Full-Track Power Trowel Cut sheet

• Full-Track walk behind power trowels
  

Patented in USA, Europe and China

• Unique spider attachment arms and stabiliser ring system
  

Exerts a constant and simultaneous pressure on all four blades giving a better, flatter finish in less time

• Quick change blades
  

Are attached by just a single bolt at the end of each arm which allows the blades to be changed quickly, easily and safely.

• Specially designed Gear box and Variable speed clutch
  

Allows speeds from 40 RPM to 200 RPM reducing finishing time and operator fatigue

• Centrifugal safety switch
  

Will shut off the engine within one quarter turn

• Stainless steel Handle
  

Is maintenance free and features rigid pitch adjustment (not cable) to
maintain the correct pitch of the blades

• Warranty 5/3/1
  

Five
years on Spider unit,
Three
years on gear box,
one
year all other parts

Full-Track power trowels will get your floors done fast!

Specifications

Type	Ø Cage Inches	Ø Work Inches	Engine HP	Weight Lbs	Floating Blades	Combo Blades	Finish Blades
FT432	34.4	32	6.5	176	●	●	●
FT436	38.4	36	6.5	196	●	●	●
FT448	50.4	48	9.0	242	●	●	●

 

Only use Walk Behind Power Trowels for Lightweight Concrete

Finishing Lightweight Concrete

 

Lightweight-aggregate, air-entrained concrete is increasingly used to cast interior, above-grade floors. There are two principal reasons for its use: cost savings and fire resistance, lightweight concrete floors are typically 25% to 35% lighter than regular concrete aggregate mixes, so there can be considerable cost savings realized by designing longer span floors with lighter structural members. Lightweight concrete slabs can also be significantly thinner than ordinary aggregate mixes and still achieve equivalent fire ratings.

Nothing has really changed in the science of lightweight concrete mixes. The same time-honored rules apply to placing and finishing. When to begin finishing is the most critical issue. Using newer equipment and technology, contractors will sometimes assume they can start finishing slabs earlier. The advent of “pan” floats makes it possible to begin finishing operations before the concrete is sufficiently firm. This can cause surface regions of a slab to be more compacted. Petro graphic studies showing compacted surfaces of ½ to ¾ inch deep, when ? to ¼ inch is normal for properly timed and finished concrete floors.

The other potential problem involves the use of riding power trowels, even though they are often used successfully on lightweight concrete. These trowels can weigh from 620 to 2200 pounds, not including the weight of the operator. With that amount of concentrated load, they can deflect the metal deck under the concrete and are capable of producing overly compacted surface finishes—sometimes down to half the thickness of a slab. Deeper compaction due to early finishing could lead to delaminating.

Lightweight concrete mixes— high air, high slump the primary reason for using lightweight concrete on a deck is to lighten the load on the structure. most specifications require mixes with unit weights of 110 to 115 pounds per cubic foot at equilibrium (weight after a sufficient interval of drying, when the relative humidity of the concrete reaches that of ambient conditions). “You can’t achieve these equilibrium densities with aggregates alone,” “Adding air entrainment in the range of 6% to 7.5% (and sometimes higher) is needed in order to meet specified weights.” So the adage that you shouldn’t use a power trowel on air-entrained

Concrete doesn’t apply in the case of lightweight concrete; you can use a power trowel, but only with proper timing.

A typical fire-rated lightweight mix calls for compressive strengths between 3500 and 4000 psi. Most lightweight concrete is pumped, with 4000-psi mixes being favored. The aggregates are generally ¾ inch minus and must be saturated with water before mixing. Pre-soaked material and then keeps a water sprinkler running over the aggregate pile. Cementitious content is typically 564 pounds per cubic yard (6 bags of cement). Slump at the pump may be as much as 8 inches in order to facilitate pumping. Normally one might expect more shrinkage and curling resulting from these mix proportions, but Gibbons says there are minimal problems. This is because the mix water not required for hydration leaves the slab slowly, resulting in well-cured concrete.

Lightweight concrete mixes are normally used for new construction, and the slabs are generally covered with carpeting. Five or 6 months can elapse from construction to the installation of finished flooring, providing time for excess moisture to leave slabs. Carpeting is the most frequently used covering, and it provides adequate moisture vapor transmission. When finished surface products that are sensitive to moisture are installed, slab relative humidity should be monitored carefully.

Timing is everything although pan floats and riding trowels make it possible to start finishing earlier, they also increase the risk of delaminating. Common finishing procedures are still the best.

Notify your ready-mix producer several days before you need concrete so there is time to stock the aggregate and pre-soak it. The pores in aggregate should be adequately filled.

After placement, wait for all bleed water sheen to disappear from the surface of the concrete before starting floating operations. When you step on the fresh concrete, your footprint indentation shouldn’t go deeper than ? to ¼ inch.

To be safe, use walk-behind finishing machines instead of ride-on machines.

Again, for safety, use float pads on your finishing machines rather than pan floats.

Don’t “burn” the finish. Lightweight floors are almost always covered with carpet, so over-finishing is unnecessary and increases the risk of problems.

Floor flatness tolerances of FF30 or 35 (FF25 is a more reasonable specification) with hard-trowel finishes. These requirements escalate the risk for possible delaminating, so greater attention to the timing and details of finishing must be observed. Use a walk-behind trowel with float pads for the first finishing step. The next step is switching to pan floats, which may be mounted on riding trowel machines. Final troweling operations are completed with riding trowels. “It’s very difficult to achieve higher FF requirements without the use of riding trowels,”

Summary There are many advantages associated with lightweight floors, especially on metal decks, but there is also a potential for delaminating. The timing of finishing steps is the critical element

Craze Map Cracking

Reducing Craze Cracking

Crazing

It’s called craze cracking or “alligator cracking,” and the more serious form “map cracking,” which effects serviceability. Craze cracking is primarily a cosmetic issue but store and warehouse owners sometimes raise objections when they see craze cracks on their floors fearing that it will lead to serviceability issues over time. But this isn’t the case because the cracks have no significant width or depth.

Craze cracks are very small and are found in the top surface regions of a slab. They are typically 1/10th of a millimeter (or 0.004 inches) or less in thickness and 1 millimeter (approximately 1/32-inch) in depth. Also there aren’t surface delimitations between the cracks. Many craze cracks aren’t even visible until the surface of a floor gets wet and starts to dry.

It seems there is a greater incidence of craze cracking on floors now but we may be more aware of them because more owners are using concrete floors as the finished surface. Craze cracking happens to everyone who installs floors. The goal is to minimize them with these suggestions.

Why it happens

As a contractor you can work to minimize craze cracks but you can’t eliminate or prevent them. The natural process of carbon dioxide (CO2) from the air combining with calcium hydroxide and other cement compounds to produce calcium carbonate causes a small amount of shrinkage on the slab surface. You can reduce the width and depth of craze cracks to avoid map cracking related problems.

Work on your mix designs

There is a trend toward using well-graded mix designs with large top-sized aggregates for retail and warehouse floor construction to produce durable floors with less shrinkage and curling. Concrete for floor slabs must be finish-able and sometimes additional small aggregate and cementitious material is excessive, resulting in more and deeper craze cracks. In addition, many floor mixes now include fly ash or slag as replacements for some of the Portland cement in the mix. The Blaine fineness of these particles (the particle size or fineness of a cement determined from air permeability tests) is higher than Portland cement, causing increased water demand and more shrinkage.

Companies always trying to find ways to minimize craze cracking in its floors. They minimize both the amount of water and cement in the concrete. Adds that they used to see craze cracking a lot in their topping mixes because the mixes commonly had 850 pounds of cement per cubic yard. Their goal is also to lower the water-cement (w/c) ratios.

Finishing considerations

The potential for craze cracking increases with the thickness of the cement paste and fine aggregate at the surface of a slab. The potential increases by using vibratory strike off tools or by early floating procedures. Large aggregate is driven down while more fine aggregate and paste rises to the surface resulting in more craze cracking. If you see “corn rows” developing between the blades or excessive cement spatter on a riding trowel, the finishing procedures started too early. Excessive bull floating immediately after strike off can increase the thickness of the paste region at the surface too.

Curing

Without proper curing there is more shrinkage, especially on the top of a slab where drying occurs first. Good curing reduces the potential for significant craze cracking. “Burned” trowel finishes compact concrete even more, further reducing the amount of water. So it’s important to keep a slab moist starting immediately after the last finishing operation followed by wet curing. Wetting and drying a slab surface afterward isn’t curing and doesn’t help.

Curling effects on Flatness of Concrete Floors.

The Effect Concrete Curling can have on Floor Flatness

Concrete Curling Effect Examined

Concrete Curling is measure when floor flatness and levelness are measured using F-number technology, timing of measurements is critical because curling of slabs on ground increase with time. The result is decreased F-numbers that may not meet specified values. Changes in F-numbers may present problems for the floor covering contractor who has an expectation of how flat and level the floor should be. The higher the initial FF number, the greater the negative effect of curling. Because of this, Section 4.8.4.1 of ACI 117-06, “Standard Tolerances for Concrete Construction and Materials,” requires that:

“Floor test surfaces shall be measured and reported within 72 hours after completion of slab concrete finishing operations and before removal of any supporting shores.”

The required time limit applies to both F-numbers (FF and FL) and gap under-straightedge measurements made in accordance with ACI 117-06, but it wasn’t always that way. Contractors should check to make sure what ACI document the project specs require. Even though ACI 117-06 is published, 80 percent of the projects are still using ACI 117-90 and a few still uses ACI 117-81.

Requirements for timing of measurements

The first ACI tolerance document, ACI 117-81, stated that:

“Floor tolerance measurements should be made the day after a concrete floor is finished and before shoring is removed, in order to eliminate any effects of shrinkage, curling, and deflection.”

However, when ACI 117-90 was published, Section 4.5 included different provisions for the timing of the measurements:

FL levelness tolerances shall be measured within 72 hours after slab concrete placement.

Floor finish tolerances as measured with a 10-foot straightedge must be done within 72 hours after slab concrete placement.

There was no time requirement on measuring FF floor flatness, and the commentary gave a reason:

“Since neither deflection nor curling will significantly changes a floor’s FF value, there is no time limit on the measurement of this characteristic.”

The statement in the commentary indicating that “neither deflection nor curling will significantly change a floor’s FF value” has since been shown to be incorrect. This is why ACI 117-06 required that all measurements – FF, FL and the gap under a straightedge – be made within 72 hours. However, not all specifiers and contractors are aware of this change. The next section explores the effects of curling on F-numbers and why the change was made.

Concrete Curling effects on F-numbers

Slab curling is caused primarily by differences in moisture content or temperature between the top and bottom of the slab. The slab edges curl upward when the top surface is drier and shrinks more – or is cooler and contracts more – than the bottom. Curling is most noticeable at construction joints, but it can also occur at saw cut joints or random cracks. The curl can result in a loss of contact between the slab and sub base. Generally, the length of lost sub base contact is about 10 percent of the slab length (measured between joints) at each joint that has load transfer (doweled or saw cut joints), and about 20 percent at each joint with no load transfer. These percentages, however, are also a function of joint spacing, concrete properties, slab thickness and sub base stiffness. Upward curl at slab corners can be as high as 1 inch but is typically about 1/4 inch.

For the most part, contractors understood that curling had an effect on F-number measurements. F-number measurements made 6 to 9 months after the concrete slab had been placed often indicated that the floor had indeed changed, because these F-numbers were lower than F-numbers measured within 72 hours of placement.

Reports on two sets of F-number measurements – one for a University of Maryland gymnasium floor and another set for an industrial warehouse slab in Pennsylvania – illustrate the magnitude of changes that occurred over time. The F-number measurements were taken within 72 hours of placement, then 7 months later for the University of Maryland floor and 12 months later for the industrial warehouse slab.

The University of Maryland data was summarized in three different testing locations along the floor:

Measurement lines parallel to the construction joint and in the middle of the strip

Measurement lines parallel to, and 1 foot away from, the construction joint

Measurement lines perpendicular to the construction joint and crossing all six placements

The box above shows that the FF values at the University of Maryland decreased by about 10 to 20 percent in 7 months.

The initial measurements for the industrial warehouse in Pennsylvania were taken in October 1990 and the final measurements in October 1991. The initial overall FF and FL were 68.7 and 73.4, respectively. One year later, the FF and FL numbers were 41.4 and 36.8, respectively. The floor flatness values had decreased by about 40 percent and the floor levelness values by about 50 percent. A sample floor surface profile illustrating the vertical deviation of the floor at the two different ages is shown in Figure 1. Curling is certainly evident in this figure as shown by the significant peaks at each saw cut joint.

 

Figure 1. Floor surface profile of an industrial warehouse illustrating changes in flatness with time. The green line represents elevation measurements taken a year after the red line measurements were taken.

Predicting effects of curling on F-numbers

As mentioned previously, the length of lost contact area as a result of curling is about 20 percent of the joint spacing length at each end of the slab. For a 15-foot joint spacing, the slab curl would be expected to change the profile for about 3 feet from each end. It is possible to take F-number readings from floors with differing profiles, download those values into a spreadsheet, then add a known amount of curl, and calculate new F-numbers. This allows a comparison of F-numbers before and after the curl.

Using this analytical procedure, we recreated the F-number data for the industrial warehouse by starting with a 15-foot panel and working with an analytical F-number profile that was FF 69 and FL 72. The actual industrial warehouse slab had a 15-foot joint spacing and was initially measured as FF 69 and FL 73. The initial analytical and measured surface profiles before curling are nearly identical. Upward curling values of 1/16 inch, 1/8 inch and 1/4 inch were assumed, along with profile variations being represented by a curve starting 3 feet from each end of the panel. Table 1 shows the results.

Table 1. Calculated changes in F-numbers for varying heights of curl.

As stated, the initial measured F-numbers for this slab were FF 69/FL 73 and these had dropped to FF 41/FL 37 a year later. This represented changes of about 40 percent and 50 percent for FF and FL, respectively. These are about the same percentage changes shown in Table 1 that would result from slightly less than 1/8 inch of curl. For the surface profile shown in Figure 1, the average curl is about 1/8 inch. This provides some verification that the analysis method gives a reasonable estimate of as-built curling variations with time.

This analysis method was also used to examine the effect of curling on floors with initial 15-foot joint spacing’s and considered to be moderately flat, flat and very flat as defined in ACI 117-06. Table 2 summarizes the data.

Table 2. Analytical results showing the effect of curling on floors with 15-ft. joint spacings, and initially finished moderately flat (FF 25), flat (FF 40) and very flat (FF 51.)

The amount of curling, as measured by upward deflection values ranging from 1/16 inch to 1/4 inch, had a greater effect on the flatness of the floors with higher initial FF numbers. Flatness of floors with an initial FF 25 didn’t change much for curling deflections of 1/16 inch and 1/8 inch. A curling deflection of 1/4 inch, however, resulted in a significant reduction in flatness.

Based on this analysis method, the ACI 117-90 statement that curling will not significantly change a floor’s FF value is not generally true. As shown by the analysis, floors with an initial FF 25 would experience a flatness change of less than 10 percent when 1/8 inch of curl occurred. At 1/4 inch of curl, however, the percentage change is much larger. For a higher initial FF value, even 1/16 inch of curl can cause a reduction in the FF value of about 10 percent. This analysis indicates that floors with high initial FF values will be more adversely affected by small amounts of curl.

Both analytical and measured values of initial and final surface profile measurements before and after curling have shown that curling can significantly affect F-numbers. To eliminate any curling effect, all F-number measurements must be made within the 72 hours stated in ACI 117-06.

Observing the time limit on F-number measurement is essential

To ensure that F-number measurements reflect only the floor flatness and levelness resulting from the concrete contractor’s efforts, these measurements must be made within 72 hours after completion of slab concrete finishing operations. Otherwise, low F-numbers are likely to be the result of curling. Thus when the floor covering contractor arrives, disputes over the floor flatness and levelness may arise. The cost for grinding or patching a floor that has curled needs to be discussed prior to construction.

Important Power Trowel Checking’s

Important checking’s

Check the bolts that attach the blades. If these bolts were loose it would be very dangerous when the rotors begin to turn. It could also affect the balance of the machine and make the trowel wobble during use.”

I also suggest, “Just as we do in our cars, it’s important to let the FULL-TRACK trowel motor idle running a few minutes before putting it on the concrete slab.”

Weekly:
Weekly inspections emphasize a closer look at your FULL-TRACK trowel’s bottom end. A bent spider arm – the part of the trowel that holds the blades or pans – can result in a swirling pattern or waviness to the finish. An experienced operator can recognize these problems during operation, but noticing these problems during a job can often be too late to fix them in time to save the slab without re-work. FULL-TRACK offer special designed spiders which will provide a constant and simultaneous pressure on all blades. This means a significant reduced deviation with much lower than the allowed tolerance levels and allows that your blades are all working on the same level.

Another maintenance item you should add to your weekly checklist concerns the drive belt. Rubber drive belts will disintegrate with heat. Make sure your trowel’s belt is in good condition, and change it when you begin to notice wear. “A lot of people use third-party belts and usually that’s not a problem, but with variable-speed FULL-TRACK trowels with a torque-compensating drive system, those belts are very specific to the application, and you need an exact match.

Monthly:
Monthly maintenance items take a step beyond your daily & weekly engine maintenance checks. In other words, while you’re checking oil levels and air filters daily & weekly, you should plan on monthly replacement or cleaning. Be sure to examine your engine manufacturer’s recommendations to determine the best engine maintenance schedule. Not all engines are the same, power trowel engines will generally need more frequent oil changes than liquid-cooled engines.

Full-Track Power Trowel Instructions

Power Trowel Action plus instruction

Timing is essential in the concrete flatwork business. The quality of the floor is established inside the period between placing and curing of the concrete. Concrete contractors know their livelihood depends on their capability to have the right device ready at the right time.

This is where the rental center enters the scene. Power trowel rentals can be a win-win situation for both the rental center operator plus service provider. The time saved on the job by renting a power trowel can far outweigh the actual rental price of the device plus will keep the service provider coming back for more trowel rentals.

Power trowels are used for together floating plus finishing large slabs. Compared to ordinary hand tools, power trowels radically add to production plus decrease expenses via their capacity to envelop additional square footage of slab area per day. At the same time, they enhance the condition of the concrete surface and help sustain flatness of the slab. Power trowels are divided into two styles, walk-behind plus ride-on.

Walk-behind trowels usually have one rotor with 4 blades, are driven by a gas engine plus are available in 32-, 36- plus 48-inch blade diameters. In general, hand tools might finish 300 to 600 square feet per day where as a 36-inch walk-behind power trowel can finish 700 to 1500 square feet per day depending on job circumstances and weather conditions.

Ride-on trowels generally have two rotors each with four or five blades are powered by one or two gasoline engines and are available in 36- plus 48-inch (single rotor diameter) models. Ride-on models can dramatically add to production. Generally, a ride-on can envelop three to five times as much concrete compared to walk-behind units. Depending on the jobsite conditions and operator proficiency, one ride-on model can replace three to four walk-behind units. Another advantage with ride-on units is improved condition and flatness off the slab.

Ride-on trowels operate in two different configurations, overlapping and non-overlapping. Usually, the non-overlapping position of the blades requires higher torque plus can accommodate pans during the floating action. The overlapping position is often used at faster rotor speeds and provides seamless coverage during the finishing process.

Besides the trowel themselves, rental center operators need to offer the correct blades for the job. In general, blades are interchangeable between most brands of walk-behind plus ride-on power trowels as long as both are the same size, i.e. 36- or 48-inch. Standard finish, combination and float blades are made of high quality steel and bolted to the trowel arms.

Float blades are 10 inches wide, with the edges turned up so the blade won’t penetrate or tear the fresh concrete surface. These blades are the first blades used on fresh concrete plus are usually rotated at a relatively low rpm. Float blades should be adjusted to little or no pitch (flat on the surface).

Finish blades are sometimes referred to as troweling blades. They are 6 inches wide with the ends turned up and are commonly rotated at a high rpm. Finish blades follow the floating function. They apply more pressure to density the surface as the concrete hardens. They are used to complete the power troweling procedure.

Use of FULL-TRACK Power Trowels for casting Concrete

How to Do Concrete Floor Casting Using a FULL-TRACK Power Trowel Machine

Using a Full-Track power trowel machine for casting concrete floors gives the finished product a professional look. Full-Track Power trowels are used for both floating and finishing concrete floors. Compared to hand trowels, Full-Track power trowels significantly increase the productivity and quality of the finished product. They come in walk-behind and riding models and they are in-expensive. However, consumers can rent power trowel machines from tool rental businesses for a reasonable amount, and then they don’t have to worry about the large expense or upkeep of the machine.

Difficulty: Moderately Challenging

Instructions:

Step 1) Rent a Full-Track power trowel machine. Unless you can buy or borrow a power trowel machine, rent one from your local home improvement store. Read the machine’s instructions because you don’t want any surprises once the concrete is ready to set.

Step 2) Prepare the area. If the floor requires any wooden forms before the concrete is poured, make sure your forms are in the correct positions. Brace the forms securely to avoid frustrating mistakes later on. Make sure the floor is reinforced according to local regulations.

Step 3) Determine how much concrete you’ll need by measuring the floor and multiplying the square footage by the depth of the intended floor. Add five to 10 percent to account for losses or spillage.

Step 4) Pour the concrete evenly on a cool, humid day. If you pour it in hot, dry weather, it will dry out before it cures properly. Have several helpers available to help you rake the concrete evenly over the area for the floor. This should be done quickly. Using a side-to-side motion, rake it evenly over the form.

Step 5) Use a bull float to float the surface and remove air bubbles from the concrete. Push the bull float away from you across the surface until the entire surface has been worked.

Step 6) Wait until the concrete has cured enough that you barely leave a print on the concrete when you walk on it.

Step 7) Before starting the Full-Track power trowel machine, check the machine for gasoline, oil and water levels. Wear safety glasses and a dust mask, and make sure that onlookers stand at a safe distance from the machine.

Step 8) Connect the battery wires. Make sure you read the operation manual for instructions specific to your model.

Step 9) Run the machine across the surface of the concrete, overlapping rows, until the entire surface has been smoothed and is completely level. If you desire a non-slip surface, you may need to roughen it up after you are done with the trowel machine.

Step 10) Clean the concrete off of the power trowel machine with water. An old paint brush can help to loosen concrete that has started to harden. Never get water on the engine while you clean the machine.