<p><p><h2>Summary of Example Specifications</h2><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Roller-Integrated Continuous Compaction Control (CCC)</div><strong>Reference(s):<br></strong><em>ISSMGE (2005)<br>RVS8S.02.6 (1999)</em></p><p>The Federal Ministry for Economic Affairs, Austria developed CCC specifications in 1990 with revisions in 1993 and 1999 (RVS 8S.02.6 1999). The International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE) TC3 committee (Geotechnics for Pavements in Transportation Infrastructure) developed a CCC specification (ISSMGE 2005) largely adopting information from the Austrian specifications. It is recommended in these specifications that the roller CCC measurements be dynamic measurements (i.e., measurements obtained using accelerometer), and the specifications are applicable to subgrade, subbase and base materials and recycled materials that can be compacted dynamically and statically. For soils that are compacted statically (e.g., cohesive materials), dynamic measurements should be obtained after static compaction (i.e., as a proof compaction pass). The specifications recommend that if the fine-grained portion of the materials (&lt; 0.06 mm) exceeds 15%, moisture content must be given special attention.<br>These specifications describe two different approaches for using roller-integrated CCC for QC and QA. Summaries of these two approaches are provided below.</p><p><u>Approach 1</u>This approach involves acceptance testing based on on-site calibration testing by developing a correlation with static Plate Load Test (PLT) or Lightweight Deflectometer (LWD) measurements (note that Austrian specification (RVS 8S.02.6 1999) did not discuss LWD testing but ISSMGE specification allows using LWD testing as an alternative to PLT). Density measurements are not recommended for correlation with CCC measurements. The calibration process involves constructing a test area of at least 100 meters (330 feet) long and as wide as the project embankment for each material type. The area must be compacted using constant operation settings (i.e., frequency, amplitude, speed). The specifications indicate that the acceptance criteria are valid for roller-soil contact and partial loss of contact roller operation, and if double jump mode is occurred, separate calibration is required. Roller CCC data is used to select nine test locations for static PLT, three each in locations corresponding to low, medium, and high roller CCC values. If LWD testing is used, the ISSMGE (2005) specification recommends increasing the number of tests by four times (i.e., 36 tests). Linear regression analysis is performed between roller CCC measurements and EV1 (initial load secant modulus obtained from static PLT) or LWD modulus (ELWD). It is recommended in the specification that EV2 (reload secant modulus obtained from static PLT) should not be used for correlation. The coefficient of determination R2 for the correlation must be at least 0.5. The target EV1 and ELWD values for subgrade, base, and subbase layers are provided in the specifications. A summary of these target values and the linear regression approach is shown in Figure 1 below. Using the relationship and the recommended target EV1 or ELWD values, minimum CCC value (MIN), mean CCC value (ME), maximum CCC value (MAX) are determined as shown in Figure 1. The MAX value is 1.5 times the MIN value. These target MIN, ME, and MAX values are used in the acceptance procedure in the production areas. In production areas, the roller CCC measurements are required to be obtained on each layer using similar machine operation settings as used in the calibration process. The acceptance criteria are as follows:<br>• The mean roller CCC value in the production area must be ≥ ME.<br>• 100% of roller CCC values in the production area must be ≥ 0.8 MIN.<br>• 90% of roller CCC values in the production area must be ≥ MIN.<br>• Compaction must be performed until the mean roller CCC value in the production area is less than 5% greater than the mean value from the previous pass.<br>• If 100% of roller CCC values in the production area are ≥ MIN, then the Coefficient Of Variation (COV) for the entire area must be ≤ 20%.<br>• If mean roller CCC value is between 0.8 MIN and MIN, then 100% of roller CCC values in the production area must be ≤ MAX.</p><p><figure id='attachment_2417' style='max-width:748px' class='caption alignnone'><img class="wp-image-2417 size-full" src="https://www.geoinstitute.org/sites/default/files/geotech-tools-uploads/…; alt="Graph and table showing a summary of target values for modulus of subgrade soils with depths relative to the subgrade." width="748" height="233" /><figcaption class='caption-text'> Figure 1. Summary of establishing target values (ISSMGE 2005).</figcaption></figure></p><p><u>Approach 2</u></p><p>This approach is recommended for small sites or for sites where calibration cannot be performed. The procedure involves obtaining roller-integrated CCC during compaction until the mean roller CCC value over an area increases by no more than 5% compared to the previous pass. Acceptance in those areas is based on PLT or LWD testing in the low CCC value areas (weakest areas). At least three PLT or nine LWD tests are recommended. The E_V1 and E_LWD values obtained must be greater than the target values based on the material type (as shown in Figure 1).<br><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Surface Covering Dynamic Compaction Control Methods</div><strong>Reference(s):<br></strong><em>ZTVE STB/TP BF-STB. (1994)</em></p><p>The Research Society of Road and Traffic, Germany earthwork compaction testing and control specifications included CCC specifications as one of the methods of compaction testing and control (referred to as M2 in the specification). It is recommended in this specification that the roller CCC measurements be dynamic measurements (i.e., measurements obtained using accelerometer), and the specification is suitable for uniform soils. The specification recommends a calibration procedure to establish roller CCC target values and use of roller CCC values for acceptance in production areas.<br>The calibration process involves construction of a test area at least 20 meters in length for each layer and material type. The area must be compacted in at least three different roller lanes with varying compactive effort – light compaction (1 pass), medium compaction (3 passes), and high compaction (as many passes required to see no increase in CCC values) – using constant machine operation settings (i.e., frequency, amplitude, and speed). Roller CCC values obtained in jump mode cannot be used. Low amplitude operation is recommended to avoid roller jumping during compaction. At least three to five EV2 (reload secant modulus from static PLT measurements) or degree of compaction measurements must be obtained in each of the low, medium, and high compaction lanes. Roller CCC data at each test point is then correlated with EV2 or degree of compaction measurements using linear regression analysis. The regression analysis should result in a coefficient of determination R2 ≥ 0.5. The target roller CCC value is then determined using a pre-established target EV2 or degree of compaction value from the linear regression relationship. If R2 ≥ 0.5 cannot be achieved, additional tests are recommended. If R2 ≥ 0.5 is not achieved even after additional tests, CCC is not permitted for that material or layer.<br>The production areas must be mapped using the same operation settings as used in the calibration process. The production area must have all areas meeting the minimum target value established using the calibration. If low roller CCC values are encountered, additional compaction or moisture content or lift thickness adjustment is recommended. If these efforts do not improve the CCC values and if these areas with low values are not limited to local spots, the calibration value may be determined as invalid.<br><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> Unbound Materials (Obundna Material)</div><strong>Reference(s):<br></strong><em>ATB VÄG (2005), Mooney et al. (2010)</em></p><p>The Road and Traffic Division, Sweden included roller CCC as a method of compaction control in their Unbound Materials specification. The CCC method was introduced in 1994 and was then revised in 2005. The specification is in Swedish. Mooney et al. (2010) provided a brief English translated summary of the specification. It is summarized here.<br>The QA of unbound material is mandated at two surface levels: (1) top of the base course and (2) a layer 300 to 750 mm (1 to 2.5 feet) below the top of the base layer. Typically, Swedish construction includes a 300 to 700 mm (1 to 2.3 feet) thick base layer and a 300 to 500 mm (1 to 1.6 feet) subbase or frost protection layer. Therefore, QA is typically performed on the surface of the base and subbase layers. QA is not required for the subgrade primarily due to the considerable thickness of base and subbase layers used. The maximum percentage of particles less than 0.06 mm (0.002 inches) permitted in base and subbase layers is 7%; therefore, by default CCC is only performed on granular materials. Swedish specifications permit the use of roller-integrated CCC to identify weak spots for PLT. Conventionally, QA of base and subbase layers is based solely on PLTs performed at a minimum of eight randomly selected locations within 5000 m2 area. Density and moisture QA are not performed. The number of tests can be reduced to five if no previous control area has failed or if the standard deviation is small. EV2 (reload secant modulus from PLT) and the ratio of initial and reload modulus (EV1/EV2) are used for QA. When employing roller-integrated CCC, the number of PLTs is reduced to 2. The PLTs are conducted at the two weakest areas as indicated by the roller CCC map. The number of PLTs can be reduced from two to one if no control area has failed the test or the previous control areas show small variations. The criteria for acceptance are summarized in Table 1. The first criterion is to meet the minimum EV2 value. If that criterion is failed, the EV1/EV2 ratio criterion must be met. It is recommended that LWD testing can be used instead of PLT “if similar results can be shown (proved)” at depths below 800 mm below the top of base course surface. The Swedish specifications provide recommended EV2 and ELWD.<br><h3>Table 1. Unbound material acceptance criteria if CCC is used (per 5,000 m² control area)</h3>(From Mooney, M.A., Rinehart, R.A., White, D.J., Vennapusa, P., Facas, N., Musimbi, O.M. Intelligent soil compaction systems, <em>NCHRP Report 676</em>, Table 2.5, p. 35. Copyright National Academy of Sciences, Washington, D.C, 2010. Reproduced with permission of the Transportation Research Board.)<br><table class='tablepress' id='tablepress-249'><thead><th>Depth below base course surface (mm)</th><th>n</th><th>Asphalt Pavements</th><th>#colspan#</th><th>Concrete Pavements</th><th>#colspan#</th></thead><tbody><tr><td >Minimum EV₂ (MPa)</td><td >Ev₂/Ev₁
(if min. EV₂ criteria is failed)
</td><td >Minimum EV₂ (MPa)</td><td >Ev₂/Ev₁
(if min. EV₂ criteria is failed)
</td></tr><tr><td >0-250</td><td >1-2</td><td >125</td><td >≤ 1 + 0.0136EV₂</td><td >105</td><td >≤ 1 + 0.0162 EV₂</td></tr><tr><td >251-500</td><td >1-2</td><td >32</td><td >≤ 1 + 0.078EV₂</td><td >45</td><td >≤1 + 0.056 EV2</td></tr><tr><td >500-550</td><td >1-2</td><td >32</td><td >NA </td><td >45</td><td >NA </td></tr><tr><td >551-650</td><td >1-2</td><td >20</td><td >NA</td><td >30</td><td >NA </td></tr><tr><td >651-750</td><td >1-2</td><td >15</td><td >NA</td><td >30</td><td >NA </td></tr></tbody></table><br><div class="grayed-title subsection"><strong>Specification Name/Number:</strong> IC Quality Compaction</div><strong>Reference(s):<br></strong><em>Mn/DOT (2007)</em></p><p>The Minnesota DOT has developed a pilot specification requiring the use of IC technology as the primary QC tool. In short, the contractor is required to develop a QC procedure that incorporates IC measurement values gathered from control (or calibration) strips. After constructing the control strip, the contractor is required to detail how their QC procedure would be implemented on the remainder of the project (anticipated number, pattern and speed of roller passes, potential corrective actions for non-compliant areas, etc.). Following successful control strip construction and development of the QC procedures, proof layers (predetermined layer that required QC measurements by the contractor and QA by the engineer) are constructed. For proof layers, the engineer (1) observes the final IC recording pass, (2) reviews and approves the QC data documenting that acceptable compaction results are obtained, (3) performs companion and verification moisture content testing, and (4) observes test rolling results to ensure compliance (less than 50 mm rut under wheel of 650 kPa (95 psi) tire pressure). Note that the Mn/DOT specification refers to the roller measurement value as IC value, however, the measurements are all required to be obtained using a constant amplitude, frequency, and speed which makes the measurement a CCC measurement. IC (i.e., with automatic feedback control) is allowed in the specification only in production compaction process, but that data is not used for QC or QA.<br>The control strips are required to be at least 100 meters (300 feet) long and 10 meters (32 feet) wide at its base (or other size approved by engineer). Thickness must be equal to that in the production areas. One control strip is required for each different type or source of grading material used. The contractor and engineer save material samples from each control strip for comparison to embankment material used in proof layers. Compaction and mixing is specified to be uniform from bottom to top and for the entire length and width of the embankment. For control strips, optimum compaction is reached when the engineer determines that additional compaction passes do not result in a significant increase in IC measurement values. After the final roller pass, the data is grouped into the following pre-defined tolerance bins: less than 70%, 70 to 80%, 80 to 90%, 90 to 130%, and greater than 130% of a trial IC target value (IC-TV). The trial IC-TV is adjusted such that 90% of the data falls within the 90-130 percent bin. Control strips are to be constructed at 65% and 100% of standard Proctor optimum moisture content of the material, so that a linear correlation between moisture content and IC-TV is obtained and a corrected IC-TV is determined for the field moisture content in the production areas. Note that all IC-TVs are obtained at constant amplitude, frequency, and machine speed. LWD-TV is also determined from the control strips by conducting LWD tests after final pass at 65% and 100% of standard Proctor optimum moisture contents.<br>All segments in production areas should be compacted so that at least 90% of the IC measurement values in the area are at least 90% of the IC-TV prior to placing the next lift. The IC-TVs are obtained using the same amplitude, frequency, and machine speed used in the applicable control test strip. If localized areas had IC measurement values of less than 80% of the IC-TV, the areas are required to be re-compacted. If a significant portion of the grade is more than 30% in excess of the selected IC-TV, the engineer should reevaluate the IC-TV. The Engineer performs a LWD test and a moisture content test at the minimum rate of one test per proof layer (per 300 meters (1,000 feet)). Each LWD measurement taken shall be at least 90% but not more than 120% of the moisture corrected LWD-TV obtained on the applicable control strip.</p></p>