5.0% of the maximum dry density of th e soils. The quantities for lime by-products 30 shall be based on 6.0% of the maximum dry density of the soils. The quantities for fly ash class C shall be based on 12.0% of the maximum dry density of the soils. Class F fly ash shall not be used. If hydrated lime, quick lime, lime by-products or portland cement are used, test results and the geotechnical consultant recommendations shall be submitted to the Engineer prior to use. If fly ash is used, the test results and the geotechnical consultant recommendations shall be submitted to the Engineer and to the Department’s Geotechnical Engineering Division for approval at least three business days prior to use. If the modifier as bid is not appropriate for the soils encountered, portland cement 40 shall be used. Portland cement, fly ash, lime, and lime by-products shall be selected from the Department’s QPLs of Cement Sources, Pozzolan Sources, and Soil Modifiers, respectively. The quantity of chemical modifier may be adjusted for different soil types. However, the source or type of chemical modifier shall not be changed during the progress of the work without approval. A change in source or type shall require a new mix design.
215.04 Storage and Handling 50
The chemical modifier shall be stor ed and handled in accordance with the manufacturer’s recommendations.
215.05 Weather Limitations The chemical soil modification shall be performed when the soil has a minimum
temperature of 45°F, measured 4 in. below the surface, and with the air temperature rising. The chemical modifier shall not be mixed with frozen soils or with soil containing frost. Chemical soil modification shall only be performed in areas which are going to be paved during the same construction season.
215.06 Preparation of Soils The soils shall be prepared in accordanc e with 207.03. All aggregates which are
larger than approximately 3 in. encountered before or after mixing the soils and chemical modifiers shall be removed.
215.07 Spreading of Chemical Modifiers Where Type A-6 or Type A-7 soils are used or encountered, the surface shall be
scarified to the specified depth prior to distribution of the chemical modifier. The chemical modifier shall be distributed uniformly by a cyclone, screw-type, or pressure manifold type distributor. If a slurry is us ed, the surface shall be scarified prior to the 70 distribution of the slurry. The chemical modifier shall not be applied when wind conditions create problems in adjacent areas or create a hazard to traffic on any adjacent roadway. The spreading of the ch emical modifier shall be limited to an 215.07 250 amount which can be incorporated into the soil within the same work day. If weather causes stoppage of work or exposes the chemical modifier to washing or blowing, additional chemical modifier may be spread when the work resumes.
215.08 Mixing The chemical modifier, soil, and water when necessary, shall be thoroughly mixed
by rotary speed mixers. The mixing shall continue until a homogenous layer of the 80 required thickness has been obtained. One hundred percent of the material, exclusive of rock particles, shall pass a 1 in. (25 mm) sieve and at least 60% shall pass a No. 4 (4.75 mm) sieve. The mixing depth shall be 14 in. The gradation test shall be performed in accordance with ITM 516. The chemically modified soil mixture shall be at least 1% above the optimum moisture content during mixing and compaction. Water shall not be added to the chemically modified soil wh en the moisture content of the soil exceeds 3% above optimum moisture. Water shall be added during mixing only. 90
215.09 Compaction Compaction of the mixture shall begin as soon as practicable after mixing and
shall be in accordance with 207.03 as appli cable. Compaction after mixing shall be as follows:
a.For portland cement modified soils, mixing shall be completed within 1 h of portland cement placement and grading and final compaction shall be completed within 3 h after mixing.
b.Fly ash modified soils sh all be compacted within 4 h. 100
c.Lime modified soils shall be compacted within 24 h. Acceptance of chemically modified soils will be determined in accordance with ITM 508 or ITM 509. Testing of the chemically modified soils will begin a minimum of 24 h after compaction. Acceptance of chemically modified soils will be determined by averaging three LWD tests obtained at random stations determined in acco rdance with ITM 802. The deflection shall be equal to or less than the allowable average deflection shown in the 110 table below. Material Type Allowable Average Deflection, (mm) Maximum Deflection at a Single Test Location (mm) Cement Modified Soils 0.27 0.31 Lime Modified Soils 0.30 0.35 For measuring the compaction with a DCP, three random test locations will be determined in accordance with ITM 802. Blow counts of 15 and above will be used to 215.08 251 determine the average for the top 6 in. of a 14 in. lift. Blow counts of 14 and above will be used to determine the average for the bottom 8 in. of a 14 in. lift. Blow counts of 18 and above will be used to determine the average for the 8 in. lift. Locations with test results less than the specified minimum blow counts will be retested and shall be reworked if the minimum blow count is not obtained. The frequency of LWD or DCP 120 testing will be three tests for each 1,400 cu yds of chemically modified soils. The chemically modified soil lift shall meet the following requirements for compaction:
a.The average DCP blow count shall not be less than 17 for the top 6 in. of a 14 in. lift.
b.The average DCP blow count shall not be less than 16 for the bottom 8 in. of a 14 in. lift. 130
c.Moisture tests for chemically modified soils mixture shall be performed in accordance with ITM 506 every 4 h during chemical and soils mixing.
d.One gradation test shall be performed for each 2,500 cu yds of chemically modified soil in accordance with 215.08 and ITM 516. Construction traffic or equipment will not be allowed on the treated soils until the soil meets the compaction test requirements. 140
215.10 Curing Moisture content shall be maintained at 1% above the optimum moisture content
for the first 48 h after mixing.
215.11 Proofrolling Proofrolling shall be performed in accordance with 203.26.
215.12 Method of Measurement
The accepted quantity of chemically modifi ed soils, for the material specified, 150 will be measured by the square yard, complete in place. All removal and replacement required to modify the soils below the specified depth will be measured in accordance with 203.27(b).
215.13 Basis of Payment
The accepted quantity of chemically modifi ed soils, for the material specified, will be paid for by the square yard, complete in place. Fly ash, when used, will be paid for as lime. 160 All removal and replacement required to modify the soils below the specified depth will be paid for in accordance with 203.28. 215.13 Adjustment of materials for chemical modification that exceeds the limits of
215.03 will be included in a change order fo r materials only and paid for as chemical
modifier adjustments. If mix design test results show that the chemical modifier as bid by the Contractor is not appropriate and the strength of the modified soil can not be achieved, a price adjustment will be made for the use of portland cement. The price adjustment will be calculated at a cost equal to the difference in the invoice cost of the chemical modifier found to be appropriate for use and the invoice or quoted delivered 170 cost of the chemical modifier as bid by the Contractor. This adjustment will be included in a change order and will be paid for as chemical modifier adjustments. Fly ash will not be considered for price adjustment. Payment for chemical modifier adjustments will be made for direct delivered material costs incurred by the Contractor in accordance with 109.05. Payment will be made under: Pay Item Pay Unit Symbol 180 Chemical Modificati on, Soils, ____ _____ ................................ SYS material The cost of performing the laboratory tests, providing a qualified geotechnical consultant, scarification of th e soil, spreading and mixing of the chemical modifier and soil, compaction of the resultant mixture, shaping the soil, work required due to adjustments of modifier proportioning, additional modification required due to weather conditions, correction of deficient areas, water required for the modification process, modified soil trimming, moisture testing, gradation testing, proofrolling, and all operations needed to meet the requirements of this specification shall be included 190 in the cost of the pay items of this section.
Source: Indiana Standard Specifications, 2024 Edition. Pages 267–270 of 1,248.