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Recommended Pavement Section Thickness <br />It should be noted that the pavement section presented below is not absolute. Depending on <br />serviceability expectations, material availability, and cost, there could be circumstances under <br />which alternative sections will be more practicable. <br />Based on an estimated R-value of 50 and a maximum of 100,000 ESAL's we recommend a <br />pavement section consisting of a minimum of 4 inches of bituminous underlain by a minimum of <br />6 inches of Class 5 aggregate base. <br />4.5 Materials <br />We recommend aggregate base meeting MN/DOT specification 3138 for Class 5 aggregate base. <br />We recommend the aggregate base be compacted to 100 percent of its maximum standard Proctor <br />dry density. <br />We recommend that the bituminous wear and base courses meet the requirement of MN/DOT <br />specification 2360. We recommend the bituminous pavements be compacted to at least 92% of the <br />maximum theoretical density. <br />Pavement reconstruction will likely include installing concrete curb and gutter. We recommend <br />specifying concrete that has a minimum 28-day compressive strength of 4,000 psi. We recommend <br />specifying 5 to 8 percent entrained air for exposed concrete to provide resistance to freeze -thaw <br />deterioration. We recommend slump, air content and compressive strength test of Portland <br />cement concrete. <br />5.0 CONSTRUCTION CONSIDERATIONS <br />5.1 Excavation <br />The soil encountered in the borings consisted of granular soil composed of poorly graded sand <br />with silt and poorly graded sand corresponding to the ASTM Classifications SP-SM and SP, <br />respectively. The soils identified in the boring will generally be Type C soils under Department <br />of Labor Occupational Safety and Health Administration (OSHA) guidelines. <br />Temporary excavations in Type C soils should be constructed at a minimum of 11/2 foot horizontal <br />to every 1 foot vertical within excavations. Slopes constructed in this manner may still exhibit <br />surface sloughing. If site constraints do not allow the construction of slopes with these <br />dimensions, then temporary shoring may be required. <br />5.2 Observations <br />A geotechnical engineer or qualified engineering technician should observe the excavation <br />subgrade to evaluate if the subgrade soils are similar to those encountered in the borings and <br />adequate to support the proposed construction. <br />10 <br />