A functional and purpose-built floor is key to a safe and hygienic production environment. Floors that are hygienic, non-slip, easy to clean, and durable provide a safe and attractive place to work. 

pilger bakery

 

Choosing and installing the right floor is critical to every work environment. This article looks at getting it right the first time--achieving satisfactory and long-term flooring in a food processing environment.

 

Substrate Design

Designing the substrate of a floor-just like all the other elements of a production area including columns, walls, equipment, and drains--depends a lot on the overall layout of the building.  All elements together will affect how the substrate is installed, and where floor joints will be placed.

 

Joints

One of the reasons joints are needed in a floor surface is to compensate for the movement of the concrete slab below. In general, the size and flexibility of a joint is determined by the amount the building moves. 

 

Joints are typically one of the weaker points in a floor.  Take chemical resistance, for instance.  It’s often considerably lower in flexible joint sealants than it is in the surrounding floor finish, especially if it’s tile.

 

Joints can’t be eliminated, but their number can and should be kept to a minimum.  They should be placed away from areas that are subject to high traffic but close to areas where there are high temperature variations (so as to allow for resultant floor movement) and close to high elevation points to avoid moisture.  They should also be detailed properly to stand up against stresses caused by small hard-plastic wheels and passing traffic, preferably by using prefabricated joint profiles.

 

Concrete Screed and Slab

Most substrates installed under a hygienic floor are cement-based. These are “in-situ” concrete structures installed directly on the ground or suspended from above.

 

Screeds aren’t as thick as slabs and are normally used to provide falls, or to create a new floor base in a renovation project.  Fully-bonded screeds follow the joint structure in the concrete substrate and are generally 75 mm thick or less. Non-bonded screeds are thicker.

 

Substrate slabs of good design are characterized by the least number of joints possible, and placing them in low-risk areas. 

 

Falls, Drainage and Junctions

Channels and gullies should be placed close to, but never under, processing equipment.  This will ensure they do their job while still remaining accessible to cleaning and maintenance.  Moving liquid across the floor to a drain is best  done using gravity created by floor falls--a gradual slope as the term suggests.  There are no set gradient standards for falls in food plants, but they generally range between 1:100 and 1:80. 

 

Falls, drains, and junctions will affect the number of joints and how they’re positioned.  A junction to a circular gulley, for instance, does not need a joint, while a junction between a long, wide channel and the floor-especially if exposed to high traffic, hot liquids, and movement--will.  Movement can be minimized through correct placement of concrete reinforcement under the channel.  Meanwhile, falls can be simplified by using longer channel drains.

Floor Finish

Floors in food and beverage manufacturing facilities must meet several different requirements. The surface has to be easy to clean and must not support bacteria growth. The surface should prevent slips and falls, and look appealing as well.  It should be robust enough to handle all possible assaults from forklift traffic, harsh cleaning chemicals, bumps and bruises, and thermal shocks.

 

The regulation for floor surfaces in the European Food Safety Directive 852/2004 states the following:

 

“Floor surfaces are to be maintained in a sound condition and they must be easy to clean and, where necessary, disinfect. This will require the use of impervious, non-absorbent, washable and non-toxic materials unless food business operators can satisfy the competent authority that other material uses are appropriate. Where appropriate, floors are to allow adequate surface drainage.”

 

A key concept behind this and the rest of the regulation is simple: unless floors are properly maintained and sanitized, they can become a breeding ground for harmful microorganisms. A common pathogen found on floors in food premises, for instance, is Listeria Monocytogenesca, which studies have shown can actually become persistent if not managed properly.

 

This occurred in a tragic case in 2009 in Canada, where this pathogen remained undetected in production machinery and other parts of a meat processing facility until it killed 22 consumers and injured dozens of others. 

 

There are other examples. Granted, flooring surfaces are not food contact surfaces, and some may argue that for this reason not a lot of attention needs to be paid to them. This attitude is very risky, simply because microorganisms, if present on the floor, can potentially be transported through water droplets, air particles, or other means onto food products and the packaging materials that contain them.

Impermeability

Hygienic floors are ones that are easy to clean and not conducive to bacteria growth.  An important characteristic of a hygienic floor is impermeability, or lack of porosity. This feature is often best provided by dense resin-rich systems.To improve their grip, some resin systems include aggregate in the binder liquid.  Caution is required, however, in how much aggregate is used.  That’s because if the ratio of aggregate weight to binder exceeds  8:1, pores in the resin surrounding the aggregate particles won’t close properly.  Topcoat sealants can be used to compensate for this, but these tend to wear out rapidly from normal traffic and abrasion resulting in a decrease in floor performance and food safety, not to mention a likely increase in maintenance and plant downtime. 

Anti-Slip Properties

The most common method of providing grip to new flooring is to broadcast aggregate onto the top of the wet surface before it hardens.   Aggregtate varies in size and type and can create numerous profiles.  The most common types are silica, quartz, flint, and aluminum oxide.

 

Transparent topcoats are applied over the aggregate to lock it in.  They prevent premature breakout, thereby extending the life of the anti-slip surface. Some resin-rich mortar systems come with aggregate already included, but they’re generally not as rough as broadcast systems. 

 

Better slip resistance requires greater surface roughness.  This, however, makes the floor more difficult to clean.  The trade-off between the two is determined by what’s taking place on the floor, the cleaning regime, and the type of contaminants that are present. 

 

The degree of slip resistance needed will likely vary from one part of the facility to another.  For instance, processing and cooking areas laden with oil and moisture will have greater demands than drier packaging and dispatch areas. 

 

There are number of tools available that can help producers define the level of slip resistance they need.   Some of the best known are the Pendulum Tester (EN 13036-4) and the Ramp Test (DIN 51130).

 

Flooring manufacturers have independent test results based on these and other testing norms.  Ask to see them.  While all measures on paper are useful, it’s still always a good idea to do a real-life roughness test in a small out-of-the-way area of the floor you want to install before going ahead with outfitting the entire space.

 

Odor

Bad smell can result in loss of products during production, and loss of sales at retail.  Odors inside the plant can include strong solvents, such as styrene and other highly volatile materials, which if inhaled can seriously affect employee health.

 

Solvents and other volatile organic compounds (VOCs) can leave a strong odor, some more than others, and the best safeguard against being exposed to them is simply to not have them present at all. In fact, most food plants have prohibited use of any coating systems containing solvents or ones that create hazardous odors. 

 

There are some coatings and surface materials on the market that emit odors while being applied, but becoming “non-taint” after they’ve cured.  In these cases, it’s important to track the time it takes for the product to set and become non-tainting.  Use only those materials that have been independently lab tested for their non-taint potential.

Durability

Mechanical shocks and impacts, wear, abrasion, exposure to chemical agents, thermal shocks, high point loads, and dragging and shifting pallets are examples of the many stresses affecting floors in a food processing plant. Falls of heavy objects, knives, hooks or other sharp objects can lead to crack in the floor.

 

The greater the thickness of the floor, the greater its ability to provide good resistance to these and other assaults.  Recommended thickness will depend on a detailed assessment of the type and magnitude of specific stresses the floor will encounter. For resin-based flooring in a food processing facility, 3 mm thickness is a minimum, but a thickness of 6 mm or more is better, especially in wet areas. For tile, thickness typically ranges anywhere from  approximately 8.5 to 20 mm, but a minimum of 12 mm will protect any high load areas.

 

When it comes to chemical resistance, different floor coatings react differently to type, concentration, temperature, and exposure duration, and should be assessed individually.   Among the most challenging are phosphoric or nitric acids, and caustic or chlorine solutions used to clean  production equipment, floors, and walls.

 

Other hazards are elements that are part of normal production, including lactic, citric, and acetic acids, blood, wet sugar, oils, fats, greases, and others.  It’s important to note that even if the relative amounts of these compounds are relatively low, evaporation can increase their concentration and corrosive properties.

 

Temperature in a plant can affect evaporation.  It can also exert significant stresses on its own.  That’s because temperatures in a food or beverage plant can often vary widely and rapidly. 

 

For instance, the temperature of the floor adjacent to a freezer may range from 0 °C or below to an ambient 21 °C or higher. The flooring system must be able to function in both conditions. What is more difficult to deal is thermal shock, which is caused by a sudden and large change in temperature, up to  100 °C or more and then back again, in a few minutes or even seconds. Thermal shocks can be caused by high temperature spills from cooking, washing and cleaning of vessels and pans.  They can also occur from hot CIP (cleaning-in-place) fluids and hot water rinses that are drained from production equipment and onto the floor after high temperature cleaning and sanitation.

 

Thermal shock can cause the flooring system to crack and in some cases de-laminate. To prevent this, the floor should have a thermal expansion coefficient close to that of the concrete substrate below, good cohesive strength, and a low modulus of elasticity.  Thickness of the floor also plays an important part.   The top layer should be no less than 9 mm thick for water or chemical discharges up to 90° C., and thicker for temperatures that are higher.

Installation

In food processing environments, especially when renovating, installing a new floor can be a bit challenging. One reason is the substrate may have a high moisture content, which can affect adhesion.  Another reason is the substrate may be contaminated with detergents and other residues from production.

Dealing with higher than average moisture conditions is usually a matter of choice.  Some flooring systems allow higher moisture levels in the concrete substrate than others, along with lower curing temperatures and shorter curing times of only a few hours. 

It’s important to choose a contractor who has experience in dealing with these and other variables, and whose workers are certified by the flooring manufacturer to install the products you choose.  A good result depends on good planning and good cooperation of all parties involved in the project.

Conclusion

There are a number of reasons that floors fail.  One has to do with poor design and construction of the substrate, another is that the floor finish is not suitable for its planned use, a third is a poorly executed installation and poor detailing.

It may seem ironic, but often it’s the most expensive floors that fail the most. And when floors fail, it’s no small matter.  Refurbishing and repairing a floor means downtime, which in turn means lost revenue.  On average, count on at least one week for a typical refurbishment of a floor, depending on the size and complexity of the repair.

An important feature of resin floors is they are continuous.  And with a good substrate design, the whole floor area can be made seamless, which greatly improves hygiene.  Minimizing joints further lessens hygienic issues while improving durability and life of the floor. 

At Sika, we can help you get the right floor installed properly from the start.  Please don’t hesitate to contact us.  In addition to making your project happen on time and on budget, we’re available at anytime to answer any questions you may have.

SIKA wishes to acknowledge and thank Mr. Timmerman for the excellent consultation he has provided to the company on the subjects of cleaning and other matters regarding the hygienic management of floors and wall systems.

GUIDELINES FOR A SUCCESSFUL FLOORING SELECTION AND INSTALLATION

The following are a few guidelines for project managers and engineers responsible for specifying and installing floor and wall coating systems: 

1. Consult with the floor manufacturer and other suppliers early in the design process and again throughout the project.  Coordination between the manufacturer, concrete contractor, and other suppliers can eliminate problems in the overall project.  

2. Select the surface texture for anti-slip purposes by considering worker safety as well as cleanup and sanitation aspects. Test potential solutions in a small test area first before deciding on the whole floor.

3. Provide detailed specification for your flooring supplier, including exact material performance expectations, installer qualifications, and sample area selections and workplace limitations.

4. Specification and selection criteria should include:

  • how to position drains
  • how to handle joints, ie., how to limit their numbers and how to place them in non-critical areas
  • how to design concrete substrates and screeds to handle stresses
  • how to make slopes drain effectively
  • how to construct details at junctions, drains, coves, and walls
  • how to ensure resistance of the floor finish to chemicals, temperature and thermal shocks
  • how to maximize long-term mechanical resistance, especially under high wear and impacts
  • how to minimize equipment vibration  through use of elastic sealants
  • how to use elastic sealants to connect metal drains and the floor slab
  • how to build effective equipment bases
  • how to maximize the hygiene of the flooring, i.e., non-taint, easy to clean, and unable to support bacteria growth
  • how to access independent tests that verify your requirements

5. Make sure that the flooring contractor has experience with similar jobs, preferably in food industry, and has relevant installation certifications

6. Ensure and promote clear lines of responsibility and communication between the main contractor, installer, floor manufacturer, and other stakeholders.

References

H.L.M Levieveld, M.A Mostert and J. Holah: Handbook of Hygiene Control in the Food Industry. 2005

EN 13036 (British Standard): Road and airfield surface characteristics – Test Methods. Part 4: Method of measurement of the slip/skip resistance of a surface: The pendulum test.

DIN 51130 (Germany). Testing of floor coverings; Determination of the anti-slip property -  Workrooms and fields of activities with slip danger, walking method – ramp test.

J. Holah and H. L. M Levieveld: Hygienic design of food factories. 2011 Fussboden Technik: Bodenanforderungen in der Lebensmittelverabeitung. 01/2002