Task 6: Material Thermal Input for Iowa Materials, May 2008

The present research project was designed to determine thermal properties, such as coefficient of thermal expansion (CTE) and thermal conductivity, of Iowa concrete pavement materials. These properties are required as input values by the Mechanistic-Empirical Pavement Design Guide (MEPDG). In this project, a literature review was conducted to determine the factors that affect thermal properties of concrete and the existing prediction equations for CTE and thermal conductivity of concrete. CTE tests were performed on various lab and field samples of portland cement concrete (PCC) at the Iowa Department of Transportation and Iowa State University. The variations due to the test procedure, the equipment used, and the consistency of field batch materials were evaluated. The test results showed that the CTE variations due to test procedure and batch consistency were less than 5%, and the variation due to the different equipment was less than 15%. Concrete CTE values were significantly affected by different types of coarse aggregate. The CTE values of Iowa concrete made with limestone+graval, quartzite, dolomite, limestone+dolomite, and limestone were 7.27, 6.86, 6.68, 5.83, and 5.69 microstrain/oF (13.08, 12.35, 12.03, 10.50, and 10.25 microstrain/oC), respectively, which were all higher than the default value of 5.50 microstrain/oF in the MEPDG program. The thermal conductivity of a typical Iowa PCC mix and an asphalt cement concrete (ACC) mix (both with limestone as coarse aggregate) were tested at Concrete Technology Laboratory in Skokie, Illinois. The thermal conductivity was 0.77 Btu/hr•ft•oF (1.33 W/m•K) for PCC and 1.21 Btu/hr•ft•oF (2.09 W/m•K) for ACC, which are different from the default values (1.25 Btu/hr•ft•oF or 2.16 W/m•K for PCC and 0.67 Btu/hr•ft•oF or 1.16 W/m•K for ACC) in the MEPDG program. The investigations onto the CTE of ACC and the effects of concrete materials (such as cementitious material and aggregate types) and mix proportions on concrete thermal conductivity are recommended to be considered in future studies.

Laboratory Performance Evaluation of CIR-Emulsion and it Comparison Against CIR-Form Test Result from Phase II, Final Report TR-578 Phase III, December 2009

Currently, no standard mix design procedure is available for CIR-emulsion in Iowa. The CIR-foam mix design process developed during the previous phase is applied for CIR-emulsion mixtures with varying emulsified asphalt contents. Dynamic modulus test, dynamic creep test, static creep test and raveling test were conducted to evaluate the short- and long-term performance of CIR-emulsion mixtures at various testing temperatures and loading conditions. A potential benefit of this research is a better understanding of CIR-emulsion material properties in comparison with those of CIR-foam material that would allow for the selection of the most appropriate CIR technology and the type and amount of the optimum stabilization material. Dynamic modulus, flow number and flow time of CIR-emulsion mixtures using CSS-h were generally higher than those of HFMS-2p. Flow number and flow time of CIR-emulsion using RAP materials from Story County was higher than those from Clayton County. Flow number and flow time of CIR-emulsion with 0.5% emulsified asphalt was higher than CIR-emulsion with 1.0% or 1.5%. Raveling loss of CIR-emulsion with 1.5% emulsified was significantly less than those with 0.5% and 1.0%. Test results in terms of dynamic modulus, flow number, flow time and raveling loss of CIR-foam mixtures are generally better than those of CIR-emulsion mixtures. Given the limited RAP sources used for this study, it is recommended that the CIR-emulsion mix design procedure should be validated against several RAP sources and emulsion types.

Embankment Quality: Phase III, TR-401, 2002

This report describes test results from a full-scale embankment pilot study conducted in Iowa. The intent of the pilot project was to field test and refine the proposed soil classification system and construction specifications developed in Phase II of this research and to evaluate the feasibility of implementing a contractor quality control (QC) and Iowa DOT quality assurance (QA) program for earthwork grading in the future. One of the primary questions for Phase III is “Was embankment quality improved?” The project involved a “quality conscious” contractor, well-qualified and experienced Iowa Department of Transportation field personnel, a good QC consultant technician, and some of our best soils in the state. If the answer to the above question is “yes” for this project, it would unquestionably be “yes” for other projects as well. The answer is yes, the quality was improved, even for this project, as evidenced by dynamic cone penetrometer test data and the amount of disking required to reduce the moisture content to within acceptable control limits (approximately 29% of soils by volume required disking). Perhaps as important is that we know what quality we have. Increased QC/QA field testing, however, increases construction costs, as expected. The quality management-earthwork program resulted in an additional $0.03 per cubic meter, or 1.6%, of the total construction costs. Disking added about $0.04 per cubic meter, or 1.7%, to the total project costs. In our opinion this is a nominal cost increase to improve quality. It is envisioned that future contractor innovations have the potential for negating this increase. The Phase III results show that the new soil classification system and the proposed field test methods worked well during the Iowa Department of Transportation soils design phase and during the construction phase. Recommendations are provided for future implementation of the results of this study by city, county, and state agencies.

Laboratory Performance Evaluation of CIR-Emulsion and its Comparison Against CIR-Foam Test Results from Phase 2, TR-474, 2009

Currently, no standard mix design procedure is available for CIR-emulsion in Iowa. The CIR-foam mix design process developed during the previous phase is applied for CIR-emulsion mixtures with varying emulsified asphalt contents. Dynamic modulus test, dynamic creep test, static creep test and raveling test were conducted to evaluate the short- and long-term performance of CIR-emulsion mixtures at various testing temperatures and loading conditions. A potential benefit of this research is a better understanding of CIR-emulsion material properties in comparison with those of CIR-foam material that would allow for the selection of the most appropriate CIR technology and the type and amount of the optimum stabilization material. Dynamic modulus, flow number and flow time of CIR-emulsion mixtures using CSS- 1h were generally higher than those of HFMS-2p. Flow number and flow time of CIR-emulsion using RAP materials from Story County was higher than those from Clayton County. Flow number and flow time of CIR-emulsion with 0.5% emulsified asphalt was higher than CIR-emulsion with 1.0% or 1.5%. Raveling loss of CIR-emulsion with 1.5% emulsified was significantly less than those with 0.5% and 1.0%. Test results in terms of dynamic modulus, flow number, flow time and raveling loss of CIR-foam mixtures are generally better than those of CIR-emulsion mixtures. Given the limited RAP sources used for this study, it is recommended that the CIR-emulsion mix design procedure should be validated against several RAP sources and emulsion types.

1240-017 Little Bear Creek Watershed Final Report

Little Bear Creek is a 21.79 mile Class A1 and B (WW2) warm water stream that encompasses approximately 29,202 acres in northern Poweshiek County. The lower 8.4 mile segment is listed as biologically impaired on both the IDNR 2008 303(d) list and 2010 303(d) draft list. A RASCAL assessment and landowner survey was completed through a development grant in 2011, and these assessments indicate that erosion and sediment delivery from cropland, lack of adequate buffers along the stream channel, and streambank conditions contribute significant sediment delivery to the stream, likely resulting in the impairment. An estimated 36,544 tons of sediment are delivered to the stream annually. A total of 11,075 acres (38%) of the watershed are high priority areas or land with sediment delivery rates greater than one. Our goal over 15 years is to install Best Management Practices (BMPs) and increase public education in order to reduce sediment and phosphorus delivery by 25% and decrease priority areas by 15%. More specific objectives for this WIRB project are to 1) Reduce annual sediment delivery by roughly 16.3% or 1,058 tons and associated phosphorus delivery by 1,375 pounds and 2) Develop an information and education program aimed at producers and residents within the headwaters of Grant and Chester townships, which account for 18% of the watershed's priority areas. The SWCD proposes to utilize 50% EQIP funds and 25% WIRB funds toward rural BMPs, and 75% WIRB funds toward urban BMPs received through this application.