Concrete is rated for strength by its ability to maintain shape and rigidity under crushing pressure. The results are measured in pounds per square inch of pressure, or “psi”.
Average driveway concrete often has a compressive strength of around 4,000 psi. This supports the weight of cars, SUVs and two-axle box trucks without cracking or crumbling.
In comparison, Agri-Rok has a compressive strength of about 10,000 to 12,000 psi when poured as an overlay over existing concrete.
This puts Agri-Rok into the realm of what the American Concrete Institute defines as High Strength Concrete. High-Strength Concrete is usually found in building projects such as skyscrapers rather than flooring applications – even floors intended to have semi-truck traffic are often made from concrete with no more than a 5,000 psi compressive strength.
For perspective, a grown man of average weight jumping up and down exerts about 80 psi on a surface, but that’s because his weight is spread out through his two feet measuring approximately twelve inches long each. If you could focus that man’s weight onto a square inch, you’d get pressure of about 3,000 psi every time he landed. An 80,000 to 100,000 pound truck obviously creates far more pressure but it’s spread out across a much greater area, allowing concrete to maintain it’s shape as long as the truck is simply driving or parking on it.
However, a nagging problem with concrete floors in an industrial setting occurs when forklift drivers turn the same corner on a steadily repeated basis. The specific stress of this activity ends up calling for a much denser, stronger floor than usually necessary.
Industrial floors are recommended to be poured using 4,000 psi concrete occasionally reinforced with bars or mesh, making it strong enough to handle most activity in a manufacturing setting. A common axle weight for an industrial forklift is about 10,000 pounds; when in use, the forklift often carries another 12,000 pounds of cargo, spreading 22,000 pounds across four wheels that connect to the concrete in about a 1’ x 1’ strip each. This spreads the weight of a loaded forklift to about 38 psi, which sounds completely reasonable.
However, this doesn’t factor in what happens when the forklift brakes and turns a corner, especially while loaded.
Cornering causes the truck to bear down far more heavily on the tires to the inside of the turn while braking, creating a grinding effect that basically stretches the concrete and makes it begin to crumble quickly.
Agri-Rok is well-suited to correct this problem since it bonds quickly and easily to previous floors and has the strength to withstand both the stretch and wear of even heavily-loaded forklifts. At 10,000 psi, it's well above the recommended concrete compressive strength even without the addition of re-rod or wire mesh to support it.
One of our most successful applications of Agri-Rok to date has been inside the loading area of a busy manufacturing facility where forklifts load and unload shipments from docked semis. The floor in this area had become eroded to rough aggregate and riddled with cracks, making it both unsightly and unsafe. After resurfacing with Agri-Rok, plant maintenance personnel tried using a sledgehammer on the new overlay to test its comparative strength against more normal concrete. Where the former concrete would’ve cracked and chipped under the hammering, Agri-Rok shrugged it off without even a dent…as it’s continued to do under the daily grind of forklift traffic that destroyed its predecessor.
That's what a "high compressive strength" ultimately means.
We've gotten a lot of hands-on experience with Agr-Rok the past few years as we answer questions from interested potential customers regarding whether the super-dense cement overlay will work for their particular application.
We've had some fascinating requests, including some really tricky ones like seeing if we can use a combination of Agri-Rok and biological sealers to cover an ocean sea wall and repel barnacles (this one's still in progress). Brainstorming sessions have sometimes gotten pretty interesting as we try things like mixing a colloidal silica troweling aid into the dry mix instead of water to see if it will become even denser. Our experiments have sometimes succeeded and sometimes failed - we haven't yet been able to find the right product that will reliably color the overlay without weird marbling or floating issues, for instance.
In the process we've learned some great tips.
1.) Agri-Rok gets stronger the less water you put in it, so don't add more. When first mixing, it doesn't seem like the correct amount of water is enough since the product initially looks very dry, but when mixing continues the dry mix suddenly melts into the perfect chocolate-milkshake consistency. The instinct to add more water at the beginning always causes problems, so the key to the right blend is to measure the water properly and resist the urge to add more.
2.) Temperature, temperature, temperature! The correct temperature of water and base floor is important to a good fast set. We once laid Agri-Rok over a newly-installed cement slab during a very cold February. There was a heater in the room, but everything was still icy to the touch and the Agri-Rok stubbornly refused to set for several hours. Considering it normally hardens to the touch in about half an hour, this was unexpected and set back our finishing process by a whole day. Using very cold water in the mix can have a similar effect, slowing the set time. Hot water will make it set too fast, before it's properly mixed. So keeping the temp at 60 degrees or more for the water and the floor definitely improves the results.
3.) Don't overmix: you'll whip bubbles into the overlay and it takes a lot more raking/troweling to get them to all rise to the surface and settle. Once the dry mix and water melt together and turn into milkshake consistency, pour it down and start raking. Otherwise there will be a quantity of small bubbles that need to be hand-troweled out, which is a pain in the neck for what is otherwise a ridiculously easy install process.
One of the biggest assets of an Agri-Rok overlay is undoubtedly it's high chemical resistance. CIP procedures are usually so harsh and abrasive that regular concrete disintegrates fast, especially since the material being cleaned off them eats away at surface in between cleanings.
We've focused initially on making a product available that would halt such disintegration, lengthening the life of the floor and reducing the downtime associated with repairing or replacing it. Since the problem with disintegrating concrete is mainly acid attack, we've presented a cement overlay that successfully resists acid.
But there's another facet to the whole issue: the character of the cleaners typically applied to industrial and agricultural concrete floors.
For years, the focus of health inspectors, janitors, vets and sanitation experts has been to destroy microbes populating dirty floors. Even visibly clean floors undergo frequent and rigorous testing because of pathogens lurking invisibly on the surface, which explains why a lot of time and effort goes into reducing crevices and dirt and other imperfections that allow killers like listeria or PEDv to flourish. So everyone scrubs and sprays and disinfects and does their very best to make sure nothing lives on their floors, whether they be in barns, poultry houses, milk parlors, packing plants or loading docks.
It's proved to be a losing battle.
No matter how much we kill, it's almost impossible to keep everything as clean as it needs to be as much as it needs to be to stop all bacteria or disease outbreaks.
Enter the probiotic cleaner.
Probiotic cleaners have a huge advantage over traditional CIP brews for a couple of reasons: they are non-toxic, PH-neutral, work without extensive scrubbing and have an afterlife that continues keeping a surface clean for several days after application.
We've been following the development of probiotic cleaners for some years now and are pretty excited by the results in a broad array of case studies. It's not easy for any farmer or healthy professional to step out and try something as unusual as an anti-disinfecting disinfectant, given the penalty of failure; but pioneers around the country are testing this new concept with surprising and encouraging results. Probiotic cleaners have been hugely effective at reducing disease and failed inspections in poultry houses, cattle barns, hog barns (where there was even success at stopping the spread of PEDv in a farrowing barn), equine barns, hospitals, schools, food service industries and more. If there's a potential bacteria problem, these powerful little bugs have been hitting it out of the park.
Probiotic cleaners work in multi-pronged ways: they use a basic cleaner to remove dirt, an infusion of live "good" bacteria to devour the shields bad bacteria build to protect themselves from harmful elements, and the same good bacteria to populate the surface and crowd out bad bacteria.
The issue with bacteria is a substance called "biofilm", a substance closely related to plastic that bacterial colonies exude to protect the colony from anything that might kill it. Biofilm is incredibly hardy, shrugging off even highly concentrated chemicals and high-heat water jets. The only thing that really damages it normally is friction, which is especially nasty because it means the bacteria or viruses sheltering beneath the biofilm are available to rub off onto people or animals and cause disease outbreaks even after the affected surface has been thoroughly disinfected.
Probiotics dismantle biofilm, allowing the bacteria to either be easily washed away or die from exposure to elements. This means the surface is deep-cleaned without dangerous fumes, corrosive effects or extensive scrubbing. After cleaning, probiotics can be reapplied to the surface to essentially crowd out and starve bad bacteria, leaving it no place to rest and grow.
Different industries have different specific solutions, but the essential goal is the same: dismantle biofilm and make surfaces no longer receptive to housing bad bacteria. In animal husbandry applications, there's a formulation injected into water lines to keep them clean (it's actually good for the guts of the animals drinking it), a surface cleaner that does wonders with even the toughest cleaning tasks, and a mist formula that's used in barns to keep all surfaces and animals covered with good bacteria to keep the bad bugs at bay.
The combination of probiotic cleaners with Agri-Rok acid resistant overlays promises to be a huge leap in the ability of both industrial and agricultural professionals to maintain sanitary, productive facilities. The applications are so exciting and varied that one of our biggest difficulties is holding ourselves on course and not trying to branch out in too many different directions.
Hey, if you had a floor which would resist the normal wear and tear and a really good cleaner which wouldn't break down even normal concrete...wouldn't that change your maintenance outlook for the better?
Abbatoir containment pens and livestock walkways have a unique set of conditions requiring multi-faceted solutions to remain in use long term with minimum repair downtime. Because stress reduction on the animals is such a huge consideration in this type of facility, the surfacing material used on the containment pens and walkways is a high priority.
How Does Agri-Rok Cement Overlay Help Meet These Goals?
Agri-Rok is a quick-curing cement overlay which bonds with concrete to produce an extremely dense, strong surface which is both acid and wear resistant, having a tensile strength of 10,000 PSI versus the usual average of 3,000 PSI for normal concrete. It does not require special preparation beyond a basic powerwashing of existing surfaces and does not create fumes or acidic dust that must be mitigated before being put to use. It is sold as a dry mix which is blended with clean water immediately before application and can be poured, troweled or sprayed-in-place depending on the surface being covered.
It's strange to think of good old rock-hard concrete as vulnerable, but anyone who deals with concrete in a tough acid environment like a hog or dairy farm will tell you it doesn't stand a chance long term. After a few years, bare concrete is usually eaten away to the point where it looks like a gravel pit more than a floor.
There are several culprits for this annoying deterioration, but the primary trouble is acid exposure.
The basic structure of concrete - while it seems tough and impervious to the naked eye - is basically porous. It's made up of sand and a variety of different rocks of various sizes that are linked together by Portland cement, which is a combination of "limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore" according to Cement.org. When Portland cement is mixed with water to form a paste, it binds all the various additives together and forms concrete.
Because Portland cement's inherent PH balance is alkaline (typically around an 11), the bane of it's existence is acid, such as acetic acid, proprionic acid and butyric acid: all components of livestock manure.
If a concrete component hasn't been formed from a dense, low moisture mix, it begins to break down very quickly under an acid attack. But even well-laid concrete doesn't hold up long. Many acids such as lactic acid (a byproduct of bacteria which can infest silage grains) or sulfuric acid (a byproduct of anaerobic bacteria in sewage or manure pits) begin to break down the concrete binding structure almost immediately. Cement turns into a type of water-soluble calcium under acid attack and literally gets washed away, leaving only larger rocks and other debris behind. Even before reaching the point of crumbling away, concrete components which have been surface-eroded by acid often have to be replaced simply to keep things hygienic.
There are three basic ways to halt or slow this process in a highly acidic environment like a manger or livestock pen. The first is to put a protective barrier like an epoxy coating on the concrete to keep acid from reaching it. The second is to basically optimize the ingredients in the concrete mix to make it as impermeable as possible. The third is to continually wash down the surface with an acid-neutralizing agent like baking soda to try to keep acid from getting a chance to start eating the concrete.
Agri-Rok falls under a hybrid of the first and the second options: to coat the concrete and reduce permeability, which seriously cuts back the chances of an acid being able to eat away at the structure of the overlay or the concrete beneath. By making the Agri-Rok itself inherently acid-resistant as well, the whole package has succeeded very well in the goal of a quick, easy way to extend the life of a barn well beyond it's current expectancy.
And that's why we're excited about this product!
With a steadily growing knowledge of food-borne bacteria and how it functions, the USDA is now upping the ante on food producers when it comes to floors, drains and methods of sterilization. A good example of the new standards is found in the July, 2011 paper Milk for Manufacturing Purposes and its Production and Processing - Recommended Requirements:
"The floors of all rooms in which milk or dairy products are processed, manufactured, packaged, or stored or in which utensils are washed shall be constructed of tile properly laid with impervious joint material, concrete, or other equally impervious material. The floors shall be smooth, kept in good repair, graded so that there will be no pools of standing water or milk products after flushing, and all openings to the drains shall be equipped with traps properly constructed and kept in good repair."
It's a case of USDA on one side, OSHA on the other, and a whole lot of headaches and money spent in between. You've got to strike just the right balance between keeping bacteria-hiding crevices to a minimum and not creating a skating rink for workers. The fewer flaws in the surface, the less likely you are to build colonies of nasties like E. coli, salmonella, and the biggest baddie of them all, L. monocytogenes. But a floor which perfectly shrugs off micro-organisms is tough to safely work on.
For almost a hundred years, dairy brick (vertical fiber red shale brick) has been the go-to favorite for any food industry floor, followed closely by acid brick, which has been carefully fired for additional corrosion resistence. Tough, attractive, adaptable and time-tested, these floors are often what industry producers wish they could install when they settle on epoxy to better fit their budget.
Standard dairy or even acid brick floors have their downside, however. Even when correctly bedded and grouted, it's gradually become apparent they can never be cleaned thoroughly enough for the USDA's ever-more-exacting standards. Advanced cleaning methods containing powerful staying-power chemicals like sodium hypochlorite quickly begin to corrode the tiles and chip away at the grout, making them even less sanitary. The process of making the bricks non-slip creates small crevices and pores where liquid and septic bacteria take up permanent residence. Dairy brick isn't a good choice if inspectors are looking for a "smooth" floor "kept in good repair" and the corroded/open pore issue means bacteria transfer rate can become a serious problem. Some of the more spectacular recent food poisoning outbreaks have been caused by hidden bacteria on the floor becoming airborne during cleaning or construction and landing on equipment that was already clean and supposedly sanitary.
One of our favorite alternatives to standard dairy or acid brick is a product called VERSI-LINE (formerly Blome) Vitrified Ceramic Tiling Systems (VTS). It has a few unique properties that make it really stand out in a market presenting a bewildering array of possible replacement options. Made by the Denmark-based company Hempel, these tiles are made from a highly non-porous type of clay only found in certain regions of Italy. While even the best acid or dairy brick typically has an absorption rate of just under 5%, VTS comes in around 0.5%, giving it a fantastic hygiene standard when properly cleaned. (As always, proper cleaning is the real first line of defense...as long as your floors aren't sabotaging your efforts!)
Available as both floor and wall tiles in a variety of colors, VTS offers a similar classic appearance to dairy brick while actually being quicker and easier to install. It's unusually tight jointing process allows it to be laid without spacers and smoothly sloped toward drains; and as a bonus, it's small grout lines (about 2 mm wide) add to it's corrosion-and-microbe-resistant properties.
As far as slip hazards go, VTS is easy on the HACCP plan. The tiles come with several slip-resistant pounded surface (rather than cut or cinder-embedded) choices that leave them non-porous but safe to walk on while wet with just standard tread shoes.
Because it holds up so well to the high-stakes cleaning situation of food production floors, the cost of installing a Vitrified Ceramic System floor sees a pretty respectable return on investment when the lifespan of the floor stretches far beyond the average 10 years until replacement. VTS initially comes with a 5-year warranty but is ultimately designed to last for a whopping 20 - 30 years.
A quick average-lifespan comparison of several types of food production floor options:
Epoxy (1/4" troweled): 8 years
Urethane Concrete: 10 years
Acid/Dairy Brick: 20 years
Vitrified Tile: 30 years
If you're looking to install a floor in your facility that will help you beat the 39% odds your next floor swabs will come back contaminated, VTS might just be the best route to go.
One of the big challenges in developing a product like Agri-Rok is the age-old dance of form versus function.
Ed Reed has a good name in the pork industry, especially in Michigan. Hailing from a beautiful little place on the western side of the Big Mitten called Marcellus, Ed left the life of a pulp-and-paper professional to begin raising pigs farrow-to-finish in a venture he says has been like having one long start-up business.
Part of his feeling of being in a start-up probably comes from his willingness to innovate and try new products. He has had his fingers in a lot of pies - including serving as president of the Michigan Pork Growers' Association, a board member of GreenStone Farm Credit and working tirelessly to promote sustainable practices among pork operations in his jurisdiction.
One of the new products tested at Reed Family Farms recently was Agri-Rok.
The Achilles heel of any swine barn - farrow, gilt, gestation or finish - tends to be the concrete areas around and below feed/water supplies. Between the liquid feed, the particularly acidic quality of pig waste and the pigs' tendency to root at everything, you have a unique challenge when it come to keeping up with pig house floor repairs. Finding a product that would work well for ongoing small repairs as well as new construction without creating a long downtime is quite a boon. And as a bonus, finding one that a single handyman can put down by himself is particularly useful.
After using it in a variety of small repairs beginning in 2013, Ed commented, "We have found Agri-Rok to be a cutting edge hard rock concrete solution for multiple uses to include finishing barn floors, gestation barns, troughs, etc. A quick and economical installation which is easy to feather."
One of the biggest benefits, he says, has been Agri-Rok's staying power. Pigs are frustratingly efficient at rooting up all manner of coatings, sealers and overlays, making it tough to keep a good barrier protection on the concrete. They can even chip bonded epoxy right off the floor within a year or two. But they've met their match when it comes to Agri-Rok. Ed is pleased to note the pigs haven't succeeded in damaging the Agri-Rok surface despite their best efforts.
A snout-resistant concrete overlay. Who knew?
It's no secret in the dairy business: as your floor goes, so goes your herd. A well-maintained surface on the dairy parlor and feed trough floors can be the difference between sanitary conditions for healthy cows and expensive herd cullings due to lameness and bacterial issues.
There are few stretches of concrete in a dairy operation which take the same beating as the hard-working milking parlor floor. The cream surface can be eaten away in a matter of months, exposing the larger aggregate and creating a whole host of problems, starting with inspections. Sanitation inspectors tend to give bare concrete in the milk house a pretty universal thumbs-down.
Epoxy coatings have been the name of the game for years when it comes to protecting dairy floors, but there've always been a few logistical hiccups. Epoxy is smelly, difficult to prepare for, expensive and takes a long time to cure - especially on cold wet refrigerated floors. The process of applying a good epoxy coating is tough to manage for most farms. You've got extensive surface prep, cure time between coats and the hassle of dealing with a two-component hazardous chemical. Getting the fumes out of the building can be even more of a strain on the time budget. Add in the need for experienced contractors to do the application and that floor gets to be one of the biggest investments in the whole barn.
That's why a super-dense corrosion-resistant concrete overlay like Agri-Rok can solve a lot of problems. A good powerwashing is usually all it takes to prepare the old floor, you can mix and pour the self-leveling overlay with nothing more specialized than a drill mixer, a gage rake and a squeegee, it's odorless and - the best part of all - cures to cow-traffic readiness in less than six hours. No expensive work crews, cure delay, ventilation of hazardous fumes or significant production loss. Add a good sealer and you have a floor ready to shrug off pretty much anything a cow can throw at it. Which can be quite a lot.
Agri-Rok doesn't depend on brand-new technology to work it's magic. The fine-ground quartz aggregate used in Agri-Rok to give it excellent corrosion-resistant properties isn't so much a new idea as an old idea done right. Because quartz is an anhydrite of an acid (orthosilicic acid, H4SiO4), it's extremely resistant to all acids except hydroflouric acid, which most people aren't going to have lying around to pour on their floors. Add in the polymers and other chemical-resistant components bolstering Agri-Rok's cement mix and you wind up with a material two or three times stronger than conventional concrete - which lets you use it in anything from a thick pour to a feather-edge repair.
This means if you have any situation involving corrosives eating a concrete floor - silage juices, cow waste, sanitizing chemicals and the like - Agri-Rok has a good chance of being the answer you need to repair the damage.
Take a quick look at this video to see an Agri-Rok dairy farm repair in action. Thanks for stopping in!