Introduction to Ningxia Yinchuan Fiberglass Geogrid

Fiberglass geogrid is a mesh structure material made of glass fiber using a certain weaving process. It is a geocomposite material that has undergone a special coating process to protect the glass fiber and improve the overall performance. The main component of glass fiber is: silicon oxide, which is an inorganic material. Its physical and chemical properties are extremely stable, with high strength, high modulus, very high wear resistance and excellent cold resistance, no long-term creep, and good thermal stability. It has a network structure. Enable aggregate interlocking and restriction to improve the load-bearing capacity of asphalt mixtures. Because the surface is coated with special modified asphalt, it has dual composite properties, which greatly improves the wear resistance and shearing capacity of the geogrid. Sometimes it is combined with self-adhesive pressure-sensitive adhesive and surface asphalt impregnation treatment to closely integrate the grille and asphalt pavement. As the interlocking force of earth and stone materials in the geogrid grid increases, the friction coefficient between them increases significantly (up to ~). The pull-out force of the geogrid embedded in the soil is due to the friction and bite force between the grid and the soil. Strong and significantly enlarged so it is a good reinforcing material. At the same time, geogrid is a lightweight and flexible plastic plane mesh that is easy to cut and connect on site. It can also be overlapped and easily constructed without the need for special construction machinery or professional technicians.
The role of fiberglass geogrid
, slowing down reflective cracks
Reflective cracks are caused by the large displacement of the old concrete surface layer near the joints or cracks, causing the asphalt overlay above it Stress concentrations within the layer are caused by horizontal displacements due to temperature and humidity changes and vertical shear displacements due to traffic loads. The former causes relatively concentrated tensile stress in the asphalt overlay above the joints or cracks, and the latter causes the asphalt overlay above the joints to undergo greater bending, tensile and shear stresses.
Due to the large modulus of geogrid, it can be used as a hard interlayer with high stiffness in the asphalt overlay. Its function is to suppress stress release strain and at the same time serve as an asphalt concrete reinforcement material to improve the tensile strength and tensile strength of the overlay layer structure. Shear resistance to reduce cracks. Practice has shown that the corresponding crack energy of a horizontal crack that has changed direction can be moved from its origin. Meters. Meters and above of width of reinforced material help to ensure that the energy is completely dissipated on both sides of the crack.
, Resistance to fatigue cracking
The main function of the asphalt overlay on the old cement concrete pavement is to improve the use function of the pavement, but it does not contribute much to the load-bearing function. The rigid concrete pavement under the overlay still plays a key role. carrying role. When asphalt overlay is carried out on the old asphalt concrete pavement, the asphalt overlay will be carried together with the old asphalt concrete pavement. Therefore, asphalt overlaying on asphalt concrete pavement will not only cause reflection cracks, but also fatigue cracking due to long-term load effects. We conducted a stress analysis on the load bearing conditions of the asphalt overlay on the old asphalt concrete pavement: Since there is a flexible surface layer under the asphalt overlay with the same properties as the asphalt overlay, the road surface will deflect when it is subjected to load. The asphalt overlay in direct contact with the wheel is under pressure, and the surface layer is under tension in the area outside the wheel load edge. Since the force properties of the two stress areas are different and they are close to each other, there is a gap at the junction of the two stress areas. That is, damage is prone to occur at sudden changes in force. Fatigue cracking occurs under long-term load.
The fiberglass geogrid in the asphalt overlay can disperse the above-mentioned compressive stress and tensile stress between two stressed areas to form a buffer zone, where the stress changes gradually instead of suddenly, reducing the impact of sudden stress changes on asphalt. Destruction of the overlay. At the same time, the low elongation of the fiberglass geogrid reduces the deflection of the road surface and ensures that the road surface will not undergo excessive deformation.
, High temperature resistant rutting
Asphalt concrete has rheology at high temperatures. The specific manifestations are: the asphalt road surface layer becomes soft and sticky in summer, and dents are formed in the stressed area under the action of vehicle load. The asphalt surface is removed after the vehicle load is removed. The layer cannot fully recover to the condition before loading, resulting in plastic deformation. Under the action of repeated rolling by vehicles, plastic deformation accumulates to form ruts. After analyzing the structure of the asphalt surface layer, we can know that due to the rheology of asphalt concrete at high temperatures, there is no mechanism in the surface layer that can restrain the movement of the aggregates in the asphalt concrete when it is loaded, causing the movement of the asphalt surface layer, which is what forms ruts. main reason.
Fiberglass geogrid is used in the asphalt overlay, which plays a skeleton role in the asphalt overlay. The aggregates in asphalt concrete penetrate between the grids to form a composite mechanical interlocking system, which limits the movement of the aggregates and increases the lateral binding force in the asphalt overlay. Each part of the asphalt overlay restrains each other and prevents the asphalt overlay from moving, thus providing resistance. The role of rutting.
Resistance to low-temperature shrinkage and cracking
The surface temperature of asphalt roads in severe cold areas is close to the air temperature in winter. Under such temperature conditions, the asphalt concrete shrinks when exposed to cold and produces tensile stress. When the tensile stress exceeds the tensile strength of asphalt concrete, cracks will occur. Cracks will occur where the cracks are concentrated and cause disease. From the perspective of the causes of cracks, how to make asphalt concrete strong enough to resist tensile stress is the key to solving the problem.
The application of fiberglass geogrid in asphalt overlay greatly improves the tensile strength of asphalt concrete and can resist large tensile stress without causing damage. In addition, even if the stress at the location where the crack occurs is too concentrated due to cracks in a local area, the crack will gradually disappear through the transmission of the fiberglass geogrid and will no longer develop into a crack. When selecting fiberglass geogrid, in addition to its performance indicators complying with the requirements in the table above, special attention should be paid to ensuring that its width is not less than . At the same time, its mesh size should be ~ times the maximum particle size of the asphalt surface material on it. This will help achieve optimal shear adhesion and promote aggregate interlocking and restriction.
(5) Engineering Applications
Fiberglass geogrid has developed rapidly in recent years and is widely used in asphalt pavements, especially in asphalt overlays to slow down reflective cracks. The School of Transportation at the Canadian University used its unique cover tester to conduct a large number of fatigue tests on the glass fiber geogrid reinforced cover to simulate the temperature cycle effect. The tests showed that the crack resistance of the reinforced asphalt specimens was better than that of the unreinforced asphalt specimens. The ribbed specimen is more than twice as high. The Wollongong Municipal Council in New South Wales, Australia, has conducted on-site comparative tests on products such as fiberglass geogrids, polypropylene geogrids, geotextiles and thick asphalt concrete overlays to control reflective cracks. The conclusion is that the laying of fiberglass geogrids is The effect of conveniently controlling reflective cracks is the most significant and the cost is moderate, so it is recommended to be promoted and applied.
In some developed countries such as Germany, the United States, Canada, Australia and Japan, fiberglass grating has been used for more than ten years in high-grade highways, municipal roads and airport pavements with higher requirements. It is widely used in many fields, and a lot of systematic research has been done on its mechanism of action, and some corresponding design and application specifications have been formulated.
The application of fiberglass geogrids in my country is relatively late. In the construction of Shanghai-Nanjing Expressway in 2000, fiberglass geogrids were first used in asphalt pavements to prevent the occurrence of reflective cracks in the asphalt surface layer caused by cracks in the base layer. After many years of observation, the results are obvious. Therefore, in the maintenance project of Shanghai-Nanjing Expressway from 2000 to 2015, fiberglass geogrids are still used in the new overlay after the original road surface is washed and planed to enhance the strength of the overlay and prevent the occurrence of reflective cracks. .
(6) Classification and construction methods of fiberglass geogrid
Currently, the commonly used fiberglass geogrids are with self-adhesive glue and without self-adhesive glue. The ones with self-adhesive glue can be directly placed on The leveled base layer without self-adhesive glue is usually fixed by nails.
. Construction site: It is required to be compacted, flat and horizontal, and sharp protrusions must be removed.
Griding laying: The main stress direction (longitudinal) of the grating installed and laid on a flat and compacted site should be perpendicular to the axis of the embankment, and it should be laid as flat as possible without wrinkles and tightened as much as possible. The main stress direction of the laid grid should be fixed with nails and earth and stone weight. It is best to have a full length without joints. The connection between the widths can be manually tied and the overlap width should not be less than 1. If the grille is installed in more than two layers, the joints between the layers should be staggered. After laying a large area, the overall straightness should be adjusted. After filling with a layer of soil and before rolling it, the grid should be tightened again manually or with machine tools. The intensity should be uniform so that the grid is in a straight and stressed state in the soil.
, Filling selection: Filling should be selected according to design requirements. Practice has proven that all materials except frozen soil, swamp soil, domestic garbage, chalk soil and diatomaceous earth can be used as filler. However, gravel soil and sand soil have stable mechanical properties and are little affected by water content and should be preferred. The particle size of the filler should not be larger than that and attention should be paid to controlling the filler gradation to ensure the compaction weight.
Paving and compacting of filler: After the grid is laid and positioned, it should be filled with soil in time to cover it. The exposure time should not be too short. The flow operation method of backfilling while laying can also be adopted. First spread the filler at both ends to fix the grid and then push it to the middle. The order of rolling is first on both sides and then in the middle. During rolling, the rollers cannot be in direct contact with the reinforcements. Generally, vehicles are not allowed to drive on uncompacted reinforcements to avoid dislocation of the reinforcements. The layered compaction degree is -. The degree of compaction must meet the design requirements, which is also the key to the success of reinforced soil projects.
. Anti-drainage measures: In reinforced soil engineering, drainage treatment inside and outside the wall must be done well, and foot protection must be done to prevent erosion. Filters and drainage measures must be set up in the soil. Geotextiles and fiberglass should be installed when necessary. Features of geogrid
The product has the characteristics of high strength, low elongation, high temperature resistance, high modulus, light weight, good toughness, corrosion resistance, long life, etc. It can be widely used in old cement pavements and airport runways. Engineering fields such as maintenance, embankments, riverbanks, slope protection, road and bridge pavement enhancement treatment and other engineering fields can strengthen and reinforce the pavement to prevent pavement rutting, fatigue cracks, hot and cold expansion cracks and reflective cracks below, and can disperse the pavement load-bearing stress to extend the service life of the pavement. High tensile strength, low elongation, no long-term creep, good physical and chemical stability, good thermal stability, fatigue cracking resistance, high temperature rutting resistance, low temperature shrinkage cracking, delay and reduction of reflective cracks. Uses of fiberglass geogrid
. Reinforce old asphalt concrete pavement to strengthen the asphalt surface layer to prevent and control diseases.
. Renovation of cement concrete pavement into composite pavement inhibits reflection cracks caused by plate shrinkage and other factors.
. Road expansion and improvement projects prevent cracks at the junction of new and old areas and uneven settlement.
. The reinforcement treatment of soft soil foundation is conducive to the consolidation of water in soft soil, effectively suppressing settlement, uniform stress distribution and enhancing the overall strength of the subgrade.
. The semi-rigid base layer of the newly built road is reinforced with shrinkage cracks to prevent pavement cracks caused by the reflection of foundation cracks.