Artificial turf was first introduced in the country in the late 1980s, and it was not widely promoted until the middle and late 1990s. Together with the plastic track, it has become the standard model of school sports venue construction, replacing a large number of sports venues originally planted with natural lawns. Although the application range of artificial turf has been limited to some extent due to reasons such as sports safety, site characteristics, and public awareness, with the development of science and technology, the production technology of artificial turf has been continuously innovated and improved. Today, the sixth-generation artificial turf made of open-net single-fiber filaments is closer to natural turf in terms of shock absorption ratio, ball rebound rolling, and steering value, and even has advantages in some characteristics.
In terms of sports safety performance, the new generation of artificial grass fiber has improved surface coating and polymerized raw materials to effectively reduce the occurrence of sports injuries such as skin scratches and foot sprains. The advantages of artificial turf and natural turf are relatively prominent, and the shortcomings and shortcomings also exist objectively. When choosing and using them, they must be considered comprehensively according to the actual situation.
Compared with natural turf, the sports performance of artificial turf is usually much harder, and the friction coefficient of chemical fiber is often smaller than that of turfgrass blades. In football, it shows that the ball speed is too fast and the rebound rate is too high. Thereby increasing the difficulty of the player's control of the ball.
The advantages of artificial turf over natural turf in terms of sports characteristics are that the uniformity of the field is excellent, and the flatness is much better, and it can fully avoid the bad conditions of the field caused by factors such as climate and maintenance, thereby affecting the competition.
Impact on the Environment Impact on air conditions Natural lawns is composed of green plants, which can absorb carbon dioxide and release oxygen through the physiological metabolic process of photosynthesis and can absorb toxic gases such as sulfur dioxide, hydrogen fluoride, ammonia, and chlorine to purify the air. The role of. Natural lawns have an obvious blocking effect on dust. The measured data show that when winds of three or four levels are blowing, the dust concentration in the sky above the bare ground is 13 times that of the sky above the lawn. Studies have shown that a 25-square-meter lawn can absorb all the carbon dioxide exhaled by a person and convert it into oxygen to meet the oxygen required by the human body in the process of breathing. Artificial turf is a non-living material made of polyethylene, polypropylene, and other polymers. It cannot carry out the metabolism of green plants, so it does not have the effect of regulating the carbon and oxygen balance in the atmosphere. Although artificial turf can block dust to a certain extent, it does not have the function of absorbing toxic gases to purify the atmosphere. In addition, low-tech artificial turf fibers often contain chlorine impurity, which will decompose and release chlorine under high temperature and strong sunlight, which will damage air quality.
Impact on climate The turf bed of a natural lawn is a mixture of sand and silt. There are sufficient pores in the structure to accumulate water during irrigation and precipitation, and play a role in conserving water. When the climate is hot, turfgrass uses the root system to absorb deep water and takes away a large amount of heat from the surrounding environment through transpiration, effectively reducing the ground temperature and regulating the microclimate within a certain range. The bed structure of artificial turf is composed of rubber, concrete, or asphalt, which basically cannot play the role of conserving water, so it cannot reduce the surface temperature, and its heat capacity is small, resulting in the surface temperature being significantly higher than the air temperature, especially in closed stadiums This problem is even more serious. At noon in summer, it can be observed that the air near the surface has obvious heating distortion on the artificial turf field. Relevant experimental data show that under high-temperature conditions above 30°C, the average surface temperature of natural lawns is 2°C to 3°C lower than the air temperature, while the surface temperature of artificial lawns is 6°C to 11°C higher than the air temperature. The increase in surface temperature of lawns is significantly higher than that of natural lawns. In the summer, the surface temperature of the artificial turf is very high. If the user rubs against it violently at this time, the skin of the contact part will be seriously injured.
As the final product, the withered grass residue produced by the natural lawn is converted into organic matter and returned to the soil under the action of the microorganisms in the turf bed sediment. In the end, a non-toxic and harmless mixture of sand and sand remains, which can be improved by adding organic matter to it for other purposes. Artificial turf has the advantages of bright appearance, four seasons green, vivid, good drainage performance, long service life, low maintenance cost, and so on.
The quality requirements for the foundation of the artificial turf sports system are mainly concentrated in three aspects: hardness, flatness, and drainage slope.
There are three commonly used artificial grass foundations: asphalt foundation, cement foundation, and gravel foundation. Which type is used is mainly determined by the local climate environment, budget and time. Asphalt foundation is particularly suitable for the climate environment with large temperature differences in the north and low winter temperatures. At the same time, because of its high cost, it is not the most suitable type of foundation for warm and humid environments. The gravel foundation is more common in the south because of its simple construction, low cost, and rapid drainage, but because of its poor rigidity and stability, After long-term use, the foundation is easy to loosen, which leads to an uneven foundation; therefore, in most areas of the country, cement concrete foundation has become an economical, practical, and very cost-effective type of artificial grass foundation.
Based on its rich experience in artificial grass systems, Shuanghe Sports will briefly introduce the artificial grass cement concrete foundation as follows:
1. High requirements on the flatness of the foundation surface to ensure the uniform thickness and uniform elasticity of the artificial grass surface layer. The pass rate of flatness is above 95%,
5m ruler error 3MM, slope: horizontal 8‰, longitudinal 5‰, semicircular area 5‰, the surface should be flat, smooth, and ensure drainage.
2. The foundation should have certain strength and stability.
3. The surface is uniform and solid, with no cracks, no rotten edges, and pitted surface, and the joints are straight and smooth. It is better to cut into pieces about 6000mm×6000mm.
4. The mat is compacted, and the density is greater than 95%. After being pressed by the medium-sized roller, there is no obvious wheel mark, no loose soil, wave, and other phenomena.
5. The cement foundation must have a water barrier. The water barrier is made of new PVC thickened water barrier film. The junction should be greater than 300mm, and the edge margin should be greater than 150mm.
6. It is necessary to consider leaving expansion joints with a width of 5 mm.
7. The basic maintenance period is 2-3 weeks. Not full of sand
In the United States, most artificial grass fiber materials used in artificial turf are high-grade nylon materials, and some use multi-element fibers. Artificial turf without sand filling can also be divided into two types: water-permeable and impermeable. This kind of lawn resembles a natural lawn in appearance, partly with a layer of shock-absorbing foam cushion, which has a variety of different densities and thicknesses. Since there are not many domestic manufacturers who really master the technology of laying artificial turf, and most of them are foreign technologies, when laying artificial turf that is not filled with sand, especially the laying of shock-absorbing foam cushions must be completed by foreign experts. A layer of smooth asphalt should be laid under the shock-absorbing foam as the foundation, and gravel, sand, and pebbles should be laid under the asphalt as the foundation, and the structure of the drainage system is the most critical link. In addition, this type of artificial turf must use special artificial turf machinery during the installation process, especially in the laying and installation of some professional or expensive sports venues, otherwise, it will not be able to meet the requirements of flatness and uniformity of the venue. For example, the hockey field of Beijing Lucheng Sports Technical College, which is the hockey training venue for the 2008 Olympic Games, and some of the movable artificial grass and block artificial grass to meet special needs must be constructed in strict accordance with the above requirements.
Filling particles
Filled particle turf is accepted by the majority of users in China because of its international advanced level of good sports performance and good practicability. Most of its materials are polymers of polyethylene (PE) or polypropylene (PP). The fibers of this lawn are longer than those without sand, and the surface is backfilled with 2-3 mm of quartz sand and rubber particles. Its sports characteristics are very close to those of natural lawns, and it can be used all year round. Usually, the lawn needs to be maintained and used for 6-8 months to reach the best condition after laying. This type of lawn is particularly suitable for laying outdoors, and its warranty period is usually 5-8 years, but its actual life span can exceed 5 years. In long-term dry weather, just sprinkle a little water on the lawn to reduce the risk of athletes being bruised.
Mixed lawn
It is no longer a dream to integrate natural lawns and artificial lawns. The grass of this kind of lawn is natural, and the root structure of the grass is reinforced with plastic, such as letting the grass grow on a net-like bottom made of plastic. In this way, the user-friendly characteristics of natural turf are well combined with the super durability of artificial turf.
In China, artificial turf filled with particles accounts for 95%, but many schools tend to overlook the most important construction link when choosing products. The construction technology of artificial turf is very important for the maintenance and service life of artificial turf in the later period.
First of all, we must make technical preparations, make the "three connections and one leveling" and be familiar with the drawings, check and accept the basic construction quality, the laying site should be clean, the surface should be dry, smooth, free of debris, wax stains, and grease, and the minimum construction temperature should be maintained Above 10°C. Use theodolite or other instruments to measure whether the surrounding facilities meet the size of the sports field. If there is any inappropriateness, it should be modified immediately, with an allowable error of ±5 mm.
Secondly, before laying artificial turf, we must check the quality of the turf together with the artificial turf production unit to check whether the material quality, density, and weaving process of the turf are qualified to meet the requirements of use. A standard site can not exceed 30 connection points. At the same time, check whether the quality of the filling meets the environmental protection requirements. During the laying process, special tools should be used to trim the edges and seams of the lawn according to the specifications and cut the overlapping lawns evenly. Use special glue for artificial grass sports ground to connect, and the seam should not be larger than 2 mm. The temperature during bonding should not be too low, and the ambient temperature should be above 10℃ for construction; in addition, it is not suitable for construction in rainy or mildew weather, otherwise, it will cause the bonding time to be too long or even cause non-sticking.
The filling of quartz sand and rubber particles is the most important part of the construction process. Only after the installation of the artificial turf surface material is completed and the leveling and firmness of the surface materials are checked to meet the requirements, the quartz sand and rubber particles can be filled. The specifications and quantity of filling are determined respectively according to the height and density of the grass. It should be noted that special sand injection machines and grass brushing equipment must be used to fill the particles in order to ensure the flatness and uniformity of the site and at the same time help improve the sports performance of the site. In addition, quartz sand and rubber particles must be completely dry materials for construction, otherwise, the grass stems will be overwhelmed and affect the filling quality. Quartz sand should be filled in multiple layers, and each layer of filling needs to be brushed back and forth with a grass brush to make the filling fall and fill up. Usually, it is better to play back and forth more than 20 times in a venue. Quality problems in raw materials and production process:
1. The lawn is unevenly colored and has chromatic aberration
Different color numbers of grass filaments are processed into lawns and pavement on a field will cause color differences.
It is a job with relatively high technical content to ensure that the thickness of each batch of grass silk is consistent, and the color is uniform. The raw material of grass silk produced by drawing equipment that does not meet the technical requirements often has color differences.
2. Obvious fading occurs after sunlight exposure, and the fading is uneven. Stability and color fastness under ultraviolet light are important indicators for evaluating artificial turf.
3. The artificial turf is often deficient or broken because the strength and wear resistance of the bottom lining are not enough. After a period of corrosion, aging, and small displacement wear, the durability of the bottom lining is a key issue in the quality of artificial turf.
4. The problem of site de-filing may also be caused by uneven bottom and back scraping, immature scraping technology, or relatively low abrasion resistance of grass silk. Especially for young athletes, the phenomenon of thread loss often affects health.
5. The grass silk is not bright enough, and the friction static is strong, and it has a sense of stagnation.
Anti-static performance and brightness are also key links in the competition of artificial turf products, which are related to the product's abrasion coefficient and the final sports effect. The evaluation of the pros and cons of artificial turf is the same as other products. It mainly depends on the selection of raw materials such as grass silk, bottom lining, and whether the post-treatment process such as scraping glue is mature and stable.
Problems in the construction process:
1 The size of the marking line is not accurate enough, and the white grass splicing is not straight.
2 The strength of the seam belt is not enough or professional lawn glue is not used, and the lawn is turned up.
3 The seam line of the venue is obvious,
4 The lodging direction of the grass filaments has not been regularly arranged, and the light reflection chromatic aberration appears.
5 The surface of the site is uneven due to uneven sand injection and rubber particles or lawn folds that have not been treated in advance.
6 The peculiar smell or discoloration of the venue is mostly a problem of the quality of the filler.
The above-mentioned problems that are easy to appear in the construction process can be avoided if you pay a little attention and strictly and carefully implement the artificial turf construction procedures.
