Abrasive mats with bristles are recommended for outdoor use, as they can be used to clean all manner of shoes – even those with a deep tread.
The size of the sweeper and therefore the efficiency of the cleaning operations depend largely on the size of the surfaces to be cleaned:
— Walk-behind push sweepers with a dirt storage capacity of up to 30lt are suitable for cleaning smaller surfaces of up to 300m²
— Walk-behind vacuum sweepers with traction drive (petrol/ diesel motor or batteryoperated) fitted with a suction element and filter system are used for medium-sized surfaces of up to 1,000m²
— Ride-on vacuum sweepers with a large container capacity and hydraulic high container emptying are used for largescale surfaces of 1,500m² or higher.
Aside from these options, cold water high-pressure cleaners are generally brought into operation if there are stubborn stains to be removed, e.g. moss, lichen, bird droppings, chewing gum or food residue. Care should be taken to ensure that enough water is available to easily loosen the dirt and transport it away from the area (600lt/h and higher). Hot water high-pressure cleaners are more adept at removing greasy stains. The cleaned surface also dries off much more quickly.
A dirt collection system tailored to the area in need of cleaning also falls under the umbrella of preventative cleaning. Mats should be distributed liberally in both the entrance and exit areas of a doorway, as people can use them to remove dirt from their shoes and thereby prevent it from being carried further into the building (at least four steps in length). Abrasive mats with bristles are recommended for outdoor use, as they can be used to clean all manner of shoes – even those with a deep tread. Indoor mats can have softer and finer bristles to remove the final traces of dirt and moisture. Soiled mats can also be regularly exchanged for clean ones or thoroughly cleaned themselves.
Gentle weed removal
Dealing with weeds effectively is a constant challenge. There are chemical products for this purpose, but these are bad for the environment and in countries like Germany are permitted for use in public spaces under very strict circumstances. Regular sweeping or solutions involving hot water, as well as mechanical brushes, are possible alternatives.
Prevention – regular sweeping
Prevention is the best cure to protect against the spreading of weeds. If you want to prevent weeds from coming up in the gaps between the tarmac and the curb, for example, regular sweeping is unavoidable. This is because it not only removes the plants’ seeds, but also the dust and dirt which, combined with rain water, create an ideal substrate for weeds.
In full growth – water and steam
Where high growth of weeds is not a particular problem, removal can begin later in the year. In this case, hot water is the most effective method. The water is heated to around 99°C and is around 92°C by the time it reaches the roots, unlike hot air, which only affects the plant itself. If temperatures above 65°C are reached there, an excess of ascorbic acid forms – which the roots transmit to the leaves, thereby destroying the plant. After treatment with hot water, the weeds look like wilted spinach; two to three days later and the weeds have completely reduced in size. This method can also be used on loose surfaces such as gravel or the red sand of sports grounds, unlike sweepers.
Alexandra Lachner
for Alfred Kärcher SE & Co. KG
