PercoCrete Maintenance

Porous Concrete Sidewalk Cleaning Trial

Using a Leaf/Litter Vacuum Machine

Craig Tosomeen

City Of Olympia

September 2006

What we did:

The City of Olympia, Washington installed a porous concrete sidewalk in 1999.  The surface was pressure washed in 2003.  The sidewalk was swept in 2004.  After a year and a half of no attention the sidewalk was cleaned with a leaf/ litter vacuum machine.  Another section of perco-crete pervious sidewalk was also cleaned at the same time. The cleaning was performed with a Minuteman Parker Vac-35.  This machine applies a vacuum directly at the surface to be cleaned. There are no brushes or scrubbing of the surface. The machine is self propelled and operates at a walking pace. 

How did it do?

The vacuum machines did a great job of removing looses debris on the sidewalk surface and of removing material from the surface voids. The machine operates quickly and was able to collect a large amount of material in a short time. We collected about 100 pounds of material in 30 minutes.  The vacuum machine does a better job of cleaning the surface voids then the sweeping machines tried on the same material.  The vacuum machine was also effective on the perco-crete porous concrete.

We encountered several problems during the trial work. 1) The vacuum machine had a tough time ingesting leaf piles when they were more than 2 to 3 inches thick.  One section of sidewalk is confined on the backside this results in a strip of deep leaf piles.  The vacuum machine had to be slowed down and worked around to collect the piles of leaves.  2) The debris collection bag is the exhaust for the air from the vacuum head. As the bag fills there is less bag for air to leave from resulting in back pressure and less suction force.  The bag should be emptied at half full. 3) The particular machine we used generated a lot of dust when empting the bag. The design of the machine made changing the bag difficult.

Conclusions

Leaf/Litter vacuum are a very effective way to clean porous sidewalks. To be effective the vacuum must be applied to the cleaning surface. The machines operate quickly and effectively.  The choice of a machine should consider the easy of emptying the debris collection bag.  Leaf/Litter vacuums are more effective than sweeper with dust control vacuum systems.

Any sidewalk cleaning program which uses these vacuum machines should probably also include a pressure washing component in the program to restore porosity if debris migrates lower than the level at which the vacuum machines can remove the material.

Photo 1. Minuteman Parker Vac-35 sitting on

PercoCrete Sidewalk

Photo 3.

Close up of cleaned and un-cleaned porous sidewalk

PHOTOS

Photo 2. One side cleaned with vacuum machine

 

PercoCrete Maintenance

PercoCrete is a fines-rich, absorbent concrete made from normal aggregates and cement using a proprietary admixture. The actual mix design will vary based on the particular requirements of each project in terms of aesthetics, performance and use. For instance, the higher the sand content is in the mix design, the finer the surface texture will be allowing most coarse debris such as leaves or pine needles to be swept or blown off. At the minimum, PercoCrete should be maintained once a year to remove any surface debris and hardened surface fines. However, actual maintenance requirements can vary depending on the mix design, site issues and use. The surface can be swept, washed or vacuumed. If the use is high or site conditions are such that fines come onto the surface frequently, more aggressive maintenance is required and may include the need for power washing or vacuum. When designing with PercoCrete in mind, efforts should be made to restrict the flow of debris onto the surface with adequate curbing and sloping of adjacent surfaces.

A valuable tool for PercoCrete maintenance

 
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Vac-35 Litter Vacuum

bulletManual models available with a choice of 6.5 hp and 10 hp
bulletSelf-Propelled models freature 4 forward speeds from 1.5 - 6 mph
bulletEase on/off standard 30" wide (76cm) intake, for cleaning up to 30,000 sq. ft. per hour
bulletRubber skirt and corner guards prevent damage to the intake
bulletChassis constructed of 12 guage welded steel providing solid, reliable framework
bulletLarge capacity 11 cubic foot flet bag comes standard with platform models
9 cubic foot bag included when platform not required
bulletBattery, Propane and Gasoline Powered



The Vac-35 is the first of its kind. It was brought to the market by Minuteman Parker in the mid 1960's and is the premier walk-behind litter vacuum. Thirteen models of the Vac-35 accommodates a wide variety of applications. Excellent on hard surgaces or turf. Unequalled vacuum power for picking up debris, litter, cans and plastic and glass bottles, combined with superior maneuverability makes the Vac-35 the best choice in litter cleanup.

The impeller is a strong but lightweight, aluminum/magnesium alloy. The 5 blade, non-sparking impeller is designed for maximum efficiency and computer balanced at the factory for optimum performance. It creates over 2,000 CFM, reducing debris down from an 8 to 1 ratio. Comes with an anti-wrap ring which prevents debris from wrapping around the impeller and engine avaoiding serious damage.

Hose kits for hard to reach spaces. 15' long hose available in widths of 4", 6" and 8". There is also a 6" by 15' exhaust hose available for dispensing debris into large containers.

Exclusive aerodynamically designed Spin Pak deflector controls airflow to direct debris downward and actually packs it into the bag thus allowing it to hold more leaves, garbage and dirt. All this, while controlling the dust and flow of litter.

Sulky Seat available for self-propelled models. Turning the Vac-35 walk-behind into a riding unit for large cleaning jobs.

Rear tires are 5" x 14" (12.7cm x 35.6cm), fully pneumatic and deeply cleated. Mounted on heavy-duty steel wheels that are positioned for ease of operation and maneuverability. Also, a variable height adjustment front caster comes standard. As an option, a dual front caster for turf use is available.

A large capacity, 11 cubic foot felt bag comes standard with platform models and a 9 cubic foot bag comes with models that do not require a platform. A bag platform is available on most models. Other bags are also available:   a nylon mesh bag for wet conditions and a canvas bag for dusty conditions.


Strong & Lightweight Impeller
5-bladed, non-sparking designed for maximum efficiency


Intake with Magnetic Bar
For Picking Up Nuts, Bolts and Loose Metal


Intake with Scraper Bar
To Break Dirty and Sticky Substances Loose



Specifications:
Manual Models: Choice of:
  • 6.5 hp or 10 hp Briggs & Stratton, gas
  • 8.5 hp Kohler, gas
  • 8 hp Honda, gas
  • 8 hp Kawasaki, propane
    • Self-Propelled Models:   Feature 4 forward speeds from 1.5 to 6 mph   
    Choice of:
  • 10 hp Briggs & Stratton, gas
  • 8.5 hp Kohler, gas
  • 8 hp Honda, gas
  • 8 hp Kawasaki, propane