<p><p><h2>Commentary</h2>Typical contract pay items and units of measurement used for chemical stabilization of subgrades and base courses include:<br><ul> <li>Subgrade modification measured by the square yard, for all equipment, labor and incidentals necessary to mix, compact, and fine grade a chemically modified subgrade.</li> <li>Cement, fly ash or lime, measured by the ton for material costs.</li> <li>Treated base course measured by the square yard, inclusive of all costs to construct a chemically modified base course.</li></ul>Most of the equipment necessary to construct a chemically modified subgrade and/or base course is common to construction activities on a highway project; therefore, additional mobilization is negligible. An exception to this could be an on-site plant used to mix a chemically modified base course (this assumes that a plant is not needed for other items of work). Mobilization costs for a plant are approximately $25,000.<br><h2>Cost Information Summary</h2>The following table lists construction cost items associated with chemically modified subgrades and base courses, along with approximate cost ranges. Cost ranges are based on data from 2007 through 2010. Readers should carefully examine the project characteristics and constraints and determine to what degree, if any, these factors may influence the actual cost associated with constructing chemically stabilized subgrades and base courses.</p><p><table class='tablepress' id='tablepress-67'><thead><th>Pay Item Description</th><th>Quantity</th><th>Unit</th><th>Low Unit Price</th><th>High Unit Price</th><th>Factors Which May Potentially Impact Costs</th></thead><tbody><tr><td >Subgrade Modification</td><td >Greater Than 10,000</td><td >SY</td><td >$2.00</td><td >$5.00</td><td >Typical depths for subgrade modification are 6” to 12”; cost increases with depth
Lime subgrade requires two passes of the mixing equipment, which increases cost
</td></tr><tr><td >Portland Cement</td><td >Greater Than 150</td><td >TON</td><td >$100</td><td >$150</td><td >Distance from the material source to the project has a significant impact on freight cost</td></tr><tr><td >Fly Ash</td><td >Greater Than
350
</td><td >TON</td><td >$40</td><td >$80</td><td >Distance from the material source to the project has a significant impact on freight cost</td></tr><tr><td >Lime</td><td >Greater Than 150</td><td >TON</td><td >$125</td><td >$175</td><td >Distance from the material source to the project has a significant impact on freight cost</td></tr><tr><td >Cement Stabilized Base Course</td><td >Greater Than
10,000
</td><td >SY</td><td >$7.50</td><td >$15.00</td><td >Typical thickness ranges from 4” to 8”, cost increases with thickness
Cost is sensitive to the mixture proportions, particularly the volume of Portland cement required per cubic yard
Material specifications and haul distance will impact the cost of aggregate(s) used in the mixture
</td></tr></tbody></table><h2>Historical Cost Information</h2>A sample of actual project costs is shown in the table below.</p><p><table class='tablepress' id='tablepress-68'><thead><th>Pay Item Description</th><th>Quantity</th><th>Unit</th><th>Low Unit Price</th><th>High Unit Price</th><th>Average Unit Price</th><th>No. of Bids</th><th>Bid Date</th><th>Source/Agency</th></thead><tbody><tr><td >(SP) Cementitious Stabilized Subgrade</td><td >19,453</td><td >SY</td><td >$1.90</td><td >$5.71</td><td >$3.85</td><td >6</td><td >3/18/2010</td><td rowspan=4 >Oklahoma DOT</td></tr><tr><td >(SP) Fly Ash</td><td >840</td><td >TON</td><td >$51.25</td><td >$90.00</td><td >$69.05</td><td >6</td><td >3/18/2010</td></tr><tr><td >(SP) Cementitious Stabilized Subgrade</td><td >148,220</td><td >SY</td><td >$0.97</td><td >$4.30</td><td >$2.33</td><td >7
</td><td >6/17/2010</td></tr><tr><td >(SP) Fly Ash</td><td >10,139</td><td >TON</td><td >$29.25</td><td >$65.00</td><td >$50.46</td><td >7
</td><td >6/17/2010</td></tr><tr><td >Processing Fly Ash Treated Subgrade</td><td >11,496</td><td >SY</td><td >$1.70</td><td >$3.50</td><td >$2.18</td><td >7</td><td >8/21/2008</td><td rowspan=4 >Colorado DOT</td></tr><tr><td >Fly Ash</td><td >470</td><td >TON</td><td >$80.00</td><td >$184.00</td><td >$97.09</td><td >7</td><td >8/21/2008</td></tr><tr><td >Processing Lime Treated Subgrade (12”)</td><td >143,962</td><td >SY</td><td >$1.25</td><td >$3.18</td><td >$2.29</td><td >6</td><td >4/29/2010</td></tr><tr><td >Hydrated Lime</td><td >3,563</td><td >TON</td><td >$125.00</td><td >$140.13</td><td >$137.41</td><td >6
</td><td >4/29/2010</td></tr><tr><td >Lime Treated Subgrade</td><td >18,292</td><td >SY</td><td >$2.00</td><td >$5.00</td><td >$2.88</td><td >9</td><td >3/20/2009</td><td rowspan=2 >Arizona DOT</td></tr><tr><td >Hydrated Lime for Subgrade Treatment</td><td >146</td><td >TON</td><td >$170.00</td><td >$290</td><td >$219.44</td><td >9</td><td >3/20/2009</td></tr><tr><td >Lime Trt Exst Matl)(8”)</td><td >126,902</td><td >SY</td><td >$0.75</td><td >$3.00</td><td >$1.96</td><td >10</td><td >11/4/2010</td><td rowspan=4 >Texas DOT</td></tr><tr><td >Lime (Hydrated Lime (Slurry)</td><td >3,197.6</td><td >TON</td><td >$128.00</td><td >$145.00</td><td >$138.28</td><td >10</td><td >11/4/2010</td></tr><tr><td >Cem Trt (Mx Exst Mtl & Nw Bs)(DC)(6”)</td><td >136,876</td><td >SY</td><td >$1.00</td><td >$3.00</td><td >$1.88</td><td >3</td><td >11/5/2010</td></tr><tr><td >Cement</td><td >1,157</td><td >TON</td><td >$110.00</td><td >$154.69</td><td >$133.88</td><td >3</td><td >11/5/2010</td></tr><tr><td >Cement Stabilized Subgrade, 16” Deep (WT:07)</td><td >42,505</td><td >SY</td><td >$2.50</td><td >$6.67</td><td >$4.53</td><td >8</td><td >3/16/2007</td><td rowspan=2 >Ohio DOT</td></tr><tr><td >Cement (WT:07)</td><td >1,762</td><td >TON</td><td >$110.00</td><td >$150.00</td><td >$123.46</td><td >8</td><td >3/16/2007</td></tr><tr><td >Manipulation for Treated Subgrade (Cement)</td><td >221,640</td><td >SY</td><td >$1.55</td><td >$1.85</td><td >$1.65</td><td >3</td><td >4/21/2010</td><td rowspan=4 >Kansas DOT</td></tr><tr><td >Cement</td><td >3,839</td><td >TON</td><td >$95.00</td><td >$125.00</td><td >$114.67</td><td >3</td><td >4/21/2010</td></tr><tr><td >Cement Treated Base</td><td >205,244</td><td >SY</td><td >$7.90</td><td >$10.00</td><td >$9.12</td><td >3</td><td >4/21/2010</td></tr><tr><td >Quality Control Testing (CTB)</td><td >205,244</td><td >SY</td><td >$0.20</td><td >$0.50</td><td >$0.32</td><td >3</td><td >4/21/2010</td></tr></tbody></table><h2>Conceptual Cost Estimating Tool</h2>The conceptual cost estimating tool is intended to be used to develop a preliminary project scoping cost estimate. This preliminary estimate can be based on the typical construction cost item values as contained in the Cost Information product or from user specified cost values when such are known. Users should read and understand the information in Cost Information product prior to using the cost estimating tool. You can download the Cost Estimating Tool to open a cost estimating spreadsheet for producing a preliminary project scoping estimate.</p><p><a class="arrow-link" href="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/… the Cost Estimating Tool</a></p><p> </p></p>