The main Function of fiberglass geogrid
Slow down reflection cracks
Reflective cracks are caused by the large displacement of the old concrete surface near the joints or cracks that cause stress concentration in the asphalt overlay above it. It includes horizontal displacement due to changes in temperature and humidity, and due to traffic loads. The vertical shear displacement is caused by the action. The former causes concentrated tensile stress in the asphalt overlay above the joint or crack; the latter causes the asphalt overlay above the joint to undergo greater flexural tensile stress and shear stress.
Because the modulus of geogrid is very large, reaching 67Gpa, it is used as a rigid interlayer in the asphalt overlay. Its function is to restrain stress and release strain. At the same time, it is used as an asphalt concrete reinforcement material to improve the structure of the overlay. Tensile and shear resistance, so as to achieve the purpose of reducing cracks. Practice has shown that the corresponding crack energy of a horizontal crack that has changed its direction can move 0.6 meters from its starting point. The reinforced material with a width of more than 1.5 meters helps to ensure that the energy is completely dissipated on both sides of the crack.
Asphalt overlay on the old cement concrete pavement, its main function is to improve the use function of the pavement, but it does not contribute much to the bearing effect. The rigid concrete pavement under the overlay still plays a key bearing role. However, it is different to make asphalt overlay on old asphalt concrete pavement. The asphalt overlay will carry the load together with the old asphalt concrete pavement. Therefore, the asphalt overlay on the asphalt concrete pavement will not only cause reflection cracks, but also fatigue cracks due to the long-term effects of the load. We analyze the load of the asphalt overlay on the old asphalt concrete pavement: because the asphalt overlay is a flexible surface of the same nature as the asphalt overlay when the load is applied, the road surface will bend. Shen. The asphalt cover layer directly in contact with the wheel is under pressure, and the surface layer is under tension in areas other than the edge of the wheel load. Because the two stressed areas have different force properties and are close to each other, the two areas are affected by tension. The junction of the force region, that is, the sudden change of force, is prone to damage. Under the action of long-term load, fatigue cracking occurs.
The fiberglass geogrid in the asphalt overlay can disperse the above-mentioned compressive and tensile stresses, forming a buffer zone between the two stressed areas, where the stress gradually changes rather than abruptly, which reduces the effect of sudden changes in the stress on the asphalt. Destruction of the overcoat. 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 does not undergo transitional deformation.
High temperature resistant rutting
Asphalt concrete has rheological properties at high temperatures, which is specifically manifested in: summer asphalt road surface is soft and sticky; under the action of vehicle load, the stressed area is dented, and the asphalt surface cannot be fully restored to before the load after the vehicle load is removed. Under the condition of the vehicle, plastic deformation has occurred; under the repeated rolling action of the vehicle, the plastic deformation continues to accumulate, forming a rut. After analyzing the structure of the asphalt surface layer, we can know that due to the rheological properties of asphalt concrete under high temperature, there is no mechanism in the surface layer that can restrict the movement of aggregates in the asphalt concrete under load, which causes the asphalt surface layer to move. This is the main reason for rutting
The fiberglass geogrid is used in the asphalt surface layer, which acts as a skeleton in the asphalt surface layer. The aggregates in the asphalt concrete penetrate between the grids to form a composite mechanical interlocking system, which restricts the movement of the aggregates and increases the lateral restraint force in the asphalt overlay. The various parts of the asphalt overlay restrict each other to prevent the asphalt surface layer from being damaged. Move, thereby playing a role in resisting rutting.
Resistance to low temperature shrinkage and cracking
Asphalt roads in severe cold areas, the surface temperature in winter is close to the air temperature. Under such temperature conditions, the asphalt concrete shrinks when cold, resulting in tensile stress. When the tensile stress exceeds the tensile strength of asphalt concrete, cracks will occur, and cracks will occur in the places where the cracks are concentrated, forming diseases. From the perspective of the causes of cracks, how to make the strength of asphalt concrete resist tensile stress is the key to solving the problem.
The application of fiberglass geogrid in the asphalt overlay greatly improves the tensile strength of asphalt concrete, which can resist large tensile stress without causing damage. In addition, even if cracks are generated in a local area, the stress at the place where the crack occurs is too concentrated, but it will gradually disappear through the transmission of the glass fiber geogrid, and the crack will no longer develop into a crack. When selecting the fiberglass geogrid, in addition to its performance indicators should meet the requirements in the above table, special attention should be paid to ensure that its width is not less than 1.5m, so that it has a sufficient cross-sectional area when used as an interlayer to control reflection cracks. Fully dissipate the crack energy; at the same time, the mesh size should be 0.5 to 1.0 times the maximum particle size of the upper asphalt surface material, which helps to achieve the best shear adhesiveness and promote aggregate interlocking and restriction.
For more information please contact to Geofantex Geosynthetics Co., Ltd.
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