Rubber mulch is a type of mulch used in gardening and landscaping that is made from recycled rubber, most often crumb rubber sourced from waste tires.
Rubber mulch is a type of mulch used in gardening and landscaping that is made from recycled rubber, most often crumb rubber sourced from waste tires.
Rubber mulch typically consists of waste tire bits or nuggets of synthetic rubber obtained from tires that have been shredded or ground up whole, with their steel bands removed. This process can involve the use of various types of tires, including those from passenger vehicles, large trucks, and trailers. The resulting rubber mulch bits or nuggets range in size from 10 mm to 32 mm, or 3/8 inch to 11⁄4 inch
For landscaping and gardening purposes, both nuggets and buffings of rubber mulch provide insulation for the soil, which can result in a soil temperature difference of 2 or 3 degrees F higher compared to wood mulches.[ citation needed ] Additionally, rubber mulch is advantageous for soil moisture, as rubber is non-porous and does not absorb water as it passes through to the soil. Moreover, it can reduce fungus growth and plant growth while acting as a weed barrier, as weed seeds dehydrate in the mulch before reaching the soil.
Another advantage over plant-material mulches is its elasticity, which gives it a springy quality when used in a fairly thick layer. This makes it a choice for playgrounds, where the springiness provides additional safety for children when they fall off of playground equipment. Tests have shown that rubber mulch is superior in breaking falls [1] to traditional bark mulches. The International Play Equipment Manufacturers Association has certified some rubber mulches for ASTM F1292-09. [2]
Unlike organic mulch, rubber mulch does not enrich soil or increase soil biodiversity through decomposition. Neither nuggets nor buffings provide any humus to compacted soil types. At worst, it leads to soil contamination (see Environmental Impact and Safety Testing) Some recycled varieties may leach chemicals (some toxic) which are harmful to plants [3] [4] [5] Rubber mulch is a particular hazard if ignited because of the resulting fumes that resemble those produced in tire fires. Rubber mulch is also more likely to ignite and harder to extinguish than other mulches. [6] Compared to organic mulches, rubber mulch can become extremely hot when in direct sunlight. [4] There is also concern about the potential for entire rubber mulch nuggets being washed off into waterways or leached chemicals being washed out into the groundwater, causing water pollution in both cases.[ citation needed ]
In the US, the Environmental Protection Agency (EPA) has launched a multi-agency Federal Research Action Plan on Recycled Tire Crumb Used on Playing Fields and Playgrounds to study key environmental human health questions concerning the safety of recycled tire crumb. [7] The EPA previously studied air and surface samples at four fields and playgrounds that use recycled tires. The limited study, conducted in August through October 2008, found that the concentrations of materials that made up tire crumb were below levels considered harmful. In addition, the overall study protocol and many of the methods were found to be appropriate and could be implemented in the field. [8] The study, however, did note that due to its limited nature and the large diversity of materials used to make tire crumb, no definitive conclusions could be reached. [8] More recently, the EPA has released a comprehensive spreadsheet with toxicity reference information. [9]
The California Office of Environmental Health Hazard Assessment (OEHHA) used guinea pigs, in an animal study, to test skin sensitization by playground surfaces made of recycled tires and observed no sensitization. This suggested that these surfaces would not cause skin sensitization in children, nor would they be expected to elicit skin reaction in children already sensitized to latex. [10] The OEHHA has conducted additional studies on potential negative human health effects associated with the use of recycled waste tires in playground and synthetic turf products. [11]
Although rubber mulch is generally regarded as safe, recycled tire rubber leachates do contain certain minerals and compounds which may be ecotoxic in high concentrations. Recycled tire mulch can contain trace amounts of various minerals from the tire manufacturing process and other chemicals that may have been picked up during the tire's service life. The greater the surface area of synthetic rubber waste pellets, the greater the potential for breakdown into harmful constituents. For leached tire debris, the (potential) environmental impact of the ingredients zinc and organic toxicants has been demonstrated. [12]
A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth, and enhancing the visual appeal of the area.
Plastic mulch is a product used in plasticulture in a similar fashion to mulch, to suppress weeds and conserve water in crop production and landscaping. Certain plastic mulches also act as a barrier to keep methyl bromide, both a powerful fumigant and ozone depleter, in the soil. Crops grow through slits or holes in thin plastic sheeting. Plastic mulch is often used in conjunction with drip irrigation. Some research has been done using different colors of mulch to affect crop growth. Use of plastic mulch is predominant in large-scale vegetable growing, with millions of acres cultivated under plastic mulch worldwide each year.
Artificial turf is a surface of synthetic fibers made to look like natural grass, used in sports arenas, residential lawns and commercial applications that traditionally use grass. It is much more durable than grass and easily maintained without irrigation or trimming, although periodic cleaning is required. Stadiums that are substantially covered and/or at high latitudes often use artificial turf, as they typically lack enough sunlight for photosynthesis and substitutes for solar radiation are prohibitively expensive and energy-intensive. Disadvantages include increased risk of injury especially when used in athletic competition, as well as health and environmental concerns about the petroleum and toxic chemicals used in its manufacture.
Agricultural wastewater treatment is a farm management agenda for controlling pollution from confined animal operations and from surface runoff that may be contaminated by chemicals in fertilizer, pesticides, animal slurry, crop residues or irrigation water. Agricultural wastewater treatment is required for continuous confined animal operations like milk and egg production. It may be performed in plants using mechanized treatment units similar to those used for industrial wastewater. Where land is available for ponds, settling basins and facultative lagoons may have lower operational costs for seasonal use conditions from breeding or harvest cycles. Animal slurries are usually treated by containment in anaerobic lagoons before disposal by spray or trickle application to grassland. Constructed wetlands are sometimes used to facilitate treatment of animal wastes.
Organic fertilizers are fertilizers that are naturally produced. Fertilizers are materials that can be added to soil or plants, in order to provide nutrients and sustain growth. Typical organic fertilizers include all animal waste including meat processing waste, manure, slurry, and guano; plus plant based fertilizers such as compost; and biosolids. Inorganic "organic fertilizers" include minerals and ash. The organic-mess refers to the Principles of Organic Agriculture, which determines whether a fertilizer can be used for commercial organic agriculture, not whether the fertilizer consists of organic compounds.
Crumb rubber is recycled rubber produced from automotive and truck scrap tires. During the recycling process, steel and tire cord (fluff) are removed, leaving tire rubber with a granular consistency. Continued processing with a granulator or cracker mill, possibly with the aid of cryogenics or by mechanical means, reduces the size of the particles further. The particles are sized and classified based on various criteria including color. The granulate is sized by passing through a screen, the size based on a dimension or mesh. Crumb rubber is often used in artificial turf as cushioning.
Nike Grind is Nike's collection of recycled materials that is composed of pre-consumer manufacturing scraps, recycled post-consumer shoes from the Reuse-A-Shoe program, and unsellable footwear. The purpose of Nike Grind is to eliminate waste in line with the tenets of sustainable fashion practices and close the loop on Nike's product lifecycle. Materials recycled include rubber, foam, fiber, leather and textile blends, which are separated and ground into granules.
Tire recycling, or rubber recycling, is the process of recycling waste tires that are no longer suitable for use on vehicles due to wear or irreparable damage. These tires are a challenging source of waste, due to the large volume produced, the durability of the tires, and the components in the tire that are ecologically problematic.
Rubberized asphalt concrete (RAC), also known as asphalt rubber or just rubberized asphalt, is noise reducing pavement material that consists of regular asphalt concrete mixed with crumb rubber made from recycled tires. Asphalt rubber is the largest single market for ground rubber in the United States, consuming an estimated 220,000,000 pounds (100,000,000 kg), or approximately 12 million tires annually.
In agriculture, gardening, and landscaping, barkdust is a form of mulch produced out of chipped or shredded tree bark. Coarser forms of barkdust may be known as bark nuggets. Trees typically used in the production of barkdust include the Douglas fir and the Western hemlock.
Tire-derived fuel (TDF) is composed of shredded scrap tires. Tires may be mixed with coal or other fuels, such as wood or chemical wastes, to be burned in concrete kilns, power plants, or paper mills. An EPA test program concluded that, with the exception of zinc emissions, potential emissions from TDF are not expected to be very much different from other conventional fossil fuels, as long as combustion occurs in a well-designed, well-operated and well-maintained combustion device.
A playground surface is the material that lies under and around swings, slides, monkey bars and other playground equipment. The surfaces are usually made of wood or rubber and designed specifically for aesthetics, child safety, and/or ADA wheelchair accessibility. Playground safety surfacing often involves the use of recycled rubber tire products such as poured rubber, rubber tiles or loose rubber mulch.
Agricultural pollution refers to biotic and abiotic byproducts of farming practices that result in contamination or degradation of the environment and surrounding ecosystems, and/or cause injury to humans and their economic interests. The pollution may come from a variety of sources, ranging from point source water pollution to more diffuse, landscape-level causes, also known as non-point source pollution and air pollution. Once in the environment these pollutants can have both direct effects in surrounding ecosystems, i.e. killing local wildlife or contaminating drinking water, and downstream effects such as dead zones caused by agricultural runoff is concentrated in large water bodies.
Sustainable landscaping is a modern type of gardening or landscaping that takes the environmental issue of sustainability into account. According to Loehrlein in 2009 this includes design, construction and management of residential and commercial gardens and incorporates organic lawn management and organic gardening techniques.
Products made from a variety of materials can be recycled using a number of processes.
Micronized rubber powder (MRP) is classified as fine, dry, powdered elastomeric crumb rubber in which a significant proportion of particles are less than 100 µm and free of foreign particulates. MRP particle size distributions typically range from 180 µm to 10 µm. Narrower distributions can be achieved depending on the classification technology.
Artificial turf is surface of synthetic fibers resembling natural grass. It is widely used for sports fields for being more hard-wearing and resistant than natural surfaces. Most use infills of crumb rubber from recycled tires; this use is controversial because of concerns that the tires contain carcinogens, though as of 2023 there is no scientific consensus as to if the use and exposure to artificial turf has an increase risk of cancers such as brain cancers, though research into the issue is ongoing.
Tire recycling in the United States is the disposal and reuse of waste tires.
