration, this produces heat and is called the heat of hydration). For every kilogram of cement about 0.25 kg of water is needed to fully complete the hydration reactions. This requires a water-cement ratio of 1:4 i.e., 0.25.

However, a mix with a w/c ratio of 0.25 may not mix thoroughly, and may not flow well enough to be placed, so more water is used than is technically necessary to react with the cement. But this adversely affects the strength of concrete. For higher-strength concrete, the required lower water: cement ratios is maintained using plasticizer to increase flowability. Typical water-cement ratio varies from 0.25 to 0.45.

74. What is Polished Concrete in flooring?
A polished concrete floor has a glossy, mirror-like finish. We provide vast design options for polished concrete. We can polish concrete in nearly any colour, creating patterns with saw cuts or embed aggregates into the concrete prior to polishing.

The reflectivity of the floor can also be controlled by using different levels of concrete polishing. Polished concrete is popular in commercial buildings because it is easy to maintain. Maintaining polished floors requires dust mopping and occasional use of a cleaning product.

Simply put, polishing concrete is similar to sanding wood. Heavy-duty polishing machines equipped with progressively finer grits of diamond-impregnated segments or disks (akin to sandpaper) are used to gradually grind down surfaces to the desired degree of shine and smoothness.
75. How to do the polishing of concrete?
• Initial Rough Grinding: The process begins with the use of coarse diamond segments bonded in a metallic matrix. These segments are coarse enough to remove minor pits, blemishes, stains, or light coatings from the floor in preparation for final smoothing. Depending on the condition of the concrete, this initial rough grinding is generally a three- to four-step process.

• Fine Grinding: The next steps involve fine grinding of the concrete surface using diamond abrasives embedded in a plastic or resin matrix. Crews use ever-finer grits of polishing disks (a process called lapping) until the floor has the desired sheen. For an extremely high-gloss finish, a final grit of 1500 or finer may be used. Our experienced polishing technicians know when to switch to the next-finer grit by observing the floor surface and the amount of material being removed.

• Impregnating Sealer Application: During the polishing process an internal impregnating sealer is applied. The sealer sinks into the concrete and is invisible to the naked eye. It not only protects the concrete from the inside out, it also hardens and densifies the concrete. This eliminates the need for a topical coating, which reduces maintenance significantly (versus if you had a coating on it). Some contractors spread a commercial polishing compound onto the surface during the final polishing step, to give the floor a bit more sheen. These compounds also help clean any residue remaining on the surface from the polishing process and leave a dirt-resistant finish.
76. What are the different ways of Polishing?
Polishing can be done by wet or dry methods:

• Dry Polishing: Although each has its advantages, dry polishing is most commonly used in the industry because it is faster, more convenient and environmentally friendly. With dry polishing, no water is required. Instead, the floor polisher is hooked up to a dust-containment system that vacuum up virtually all of the mess.

• Wet polishing: Wet polishing uses water to cool the diamond abrasives and eliminate grinding dust. Because the water reduces friction and acts as a lubricant, it increases the life of the polishing abrasives. The chief disadvantage of this method is the cleanup. Wet polishing creates a tremendous amount of slurry that crews must collect and dispose of in an environmentally sound manner.

Typically, dry polishing is used for the initial grinding steps, when more concrete is being removed. As the surface becomes smoother, and crews switch from the metal-bonded to the finer resin-bonded diamond abrasives, they generally change to wet polishing.
77. What is the Work Methodology of Concrete Polishing?
(Concrete Polishing Specifications or Concrete Polishing Methodology or Concrete Polishing Procedure or Concrete Polishing Specification)

• Remove existing coatings (for thick coatings, use a 16- or 20-grit diamond abrasive or more aggressive tool specifically for coating removal).

• Seal cracks and joints with an epoxy or other semi-rigid filler.

• Grind with a 30- or 40-grit metal-bonded diamond.

• Grind with an 80-grit metal-bonded diamond.

• Grind with a 150-grit metal-bonded diamond (or finer, if desired).

• Apply a chemical hardener to densify the concrete.

• Polish with a 100- or 200-grit resin-bond diamond, or a combination of the two.

• Polish with a 400-grit resin-bond diamond.

• Polish with an 800-grit resin-bond diamond.

• Finish with a 1500- or 3000-grit resin-bond diamond (depending on the desired sheen level).

• Optional: Apply a stain guard to help protect the polished surface and make it easier to maintain.