With the increase of road traffic and vehicle load, the damage to the pavement structure is increasing as time goes on. More and more old concrete pavements in Jakarta, Indonesia are facing repair and maintenance work. Compared with asphalt pavement, the repair of cement concrete pavement is more difficult. Overlaying asphalt overlay on old concrete pavement is an effective measure to improve its performance, but reflection cracks in asphalt overlay is still the main problem to be solved. Reflective cracks themselves have little effect on the performance of the surface layer, but the negative effects of environmental factors (rain, snow, oxidation, dust) often cause the cracks to rapidly expand around and shorten the life of the surface layer. In order to effectively slow down the old cement reflection speed of cracks on concrete pavement, or the thickness of asphalt surface layer thinning, Indonesian researchers conducted a lot of experiments, and finally chose to use geogrid fabric to repair the road. Our geosynthetics product have a good reputation in the Indonesian market. It is well received by local construction units. Our fiberglass geogrid fabric is made of high-quality reinforced alkali-free glass fiber yarn, woven into the base material by advanced warp knitting machine, and warp-knitted oriented structure, making full use of the strength of the yarn in the fabric, improving its mechanical properties and making it have good resistance Tensile strength, tear strength and creep resistance, and are produced by coating with high-quality modified asphalt. It follows the principle of similar compatibility, focuses on its composite performance with asphalt mixture, and fully protects the glass fiber base material, which greatly improves the wear resistance and shear resistance of the base material, so that it can be used for pavement enhancement and resistance. The occurrence of road diseases such as cracks and ruts has ended the difficulty of strengthening the asphalt pavement.
1 Specifications of Fiberglass Geogrid Fabric for Road Construction Project in Indonesia
- Total fiberglass geogrid fabric quantity – 56,000 square meters
- Specification – 100KN/30KN
- Roll Size – 4m * 100m
2 What is the Purpose of the Fibergalss Geogrid Fabric?
Fiberglass geogrid is utilized in the asphalt surface layer, acting as a structural framework and creating a composite mechanical interlocking system. This enhances the lateral binding force and promotes interlocking between different parts of the asphalt surface layer.
2.1 Mitigate reflection cracks
Reflective cracks are caused by the stress concentration in the asphalt overlay above the old concrete surface due to the large displacement of the old concrete surface near the joint or crack. It includes horizontal displacement due to changes in temperature and humidity, as well as due to traffic loads. The vertical shear displacement caused by the action. The former leads to a relatively concentrated tensile stress in the asphalt overlay above the joint or crack; the latter causes the asphalt overlay above the splicing to experience greater flexural tensile stress and shear stress. Since the modulus of the ten-gong fiberglass geogrid is very large, reaching 67Gpa, it is used as a hard interlayer with high rigidity in the asphalt overlay. Its function is to restrain stress and release strain. At the same time, it is used as a reinforcing material for asphalt concrete to improve the structure of the overlay. The tensile and shear resistance can be reduced to achieve the purpose of reducing cracks. Practice has shown that the corresponding crack energy of a horizontal crack that has changed direction can be moved 0.6 meters from its starting point, and reinforcement materials with a width of more than 1.5 meters help ensure that the energy is completely dissipated on both sides of the crack.
2.2 Anti-fatigue cracking
The main function of the asphalt overlay on the old cement concrete pavement is to improve the use function of the pavement, and it does not contribute much to the bearing effect. The rigid concrete pavement under the overlay still plays a key bearing role. The asphalt overlay on the old asphalt concrete pavement is different, the asphalt overlay will carry the load together with the old asphalt concrete pavement. Therefore, in addition to reflection cracks, fatigue cracking will also occur due to the long-term action of the load when the asphalt overlay is applied on the asphalt concrete pavement. We do a stress analysis on the loading of the asphalt overlay on the old asphalt concrete pavement. Since the asphalt surface layer is a flexible surface layer with the same properties as the asphalt surface layer, when subjected to load, the road surface will deflect. The asphalt surface layer directly in contact with the wheel is under pressure, and in the area other than the wheel load edge, the surface layer is under tension. Since the force properties of the two stressed areas are different and they are close to each other, the junction of the force area, that is, the sudden change of force, is prone to damage. Fatigue cracking occurs under long-term loading.
In the asphalt surface layer, the glassfiber geogrid fabric can disperse the above-mentioned compressive stress and tensile stress, and form a buffer zone between the two stressed areas, where the stress gradually changes instead of abruptly reducing the sudden change of stress. Destruction of the surface layer. At the same time, the low elongation of the glass fiber geogrid reduces the deflection of the pavement and ensures that the pavement will not undergo transitional deformation.
2.3 High temperature rutting
Asphalt concrete has rheological properties at high temperature, which is embodied in the asphalt road surface in summer becomes soft and sticky; under the action of vehicle load, the stressed area is dented, and the asphalt surface layer cannot be completely restored to before the load after the vehicle load is removed Under the action of repeated rolling 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 when it is loaded, causing the asphalt surface layer to move, which is the main reason for the formation of ruts. Fiberglass geogrids are used in the asphalt overlay, which acts as a skeleton in the asphalt overlay. The aggregate in the asphalt concrete runs through the geogrids, forming a composite mechanical interlocking system, restricting the movement of the aggregate, and increasing the lateral restraint force in the asphalt surface layer. move, so as to play a role in resisting rutting.
2.4 Resistance to low temperature shrinkage cracking
On asphalt roads in severe cold areas, the temperature of the road surface 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, resulting in diseases. From the perspective of the causes of cracks, how to make the strength of asphalt concrete resist the tensile stress is the key to solving the problem.
2.5 Mechanism of glass fiber grating to prevent reflection cracks
According to the characteristics of the above-mentioned fiberglass geogrid fabric and the urban asphalt road reconstruction, it is decided to arrange the fiberglass geogrid reinforced layer on the old asphalt pavement and the old cement concrete pavement, and then lay the asphalt concrete surface layer on it. The pavement paved in this way has a significant effect on preventing the reflection of cracks in the base layer, reducing road rutting and prolonging the life of the road surface. The glassfiber geogrid has high tensile strength, low elongation, no creep, and is compatible with asphalt warm mixes. It has the characteristics of good performance, stable physical and chemical properties, high temperature resistance, strong interlocking and restricting effect, etc. Its main function is to transmit the axial load evenly, and to transfer the reflected crack stress from the vertical direction to the horizontal direction. The use of fiberglass geogrid fabric can enhance the overall tensile strength of the asphalt mixture, effectively improve the stress distribution of the pavement structure, resist and delay the occurrence of reflective cracks in the asphalt concrete pavement caused by cracks in the base layer of the dry pavement, thereby improving the use of the pavement life.
3 Construction Technology of Fiberglass Geogrid Fabric Indonesia
3.1 The external principle of pavement
The use effect of glass fiber geogrid is closely related to the treatment of pavement. Before laying, the substances on the pavement that may affect the bonding strength of the grating and the bottom layer, such as grease, paint, sealing material, water stains, dirt, etc., must be thoroughly cleaned. Clean and dry the paved surface.
3.2 Laying and fixing of fiberglass grating
The grating can be laid by tractors or special equipment modified by automobiles, or manually. The two ends of the paper tube of each roll of fiberglass grating are marked with orange and blue marks. Before starting to lay, the glue side should be downward. , Make sure that the above marking colors are at one end, so as to facilitate the construction and avoid laying the glue surface wrong. When the grille is laid, it should be kept flat and taut, without wrinkling, so that the grille has effective tension, and then roll it again with a clean drum roller after laying.
At present, there are two kinds of glass fiber gratings with self-adhesive and without self-adhesive. Indonesian customers use fiberglass grating without self-adhesive, and the materials required for fixing are:
①50x50x0.3mm fixed iron sheet, it is required to be flat and not warped, and the periphery should be chamfered
②2 inch steel nails.
When laying glass fiber grating by Zhoudinggang method, first fix one end of iron sheet and steel nails on the lower structure of asphalt, and the steel nails can be injected by hammering or shooting nails. Then tighten the grille longitudinally and fix it in sections, with each section having a length of 2~5m. It can also be divided into sections according to the spacing of the shrinkage joints, and the position of the steel nails is set outside the joints. It is required that when the grid is tightened, the longitudinal and transverse directions of the glass fiber are out of the straight and tensioned state. Orientation places the previous image on top of the latter. When fixing, the steel nails cannot be nailed to the fiberglass grille, and the fiberglass grille cannot be directly hit with a hammer. After fixing, if the steel nails are broken or the iron sheet is loose. It needs to be re-fixed. After the fiberglass grid is laid and fixed, it must be fixed with glue. The roller road roller is moderately rolled and stable, so that the grille and the original road layer are firmly bonded.
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