Build-Up Method

Trowel Applied Mortar Systems

Trowel applied mortar systems is the heavy build method we use when a bund has to take mechanical loading, thermal shock or chemical attack that a film coating cannot survive. Resin bound mortars and polyurethane concrete are placed by hand, compacted to thickness and finished as a single high integrity layer, sitting between protective coatings and reinforced lay up. Where forklifts roll, hot product spills and drums get dropped, this is the build up that holds.

Overview

How Trowel Applied Mortar Systems Work

We treat a trowel mortar system as a placement operation more than a coating one. The material is heavy, fast stiffening and self supporting, and the discipline is getting it down at consistent thickness and properly compacted across the bund. Our standard sequence is:

When Is This Required?

  • Substrate assessment: concrete soundness, profile, moisture and freedom from contamination, since trowel mortars rely on a strong mechanical and chemical bond to the slab.
  • Aggressive surface preparation: abrasive blasting, scabbling or shot blasting to ICRI CSP 5 to 9, exposing a deep profile the mortar can lock into.
  • Detail repair: broken arrises, blowholes and spalled corners reinstated with compatible polymer mortar before priming.
  • Slurry or scratch coat primer: a thin bond layer worked into the prepared substrate, giving the trowel mortar a wet film to adhere to.
  • Mortar mixing: in controlled batches, with strict ratio, mix time and pot life, since over or under mixed material is a common cause of early failure.
  • Trowel placement: at specified thickness, worked from screeds, datum pins or preset rails for a controlled finished level.
  • Compaction: by trowel pressure or specialist tooling to expel air and consolidate the mortar against the substrate.
  • Surface finishing: smoothed, textured or broadcast with aggregate to suit the duty, from a slip resistant tanker bay to a smoother factory floor or hygienic food area.
  • Optional sealing topcoat: applied once the mortar has cured, for a chemical resistant surface or an aesthetic finish.
  • Cure, inspection and testing: before any return to service.

Trowel Mortar Types

Resin bound trowel mortars: heavily filled epoxy, vinyl ester or novolac systems, the workhorse mortar lining for industrial bunds with chemical and mechanical loading.
Heavy duty acid resistant mortars: vinyl ester binders with selected aggregates, for plating lines, acid stores and reagent bunds.
Conductive trowel mortars: formulated to ATEX compliant electrical resistance, for solvent and fuel bunds where static dissipation is part of the safety case.
Polyurethane concrete (PUC or PUMA): cementitious PU hybrid mortars with outstanding thermal shock resistance, commonly specified for food and beverage production floors and bunds.
Cement mortar linings: polymer modified cementitious systems for lower aggression duties, or where compatibility with the concrete substrate matters more than chemical performance. Related to the cement mortar pipe linings used in water mains, but specified differently for bund work.
Slip resistant trowel mortars: broadcast or integrally textured for traffic and wash down areas where underfoot grip is needed.

Trowel Mortar Performance and Thickness

A typical trowel mortar in bund service is built to substantial thickness in a single placement. The right range depends on what the system has to absorb:

  • Light-duty applications: 4–6 mm, where mechanical loading is moderate but a mortar build is preferred over a coating for substrate or wear reasons.
  • Standard-duty applications: 6–12 mm, the typical specification for production floors, plant rooms and general-purpose industrial bunds.
  • Heavy-duty applications: 12–25 mm, used on tanker offload aprons, drum decks, forge shop floors and any zone with sustained mechanical or thermal loading.
  • Extreme-duty applications: 25–50 mm, applied where impact, wear and thermal shock combine, including foundry, heavy industry and high-end food production environments.

Once cured, a properly placed mortar system delivers a robust, monolithic layer with measurable adhesion to the substrate, holiday-free coverage and a service life that typically reaches 15–25 years on demanding duty when properly maintained.

Materials

Trowel Mortar Material

The right material depends on the duty above the floor, as chemistry, temperature and the cleaning regime all narrow the choice. The materials in our range that we apply as part of a trowel applied mortar system are:

Epoxy Resins

The most common binder for trowel mortars in industrial bund service, offering a dependable balance of chemical resistance, mechanical performance and value across most duties.

Polyurethane Resins

The basis of polyurethane concrete and PU screed mortars, the natural choice for thermal shock duty and the food and beverage sector where hot CIP and cold handling alternate daily.

Polyurea Resins

Generally not used as the binder in trowel mortar systems because their rapid cure is incompatible with hand placement and compaction. We apply polyurea as a sealing or topcoat layer above a trowel mortar where the duty calls for it.

Vinyl Ester Resins

The standard binder for acid-resistant trowel mortars, used in plating lines, reagent bunds and any acid-handling area where epoxy mortars would be chemically degraded.

Novolac Epoxy Resin

Uprated chemistry for hot acid, hot solvent and elevated-temperature mortar duty, including hot oil quench tanks and severe chemical service.

Advantages

Advantages of Trowel Applied Mortar Systems

  • The highest mechanical loading capability of any bund lining build-up, easily handling forklift, drum and plant movement
  • Excellent thermal shock resistance, particularly with polyurethane concrete systems, which absorb hot–cold cycling that cracks rigid coatings
  • Single-pass high build that delivers substantial thickness in one application, without the multi-coat cure stack of a film system
  • Self-supporting around features such as kicker walls, kerb edges and step changes, where coatings cannot hold profile
  • Robust against impact, dropped tools and incidental damage, with a long service life under heavy use
  • Compatible with broadcast aggregates and integral texture for slip resistance, including hygienic finishes for food production environments
  • Provides both chemical resistance and a structural wearing surface in a single specification
Limitations

Trowel Mortar Limitations and Considerations

  • Cost: higher upfront cost than film coatings, justified only where mechanical, thermal or chemical loading require it.
  • Longer programme: the material is denser, mixing is batch controlled and cure between layers is significant.
  • Rougher finish: than a coating, with more dirt traps and reduced cleanability where hygiene matters.
  • Needs skilled applicators: an inexperienced trowel team leaves cold joints, voids and finish defects.
  • Sound substrate needed: trowel mortar amplifies slab problems beneath it rather than hiding them.
  • Limited flexibility: mortars are essentially rigid, with no meaningful crack bridging across moving substrates.
  • Not always the barrier: severe chemical duty is sometimes better held by a vinyl ester FRP or GRP lay up.
Get Expert Lay-Up Advice

Need a lay-up specified for a demanding bund?

Speak to Reschem about the right laminate build-up, resin choice and inspection regime for aggressive chemical duty, confined structures or long-life containment assets.

choosing

When to Choose Trowel Applied Mortar Systems

We specify a trowel mortar build up when one or more of these apply:

Forklift, Drum and Plant Traffic Resistance

The bund will see significant forklift, drum or plant traffic that a coating film could not survive

Thermal Shock Resistance

Hot product spillage or steam cleaning will create thermal shock that rigid coatings cannot absorb

Heavy Mechanical Wear

The duty involves heavy mechanical wear. Tanker offload aprons, drum decks, forge floors foundry slabs

High-build Rebuild

The substrate has surface damage that justifies a high-build rebuild rather than a thin-film overlay

Structural Wearing Surface

A monolithic, structural wearing surface is required as part of the bund's design rather than a sacrificial layer

Chemical and Mechanical Performance

The operator wants a single specification that delivers both chemical and mechanical performance, with the topcoat and barrier integrated into the mortar

Slip Resistance

Slip resistance and underfoot durability are essential, including in food and beverage hygiene-led environments

Applications

Trowel Mortar Applications and Industries

Trowel applied mortar systems are the heavy duty default across several sectors and structure types:

Food & Beverage

Polyurethane concrete production floors, ingredient stores, cold rooms and hot CIP areas where thermal shock and hygiene are both part of the design case.

Chemical Processing

Acid bund mortars, plating lines and reagent stores where vinyl ester and novolac mortars hold up under aggressive chemistry.

Oil, Gas and Petrochemical

Tanker offload aprons, drum decks and heavy-duty forecourt areas where vehicle and drum movement combine with hydrocarbon exposure.

Sewage and Waste Water Treatment

Sludge cake reception floors, lorry loading bays and tipping areas where mechanical wear and BSA chemistry meet.

Power Generation and Transmission

Transformer maintenance bays, generator yard aprons and standby fuel offload zones with vehicle loading.

Agriculture & Aquaculture

Silage clamp wear floors, AD plant tipping floors and feed pad bunds with tractor and trailer movement.

Nuclear Facilities

Shielded floors, decommissioning yard hardstanding and heavy-duty handling areas where mechanical and chemical loading combine.

Prep

Surface Preparation Requirements

  • Prepare concrete by abrasive blasting, scabbling or shot blasting to ICRI CSP 5 to 9, removing all laitance, oil and unsound concrete and exposing a deep mechanical profile.
  • Prepare steel features by abrasive blasting to SA 2.5, primed within the manufacturer's window.
  • Reinstate details: broken arrises, spalled corners and blowholes made good with compatible polymer mortar before slurry coating.
  • Check moisture is below the manufacturer's threshold, normally under 4% by weight, by hygrometer or calcium chloride test. Polyurethane concrete tolerates higher moisture but still needs verifying.
  • Confirm temperature is within the resin's envelope and at least 3°C above dew point, monitored across the day.
  • Apply slurry or scratch coat primer immediately before the mortar, while still wet, to give a positive bond layer.
QA

Trowel Mortar Quality Assurance and Testing

  • Visual inspection during placement and finishing, confirming consistent thickness, no cold joints and a defect-free surface.
  • Thickness measurement using witness pins, calibrated datum points or destructive coupons at representative locations across the bund.
  • Hardness testing post-cure, using Shore D or Barcol gauges as appropriate to confirm the mortar has reached its specified hardness.
  • Adhesion pull-off testing at agreed locations, confirming bond strength against the design value, particularly important on trowel mortars given the loads they carry.
  • Holiday (spark) testing of any sealing topcoat layer to identify pinholes and discontinuities.
  • Pre-handover hydrostatic (wet) test of the bund where the system forms part of secondary containment and integrity has to be evidenced before service.
Frequently Asked Questions

Trowel Applied Mortar System FAQs

Most trowel mortar projects cause moderate to high disruption over several consecutive days, covering aggressive substrate prep, slurry coating, mortar placement and cure before the bund can return to service. Programmes are usually compressed into planned shutdowns rather than spread across phased outages, since cold joints between batches are a common failure point.

Our Work

Featured Case Studies

View all projects
Get Independent Expert Advice

Get Independent Expert Advice

Speak to our technical specialists about your bund lining requirements. Free, no-obligation site surveys available nationwide.