Geotextiles and geogrids have been widely used in various fields of geotechnical engineering due to their excellent tensile resistance, mass production in factories, stable quality and simple construction on site.
In the road surface engineering, geotextile is mainly used in the old road surface to prevent the reflection cracks and delay the occurrence and development of reflection cracks. In the subgrade engineering, geogrid is mainly used to treat the soft soil foundation, accelerate the consolidation of the foundation, and improve the bearing capacity of the foundation.
1、 Application of Geotextile in pavement crack prevention
It is a common pavement repair technology to pave asphalt surface on the old cement concrete pavement. It has the characteristics of short construction period, low cost, little impact on traffic and good service performance of pavement repair.
But the main problem is that reflection cracks are easy to appear in asphalt overlay, and setting geotextile is one of the main measures to delay reflection cracks.
In the reconstruction project of Zaomu Road Old Pavement in Zaozhuang City, the above measures are well adopted. As the traffic volume of cement concrete pavement of Zaomu road increases continuously, there are large areas of subsidence, broken slab and other diseases, which can not prevent the development of the disease even after several large areas of patching.
Types of geotextile and specification:
After negotiation between the owner and the designer, it is decided to use asphalt geotextile on the old cement concrete face slab.
The geotextile road material is special geotextile for road, the model is GTM nonwoven geotextile 010 / 140, the mass per unit area is 140g / m2, the thickness is 1.95mm, the tensile strength is 400N / 5cm in longitudinal direction and 280n / 5cm in transverse direction, the elongation is 60% in longitudinal direction and 65% in transverse direction, and the melting point is 230 ℃ ~ 240 ℃.
Geotextile Road Fabric Installation Guideline:
- Construction preparation: the old cement concrete pavement shall be cleaned before laying earthwork in high temperature weather; the damaged part of the original plate shall be cleaned first, and then 6% cement bound macadam material shall be used for leveling and compaction, and the surface flatness shall meet the requirements.
- Asphalt distribution: ordinary hot asphalt is selected as the tack coat oil for asphalt material, and the asphalt distribution amount is determined according to the test, which is controlled at 0.9-1.1kg/m2. The asphalt distribution is carried out by the distributor truck, and the distribution amount shall be tested in advance to meet the requirements. The width of the spraying surface shall be controlled at 20cm over the geotextile, and the distribution speed shall be determined according to the actual paving speed and rolling speed of the geotextile; the excessive asphalt shall be removed in time.
- Laying of geotextile: the geotextile shall be laid before the asphalt cooling loses its cohesiveness; the geotextile shall be laid flat without folding and wrinkle; after laying, it shall be rolled with a tyre roller to make it closely combined, and the length of geotextile pick-up and connection shall be 15cm; the places where the geotextile is damaged and pasted poorly shall be removed from the places where it is repaved and folded, and the asphalt shall be spread or brushed manually, and the folded places shall be pasted again, After rolling, the upper and lower layers of geotextile are bonded together.
- Asphalt mixture paving: after the geotextile is paved, the hot asphalt mixture should be paved immediately, and the temperature should be controlled within 160 ℃; because there is no closed traffic on the road, in order to facilitate the driving of other vehicles, some sand or hot stone chips should be sprinkled on the geotextile; after the asphalt mixture is paved, rolling compaction should be carried out immediately until it meets the requirements of the construction technical specifications.
Geotextiles are good to use to treat road crack.Geotextiles in road construction play an important role.