Evaluation of Fly Ash in Water Reduced Paving Mixtures, June 1985

Fly ash was used to replace 15% of the cement in C3WR and C6WR concrete paving mixes containing ASTM C494 Type A water reducin9 admixtures. Two Class C ashes and one Class F ash from Iowa approved sources were examined in each mix. When Class C ashes were used they were substituted on the basis of 1 pound of ash added for each pound of cement deleted. When Class F was used it was substituted on the basis of 1.25 pounds of ash added for each pound of cement deleted. Compressive strengths of the water reduced mixes, with and without fly ash, were determined at 7, 28, and 56 days of age. In every case except one the mixes containing the fly ash exhibited higher strengths than the same concrete mix without the fly ash. An excellent correlation existed between the C3WR and C6WR mixes both with and without fly ash substitutions. The freeze-thaw durability of the concrete studied was not affected by presence or absence of fly ash. The data gathered suggests that the present Class C water reduced concrete paving mixes can be modified to allow the substitution of 15% of the cement with an approved fly ash.

Evaluation of Fly Ash in lean Portland Cement Concrete Base "Econocrete", August 1986

Fly ash was used in this evaluation study to replace 30, 50 and 70 percent of the 400 1bs. of cement currently used in each cu. yd. of portland cement econocrete base paving mix. Two Class "c" ashes and one Class "F" ash from Iowa approved sources were examined in each mix. When Class "c" ashes were used, they were substituted on the basis of 1.0 pound for each pound of cement removed. When Class "F" ash was used, it was substituted on the basis of 1.25 pounds of ash for each pound of cement removed. Compressive strengths with and without fly ash were determined at 7, 28 and 56 days of age. In most cases, strengths were adequate. The freeze/thaw durability of the econocrete mixes studied was not adversely affected by the presence of fly ash. The tests along with erodibility and absorption tests have demonstrated the feasibility of producing econocrete with satisfactory mechanical properties even when relatively low quality and/or locally available aggregate is being used at no sacrifice to strength and/or durability.

Iowa Sex Offender Treatment and Supervision Task Force Report to the Iowa General Assembly, January 15, 2007

Over the last several years, lawmakers have been responding to several highly publicized child abduction, assault and murder cases. While such cases remain rare in Iowa, the public debates they have generated are having far-reaching effects. Policy makers are responsible for controlling the nature of such effects. Challenges they face stem from the need to avoid primarily politically-motivated responses and the desire to make informed decisions that recognize both the strengths and the limitations of the criminal justice system as a vehicle for promoting safe and healthy families and communities. Consensus was reached by the Task Force at its first meeting that one of its standing goals is to provide nonpartisan guidance to help avoid or fix problematic sex offense policies and practices. Setting this goal was a response to the concern over what can result from elected officials’ efforts to respond to the types of sex offender-related concerns that can easily become emotionally laden and politically charged due to the universally held abhorrence of sex crimes against children. The meetings of the Task Force and the various work groups it has formed have included some spirited and perhaps emotionally charged discussions, despite the above-stated ground rule. However, as is described in the report, the Task Force’s first set of recommendations and plans for further study were approved through consensus. It is hoped that in upcoming legislative deliberations, it will be remembered that the non-legislative members of the Task Force all agreed on the recommendations contained in this report. The topics discussed in this first report from the Task Force are limited to the study issues specifically named in H.F. 619, the Task Force’s enabling legislation. However, other topics of concern were discussed by the Task Force because of their immediacy or because of their possible relationships with one or more of the Task Force’s mandated study issues. For example, it has been reported by some probation/parole officers and others that the 2000 feet rule has had a negative influence on treatment participation and supervision compliance. While such concerns were noted, the Task Force did not take it upon itself to investigate them at this time and thus broaden the agenda it was given by the General Assembly last session. As a result, the recently reinstated 2000 feet rule, the new cohabitation/child endangerment law and other issues of interest to Task Force members but not within the scope of their charge are not discussed in the body of this report. An issue of perhaps the greatest interest to most Task Force members that was not a part of their charge was a belief in the benefit of viewing Iowa’s efforts to protect children from sex crimes with as comprehensive a platform as possible. It has been suggested that much more can be done to prevent child-victim sex crimes than would be accomplished by only concentrating on what to do with offenders after a crime has occurred. To prevent child victimization, H.F. 619 policy provisions rely largely on incapacitation and future deterrent effects of increased penalties, more restrictive supervision practices and greater public awareness of the risk presented by a segment of Iowa’s known sex offenders. For some offenders, these policies will no doubt prevent future sex crimes against children, and the Task Force has begun long-term studies to look for the desired results and for ways to improve such results through better supervision tools and more effective offender treatment. Unfortunately, much of the effects from the new policies may primarily influence persons who have already committed sex offenses against minors and who have already been caught doing so. Task Force members discussed the need for a range of preventive efforts and a need to think about sex crimes against children from other than just a “reaction- to-the-offender” perspective. While this topic is not addressed in the report that follows, it was suggested that some of the Task Force’s discussions could be briefly shared through these opening comments. Along with incapacitation and deterrence, comprehensive approaches to the prevention of child-victim sex crimes would also involve making sure parents have the tools they need to detect signs of adults with sex behavior problems, to help teach their children about warning signs and to find the support they need for healthy parenting. School, faithbased and other community organizations might benefit from stronger supports and better tools they can use to more effectively promote positive youth development and the learning of respect for others, respect for boundaries and healthy relationships. All of us who have children, or who live in communities where there are children, need to understand the limitations of our justice system and the importance of our own ability to play a role in preventing sexual abuse and protecting children from sex offenders, which are often the child’s own family members. Over 1,000 incidences of child sexual abuse are confirmed or founded each year in Iowa, and most such acts take place in the child’s home or the residence of the caretaker of the child. Efforts to prevent child sexual abuse and to provide for early interventions with children and families at risk could be strategically examined and strengthened. The Sex Offender Treatment and Supervision Task Force was established to provide assistance to the General Assembly. It will respond to legislative direction for adjusting its future plans as laid out in this report. Its plans could be adjusted to broaden or narrow its scope or to assign different priority levels of effort to its current areas of study. Also, further Task Force considerations of the recommendations it has already submitted could be called for. In the meantime, it is hoped that the information and recommendations submitted through this report prove helpful.

Iowa Sex Offender Treatment and Supervision Task Force Report to the Iowa General Assembly, January 15, 2008

Over the last several years, lawmakers have been responding to several highly publicized child abduction, assault and murder cases. While such cases remain rare in Iowa, the public debates they have generated are having far-reaching effects. Policy makers are responsible for controlling the nature of such effects. Challenges they face stem from the need to avoid primarily politically-motivated responses and the desire to make informed decisions that recognize both the strengths and the limitations of the criminal justice system as a vehicle for promoting safe and healthy families and communities. Consensus was reached by the Task Force at its first meeting that one of its standing goals is to provide nonpartisan guidance to help avoid or fix problematic sex offense policies and practices. Setting this goal was a response to the concern over what can result from elected officials’ efforts to respond to the types of sex offender-related concerns that can easily become emotionally laden and politically charged due to the universally held abhorrence of sex crimes against children. The meetings of the Task Force and the various work groups it has formed have included some spirited and perhaps emotionally charged discussions, despite the above-stated ground rule. However, as is described in the report, the Task Force’s first set of recommendations and plans for further study were approved through consensus. It is hoped that in upcoming legislative deliberations, it will be remembered that the non-legislative members of the Task Force all agreed on the recommendations contained in this report. The topics discussed in this first report from the Task Force are limited to the study issues specifically named in H.F. 619, the Task Force’s enabling legislation. However, other topics of concern were discussed by the Task Force because of their immediacy or because of their possible relationships with one or more of the Task Force’s mandated study issues. For example, it has been reported by some probation/parole officers and others that the 2000 feet rule has had a negative influence on treatment participation and supervision compliance. While such concerns were noted, the Task Force did not take it upon itself to investigate them at this time and thus broaden the agenda it was given by the General Assembly last session. As a result, the recently reinstated 2000 feet rule, the new cohabitation/child endangerment law and other issues of interest to Task Force members but not within the scope of their charge are not discussed in the body of this report. An issue of perhaps the greatest interest to most Task Force members that was not a part of their charge was a belief in the benefit of viewing Iowa’s efforts to protect children from sex crimes with as comprehensive a platform as possible. It has been suggested that much more can be done to prevent child-victim sex crimes than would be accomplished by only concentrating on what to do with offenders after a crime has occurred. To prevent child victimization, H.F. 619 policy provisions rely largely on incapacitation and future deterrent effects of increased penalties, more restrictive supervision practices and greater public awareness of the risk presented by a segment of Iowa’s known sex offenders. For some offenders, these policies will no doubt prevent future sex crimes against children, and the Task Force has begun long-term studies to look for the desired results and for ways to improve such results through better supervision tools and more effective offender treatment. Unfortunately, much of the effects from the new policies may primarily influence persons who have already committed sex offenses against minors and who have already been caught doing so. Task Force members discussed the need for a range of preventive efforts and a need to think about sex crimes against children from other than just a “reaction- to-the-offender” perspective. While this topic is not addressed in the report that follows, it was suggested that some of the Task Force’s discussions could be briefly shared through these opening comments. Along with incapacitation and deterrence, comprehensive approaches to the prevention of child-victim sex crimes would also involve making sure parents have the tools they need to detect signs of adults with sex behavior problems, to help teach their children about warning signs and to find the support they need for healthy parenting. School, faithbased and other community organizations might benefit from stronger supports and better tools they can use to more effectively promote positive youth development and the learning of respect for others, respect for boundaries and healthy relationships. All of us who have children, or who live in communities where there are children, need to understand the limitations of our justice system and the importance of our own ability to play a role in preventing sexual abuse and protecting children from sex offenders, which are often the child’s own family members. Over 1,000 incidences of child sexual abuse are confirmed or founded each year in Iowa, and most such acts take place in the child’s home or the residence of the caretaker of the child. Efforts to prevent child sexual abuse and to provide for early interventions with children and families at risk could be strategically examined and strengthened. The Sex Offender Treatment and Supervision Task Force was established to provide assistance to the General Assembly. It will respond to legislative direction for adjusting its future plans as laid out in this report. Its plans could be adjusted to broaden or narrow its scope or to assign different priority levels of effort to its current areas of study. Also, further Task Force considerations of the recommendations it has already submitted could be called for. In the meantime, it is hoped that the information and recommendations submitted through this report prove helpful.

Iowa Sex Offender Research Council Report to the Iowa General Assembly January 22, 2009

Over the last several years, lawmakers have been responding to several highly publicized child abduction, assault and murder cases. While such cases remain rare in Iowa, the public debates they have generated are having far-reaching effects. Policy makers are responsible for controlling the nature of such effects. Challenges they face stem from the need to avoid primarily politically-motivated responses and the desire to make informed decisions that recognize both the strengths and the limitations of the criminal justice system as a vehicle for promoting safe and healthy families and communities. Consensus was reached by the Task Force at its first meeting that one of its standing goals is to provide nonpartisan guidance to help avoid or fix problematic sex offense policies and practices. Setting this goal was a response to the concern over what can result from elected officials’ efforts to respond to the types of sex offender-related concerns that can easily become emotionally laden and politically charged due to the universally held abhorrence of sex crimes against children. The meetings of the Task Force and the various work groups it has formed have included some spirited and perhaps emotionally charged discussions, despite the above-stated ground rule. However, as is described in the report, the Task Force’s first set of recommendations and plans for further study were approved through consensus. It is hoped that in upcoming legislative deliberations, it will be remembered that the non-legislative members of the Task Force all agreed on the recommendations contained in this report. The topics discussed in this first report from the Task Force are limited to the study issues specifically named in H.F. 619, the Task Force’s enabling legislation. However, other topics of concern were discussed by the Task Force because of their immediacy or because of their possible relationships with one or more of the Task Force’s mandated study issues. For example, it has been reported by some probation/parole officers and others that the 2000 feet rule has had a negative influence on treatment participation and supervision compliance. While such concerns were noted, the Task Force did not take it upon itself to investigate them at this time and thus broaden the agenda it was given by the General Assembly last session. As a result, the recently reinstated 2000 feet rule, the new cohabitation/child endangerment law and other issues of interest to Task Force members but not within the scope of their charge are not discussed in the body of this report. An issue of perhaps the greatest interest to most Task Force members that was not a part of their charge was a belief in the benefit of viewing Iowa’s efforts to protect children from sex crimes with as comprehensive a platform as possible. It has been suggested that much more can be done to prevent child-victim sex crimes than would be accomplished by only concentrating on what to do with offenders after a crime has occurred. To prevent child victimization, H.F. 619 policy provisions rely largely on incapacitation and future deterrent effects of increased penalties, more restrictive supervision practices and greater public awareness of the risk presented by a segment of Iowa’s known sex offenders. For some offenders, these policies will no doubt prevent future sex crimes against children, and the Task Force has begun long-term studies to look for the desired results and for ways to improve such results through better supervision tools and more effective offender treatment. Unfortunately, much of the effects from the new policies may primarily influence persons who have already committed sex offenses against minors and who have already been caught doing so. Task Force members discussed the need for a range of preventive efforts and a need to think about sex crimes against children from other than just a “reaction- to-the-offender” perspective. While this topic is not addressed in the report that follows, it was suggested that some of the Task Force’s discussions could be briefly shared through these opening comments. Along with incapacitation and deterrence, comprehensive approaches to the prevention of child-victim sex crimes would also involve making sure parents have the tools they need to detect signs of adults with sex behavior problems, to help teach their children about warning signs and to find the support they need for healthy parenting. School, faithbased and other community organizations might benefit from stronger supports and better tools they can use to more effectively promote positive youth development and the learning of respect for others, respect for boundaries and healthy relationships. All of us who have children, or who live in communities where there are children, need to understand the limitations of our justice system and the importance of our own ability to play a role in preventing sexual abuse and protecting children from sex offenders, which are often the child’s own family members. Over 1,000 incidences of child sexual abuse are confirmed or founded each year in Iowa, and most such acts take place in the child’s home or the residence of the caretaker of the child. Efforts to prevent child sexual abuse and to provide for early interventions with children and families at risk could be strategically examined and strengthened. The Sex Offender Treatment and Supervision Task Force was established to provide assistance to the General Assembly. It will respond to legislative direction for adjusting its future plans as laid out in this report. Its plans could be adjusted to broaden or narrow its scope or to assign different priority levels of effort to its current areas of study. Also, further Task Force considerations of the recommendations it has already submitted could be called for. In the meantime, it is hoped that the information and recommendations submitted through this report prove helpful.

Iowa Sex Offender Research Council Report to the Iowa General Assembly, January 15, 2010

Over the last several years, lawmakers have been responding to several highly publicized child abduction, assault and murder cases. While such cases remain rare in Iowa, the public debates they have generated are having far-reaching effects. Policy makers are responsible for controlling the nature of such effects. Challenges they face stem from the need to avoid primarily politically-motivated responses and the desire to make informed decisions that recognize both the strengths and the limitations of the criminal justice system as a vehicle for promoting safe and healthy families and communities. Consensus was reached by the Task Force at its first meeting that one of its standing goals is to provide nonpartisan guidance to help avoid or fix problematic sex offense policies and practices. Setting this goal was a response to the concern over what can result from elected officials’ efforts to respond to the types of sex offender-related concerns that can easily become emotionally laden and politically charged due to the universally held abhorrence of sex crimes against children. The meetings of the Task Force and the various work groups it has formed have included some spirited and perhaps emotionally charged discussions, despite the above-stated ground rule. However, as is described in the report, the Task Force’s first set of recommendations and plans for further study were approved through consensus. It is hoped that in upcoming legislative deliberations, it will be remembered that the non-legislative members of the Task Force all agreed on the recommendations contained in this report. The topics discussed in this first report from the Task Force are limited to the study issues specifically named in H.F. 619, the Task Force’s enabling legislation. However, other topics of concern were discussed by the Task Force because of their immediacy or because of their possible relationships with one or more of the Task Force’s mandated study issues. For example, it has been reported by some probation/parole officers and others that the 2000 feet rule has had a negative influence on treatment participation and supervision compliance. While such concerns were noted, the Task Force did not take it upon itself to investigate them at this time and thus broaden the agenda it was given by the General Assembly last session. As a result, the recently reinstated 2000 feet rule, the new cohabitation/child endangerment law and other issues of interest to Task Force members but not within the scope of their charge are not discussed in the body of this report. An issue of perhaps the greatest interest to most Task Force members that was not a part of their charge was a belief in the benefit of viewing Iowa’s efforts to protect children from sex crimes with as comprehensive a platform as possible. It has been suggested that much more can be done to prevent child-victim sex crimes than would be accomplished by only concentrating on what to do with offenders after a crime has occurred. To prevent child victimization, H.F. 619 policy provisions rely largely on incapacitation and future deterrent effects of increased penalties, more restrictive supervision practices and greater public awareness of the risk presented by a segment of Iowa’s known sex offenders. For some offenders, these policies will no doubt prevent future sex crimes against children, and the Task Force has begun long-term studies to look for the desired results and for ways to improve such results through better supervision tools and more effective offender treatment. Unfortunately, much of the effects from the new policies may primarily influence persons who have already committed sex offenses against minors and who have already been caught doing so. Task Force members discussed the need for a range of preventive efforts and a need to think about sex crimes against children from other than just a “reaction- to-the-offender” perspective. While this topic is not addressed in the report that follows, it was suggested that some of the Task Force’s discussions could be briefly shared through these opening comments. Along with incapacitation and deterrence, comprehensive approaches to the prevention of child-victim sex crimes would also involve making sure parents have the tools they need to detect signs of adults with sex behavior problems, to help teach their children about warning signs and to find the support they need for healthy parenting. School, faithbased and other community organizations might benefit from stronger supports and better tools they can use to more effectively promote positive youth development and the learning of respect for others, respect for boundaries and healthy relationships. All of us who have children, or who live in communities where there are children, need to understand the limitations of our justice system and the importance of our own ability to play a role in preventing sexual abuse and protecting children from sex offenders, which are often the child’s own family members. Over 1,000 incidences of child sexual abuse are confirmed or founded each year in Iowa, and most such acts take place in the child’s home or the residence of the caretaker of the child. Efforts to prevent child sexual abuse and to provide for early interventions with children and families at risk could be strategically examined and strengthened. The Sex Offender Treatment and Supervision Task Force was established to provide assistance to the General Assembly. It will respond to legislative direction for adjusting its future plans as laid out in this report. Its plans could be adjusted to broaden or narrow its scope or to assign different priority levels of effort to its current areas of study. Also, further Task Force considerations of the recommendations it has already submitted could be called for. In the meantime, it is hoped that the information and recommendations submitted through this report prove helpful.

Iowa Sex Offender Research Council Report to the Iowa General Assembly, January 15, 2011

Over the last several years, lawmakers have been responding to several highly publicized child abduction, assault and murder cases. While such cases remain rare in Iowa, the public debates they have generated are having far-reaching effects. Policy makers are responsible for controlling the nature of such effects. Challenges they face stem from the need to avoid primarily politically-motivated responses and the desire to make informed decisions that recognize both the strengths and the limitations of the criminal justice system as a vehicle for promoting safe and healthy families and communities. Consensus was reached by the Task Force at its first meeting that one of its standing goals is to provide nonpartisan guidance to help avoid or fix problematic sex offense policies and practices. Setting this goal was a response to the concern over what can result from elected officials’ efforts to respond to the types of sex offender-related concerns that can easily become emotionally laden and politically charged due to the universally held abhorrence of sex crimes against children. The meetings of the Task Force and the various work groups it has formed have included some spirited and perhaps emotionally charged discussions, despite the above-stated ground rule. However, as is described in the report, the Task Force’s first set of recommendations and plans for further study were approved through consensus. It is hoped that in upcoming legislative deliberations, it will be remembered that the non-legislative members of the Task Force all agreed on the recommendations contained in this report. The topics discussed in this first report from the Task Force are limited to the study issues specifically named in H.F. 619, the Task Force’s enabling legislation. However, other topics of concern were discussed by the Task Force because of their immediacy or because of their possible relationships with one or more of the Task Force’s mandated study issues. For example, it has been reported by some probation/parole officers and others that the 2000 feet rule has had a negative influence on treatment participation and supervision compliance. While such concerns were noted, the Task Force did not take it upon itself to investigate them at this time and thus broaden the agenda it was given by the General Assembly last session. As a result, the recently reinstated 2000 feet rule, the new cohabitation/child endangerment law and other issues of interest to Task Force members but not within the scope of their charge are not discussed in the body of this report. An issue of perhaps the greatest interest to most Task Force members that was not a part of their charge was a belief in the benefit of viewing Iowa’s efforts to protect children from sex crimes with as comprehensive a platform as possible. It has been suggested that much more can be done to prevent child-victim sex crimes than would be accomplished by only concentrating on what to do with offenders after a crime has occurred. To prevent child victimization, H.F. 619 policy provisions rely largely on incapacitation and future deterrent effects of increased penalties, more restrictive supervision practices and greater public awareness of the risk presented by a segment of Iowa’s known sex offenders. For some offenders, these policies will no doubt prevent future sex crimes against children, and the Task Force has begun long-term studies to look for the desired results and for ways to improve such results through better supervision tools and more effective offender treatment. Unfortunately, much of the effects from the new policies may primarily influence persons who have already committed sex offenses against minors and who have already been caught doing so. Task Force members discussed the need for a range of preventive efforts and a need to think about sex crimes against children from other than just a “reaction- to-the-offender” perspective. While this topic is not addressed in the report that follows, it was suggested that some of the Task Force’s discussions could be briefly shared through these opening comments. Along with incapacitation and deterrence, comprehensive approaches to the prevention of child-victim sex crimes would also involve making sure parents have the tools they need to detect signs of adults with sex behavior problems, to help teach their children about warning signs and to find the support they need for healthy parenting. School, faithbased and other community organizations might benefit from stronger supports and better tools they can use to more effectively promote positive youth development and the learning of respect for others, respect for boundaries and healthy relationships. All of us who have children, or who live in communities where there are children, need to understand the limitations of our justice system and the importance of our own ability to play a role in preventing sexual abuse and protecting children from sex offenders, which are often the child’s own family members. Over 1,000 incidences of child sexual abuse are confirmed or founded each year in Iowa, and most such acts take place in the child’s home or the residence of the caretaker of the child. Efforts to prevent child sexual abuse and to provide for early interventions with children and families at risk could be strategically examined and strengthened. The Sex Offender Treatment and Supervision Task Force was established to provide assistance to the General Assembly. It will respond to legislative direction for adjusting its future plans as laid out in this report. Its plans could be adjusted to broaden or narrow its scope or to assign different priority levels of effort to its current areas of study. Also, further Task Force considerations of the recommendations it has already submitted could be called for. In the meantime, it is hoped that the information and recommendations submitted through this report prove helpful.

Field Evaluation of Class A Subbase Using Fly Ash, MLR-87-3, 1988

This project consisted of slipforming a 4-inch thick econocrete subbase on a 6-mile section of US 63. The project location extends south from one mile south of Denver, Iowa to Black Hawk County Road C-66 and consisted of the reconstruction and new construction of a divided four-lane facility. The econocrete was placed 27.3 feet wide in a single pass. Fly ash was used in this field study to replace 30, 45 and 60 percent of the portland cement in three portland cement econocrete base paving mixes. The three mixes contained 300, 350 and 400 pounds of cementitious material per cubic yard. Two Class "C" ashes from Iowa approved sources were used. The ash was substituted on the basis of one pound of ash for each pound of cement removed. The work was done October 6-29, 1987 and May 25-June 9, 1988. The twelve subbase mixes were placed in sections 2500 to 3000 feet in length on both the north and southbound roadways. Compressive strengths of all mixes were determined at 3 and 28 days of age. Flexural strengths of all mixes were determined at 7 and 14 days. In all cases strengths were adequate. The freeze/thaw durability of the econocrete mixes used was reduced by increased fly ash levels but remained above acceptable limits. The test results demonstrate the feasibility of producing econocrete with satisfactory properties even using fly ash at substitution rates up to 45 percent.

Evaluation of Asphalt Mix Permeability, MLR-90-2, 1992

Efforts to eliminate rutting on the Interstate system have resulted in 3/4 in. aggregate mixes, with 75 blow Marshall, 85% crushed aggregate mix designs. On a few of these projects paved in 1988-1989, water has appeared on the surfaces. Some conclusions have been reached by visual on-sight investigations that the water is coming from surface water, rain and melting snow gaining entry into the surface asphalt mixture, then coming back out in selected areas. Cores were taken from several Interstate projects and tested for permeability to investigate the surface water theory that supposedly happens with only the 3/4 in. mixtures. All cores were of asphalt overlays over portland cement concrete, except for the Clarke County project which is full depth AC. The testing consisted of densities, permeabilities, voids by high pressure airmeter (HPAM), extraction, gradations, AC content, and film thicknesses. Resilient modulus, indirect tensile and retained strengths after freeze/thaw were also done. All of the test results are about as expected. Permeabilities, the main reason for testing, ranged from 0.00 to 2.67 ft per day and averages less than 1/2 ft per day if the following two tests are disregarded. One test on each binder course came out to 15.24 ft/day, and a surface course at 13.78 ft/day but these are not out of supposedly problem projects.

Characteristics of Iowa Fine Aggregate, MLR-92-6, 1996

The objective of this research was to evaluate the quality (angularity, mortar strengths and alkali-silica reactivity) of fine aggregate for Iowa portland cement concrete (PCC) pavements. Sands were obtained from 30 sources representative of fine aggregate across Iowa. The gradation, fineness modulus and mortar strengths were determined for all sands. Angularity was evaluated using a new National Aggregate Association (NAA) flow test. The NAA uncompacted void values are significantly affected by the percent of crushed particles and are a good measure of fine aggregate angularity. The alkali-silica reactivity of Iowa sands was measured by the ASTM P214 test. By P214 many Iowa sands were identified as being reactive while only two were innocuous. More research is needed on P214 because pavement performance history has shown very little alkali-silica reactivity deterioration of pavement. Six of the sands tested by P214 were evaluated using the Canadian Prism Test. None were identified as being reactive by the Canadian Prism Test.

Improved Aggregate Gradation for Portland Cement Concrete Mixes, HR-563, 1996

Improving the aggregate gradation for a portland cement concrete mix may result in higher compressive strengths. With an improved gradation, the cement factor may be reduced to achieve a more economical concrete mix since cement is the most expensive component in a Portland cement concrete mix. This project located on I-80 westbound in Scott County, Iowa examined three different mixes. 1. Standard Class C mix with project aggregates. 2. Standard Class C mix with an improved aggregate gradation. 3. Standard Class C mix with an improved aggregate gradation and 10% cementitious reduction.

Dynamic Deflections to Determine Roadway Support Ratings, HR-245, 1983

The Benkelman Beam structural test of flexible pavements was replaced in 1976 by dynamic deflection testing with a model 400 Road Rater. The Road Rater is used to determine structural ratings of flexible pavements. New pavement construction in Iowa has decreased with a corresponding increase of restoration and rehabilitation. A method to determine structural ratings of layered systems and rigid pavements is needed to properly design overlay thickness. The objective of this research was to evaluate the feasibility of using the Road Rater to determine support values of layered systems and rigid pavements. This evaluation was accomplished by correlating the Road Rater with the Federal Highway Administration (FHWA) Thumper, a dynamic deflection testing device. Data were obtained with the Road Rater and Thumper at 411 individual test locations on 39 different structural sections ranging from 10" of PCC pavement and 25" of asphalt pavement to a newly graveled unpaved roadway. A high correlation between a 9000 pound Thumper deflection and the 1185 pound Road Rater deflection was obtained. A Road Rater modification has been completed to provide 2000 pound load inputs. The basin, defined by four sensors spaced at 1 foot intervals, resulting from the 2000 pound loading is being used to develop a graph for determining relative subgrade strengths. Road Rater deflections on rigid pavements are sufficient to support the potential for this technique.

Thermoset Composite Concrete Reinforcement, HR-325, Part 1, 1992

The feasibility of substituting fibercomposite (FC) (thermoset) pavement dowels for steel pavement dowels was investigated in this research project. Load transfer capacity, flexural capacity, and material properties were examined. The objectives of Part 1 of this final report included the shear behavior and strength deformations of FC dowel bars without aging. Part 2 will contain the aging effects. This model included the effects of modulus of elasticity for the pavement dowel and concrete, dowel diameter, subgrade stiffness, and concrete compressive strength. An experimental investigation was carried out to establish the modulus of dowel support which is an important parameter for the analysis of dowels. The experimental investigation included measured deflections, observed behavioral characteristics, and failure mode observations. An extensive study was performed on various shear testing procedures. A modified Iosipescu shear method was selected for the test procedure. Also, a special test frame was designed and fabricated for this procedure. The experimental values of modulus of support for shear and FC dowels were used for arriving at the critical stresses and deflections for the theoretical model developed. Different theoretical methods based on analyses suggested by Timoshenko, Friberg, Bradbury, and Westergaard were studied and a comprehensive theoretical model was developed. The fibercomposite dowels were found to provide strengths and behavioral characteristics that appear promising as a potential substitute for steel dowels.

Performance of a Nongrouted Thin Bonded PCC Overlay, HR-291, 1992

The use of a thin bonded concrete overlay atop an older surface has been widely incorporated for pavement rehabilitation in Iowa since the early 70's. Two test sections were constructed in 1985 on county road T61 on the Monroe-Wapello County line without the use of grout as a bonding agent to determine if adequate bond could be achieved and structural capacity uncompromised. Both test sections have performed well with one section having higher bond strengths, lower roughness values, higher structural capacity, and less debonding at the joints than the other section. Overall, both ungrouted sections have performed well under substantial truck traffic with minimal surface distress. More attention should be given, however, to rectifying apparent debonding at the joints when no grout is used as a bonding agent.

Coarse Aggregate Gradations for P.C. Concrete, MLR-94-8, 1995

The effect of coarse aggregate gradation and cement content on strength of concrete was studied. Concrete made of Iowa Department of Transportation Standard Mix C-3 and Aggregate Gradation No. 3 were selected as reference. C-3 proportions were used for mixes #1 and #2. C-3 mix with 10% reduction of the cement content was used for mix #3. C-3 mix with 20% reduction of the cement content was used for mix #4. On the other hand, mix #1 used coarse aggregate of Gradation No. 3, while mixes #2, #3, and #4 used coarse aggregate mix of 65% concrete stone and 35% 3/8 in. chips. It was found that strengths of portland cement concrete decrease with decreasing cement factor. On the other hand, 35% of chip replacement for coarse aggregate increases strengths of concrete. By replacing 35% of coarse aggregate with chips, one could reduce cement factor 10% and achieve equivalent strengths.