The design institute Voronezh branch of JSC GIPRODORNII provides for a protective and reinforcing layer of Geospan TN-40 woven geotextile made of polypropylene threads or an analogue at the border of the crushed stone and sand underlying layer in the pavement structure. Road pavement structure (asphalt concrete - 5 + 6 + 12 cm, bearing base of C-6 mixture - 40 cm, protective and reinforcing layer Geospan TN-40 (TN-50), additional base layer of medium-sized sand - 50 cm, earthen soil pavement - fine sand) with the accepted design data meets the criteria of ODN 218.046.-01, which is confirmed by the calculations of the road pavements in the CREDO RADON program.
Calculations of the influence of the reinforcing effect were carried out with the introduction of reinforcement coefficients in accordance with STO 18603495.008-2013 "Geospan TN woven geotextile". Recommendations for use in road construction", developed jointly with the specialists of the Federal State Unitary Enterprise "ROSDORNII". Verification calculations of the Institute of Soyuzdorproekt JSC according to the ODM 218.5-002-2008 method confirmed the compliance of the adopted design with the practice of designing pavements at federal road facilities.
Fig. 6 Calculation of pavement in the program CREDO RADON
When choosing the type and brand of geosynthetic material, a comparative analysis of various materials used in the lower layers of the pavement base as protective and reinforcing layers was carried out (table).
| № |
Name and brand of geomaterial |
Non-woven geotextile IP-250 Kanvalan |
Woven geotextile Geospan TN-40 |
Geogrid type SD-40 |
| 1 |
Raw material: |
PP |
PP |
PP |
| 2 |
Purpose and function of geomaterial according to ODM 218.2.046-2014 |
Protection layer |
Protective-reinforcing layer |
Reinforcing layer |
| 3 |
Reinforcing effect, the possibility of optimizing the thickness of the lower layers of the pavement |
None |
Determined by calculation |
Determined by calculation |
| 4 |
Strength indicators:
|
14 kN/m |
40 kN/m |
40 kN/m |
| 5 |
Requirements for strength indicators according to road standards:
|
GOST R 56419 |
GOST R 56338 |
GOST R 56338 |
| 6 |
Technology (construction with the arrival of machinery on the material webs) |
Not allowed |
Allowed |
Possible |
It is recommended to use geosynthetic materials that perform a combined function (Reinforcement + Separation) as a protective and reinforcing layer at the boundary of the ShchGPS S-6 fraction 0-40 and the sandy underlying layer at the base of the pavement. Geogrids without an additional substrate of non-woven geotextile in this case will not provide effective separation of the layers.
The requirements for the main indicators of the quality of the protective and reinforcing layer are determined by the current standards:
GOST R 56338-2015 "Public automobile roads. Geosynthetic materials for reinforcing the lower layers of the pavement base. Technical requirements."
SP 34.13330.2012 (Table D.2 - recommendations on the technical characteristics of geosynthetic materials depending on their area of application).
From June 2014 to 2016, Transstroymekhanizatsiya LLC carried out construction work on the arrangement of layers of pavement on the interval km 517 - km 544, from 2018 to 2019 on the interval km 633 - km 715. The total volume of delivered and laid Geospan TN-40 and Geospan TN-50 materials is more than 2,000,000 m².
The input control of Geospan geotextiles supplied to the facility was carried out in accordance with the STO for marking rolls, a quality certificate and a laboratory test report for each batch for compliance with the requirements of project documentation (the templates for quality certificate and test report are contained in Appendix D).
Fig. 7. Photo from the work site (September 2014)
