Application and laying technology of non-woven fabric in highway maintenance

Nowadays, with the implementation of channelized traffic on high-grade highways, asphalt pavements will experience varying degrees of rutting due to the combined effects of vehicles and environmental factors. In order to effectively prevent the spread and development of asphalt pavement diseases such as ruts and cracks, the team led the construction and testing of some test roads and found that using non-woven fabric reinforcement materials can improve the structural strength and performance of the pavement, especially in preventing and delaying the development of cracks. Research has shown that using non-woven fabrics to reinforce asphalt pavement structures can effectively improve the road's resistance to strain and extend its service life. Under the same load, while meeting the designed traffic capacity of the pavement, the thickness of the pavement structure layer can be reduced, and the non-woven fabric reinforced pavement can exhibit better road performance. However, cracks or mesh cracks of varying degrees have already appeared locally or in patches, and if not repaired in a timely manner, they may cause extensive damage due to water infiltration. If the area of mesh cracking or cracking is large or has already formed patches, non-woven fabric can be laid as a whole for treatment.

The laying process of non-woven fabric: 1. manual rolling laying; The fabric surface should be flat and leave appropriate deformation allowance. The installation of long or short fiber non-woven fabrics usually involves several methods such as overlapping, sewing, and welding. The width of stitching and welding is generally above 0.1m, and the overlap width is generally above 0.2M. non-woven fabrics that may be exposed for a long time should be welded or sewn. The stitching of non-woven fabrics must be continuous (for example, point stitching is not allowed). Before overlapping, the non-woven fabric must overlap by at least 150mm. The distance between the small sewing needle and the woven edge (the exposed edge of the material) should be at least 25mm. The sewn non-woven fabric seam includes a single line of interlocking chain seam method. The thread used for stitching should be made of resin material with a small tension exceeding 60N, and have chemical corrosion resistance and UV resistance equivalent to or exceeding that of non-woven fabric. Any 'missing needle' on the sewn non-woven fabric must be re sewn in the affected area. Corresponding measures must be taken to prevent soil, particulate matter, or foreign substances from entering the non-woven fabric layer after installation. The overlapping of fabrics can be divided into natural overlapping, seam joining, or welding according to the terrain and usage function. During construction, the non-woven fabric on top of the geomembrane is naturally overlapped, and the upper layer of non-woven fabric on the geomembrane is sewn or hot air welded. Hot air welding is the first method of connecting long filament non-woven fabrics, which involves using a hot air gun to instantly heat the connection between two pieces of fabric at high temperatures, causing some of them to reach a molten state, and immediately applying a certain amount of external force to firmly bond them together. In humid (rainy and snowy) weather where thermal bonding cannot be carried out, non-woven fabrics should be connected using another method - sewing connection method, which is to use a dedicated sewing machine for double line sewing connection and use chemical UV resistant sewing thread. When sewing, the small width is 10cm. When natural overlapping, the small width is 20cm. When hot air welding, the small width is 20cm. For sewing, the same quality of sewing thread as non-woven fabric should be used, and the sewing thread should be made of a material with stronger resistance to chemical damage and ultraviolet light irradiation. 6. After the non-woven fabric is laid and approved by the on-site supervising engineer, the non-woven fabric membrane shall be laid. The non-woven fabric on the geomembrane is laid as above after the geomembrane is approved by Party A and the supervisor. The non-woven fabrics on each layer are numbered TN and BN. The upper and lower layers of non-woven fabric on the membrane should be buried together with the non-woven fabric in the anchoring groove where there is an anchoring groove.

Basic requirements for laying non-woven fabric:

a. The joint must intersect with the slope line; The distance between the horizontal joint and the point where there is balance or potential stress at the foot of the slope must be greater than 1.5m.

b. On the slope, anchor one end of the non-woven fabric and then lower the roll material onto the slope to ensure that the non-woven fabric remains taut.

c. All non-woven fabrics must be pressed with sandbags, which will be used during the laying period and retained on the top layer of material.

Requirements for the laying process of non-woven fabric

1. Grassroots inspection: Check whether the grassroots is flat and solid. If there are foreign objects, they should be handled properly. 2. Trial laying: Determine the size of the non-woven fabric according to the on-site situation, cut it and conduct a trial laying. The cutting size should be accurate. 3. Check if the width of the Sarah is appropriate, the overlap should be flat, and the tightness should be moderate. 4. Positioning: Use a hot air gun to bond the overlapping parts of two non-woven fabrics, and the spacing between the bonding points should be appropriate. 5. When suturing the overlapping area, the suture line should be straight and the stitches should be even. 6. After stitching, the non-woven fabric should be checked for flatness and any defects. 7. If there are any non compliant phenomena, they should be repaired in a timely manner.

Self inspection and repair

a. All non-woven fabric sheets and joints must be inspected. Defective non-woven fabric sheets and seams must be clearly marked on the non-woven fabric and repaired.

b. Worn non-woven fabric must be repaired by laying and heat connecting small pieces of non-woven fabric, which should be 200mm shorter than the edge of the defect in all directions. Heat connection must be strictly controlled to ensure that the non-woven fabric patch and non-woven fabric are tightly bonded and not damaged.

c. Before the end of each laying day, visually inspect the surface of all non-woven fabrics laid that day to ensure that all damaged areas have been marked and repaired immediately, and to ensure that there are no foreign substances on the laid surface that may cause damage, such as fine needles, small iron nails, etc.

d. When repairing damaged non-woven fabrics, the following technical requirements should be met:

e. The patch material used to repair holes or cracks should be consistent with the non-woven fabric.

f. The patch should extend at least 30 centimeters beyond the range of the damaged non-woven fabric.

g. At the bottom of the landfill site, if the crack in the non-woven fabric exceeds 10% of the width of the roll, the damaged part must be cut off and the two non-woven fabrics connected; If the crack on the slope exceeds 10% of the width of the roll, the non-woven fabric roll must be removed and replaced with a new roll.