With the large-scale construction of highways in China, it often encounters problems such as difficulty in construction of special soils such as soft soil and expansive soil, and poor quality control. The application of geosynthetics has solved the problems of civil engineering construction to a certain extent. The so-called geosynthetic material is a general term for various synthetic fiber fabrics, including geogrid, geonet, geomembrane, and geomat. Among them, the geogrid has the characteristics of high tensile strength, large deformation modulus, corrosion resistance, anti-aging, large friction coefficient with soil particles, strong chain effect, and good reinforcement effect. The geogrid is buried in the soil. In the body, as a reinforcement material for the foundation, it can enhance the bearing capacity of the foundation. At the same time, by restraining the lateral dilatancy deformation of the soil, the overall stress condition of the soil can be improved, and the overall strength of the soil and the overall stability of the geotechnical structure can be improved. Therefore, the glass fiber geogrid is unique in highway construction. Application prospects.

The glass fiber geogrid is made of high-quality reinforced alkali-free glass fiber yarn, which is woven into the base material by foreign advanced warp knitting machine, and adopts the warp-knitting orientation structure to make full use of the yarn strength in the fabric, improve its mechanical properties, and make it have good It is a flat network material with high tensile strength, tear strength and creep resistance, and is coated with high-quality modified asphalt. Based on the principle of similar compatibility, it focuses on its composite performance with asphalt mixtures, and fully protects the glass fiber substrate, which greatly improves the wear resistance and shear resistance of the substrate, so that it can be used for pavement reinforcement and resistance The occurrence of road diseases such as cracks and ruts has ended the problem of difficulty in strengthening asphalt pavements.

Characteristics of fiberglass geogrid

The glass fiber geogrid is a semi-rigid product made of alkali-free glass fiber mesh after surface coating treatment. The excellent performance characteristics of fiberglass geogrid are as follows:

1. High tensile strength, low elongation: The glass fiber geogrid is made of glass fiber. Beyond other fibers and metals. At the same time, it has a high modulus, while the strength of glass fiber is high. It has high resistance to deformation and the elongation at break is less than 3%.

2. No long-term creep: fiberglass geogrid is used as a reinforcing material. This ensures that the product can temporarily maintain performance. The ability to resist deformation under temporary load, that is, creep resistance is extremely important, glass fiber does not creep. Ensure that the glass fiber geogrid can maintain long-term performance.

3. Thermal stability: The melting temperature of glass fiber is above 1000℃, and there will be no change at 28℃, which ensures the stability of the glass fiber geogrid to withstand excessive heat during paving operations.

4. Compatibility with asphalt mixture: The coating material of the glass fiber geogrid in the post-treatment process is that each fiber designed for the asphalt mixture is fully coated. This ensures that the glass fiber grid will not be isolated from the asphalt mixture in the asphalt layer, and has high compatibility with asphalt. It is firmly combined.

5. Physical and chemical stability: coating treatment with special post-treatment agent. Ensure that its performance is not affected. Fiberglass geogrid can resist all kinds of physical abrasion, chemical erosion, biological erosion and climate change.

6. Aggregate interlocking and restriction: Because the fiberglass geogrid is a mesh structure. This forms a mechanical interlock. This restriction hinders the movement of aggregates, which can penetrate through the aggregates in asphalt concrete. The asphalt mixture can achieve a better compaction state, higher load-bearing capacity, better load transmission performance and smaller deformation under load.

The application of glass fiber geogrid in highway engineering

(1) Application of glass fiber geogrid in roadbed reinforcement and soft foundation treatment

The new construction and overhaul of urban roads mainly consider the two major issues of roadbed stability and settlement. Generally, there is no reinforced embankment, and the damage is caused by circular arc sliding or punching settlement on the thick soft soil layer; on the thin soft soil layer, it is lateral extrusion failure. When the road passes through the soft soil foundation, the general simple treatment method is to replace the soil or spread a layer of gravel or crushed stone on the soft soil foundation and then compact it. The land exchange method is costly and uneconomical. After the crushed gravel is compacted, a limited amount of granular material is squeezed into the soft foundation soil. The soil material is mixed, which reduces the material strength, and the road surface is still prone to subsidence under the action of driving. With the continuous in-depth research of geosynthetics, we have found that the use of glass fiber geogrids can not only solve the problem of the stability of soft soil foundations, but also effectively reduce the uneven settlement caused by the filling of the roadbed. Lay the glass fiber geogrid directly on the soft foundation, and then pave the granular base layer. This not only ensures that the granules and the foundation soil are not mixed, but also the occlusion between the grid and the granular material is further strengthened, and the base layer is resistant Tensile strength, thereby improving the bearing capacity of soft soil foundation.

The economic benefit of using glass fiber geogrid lies in: reducing the requirements for filling materials. When the filling material that meets the design requirements is far away, the nearby sandy filling material can meet the design requirements after adding the geogrid. ; Reduce the amount of filling works; reduce the cost of earth filling and rolling.

(2) Application of fiberglass geogrid in preventing reflection cracks

It is a common pavement repair technique to add asphalt surface layer on old cement concrete pavement and old asphalt concrete pavement. It has the advantages of short construction period, low cost, little impact on traffic, and good service performance for road repair. However, the main problem is that reflective cracks are prone to appear in the asphalt overlay, that is, the horizontal cracks and longitudinal cracks formed by the asphalt surface layer due to temperature shrinkage, traffic load and local settlement of the roadbed during use, and the crack width will gradually increase with time. Great, affect the effect of road use. According to the conventional treatment method, it is necessary to cut the surface layer, remove the base layer, and then re-pave the surface layer. The construction process is complicated and the economic benefit is poor. The installation of glass fiber geogrid is one of the main measures to delay reflective cracks. After adding a glass fiber geogrid anti-cracking layer to the asphalt surface layer, it can effectively reduce the stress intensity factor amplitude at the crack tip in the asphalt surface layer and change The stress distribution on the surface of the asphalt layer improves the fatigue resistance, and the cracks will not spread quickly. Relevant tests show that after laying the fiberglass geogrid anti-crack layer, the fatigue load resistance of the surface layer is more than 10 times higher than that of the unpaved fiberglass geogrid anti-crack layer. At the same time, laying a glass fiber geogrid anti-crack layer can reduce the temperature shrinkage and moisture shrinkage of the roadbed, and delay the propagation time of reflection cracks. The use of glass fiber geogrid treatment does not need to damage the pavement structure, the construction is rapid, and the use effect and economic benefits are obvious.

Mechanism of glass fiber geogrid

The glass fiber geogrid is used in the road structure layer, and it mainly has the functions of fatigue cracking resistance, roadbed reinforcement and reflection crack prevention. Its mechanism is as follows:

(1) The mechanism of anti-fatigue cracking

 Asphalt pavement must have a certain load-bearing capacity and no fatigue damage can occur within the specified time. Asphalt pavement is under pressure on the lower layer directly in contact with the wheel, and pulls in the area outside the edge of the wheel load. Because the two force areas are different in nature and close to each other, they are at the junction of the two force areas. Where damage occurs, fatigue cracking occurs under long-term load.

The glass fiber geogrid in the asphalt surface layer can disperse the above-mentioned compressive and tensile stresses, forming a buffer zone between the two stressed areas, reducing the damage to the asphalt surface layer caused by sudden stress changes. At the same time, the low elongation of the glass fiber geogrid reduces the deflection of the road surface and ensures that the road surface will not be excessively deformed.

(2) The mechanism of roadbed reinforcement and reflection crack prevention

The glass fiber geogrid acts on roadbed reinforcement and prevention of reflection cracks through two important mechanisms: direct tensile stress and lateral displacement of the confined soil. For asphalt concrete added with fiberglass geogrid, the mesh structure of the fiberglass geogrid makes the fiberglass geogrid act as a reinforcement for the asphalt mixture in the mesh. Therefore, when the foundation at the bottom of the asphalt concrete structure layer is under load, cracks appear and extend to the glass fiber geogrid. The existence of the geogrid changes the stress on the crack tip and makes the crack open. Deformation is limited, so as to strengthen the roadbed and inhibit the upward development of cracks.

The stability of the mesh structure of the glass fiber geogrid is enhanced by the mutual filling with the asphalt mixture, and the high tensile strength of the glass fiber geogrid itself is the main factor in restraining the opening deformation. Asphalt concrete added with glass fiber geogrid can effectively improve the stress distribution of the pavement structure, resist and delay the occurrence of pavement diseases caused by roadbed cracks, so that the asphalt concrete structure layer will not suffer from tension deformation in a long period of time. Compared with the asphalt concrete structure layer without glass fiber geogrid, the use of glass fiber geogrid can greatly increase the service life of the road surface.