AirSprayTech Academy Certificate Program
Commercial and Industrial Floor Coatings for Professional Contractors
Broadcast, Slurry, Mortar, and Self-Leveling Floor Systems
Article 15 of 24
Resinous flooring systems are defined not only by chemistry but also by
the way resin, aggregate, thickness, and installation method work
together. Broadcast, slurry, mortar, and self-leveling systems serve
different purposes and require different crew skills, tools, and
quality controls.
System Form Changes Floor Performance
The same general resin chemistry can be installed as a thin coating,
aggregate broadcast, flowable slurry, troweled mortar, or self-leveling
layer. These systems differ in:
- Installed thickness
- Resin-to-aggregate ratio
- Application method
- Texture and appearance
- Impact and wear performance
- Ability to fill surface irregularities
- Required labor and equipment
- Material consumption and cost
The selected system form must match the expected service and condition
of the concrete.
Comparing the Four System Types
| System |
General Construction |
Common Purpose |
| Broadcast |
Dry aggregate or decorative media is broadcast into wet resin
and later sealed.
|
Builds thickness, texture, reinforcement, wear resistance,
and decorative appearance.
|
| Slurry |
A flowable mixture of resin and aggregate is spread across
the floor.
|
Provides greater build and durability than a thin coating
while remaining relatively efficient to place.
|
| Mortar |
A high-aggregate mixture is placed, compacted, and finished
by trowel or screed.
|
Heavy-duty resurfacing, impact service, slope correction,
deep repair, and severe-use flooring.
|
| Self-leveling |
A flowable resinous material is distributed at a controlled
thickness to create a smooth surface.
|
Smooth, seamless, cleanable floors with controlled appearance
and greater build than ordinary coatings.
|
These descriptions are general. The manufacturer's complete system
determines the actual properties and limitations.
Broadcast Flooring Systems
Broadcast flooring begins with a wet resin layer that receives dry
aggregate, colored quartz, decorative flakes, or another approved
material.
Broadcast levels may include:
- Light or partial broadcast
- Full broadcast
- Broadcast to refusal
- Multiple broadcast layers
In a broadcast-to-refusal system, aggregate is applied until the wet
resin will no longer accept additional material and the surface appears
uniformly dry. The exact procedure depends on the system.
Broadcast-System Advantages
- Adds thickness and reinforcement
- Provides slip-resistant texture
- Improves wear performance
- Offers decorative quartz or flake appearance
- Helps disguise minor substrate variation
- Creates a mechanical surface for subsequent coats
Broadcast Technique
Aggregate should generally fall into the wet resin rather than be
thrown forcefully at a low angle. Throwing it forward and upward can
help it fall more evenly onto the surface.
Control:
- Aggregate cleanliness and dryness
- Broadcast timing
- Throwing height and pattern
- Quantity per batch area
- Coverage around edges and details
- Worker access over wet material
- Batch-to-batch consistency
Broadcasting too early may allow aggregate to sink. Broadcasting too
late may prevent proper embedment.
Removing Excess Broadcast Aggregate
After the resin cures, loose aggregate must be removed before applying
the next layer.
The approved procedure may include:
- Sweeping or scraping the surface in multiple directions.
- Sanding or lightly grinding high points when required.
- Vacuuming all loose aggregate and dust.
- Inspecting for bare resin, bald spots, and uneven texture.
- Repairing nonuniform areas using the approved procedure.
Recovered aggregate should not be reused unless the manufacturer and
project procedures specifically permit it and its cleanliness is
controlled.
Slurry Flooring Systems
A slurry is a flowable blend of resin and graded aggregate. It is often
distributed with a squeegee, gauge rake, or other specified tool and may
receive a broadcast aggregate or seal coat.
Potential Advantages
- Greater thickness than conventional coatings
- Efficient installation across large areas
- Improved wear and impact performance
- Ability to fill a moderately aggressive surface profile
- Compatibility with smooth or textured finish options
Installation Challenges
- Aggregate can settle if mixing and placement are delayed.
- Inconsistent proportioning changes flow and performance.
- Incorrect rake settings produce thickness variation.
- Batch lines can remain visible.
- Porous concrete can contribute to pinholes and air release.
Mortar Flooring Systems
Resinous mortar contains a relatively high proportion of graded
aggregate. It is placed and compacted with screeds, trowels, power
equipment, or other approved tools.
Mortar systems may be selected for:
- Heavy traffic and impact
- Resurfacing deteriorated floors
- Repairing deep or widespread damage
- Creating slope toward drains
- Correcting elevation and transitions
- Building heavy-duty sanitary flooring
- Supporting severe industrial service
Mortar placement requires skilled labor. The crew must control mixing,
consistency, elevation, compaction, trowel finish, and working time.
Mortar Resin-to-Aggregate Balance
Resin and aggregate must remain in the specified proportion.
Too Much Resin
- Sticky placement
- Trowel drag
- Resin-rich areas
- Uneven texture
- Higher material cost
Too Little Resin
- Dry or crumbly mortar
- Poor consolidation
- Excessive porosity
- Weak edges
- Aggregate loss
Do not add aggregate or resin in the field unless the written system
instructions permit the adjustment.
Mortar Placement and Compaction
Mortar must be compacted sufficiently to close internal voids and
establish the required surface without overworking the resin.
A controlled installation includes:
- Setting guides, screeds, or elevation references
- Placing material within its working time
- Maintaining a consistent mortar thickness
- Compacting edges, corners, drains, and terminations
- Keeping tools clean without introducing contaminants
- Maintaining a live edge between batches
- Inspecting for dry pockets and open texture
A porous mortar surface may require one or more grout or seal coats to
close voids and create the required finish.
Self-Leveling Flooring Systems
Self-leveling resinous flooring is formulated to flow and produce a
relatively smooth, seamless surface. The term does not mean the
material will automatically correct every slope, depression, ridge, or
elevation problem.
Successful placement requires:
- Measured floor elevations
- Completed repairs and sealed openings
- Correct primer application
- A known material quantity for each placement area
- Correct gauge-rake or spreader setting
- Prompt delivery of mixed material
- Maintained wet edges
- Approved air-release or spiked rolling
- Protection from drafts, debris, insects, and traffic
Self-Leveling Does Not Mean Self-Correcting
Flowable resin follows gravity and existing elevations. It may collect
in low areas and become thin over high spots. Unsealed cracks, joints,
penetrations, and floor openings can allow material to drain away.
Survey the floor, repair openings, and calculate material quantities
before installation.
Edges, Terminations, and Vertical Surfaces
Flowable systems require defined termination points. Material may need
to stop at:
- Doorways
- Floor drains and trenches
- Expansion joints
- Equipment pads
- Stairs and ramps
- Transitions to other flooring
- Wall and cove interfaces
Terminations may require saw cuts, keyways, metal strips, coves, flexible
sealants, or other approved details. Plan these before mixing begins.
Primer and Pore Sealing
Broadcast, slurry, mortar, and self-leveling systems often rely on an
approved primer. Primer application may:
- Wet the prepared concrete
- Improve adhesion
- Reduce air release from pores
- Reveal porous or absorptive areas
- Receive aggregate or the next flooring layer
Porous concrete may absorb primer unevenly. Dry areas, pinholes, or
open pores should be corrected using the manufacturer's approved
procedure before a flowable layer is placed.
Outgassing and Air Release
Air escaping from concrete, repairs, or porous layers can create
pinholes, bubbles, and craters.
Risk may increase with:
- Rising concrete temperature
- Direct sunlight
- Highly porous concrete
- Aggressive surface profile
- Inadequate primer
- Porous patches and underlayments
- Excessive mixing or rolling
Follow the system's primer, timing, temperature, and air-release
requirements. Do not continue rolling material after it begins to set.
Mixing and Batch Consistency
Every batch should have the same component ratio, aggregate quantity,
mixing time, temperature, and delivery sequence.
Use:
- Complete premeasured units when practical
- Clean containers and specified mixers
- Timers for every batch
- Separate measuring controls for permitted aggregate additions
- Batch records
- Dedicated mixing-station supervision
- Immediate delivery to the placement crew
Inconsistent batches can produce changes in flow, thickness, color,
texture, cure, and strength.
Crew Staging and Production Flow
These systems require a coordinated production process. Assign
responsibilities before mixing begins.
Mixers
Verify products, control proportions, time batches, and maintain records.
Material Runners
Deliver batches promptly without spilling or delaying placement.
Spreaders and Finishers
Control thickness, elevation, wet edges, compaction, and finish.
Broadcast and Detail Crew
Apply aggregate and complete edges, drains, coves, and terminations.
Controlling Thickness
Thickness must be controlled across the entire floor—not merely averaged
from total material use.
Control methods may include:
- Measured placement areas
- Known batch volume
- Gauge-rake or screed settings
- Depth gauges or spot checks where appropriate
- Material-use calculations
- Elevation references
- Inspection of high and low areas
High spots can create thin flooring. Depressions can consume additional
material and delay cure.
Grout Coats and Seal Coats
Broadcast and mortar systems often require one or more grout or seal
coats to:
- Lock aggregate in place
- Fill surface porosity
- Control final texture
- Improve cleanability
- Provide color and chemical protection
- Create a suitable surface for the final topcoat
Insufficient seal coat can leave open texture, exposed aggregate, and
sanitation problems. Excess material may fill too much texture, puddle
in low areas, or reduce desired traction.
Choosing the Right System Form
| Project Priority |
Possible System Direction |
| Decorative texture and moderate build |
Decorative flake or quartz broadcast system |
| Heavy-duty impact and resurfacing |
Trowel-applied mortar system |
| Smooth, seamless, cleanable finish |
Self-leveling or flowable system |
| Efficient medium-build installation |
Slurry or slurry-broadcast system |
| Aggressive slip-resistant texture |
Broadcast system with controlled seal coats |
| Slope correction |
Compatible mortar or approved underlayment before flooring |
This table is only a starting point. Chemistry, thickness, service,
details, moisture, cure, and manufacturer requirements must also be
considered.
Do Not Change the Approved Aggregate
Aggregate type, size, shape, gradation, cleanliness, and moisture
content affect resin demand, flow, strength, texture, and appearance.
Do not substitute locally available sand, decorative material, or
traction aggregate without written approval from the flooring-system
manufacturer.
Common Installation Defects
| Defect |
Possible Contributors |
| Bald or resin-rich broadcast areas |
Late, uneven, or insufficient aggregate broadcast. |
| Dry or crumbly mortar |
Incorrect resin-to-aggregate ratio or poor compaction. |
| Rake or screed lines |
Incorrect setting, poor technique, viscosity change, or delayed rolling. |
| Pinholes and bubbles |
Outgassing, porous concrete, trapped air, or insufficient priming. |
| Cold joints and batch lines |
Slow mixing, poor staging, insufficient labor, or lost wet edge. |
| Uneven texture |
Inconsistent aggregate, seal-coat coverage, scraping, rolling, or troweling. |
| Thin areas |
High spots, inadequate material, incorrect tool setting, or uneven spreading. |
Installation Checklist
- Confirm the system form matches traffic, impact, texture, and appearance requirements.
- Verify the specified chemistry and installed thickness.
- Inspect concrete profile, cleanliness, soundness, moisture, and repairs.
- Seal cracks, joints, penetrations, and openings as required.
- Establish terminations, elevations, slopes, and drain details.
- Confirm primer and pore-sealing requirements.
- Condition resin and aggregate properly.
- Use approved clean, dry aggregate.
- Plan batch size, crew assignments, and application direction.
- Use a timed, repeatable mixing procedure.
- Control gauge-rake, screed, trowel, and broadcast technique.
- Maintain wet edges and consistent batch timing.
- Measure material use and installed thickness.
- Inspect each layer before applying grout, seal, or topcoat.
- Protect the completed system throughout cure.
Key Takeaway
Broadcast, slurry, mortar, and self-leveling systems use resin and
aggregate in different ways. Their performance depends on selecting the
correct system form and controlling preparation, proportioning,
thickness, placement, texture, sealing, and cure.
The application method is part of the flooring design—not merely a
way to spread material.
Knowledge Check
1. What is the basic difference between a broadcast system and a slurry?
Show answer
A broadcast system places dry aggregate into wet resin. A slurry
mixes resin and aggregate into a flowable material before it is
spread across the floor.
2. Why must excess broadcast aggregate be removed before recoating?
Show answer
Loose aggregate can interfere with coverage, texture, adhesion, and
the uniform application of grout or seal coats.
3. Why does self-leveling material not automatically correct an uneven floor?
Show answer
The material follows gravity and existing elevations, collecting in
low areas and becoming thin over high spots unless the floor is
surveyed and the placement is planned.
4. What can happen when an epoxy mortar contains too little resin?
Show answer
The mortar may become dry, crumbly, porous, poorly consolidated,
weak at the edges, and prone to aggregate loss.
5. Why should aggregate substitutions require written approval?
Show answer
Aggregate size, shape, gradation, cleanliness, and moisture affect
resin demand, flow, strength, texture, appearance, and system
performance.
Technical References
Consult current editions, the project specification, and the flooring
manufacturer's written system requirements. Relevant references may
include:
-
ASTM C579: Standard test methods for compressive
strength of chemical-resistant mortars, grouts, monolithic
surfacings, and polymer concretes.
-
ASTM C307: Standard test method for tensile
strength of chemical-resistant mortar, grouts, and monolithic
surfacings.
-
ASTM D4060: Standard test method for abrasion
resistance of organic coatings by the Taber Abraser.
-
ASTM D7234: Standard test method for pull-off
adhesion strength of coatings on concrete using portable pull-off
adhesion testers.
-
ICRI Technical Guideline No. 310.2R: Selecting and
specifying concrete surface preparation for sealers, coatings,
polymer overlays, and concrete repair.
-
The resin and aggregate manufacturers' current technical data
sheets, safety data sheets, mix instructions, aggregate requirements,
thickness requirements, coverage rates, recoat windows, and cure schedules.
Laboratory results provide comparative information under stated
conditions and do not replace evaluation of the actual service
environment. Standards and manufacturer instructions may be revised;
verify the required edition before use.
