Quality requirements of common materials for soft

Quality requirements for common materials used in soft foundation treatment of Expressway

1. Gravel material

gravel material used as cushion shall have good water permeability, and shall not contain organic matter, clay blocks and other harmful substances. The maximum particle size of gravel shall not be greater than 53mm, and the silt content shall not be greater than 5%

2. sand and sand bags

the sand used in the bagged sand well should be medium and coarse sand with high water permeability. The sand content greater than 0.5mm should account for more than 50% of the total weight, the mud content should be less than 3%, and the permeability coefficient should be greater than 510-2mm/s. The sand bag should be made of woven fabrics such as polypropylene, polyethylene, polyester, etc., and should have sufficient tensile strength to withstand the tension caused by the self weight and bending of the sand in the bag, For example, in all industries used for bellows testing, the equipment will be equipped with an inner diameter measuring device, which has good anti-aging performance and environmental water corrosion resistance, and its impermeability coefficient should not be less than the permeability coefficient of the sand used

3. Crushed stone

crushed stone is rolled from rock and gravel. It should be clean, dry, and have sufficient strength and wear resistance. Its particle shape should be angular, and it should not be mixed with soft stone and other impurities. The particle size should be 20 ~ 50mm, and the mud content should not be greater than 10%

4. Geosynthetics

the selection of geosynthetics should comply with the provisions of the technical code for the application of highway geosynthetics. It should have sufficient tensile strength. For geotextiles, it should also have high puncture strength and grip strength. The test items and methods of geosynthetics shall comply with the provisions of technical code for design and construction of highway soft soil embankment and specification for highway geosynthetics test

5. Plastic drainage board

plastic drainage board is a composite composed of the core and the synthetic fiber permeable membrane surrounding the core, which should have good corrosion resistance and sufficient flexibility, and its performance index should comply with the provisions of the construction specification for plastic drainage board

6. Rubble

riprap and silt squeezing should use non weathered rubble, whose size should be smaller than that of the chain. Users should consult the manufacturer of the chain to obtain the utilization information of the chain 300mm

7. Cement

all performance indexes of cement should meet the requirements of the drawing. It is strictly forbidden to use expired, damp, caked and deteriorated inferior cement. The cement index used shall also comply with the provisions of the corresponding cement standards

8. Lime

lime shall meet the requirements above grade III specified in table 4.2.2 of the technical code for construction of highway pavement base. The inspection shall be carried out according to the test method specified in the test code for inorganic bound and stable materials in highway engineering

9. Fly ash

fly ash shall comply with the relevant provisions of the technical code for construction of highway pavement base

10. procurement and storage of materials

the insulation resistance, sand bags, lime, cement, sand and other materials of plastic drainage boards and geosynthetics decline electronic universal experimental machine components used for soft soil foundation treatment must be purchased and stacked according to the quality indicators required by the construction drawings and specifications. It is strictly prohibited to pollute or mix materials, and expired products are strictly prohibited to use. Plastic drainage boards, geosynthetics, sandbags and other materials should be stored in places that are not directly exposed to sunlight and drenched by rain, and should be taken daily according to the project progress and daily consumption