814Soil Base Materials

814.1 General Description

This section includes the requirements for soil base materials, including topsoil or sand-clay, soil-cement, sand for bituminous stabilization, and chert.

814.1.01 Related References

A. Standard Specifications Section 209–Subgrade Construction Section 301–Soil-Cement Construction Section 800–Coarse Aggregate Section 810–Roadway Materials Section 831–Admixtures B. Referenced Documents AASHTO T 89 AASHTO T 90 ASTM D 516 GDT 4 GDT 6 GDT 7 GDT 65 GDT 67 GDT 98

814.2 Materials

814.2.01 Topsoil or Sand-Clay

A. Requirements Use topsoil or sand-clay that is a natural or artificial mixture of clay or soil binder with sand or other aggregate. • Do not use a mixture that contains substances detrimental to the material. • Obtain the materials from sources approved by the Engineer. • Ensure that the aggregate retained on No. 10 (2 mm ) sieve (coarse aggregate) is of hard, durable particles. Sand and Binder Use hard, sharp, durable, siliceous particles. Use binder made from quality clay. Oversize Remove particles with diameters greater than 2 in. (50 mm) before depositing the topsoil or sand-clay on the road. Remove particles with screens or grizzlies, or by hand if few oversized pieces exist. You may crush the oversized pieces and use them. Topsoil Use a topsoil that is a natural, generally pebbly material occurring in shallow surface deposits on usually elevated areas. Natural Sand-Clay Use a natural sand-clay that is a mixture of natural material, largely sand and clay in proper proportions, occurring in deposits of considerable depth. Artificial Sand-Clay Use an artificial sand-clay that is largely a mixture of artificial sand and clay. You may make the mixture by combining clay or soil binder and sand or aggregate in the proper proportions. Topsoil and Sand-Clay Use topsoil and sand- clay with the following properties: Sieve Size Amount Passing 2 in. (50 mm) 100% by weight Passing 1-1/2 in. (37.5 mm) 80-100% by weight Passing No. 40 (425 µm) Liquid Limit (LL) of 25 or less Plasticity Index (PI) of 9 or less Ensure that material passing the No. 10 (2 mm) sieve meets the following requirements: Sieve Size Percent Passing by Weight Passing No. 10 (2 mm) sieve 100 Passing No. 60 (250 µm) sieve 15-85 Passing No. 200 (75 µm) sieve 9-35 Clay 9-25 Volume change, max. percent 12 Maximum density, lb./ft.³ (kg/m³) 110+ (1760+) B. Fabrication General Provisions 101 through 150. C. Acceptance The Department or Producer will test as follows: Test Method Soil gradation GDT 4 Volume change GDT 6 Maximum density GDT 7 or GDT 67 Liquid Limit AASHTO T 89 Plastic Limit and Plasticity Index AASHTO T 90 D. Materials Warranty General Provisions 101 through 150.

814.2.02 Soil-Cement Material

A. Requirements Ensure that the material for soil-cement base will: a. Meet the requirements of Subsection 810.2.01 for Classes IA1, IA2, IA3, or IIB1 with the following modifications: Clay content 5 to 25% Volume change 18% maximum Liquid Limit 25% maximum Plasticity Index 10% maximum Maximum dry density 95 lb./ft.³ (1520 kg/m³) minimum Sulfates 4000 ppm maximum pH 4.0 minimum b. Be friable and not contain large amounts of heavy or plastic clay lumps, organic material, roots, or other substances that would interfere with how the Portland cement sets, plant production, or the finished surface of the base and meet the requirements of Subsection 301.3.05.A.2, Pulverization or Subsection

301.3.05 B.1, Soil.

c. Produce a laboratory unconfined compressive strength of at least 450 psi (3.1 MPa). To make the sample, mix in a minimum of 5% to a maximum of 9 percent Type I Portland cement, moist-cure for 7 days, and test with GDT 65. Analyze the soil-cement design and create a Job Mix Formula for each Project where soil-cement base or subbase is specified. Have the Job Mix Formula approved by the Engineer before starting base or subbase construction. You may use fly ash or slag that meets the requirements of Subsection 831.2.03 as admixtures for poorly reacting soils when the blend of soil and fly ash, or slag, meets the design requirements in this Subsection. Ensure that subgrade material used underneath the soil-cement base meets the sulfate and pH requirements of this subsection (See Subsection 209.3.05.A.7). B. Fabrication General Provisions 101 through 150. C. Acceptance Test as follows: Test Method Soil gradation GDT 4 Volume Change GDT 6 Maximum density GDT 7 or GDT 67 Soil-Cement Design GDT 65 pH GDT 98 Sulfates ASTM D 516 Test Method Liquid Limit AASHTO T 89 Plastic Limit and Plasticity Index AASHTO T 90 D. Materials Warranty General Provisions 101 through 150.

814.2.03 Sand for Bituminous Stabilization

A. Requirements Submit the bituminous stabilization sand materials to the laboratory in advance. If the laboratory approves the mater ial, use it in constructing the sand- bituminous base course. Use hard, durable particles without organic impurities such as roots or trash that may prevent the bituminous mater ial from bonding with the individual particles. Grade the material as follows: Size Percent Passing by Weight Passing 1 in. (25 mm) sieve 100 Passing No. 10 (2.00 mm) sieve 80-100 Passing No. 200 (75 µm) sieve 0-25 Clay 0-16 B. Fabrication General Provisions 101 through 150. C. Acceptance Test as follows: Test Method Soil gradation GDT 4 D. Materials Warranty General Provisions 101 through 150.

814.2.04 Chert

A. Requirements Use materials that are natural mixtures of binder and chert rock with the following characteristics: • Ensure that the aggregate retained on the No. 10 (2 mm) sieve (coarse aggregate) is a hard, durable chert rock meeting requirement for Class A or B coarse aggregate (see Subsection 800.2.01). Use aggregate sizes in the final mix that can be properly placed, compacted, and finished. • Ensure that the portion of material passing the No. 10 (2 mm) sieve is sand and clay or another satisfactory bonding material. Gradation Grade the material as follows: Size Percent by Weight Passing 1-1/2 in (37.5 mm) sieve 80-100 Passing No. 10 (2 mm) sieve 30-60 Material Passing No. 10 (2 mm) Sieve Passing No. 10 (2 mm) sieve 100 Passing No. 60 (250 µm) sieve 20-85 Passing No. 200 (75 µm) sieve ( silt less clay) 5-25 Clay 15-50 Ensure that the material passing the No. 40 (425 µm) sieve has a Liquid Limit (LL) of 35 or less and a Plasticity Index (PI) of 10 or less. Stockpiles In all cases, stockpile the end product so that the material will be blended before any of it is loaded and delivered to the job. a. Make a stockpile big enough to uniformly blend the workable strata in the pit. b. The Engineer will determine the minimum volume of the stockpile. The Engineer will also be the sole authority as to the quality and workability of the various strata occurring in the pit. c. Maintain the minimum volume of the stockpile until the suitable material in the pit has all been stockpiled or until the material remaining in the stockpile is enough to complete the operation, as governed by haul limitations. Equipment for Delivery Use equipment that will mix the material again while the material is being loaded for delivery. B. Fabrication General Provisions 101 through 150. C. Acceptance Test as follows: Test Method Soil gradation GDT 4 Liquid Limit AASHTO T 89 Plastic Limit and Plastic Index AASHTO T 90 D. Materials Warranty General Provisions 101 through 150.