Application of Catalyst in Rubber Runway and Plastic Runway
plastic track
Plastic track, also known as all-weather track and field track, is composed of polyurethane prepolymer, mixed polyether, waste tire rubber, EPDM rubber particles or PU particles, pigments, additives and fillers. The plastic track has the characteristics of good flatness, high compressive strength, appropriate hardness and elasticity, and stable physical performance, which is conducive to the development of athletes’ speed and technology, effectively improving sports performance, and reducing the rate of falls. The plastic runway is composed of polyurethane rubber and other materials. It has certain elasticity and color, and has certain ultraviolet resistance and aging resistance. It is internationally recognized as a good all-weather outdoor sports ground material.
Plastic runway is toxic?
Domestic plastic runways are generally made of polyurethane materials, supplemented by pigments, additives, etc. Generally, qualified polyurethane will not volatilize harmful substances. Polyurethane is a chain molecule polymerized by two monomers: “polyether polyol” and “diisocyanate”. If these two monomers are completely polymerized, polyurethane itself is not harmful. The key is that there will be more of these two monomers that are not fully polymerized in poor polyurethane, and one of the sources harmful to human health is these two monomers.
How to detect whether it is “toxic”? more
Conventional testing methods generally include: test method for resistance of vulcanized rubber to sunlight exposure under glass, determination of component content of rubber and rubber products, thermogravimetric analysis, etc. For ordinary people, the simple way is to smell by nose. If there is an odor, it is likely to be caused by the volatilization of harmful residues from the plastic runway.
Why do Japanese and Korean primary and secondary schools have sandy runways? more
First of all, most schools in Japan and South Korea are private schools. Laying plastic runways requires a lot of financial and material resources. In order to maximize the benefits, the school authorities have reserved sandy land; Secondly, once encountering inferior plastic runways, toxic gases will volatilize. For health reasons, most primary and secondary schools in Japan and South Korea have not built plastic runways.
Content sorting and insect catching action
Chinese name Plastic runway Foreign name Tartan type Breathable mixed composite all plastic main materials Polyurethane prepolymer, mixed polyether, etc. Features high compressive strength, hardness and elasticity Suitable scope of application Indoor, outdoor and other sports/activity venues
catalogue
1 Construction standards
2 Runway characteristics
3 Price estimation
4 Maintenance management
5 Main components
6 Scope of application
7 Main classification
8 Main materials
9 Maintenance knowledge
10 Standard query
11 Relevant laws
12 National Standards
13 Related reports
Construction standards
The standard runway is 400m long and consists of two parallel straight roads and two curves with equal radius. Except for the grassland runway, the inner side of the runway shall be demarcated with a sharp edge made of suitable materials. The protrusion is about 5 cm high and at least 5 cm wide.
2. The runway length shall be measured 30 cm beyond the outer edge of the inner edge of the runway. If there is no protruding edge, it shall be measured 20 cm away from the outer edge of the marking line. Note: IAAF Track and Field Facilities Manual contains all technical information about runway structure, design and marking. This rule gives the basic principles that should be followed.
3. For each track of 400 meters and below, each athlete should have a lane, which is 1.22 meters wide, 1.25 meters wide, and 5 centimeters wide. All lanes should have the same width. The length of the lane shall be measured according to paragraph 2 above, and the length of other lanes shall be measured 20 cm beyond the outer edge of the inner lane.
Note: The lane width shall include the right lane
The construction of plastic runway is based on asphalt or cement, and the foundation method is roughly the same as that of road construction. The flatness of the foundation surface is required to be high to ensure that the thickness of the plastic surface is consistent and the elasticity is uniform. The quality requirements for the foundation are as follows:
Gradient: transverse<1% (8 ‰ for curve, 5 ‰ for straight, 5 ‰ for semicircular area), longitudinal<1 ‰,<0.4% for high jump area. The surface shall be flat and smooth with smooth drainage.
Flatness: the qualification rate of flatness is above 95%, and the error of 3m ruler is 3mm.
Positioning: to meet the needs of accurate construction and line drawing, four semicircle tangent points and two circle centers of the runway site shall be marked with firm and distinct markers.
Drainage: the drainage system must discharge accumulated water two hours after heavy rain. In frozen areas, a geotextile buffer layer should be added between the asphalt layer and the gravel layer. The foundation along the drainage ditch shall be provided with special waterproof treatment.
Strength and stability: the foundation shall have a certain strength and stability, with uniform and solid surface, no cracks, no broken edges, and straight and smooth joints. The cushion shall be compacted with a compactness greater than 95%, and there shall be no obvious wheel tracks, loose topsoil, waves and other phenomena after being compacted by a medium-sized roller.
Runway characteristics
Color: special polyurethane particles, soft surface color, granular surface, prevent dazzling sunlight reflection, beautiful and durable, and can use multi color matching.
Economical: easy maintenance, saving governance costs.
Safety: It can prevent sports injuries caused by falls.
Adhesion: special construction treatment, strong adhesion, can inhibit the rise of water, no bubbles, peeling and other phenomena.
Flatness: self leveling materials shall be used for construction, with flat surface, which can meet the requirements of a particularly flat playing field.
Impact resistance: It has a strong elastic layer and buffer layer, which can absorb strong impact, and the surface will not be damaged.
Nail resistance: it will not be damaged by spikes or starting gear at the 100 meter starting point where the force is large and frequently used.
Wear resistance: It will not be unable to recover elasticity due to the heavy pressure of track and field equipment.
Wear resistance: the wear resistance is less than 2.5%, meeting the needs of principals at all levels for time and high use frequency.
Impact absorption: moderately absorb foot impact, reduce sports injuries, and long-term training and competition are appropriate.
Price estimation
1、
plastic track
plastic track
The price of mixed plastic runway is generally about 190/m2
2. The cost of cement foundation is about 120 yuan (asphalt foundation is about 200 yuan more expensive). The thickness of cement concrete foundation C20 is 15 cm. The foundation is compacted with original soil – 27 lime soil 20 cm – gravel stabilized layer 15 cm – C20 concrete; The asphalt concrete foundation is 7-10cm AC-8, AC-10 asphalt aggregate, and the foundation is compacted with original soil – 20cm of 37 lime soil – 15cm of inorganic material stabilized layer – asphalt concrete.
maintenance management
1. After the completion of the laying of the plastic runway, it is necessary to take care of it for 7-10 days before it can be used.
2. The plastic runway is suitable for all-weather operation with certain drainage equipment. The plastic track is not suitable for other purposes, as it is used for sports practice, competition, students’ static and fitness training;
3. Prevent the purification of hazardous materials, always keep them clean, and prevent violent mechanical impact and friction. No vehicles are allowed to run on the runway, and heavy objects and sharp objects are piled up (except for standard running shoes). Special nail shoes must be worn for sports. The length of nails shall not exceed 7mm individually, and the length of jump shoes shall not exceed 11mm individually. If the nail shoelace has a long nail, it is not allowed to use it on the plastic runway;
4. Prevent temporary load;
5. Prevent smoking and fire, isolate heat source, and prevent contact with organic solvents, chemicals, cigarette butts and other kindling, purification materials, etc.
6. Spray water frequently for cleaning. After cleaning, a large amount of residual water on the adhesive surface can be removed with a dry cloth. Oil stain can be cleaned with 10% ammonia water or detergent and detergent.
Main components
The main components of the plastic runway are acrylic acid and high-quality resin. Its material is similar to the convenient bag for food, meeting the requirements of environment-friendly surface materials. The raw materials of the plastic track have been certified by the National Plastic Industry Association, which is non-toxic and harmless to the environment and human body. It has the characteristics of anti ultraviolet light, anti abrasion, anti burst, anti-aging, long service life, easy maintenance, low maintenance cost, etc.
Scope of application
It is used for kindergartens at all levels and in various schools, professional stadiums, track and field runways, semicircles and auxiliary facilities
plastic track
plastic track
Assisted area, national fitness path, indoor gym training track, playground road pavement, indoor and outdoor track, tennis, basketball, volleyball, badminton, handball and other venues, parks, residential areas and other activity venues.
Main classification
Generally speaking, the runways usually refer to the runways in various schools and professional stadiums at all levels
There are two kinds of track and field runways: standard track and non-standard track. The standard track refers to the one with a perimeter of 400 meters and a radius of 36.5 meters (there are also 36 meters and 37.898 meters). The non-standard track refers to the one with a perimeter of 200 meters and 300 meters that can be adjusted appropriately according to the shape and size of the playground land area.
The plastic runway can be divided into:
Prefabricated plastic runway All plastic runway Mixed plastic runway Composite plastic runway Breathable plastic runway EPDM plastic runway
Prefabricated plastic track and full plastic track are common types of professional track and field sports ground because of their incomparable excellent performance, but their high prices are unbearable for ordinary universities, middle schools and primary schools;
The performance of hybrid plastic runway and composite plastic runway is between full plastic and breathable ones, and the price is slightly lower than that of plastic runway such as full plastic runway, but it is also much higher than that of breathable one, requiring higher foundation;
The performance of the breathable plastic runway can completely meet the requirements of GB/14833-93, and it is breathable
Permeable, short construction period, easy maintenance and renovation, cost-effective, and also the first choice for universities, middle schools and primary schools;
EPDM plastic track is mainly used for non-standard track in primary schools or kindergartens.
Full plastic plastic runway
Product features:
The main material is two-component polyurethane, the base layer is natural rubber and artificial rubber, and the mixture of mineral filler, stabilizer and pigment is formed in a whole by adding sulfur at 280-300 ℃. The combination of sports science and material science can fully meet and reflect the professional requirements of athletes’ participants on the track.
Solventless plastic runway
Process description of solvent-free plastic runway:
Solventless plastic track is an environment-friendly plastic track made of non-toxic sports surface materials, which belongs to diphenylmethane diisocyanate (MDI) system. MDI synthetic surface material is a solvent-free, odorless and pollution-free waterborne polyurethane runway material. It is an environment-friendly sports pavement material that eliminates toxic TDI system polyurethane runway materials. It has advanced performance, high-tech content, safety, renewable, suitable for use under various conditions, and is less harmful to human health. Its specific characteristics are as follows:
1: It does not contain TDI, toxic volatile solvents such as benzene, toluene, xylene, plasticizers, harmful additives such as heavy metals, and any volatile smell. It is friendly to human body and the environment and fully complies with environmental requirements;
2: Convenient construction, strong adhesion, high paving efficiency, fast curing speed, adapt to different construction requirements such as spraying or mechanical paving, and the paving process has no odor, which will not affect the normal teaching activities of the school and the normal life of the surrounding residents;
3: After being put into use, there shall be no peculiar smell, no harmful substances discharged, and the pollution to the environment shall be reduced.
Prefabricated type
Precast runway pavement process description:
Safe, environmentally friendly, excellent weather resistance, economical
Durable, multi color effect. The installation is convenient. With a small amount of manpower and machinery, the runway coiled material can be paved on a dense foundation by using the special adhesive provided by us. The runway can be put into normal use 24 hours after it is completely installed. And it is maintenance free.
mixed type
Description of mixed runway pavement process:
The construction process of plastic runway pavement is a three-step construction method. First, add an appropriate amount of rubber particles into the glue solution, and pave the primer with a thickness of 8mm. After it is cured, pave the glue solution with a thickness of 2mm on it. Manually evenly sprinkle red particles, recover the excess glue particles, and then spray a layer of glue solution on it.
Process diagram:
Site cleaning → primer batching → mixing → paving → defoaming → curing → surface glue batching → mixing and mixing → paving → defoaming → particle scattering → rubber particle recycling → glue rolling → measuring and marking → testing point line → completion
2. Description of laying process:
⑴ First check the flatness of the foundation layer and level the concave and convex parts (such as the cement concrete foundation needs pickling).
(2) Laying of primer:
Clean the foundation before laying the primer, and prepare the tools for construction.
a) The position of the construction line shall be measured according to the process requirements, and the construction line shall be set out.
b) The laying shall start from one side of the site, and the glue shall be scraped once according to the width of the site.
c) The speed of glue scraping shall be even, and the exposed bottom, depression and bulge shall be repaired or leveled in time.
d) After the glue is formed, the whole site shall be inspected to ensure the thickness of the surface glue.
(3) Paving of surface glue:
a) The interval time between each bucket of glue liquid shall be shortened as far as possible during glue scraping to make the glue forming speed uniform.
b) Observe the thickness of the adhesive surface at all times.
c) Scrape the surface glue, sprinkle red particles before the surface glue is cured, and clean up the excess surface glue particles after it is completely cured.
Breathable type
Product characteristics:
1. Meet national standards. Mechanical paving and spraying, with excellent flatness and no threshing.
2. Porous, water permeable, breathable, excellent elasticity, no blistering.
3. It can be used in all weather, with strong wear resistance, good weather resistance, strong compression resistance, good impact resistance, and durability.
4. Price economy.
Construction steps:
1. The site is clean, the concrete is coated with primer, and the asphalt surface is scraped
2. Mechanical laying of 11mm thick bottom layer, one component adhesive+rubber particles
3. Mechanical spraying of 1.5mm thick surface layer, one component adhesive+EPDM particles, and then spraying in the opposite direction.
4. Runway survey, setting out and marking.
5. Site cleaning and demobilization.
Construction technical indicators:
Specific gravity marked value ± 0.10
Hardness (HS) 45 ～ 65
Tensile strength (kgf/c ㎡ (Mpa) above 25 (2.45)
Tear strength (kgf/cm (N/mm) above 10 (98)
Elongation above% 250
Compression permanent deformation rate above% 35
Abrasion resistance below 2.5
Hardness (HS) Change of original hardness value ± 5
composite
The combination of mixed surface layer and breathable bottom layer can not only shorten the construction period, but also reduce the cost without degranulation.
Picture of compound runway
Picture of compound runway
Self knotting
First layer: polyurethane mixture plus black rubber particles.
The second intermediate layer: self textured slurry cleaning, paving and forming a closed cell micro bubble interlayer. Its elasticity, hardness and friction can not only slow down the impact of the impact force on each joint of the human leg when the foot touches the ground, but also enable the human body to obtain the kinetic energy of moving forward continuously. It meets the requirements of 35%~50% of the new standard of shock absorption rate issued by IAAF.
Picture of self textured runway
Picture of self textured runway
Three surface layer: self textured paste, which is pure glue (paste) mixed with carborundum powder and variable promoter, sprayed on by professional machine. After several hours of reaction, it naturally forms pure polyurethane glue and anti-skid surface layer. This process can not only overcome the self leveling characteristics of polyurethane materials, but also retain the weather resistance and aging resistance of polyurethane materials, and overcome the common problem of polyurethane runways that are easy to drop particles. Wear resistant, uniform surface particles, uniform stress, clear and full scribing, neat and beautiful, environmentally friendly products.
Main materials
Two component polyurethane slurry – mainly used for
plastic track
plastic track
Full plastic runway, mixed plastic runway, composite plastic runway
One component polyurethane glue – mainly used for composite plastic runway, breathable plastic runway and EPDM plastic runway
PU particles, EPDM particles, black waste tire particles, etc
Maintenance knowledge
The plastic runway is beautiful and durable. If it can be maintained regularly, its service life will be greatly extended. Pay attention to the following points in daily use and maintenance:
After the plastic runway is paved, it needs to be maintained for 7-10 days before it can be used.
With certain drainage facilities, the plastic track is suitable for all-weather use. The plastic track is used for athlete training, competition, student sports and fitness exercises, not for other purposes;
The rubber runway shall avoid the pollution of harmful substances and severe mechanical impact and friction. No vehicles, heaps of heavy objects and sharp objects are allowed on the runway. Athletes must wear special sports shoes or sneakers. Jumpers shall not exceed 12mm. If the sneakers have long nails, the length of the sneakers’ nails shall not exceed 9mm.
Special attention shall be paid to the protection of the edge of the plastic runway. In case of any damage or blistering of the road teeth, the Contractor shall be notified to repair them in time to avoid more serious damage.
Keep the plastic runway clean and wash it with water spray frequently. After washing, a small amount of residual water on the adhesive surface can be wiped off with a dry cloth. If the plastic runway is stained with oil, it can be cleaned with 10% ammonia or detergent, washing powder, etc.
During the construction of polyurethane plastic materials, it is not allowed to encounter a drop of water before the initial curing of the glue, which will produce a large bubble. Therefore, the construction personnel should prepare towels to wipe sweat when working under high temperature conditions. When paving the adhesive surface, the weather conditions must be known and emergency measures to prevent sudden showers must be taken. The glue laying time should avoid the morning when the atmosphere and the ground humidity are high. Even on a sunny normal working day, it is generally better to formally lay the plastic runway after 9:00 a.m.
The actual paving thickness of the glue surface refers to the center of the glue particles from the bottom to the surface, which is generally controlled from two aspects. First, pre check the thickness and size through formwork erection, and trim or hammer the local part of the base course higher to lower it. If the height is not much higher, the flat scraper can be used to add fixtures to scrape slurry to ensure the thickness. In order to ensure the thickness of the main area of the plastic track in the northern suburbs of the 11th Asian Games, the error control is positive, so the average thickness is more than 14MM.
To prevent local blistering and shelling after the pavement of the adhesive surface, the compactness of the base course shall be strictly controlled to prevent the asphalt foundation layer from being embedded and not compacted, shelling and shelling, resulting in poor adhesion, surface gasification and tensile fracture of the adhesive surface. Where the compactness of the base course is not enough, the method of drilling with a drill and grouting with glue (rubber nails) can be used for reinforcement.
In order to ensure the flatness and gradient, after the mold strip is nailed, use a level to simulate the correction. The individual high places of the base course shall be leveled first, and the individual low places shall be filled with glue.
The foundation parts polluted and corroded by diesel oil shall be dug out and filled with glue.
Standard query
Chen Lei, Deputy Secretary General of the Field Management Center of the National Athletics Association, said in an interview: “There is no scientific basis for the 0.7% standard. It was proposed that China had tested according to the international testing standards in 1995, and all the indicators of the testing results met the international standards, but the testing machines were different, so it is difficult to say that the testing results are scientific.”
Chen Lei said: “At present, the acceptance of plastic runways in China is mainly about the detection of their physical indicators, while the chemical indicators of environmental protection have not been available. In the long run, it is scientific to introduce international testing standards. Although some enterprises with low qualifications will not be able to enter this’ threshold ‘, only in this way can we prevent some potentially harmful plastic runways from muddling through.”
Wang Zheguang, a teacher at China Youth Political College, opposes the statement that “as long as the indoor decoration standard is not greater than or equal to 0.7%, the plastic field will not cause any harm to the human body”. For general coatings such as paint, there is an international standard of no more than or equal to 0.5%. He wrote in the article “Environmental Protection Problems Neglected in the” Green Olympics “Beijing Atmospheric Environment Treatment Measures — Environmental Protection Hazards and Countermeasures of Laying TDI Polyurethane Runways in Large Areas in Schools”, “At present, TDI polyurethane plastic runway is widely laid. Its raw materials contain a variety of toxic and harmful chemicals, which will release toxic gases at temperatures above 20 degrees Celsius or under ultraviolet radiation. If some people do not have professional knowledge to lay it, or the reaction of toxic substances in the laying process is incomplete, this plastic runway will become a ‘poison gas tank’.”
Relevant laws
Article of the General Provisions These Measures are formulated in accordance with the Sports Law of the People’s Republic of China and other relevant laws and regulations and in the light of the actual conditions of the province in order to strengthen the construction and management of sports facilities, develop sports undertakings, enhance the people’s physique, improve the level of sports, and promote the construction of socialist material and spiritual civilization.
Article 2 The sports facilities referred to in these Measures refer to the sports venues, buildings and supporting equipment built according to the standards set by the State for sports training, competitions and fitness activities, including:
（1） Public sports facilities invested or financed by the state and open to the public; （2） Sports facilities for internal use by state organs, social organizations, enterprises and institutions; （3） All kinds of commercial sports facilities.
Article 3 These Measures shall apply to the planning, construction, use and management of sports facilities within the administrative areas of this province.
Article 4 The planning and construction of sports facilities shall follow the principles of overall arrangement, rational layout, standardization and practicality, and convenience for the masses.
Article 5 The people’s governments at or above the county level shall strengthen their leadership over the planning, construction, use and management of sports facilities, incorporate the construction of public sports facilities into their national economic and social development plans, and organize their implementation.
Article 6 The administrative departments for physical culture and sports of the people’s governments at or above the county level or the institutions authorized by the people’s governments at the same level (hereinafter collectively referred to as the administrative departments for physical culture and sports at or above the county level) shall be responsible for supervising, inspecting and guiding the construction and management of sports facilities within their respective administrative areas.
Other relevant departments of the people’s governments at or above the county level shall, within the scope of their respective duties, do a good job in the construction and management of sports facilities.
Article 7 The people’s governments at or above the county level shall commend and reward the organizations and individuals that have made contributions to the construction and management of sports facilities.
Chapter II Planning and Construction Article 8 The people’s governments at or above the county level shall incorporate the construction of urban public sports facilities into the overall urban planning and the overall land use planning in accordance with the provisions of the State on the quota of land for urban public sports facilities.
The newly built, reconstructed and expanded urban residential areas shall reserve land for public sports facilities in accordance with national regulations.
The construction of public sports facilities in villages and towns should be included in the township construction plan.
Article 9 The people’s governments at or above the county level shall make overall arrangements for funds for the construction of public sports facilities, include the funds for sports capital construction in their own financial budgets and capital construction investment plans, and gradually increase their input with the development of the local national economy.
Schools shall be equipped with sports facilities according to the standards prescribed by the administrative department of education under the State Council. If sports facilities fail to meet the prescribed standards, measures shall be taken to gradually meet the prescribed standards. In cities and towns with dense schools, sports centers in primary and secondary schools should be gradually established.
State organs, social organizations, enterprises and institutions shall build sports facilities according to local conditions.
Article 12 The area of public sports facilities in newly built, rebuilt and expanded urban residential areas shall meet the standards set by the State. The construction of public sports facilities in rural residential areas should conform to rural reality.
Article 13 For the construction of new public sports facilities, the approval procedures shall be gone through according to the planning and construction project management procedures.
The alteration, expansion and removal of public sports facilities shall be subject to the consent of the property owner. We will strictly control the removal of public sports facilities located in central urban areas to remote areas. The reconstruction of public sports facilities shall not be allowed to reduce the scale, change the nature and use.
If it is really necessary to change the nature and use of public sports facilities, the local sports administrative departments at or above the county level must be consulted before going through the procedures for planning and construction approval, and the new sports facilities should be built in the first place for repayment in accordance with the principle of not being lower than the original sports facility standard and scale.
Article 14 The newly built, rebuilt and expanded sports facilities shall conform to the provisions of the State on fire control, safety, health and environmental protection.
Large and medium-sized public sports facilities should have barrier free facilities for the disabled.
Article 15 The construction of sports facilities must strictly implement the relevant technical standards prescribed by the State. The construction of commercial sports facilities shall seek the opinions of the local construction and sports administrative departments. The sports administrative departments at or above the county level shall participate in the completion acceptance of sports facilities projects.
Article 16 The administrative unit of public sports facilities shall establish and improve the management system of maintenance, use, safety and health, and assign full-time personnel for management. The sports facilities within the state organs, social organizations, enterprises and institutions shall have full-time or part-time managers, and a sound management system shall be established.
national standard
The compulsory national standard “Synthetic Material Surface Sports Ground for Primary and Secondary Schools” was organized by the Ministry of Education and drafted with the participation of dozens of scientific research institutes and testing institutions. After more than two years of revision, it was implemented on November 1, 2018. The new national standard refers to the relevant standards at home and abroad, specifically solves the outstanding problems of safety, environmental protection, sports protection, etc. in the construction of synthetic material surface sports ground, comprehensively considers the main risk points in each link of the whole life cycle of the synthetic material surface sports ground in primary and secondary schools, and puts forward various technical indicators that meet the requirements of green development, technological progress, industry specifications and student health protection.
Compared with the relevant old national standards, the new national standards not only changed from “national recommended standards” to “national mandatory standards”, but also added many contents, including thickness requirements, physical properties, requirements for inorganic filler content, requirements for anti-skid rubber particle polymer content, limits for harmful substances in finished surface products, and limits for harmful substances in non solid and solid raw materials. The reporter of Beiqing Daily saw that the new national standard has stipulated the limit of 18 harmful substances that may be produced in the construction of plastic runway on campus, and the limit of volatile organic compounds in the completed runway has been set according to the home decoration standard. For example, the release amount of harmful substances in the “Limit of Harmful Substances and Odor Requirements for Finished Products of Cast in situ and Prefabricated Surfacing”, the total volatile organic compounds shall not be higher than 5 mg/m3, formaldehyde shall not be higher than 0.4 mg/m3, carbon disulfide shall not be higher than 7 mg/m3, benzene shall not be higher than 0.1 mg/m3, and the odor level shall not be higher than 3. The new national standard has also formulated in detail the sampling requirements, inspection rules, judgment rules and other issues of plastic runways in primary and secondary schools. In addition, the campus artificial lawn is also included in the national standard mandatory testing scope for the first time
