Construcción de un Test de Conocimiento General. Development of a General Knowledge Test

Entre los factores que contribuyen a predecir el rendimiento académico se pueden destacar aquellos que reflejan capacidades cognitivas (inteligencia, por ejemplo), y aquellas diferencias individuales consideradas como no-cognitivas (rasgos de personalidad, por ejemplo). En los últimos años, también se considera al Conocimiento General (CG) como un criterio para el éxito académico (ver Ackerman, 1997), ya que se ha evidenciado que el conocimiento previo ayuda en la adquisición de nuevo conocimiento (Hambrick & Engle, 2001). Uno de los objetivos de la psicología educacional consiste en identificar las principales variables que explican el rendimiento académico, como también proponer modelos teóricos que expliquen las relaciones existentes entre estas variables. El modelo teórico PPIK (Inteligencia-como-Proceso, Personalidad, Intereses e Inteligencia-como-Conocimiento) propuesto por Ackerman (1996) propone que el conocimiento y las destrezas adquiridas en un dominio en particular son el resultado de la dedicación de recursos cognitivos que una persona realiza durante un prolongado período de tiempo. Este modelo propone que los rasgos de personalidad, intereses individuales/vocacionales y aspectos motivacionales están integrados como rasgos complejos que determinan la dirección y la intensidad de la dedicación de recursos cognitivos sobre el aprendizaje que realiza una persona (Ackerman, 2003). En nuestro medio (Córdoba, Argentina), un grupo de investigadores ha desarrollado una serie de recursos técnicos necesarios para la evaluación de algunos de los constructos propuesto por este modelo. Sin embargo, por el momento no contamos con una medida de Conocimiento General. Por lo tanto, en el presente proyecto se propone la construcción de un instrumento para medir Conocimiento General (CG), indispensable para poder contar con una herramienta que permita establecer parámetros sobre el nivel de conocimiento de la población universitaria y para en próximos trabajos poner a prueba los postulados de la teoría PPIK (Ackerman, 1996). Between the factors that contribute to predict the academic achievement, may be featured those who reflect cognitive capacities (i.g. intelligence) and those who reflect individual differences that are considered like non-cognitive (i.g. personality traits). In the last years, also the General Knowledge has been considered like a criterion for the academic successfully (see Ackerman, 1997), since it has been shown that the previous knowledge helps in the acquisition of the new knowledge (Hambrick & Engle, 2001). An interesting theoretical model that has proposed an explanation for the academic achievement, is the PPIK (intelligence like a process, interests and inteligence like knowledge) proposed by Ackerman (1996), who argues that knowledge and the acquired skills in a particular domain are the result of the dedication of cognitive resources that a person perform during a long period of time. This model proposes that personality traits, individuals interests and motivational aspects are integrated as complex traits that determine the direction and the intensity of the dedication of cognitive resources on the learning that a person make (Ackerman, 2003). In our context, (Córdoba, Argentina), a group of researcher has developed a series of necessary technical resoures for the assesment of some of the theoretical constructs proposed by this model. However, by the moment, we do not have an instrument for evaluate the General Knowledge. Therefore, this project aims the construction of an instrument to asess General Knowledge, essential to set parameters on the knowledge level of the university population and for in next works test the PPIK theory postulates.

Identification of the Best Practices for Design, Construction, and Repair of Bridge Approches, 2005

Bridge approach settlement and the formation of the bump is a common problem in Iowa that draws upon considerable resources for maintenance and creates a negative perception in the minds of transportation users. This research study was undertaken to investigate bridge approach problems and develop new concepts for design, construction, and maintenance that will reduce this costly problem. As a result of the research described in this report, the following changes are suggested for implementation on a pilot test basis: • Use porous backfill behind the abutment and/or geocomposite drainage systems to improve drainage capacity and reduce erosion around the abutment. • On a pilot basis, connect the approach slab to the bridge abutment. Change the expansion joint at the bridge to a construction joint of 2 inch. Use a more effective joint sealing system at the CF joint. Change the abutment wall rebar from #5 to #7 for non-integral abutments. • For bridges with soft foundation or embankment soils, implement practices of better compaction, preloading, ground improvement, soil removal and replacement, or soil reinforcement that reduce time-dependent post construction settlements.

Identification of the Best Practices for Design, Construction, and Repair of Bridge Approaches, January 2005

Bridge approach settlement and the formation of the bump is a common problem in Iowa that draws upon considerable resources for maintenance and creates a negative perception in the minds of transportation users. This research study was undertaken to investigate bridge approach problems and develop new concepts for design, construction, and maintenance that will reduce this costly problem. As a result of the research described in this report, the following changes are suggested for implementation on a pilot test basis: • Use porous backfill behind the abutment and/or geocomposite drainage systems to improve drainage capacity and reduce erosion around the abutment. • On a pilot basis, connect the approach slab to the bridge abutment. Change the expansion joint at the bridge to a construction joint of 2 inch. Use a more effective joint sealing system at the CF joint. Change the abutment wall rebar from #5 to #7 for non-integral abutments. • For bridges with soft foundation or embankment soils, implement practices of better compaction, preloading, ground improvement, soil removal and replacement, or soil reinforcement that reduce time-dependent post construction settlements.

Material and Construction Optimization for Prevention of Premature Pavement Distress in PCC Pavements, September 2004

The chemistry of today’s concrete mixture designs is complicated by many variables, including multiple sources of aggregate and cements and a plethora of sometimes incompatible mineral and chemical admixtures. Concrete paving has undergone significant changes in recent years as new materials have been introduced into concrete mixtures. Supplementary cementitious materials such as fly ash and ground granulated blast furnace slag are now regularly used. In addition, many new admixtures that were not even available a few years ago now have widespread usage. Adding to the complexity are construction variables such as weather, mix delivery times, finishing practices, and pavement opening schedules. Mixture materials, mix design, and pavement construction are not isolated steps in the concrete paving process. Each affects and is affected by the other in ways that determine overall pavement quality and long-term performance. Equipment and procedures commonly used to test concrete materials and concrete pavements have not changed in decades, leaving serious gaps in our ability to understand and control the factors that determine concrete durability. The concrete paving community needs tests that will adequately characterize the materials, predict interactions, and monitor the properties of the concrete.

Developing a Simple and Rapid Test for Monitoring the Heat Evolution of Concrete Mixtures for Both Laboratory and Field Applications, January 2006

Various test methods exist for measuring heat of cement hydration; however, most current methods require expensive equipment, complex testing procedures, and/or extensive time, thus not being suitable for field application. The objectives of this research are to identify, develop, and evaluate a standard test procedure for characterization and quality control of pavement concrete mixtures using a calorimetry technique. This research project has three phases. Phase I was designed to identify the user needs, including performance requirements and precision and bias limits, and to synthesize existing test methods for monitoring the heat of hydration, including device types, configurations, test procedures, measurements, advantages, disadvantages, applications, and accuracy. Phase II was designed to conduct experimental work to evaluate the calorimetry equipment recommended from the Phase I study and to develop a standard test procedure for using the equipment and interpreting the test results. Phase II also includes the development of models and computer programs for prediction of concrete pavement performance based on the characteristics of heat evolution curves. Phase III was designed to study for further development of a much simpler, inexpensive calorimeter for field concrete. In this report, the results from the Phase I study are presented, the plan for the Phase II study is described, and the recommendations for Phase III study are outlined. Phase I has been completed through three major activities: (1) collecting input and advice from the members of the project Technical Working Group (TWG), (2) conducting a literature survey, and (3) performing trials at the CP Tech Center’s research lab. The research results indicate that in addition to predicting maturity/strength, concrete heat evolution test results can also be used for (1) forecasting concrete setting time, (2) specifying curing period, (3) estimating risk of thermal cracking, (4) assessing pavement sawing/finishing time, (5) characterizing cement features, (6) identifying incompatibility of cementitious materials, (7) verifying concrete mix proportions, and (8) selecting materials and/or mix designs for given environmental conditions. Besides concrete materials and mix proportions, the configuration of the calorimeter device, sample size, mixing procedure, and testing environment (temperature) also have significant influences on features of concrete heat evolution process. The research team has found that although various calorimeter tests have been conducted for assorted purposes and the potential uses of calorimeter tests are clear, there is no consensus on how to utilize the heat evolution curves to characterize concrete materials and how to effectively relate the characteristics of heat evolution curves to concrete pavement performance. The goal of the Phase II study is to close these gaps.

Méthodologie intégrée de microgravimétrie en milieu urbain : test d'application au génie civil sur le métro M2 de Lausanne

RESUME Dès le printemps 2004, la construction d'une 2ème ligne de métro est entreprise dans la ville de Lausanne en Suisse. En reliant Ouchy, au bord du lac Léman (alt. 373 m) à Epalinges (alt. 711 m), le nouveau métro "M2" traversera dès 2008 l'agglomération lausannoise du Sud au Nord sur une distance de 6 km. Depuis l'avant-projet, en 1999, une grande quantité de données géologiques a été récolté et de nombreux forages exécutés sur le site. Ceci nous a donné une occasion unique d'entreprendre une étude de microgravimétrique urbaine de détail. Le mode de creusement du tunnel dépend fortement des matériaux à excaver et il est classiquement du domaine du géologue, avec ses connaissances de la géologie régionale et de la stratigraphie des forages, de fournir à l'ingénieur un modèle géologique. Ce modèle indiquera dans ce cas l'épaisseur des terrains meubles qui recouvrent le soubassement rocheux. La représentativité spatiale d'une information très localisée, comme celle d'un forage, est d'autant plus compliquée que le détail recherché est petit. C'est à ce moment là que la prospection géophysique, plus spécialement gravimétrique, peut apporter des informations complémentaires déterminantes pour régionaliser les données ponctuelles des forages. La microgravimétrie en milieu urbain implique de corriger avec soin les perturbations gravifiques sur la mesure de la pesanteur dues aux effets de la topographie, des bâtiments et des caves afin d'isoler l'effet gravifique dû exclusivement à l'épaisseur du remplissage des terrains meubles. Tenant compte de l'intensité des corrections topographiques en milieu urbain, nous avons donné une grande importance aux sous-sols, leurs effets gravifiques pouvant atteindre l'ordre du dixième de mGal. Nous avons donc intégré ces corrections celle de topographie et traité les effets des bâtiments de manière indépendante. Nous avons inclus dans le modèle numérique de terrain (MNT) la chaussée et les sous-sols afin de construire un modèle numérique de terrain urbain. Nous utiliserons un nouvel acronyme « MNTU »pour décrire ce modèle. Nous proposons d'établir des cartes de corrections topographiques préalables, basées sur les données à disposition fournies par le cadastre en faisant des hypothèses sur la profondeur des sous-sols et la hauteur des bâtiments. Les deux zones de test choisies sont caractéristiques des différents types d'urbanisation présente à Lausanne et se révèlent par conséquent très intéressantes pour élaborer une méthodologie globale de la microgravimétrie urbaine. Le but était d'évaluer l'épaisseur du remplissage morainique sur un fond rocheux molassique se situant à une profondeur variable de quelques mètres à une trentaine de mètres et d'en établir une coupe dans l'axe du futur tracé du métro. Les résultats des modélisations se sont révélés très convaincants en détectant des zones qui diffèrent sensiblement du modèle géologique d'avant projet. Nous avons également démontré que l'application de cette méthode géophysique, non destructive, est à même de limiter le nombre de sondages mécaniques lors de l'avant-projet et du projet définitif, ce qui peut limiter à la fois les coûts et le dérangement engendré par ces travaux de surface. L'adaptabilité de la technique gravimétrique permet d'intervenir dans toutes les différentes phases d'un projet de génie civil comme celui de la construction d'un métro en souterrain. KURZFASSUNG Seit dem Frühling 2004 ist in der Stadt Lausanne (Schweiz) die neue U-Bahn "M2" in Konstruktion. Diese soll auf 6 km Länge die Lausanner Agglomeration von Süd nach Nord durchqueren. Die dem Projekt zu Grunde liegende technische Planung sieht vor, daß die Bahnlinie hauptsächlich in der Molasse angesiedelt sein wird. Seit dem Vorentwurf (1999) ist eine große Anzahl geologischer Angaben gesammelt worden. Daraus ergab sich die einmalige Gelegenheit, die Informationen aus den damit verbundenen zahlreichen Bohrungen zu einer detaillierten mikrogravimetrischen Studie der Stadt Lausanne zu erweitern und zu vervollständigen. Das Ziel bestand darin, die Mächtigkeit der die Molasseüberdeckenden Moräneablagerung abzuschätzen, um eine entsprechendes geologisches Profile entlang der künftigen Bahnlinie zu erstellen. Weiterhin sollte gezeigt werden, daß die Anwendung dieser nicht-invasiven geophysikalischen Methode es ermöglicht, die Anzahl der benötigten Bohrungen sowohl in der Pilotphase wie auch im endgültigen Projekt zu reduzieren, was zu wesentlichen finanziellen Einsparungen in der Ausführung des Werkes beitragen würde. Die beiden in dieser Studie bearbeiteten Testzonen befinden sich im Nordteil und im Stadtzentrum von Lausanne und sind durch eine unterschiedliche Urbanisierung charakterisiert. Das anstehende Gestein liegt in verschiedenen Tiefen: von einigen Metern bis zu etwa dreißig Metern. Diese Zonen weisen alle Schwierigkeiten einer urbanen Bebauung mit hoher Verkehrsdichte auf und waren daher massgebend bei der Ausarbeitung einer globalen mikrogravimetrischen Methodologie für die Stadt Lausanne. Die so entwickelte Technik ermöglicht, die störenden Auswirkungen der Topographie, der Gebäude, der Keller und der Öffentlichen Infrastrukturen sorgfältig zu korrigieren, um so die ausschließlich auf die Mächtigkeit des Lockergesteins zurückzuführenden Effekte zu isolieren. In Bezug auf die Intensität der Auswirkungen der topographischen Korrekturen im Stadtgebiet wurde den Untergeschossen eine besonders grosse Bedeutung zugemessen da die entsprechenden Schwerkrafteffekte eine Grösse von rund einem Zehntel mGal erreichen können. Wir schlagen deshalb vor, vorläufige Karten der topographischen Korrekturen zu erstellen. Diese Korrekturen basieren auf den uns vom Katasterplan gelieferten Daten und einigen Hypothesen bezüglich der Tiefe der Untergeschosse und der Höhe der Gebäude. Die Verfügbarkeit einer derartigen Karte vor der eigentlichen gravimetrischen Messkampagne würde uns erlauben, die Position der Meßstationen besser zu wählen. Wir sahen zudem, daß ein entsprechenden a priori Filter benutzt werden kann, wenn die Form und die Intensität der Anomalie offensichtlich dem entsprechenden Gebäude zugeordnet werden können. Diese Strategie muß jedoch mit Vorsicht angewandt werden, denn falls weitere Anomalien dazukommen, können bedeutende Verschiebungen durch Übèrlagerungen der Schwerewirkung verschiedener Strukturen entstehen. Die Ergebnisse der Modellierung haben sich als sehr überzeugend erwiesen, da sie im Voraus unbekannte sensible Zonen korrekt identifiziert haben. Die Anwendbarkeit der in dieser Arbeit entwickelten gravimetrischen Technik ermöglicht es, während allen Phasen eines Grossbauprojekts, wie zum Beispiel bei der Konstruktion einer unterirdischen U-Bahn, einzugreifen. ABSTRACT Since Spring of 2004 a new metro line has been under construction in the city of Lausanne in Switzerland. The new line, the M2, will be 6 km long and will traverse the city from south to north. The civil engineering project determined that the line would be located primarily in the Molasse. Since the preparatory project in 1999, a great quantity of geological data has been collected, and the many drillings made on the site have proved to be a unique opportunity to undertake a study of urban microgravimetry. The goal was to evaluate the thickness of the morainic filling over the molassic bedrock, and to establish a section along the axis of the future line. It then had to be shown that the application of this nondestructive geophysical method could reduce the number of mechanical surveys required both for a preparatory and a definitive project, which would lead to real savings in the realization of a civil engineering project. The two test zones chosen, one in the northern part of the city and one in the city centre, are characterised by various types of urbanisation. Bedrock is at a depth varying from a few metres to about thirty metres. These zones well exemplify the various difficulties encountered in an urban environment and are therefore very interesting for the development of an overall methodology of urban microgravimetry. Microgravimetry in an urban environment requires careful corrections for gravific disturbances due to the effects of topography, buildings, cellars, and the infrastructure of distribution networks, in order to isolate the gravific effect due exclusively to the thickness of loose soil filling. Bearing in mind the intensity of the topographic corrections in an urban environment, we gave particular importance to basements. Their gravific effects can reach the order of one tenth of one meal, and can influence above all the precision of the Bouguer anomaly. We propose to establish preliminary topographic correction charts based on data provided to us by the land register, by making assumptions on the depths of basements and the heights of buildings. Availability of this chart previous to a gravimetry campaign would enable us to choose optimum measuring sites. We have also seen that an a priori filter can be used when the form and the intensity of the anomaly correspond visually to the corresponding building. This strategy must be used with caution because if other anomalies are to be associated, important shifts can be generated by the superposition of the effects of different structures. The results of the model have proved to be very convincing in detecting previously unknown sensitive zones. The adaptability of the gravimetry technique allows for application in all phases of a civil engineering project such as the construction of an underground metro line. RIASSUNTO Dalla primavera 2004 una nuova linea metropolitana é in costruzione nella città di Losanna in Svizzera. La nuova metropolitana "M2" traverserà per la lunghezza di 6 km il centro urbano di Losanna da sud a nord. II progetto d'ingegneria civile prevedeva un tracciato situato essenzialmente nel fondo roccioso arenaceo terziario (molassa). Dalla redazione del progetto preliminare, avvenuta nel 1999, una grande quantità di dati geologici sono stati raccolti e sono stati eseguiti numerosi sondaggi. Questo sì é presentato come un'occasione unica per mettere a punto uno studio microgravimetrico in ambiente urbano con lo scopo di valutare lo spessore dei terreni sciolti di origine glaciale che ricoprono il fondo roccioso di molassa e di mettere in evidenza come l'applicazione di questo metodo geofisico non distruttivo possa limitare il numero di sondaggi meccanici nella fase di progetto preliminare ed esecutivo con conseguente reale risparmio economico nella realizzazione di una tale opera. Le due zone di test sono situate una nella zona nord e la seconda nel centro storico di Losanna e sono caratterizzate da stili architettonici differenti. II fondo roccioso é situato ad una profondità variabile da qualche metro ad una trentina. Queste due zone sembrano ben rappresentare tutte le difficoltà di un ambiente urbano e ben si prestano per elaborare una metodologia globale per la microgravimetria in ambiente urbano. L'applicazione di questa tecnica nell'ambiente suddetto implica la correzione attenta delle perturbazioni sulla misura dell'accelerazione gravitazionale, causate dalla topografia, gli edifici, le cantine e le infrastrutture dei sottoservizi, per ben isolare il segnale esclusivamente causato dallo spessore dei terreni sciolti. Tenuto conto, dell'intensità delle correzioni topografiche, abbiamo dato grande importanza alle cantine, poiché il loro effetto sulle misure può raggiungere il decimo di mGal. Proponiamo quindi di redigere una carta delle correzioni topografiche preliminare all'acquisizione, facendo delle ipotesi sulla profondità delle cantine e sull'altezza degli edifici, sulla base delle planimetrie catastali. L'analisi di questa carta permetterà di scegliere le posizioni più adatte per le stazioni gravimetriche. Abbiamo anche osservato che un filtro a priori, qualora la forma e l'intensità dell'anomalia fosse facilmente riconducibile in maniera visuale ad un edificio, possa essere efficace. Tuttavia questa strategia deve essere utilizzata con precauzione, poiché può introdurre uno scarto, qualora più anomalie, dovute a differenti strutture, si sovrappongano. I risultati delle modellizzazioni si sono rivelati convincenti, evidenziando zone sensibili non conosciute preventivamente. L'adattabilità della tecnica gravimetrica ha mostrato di poter intervenire in differenti fasi di un progetto di ingegneria civile, quale è quella di un'opera in sotterraneo.

Evaluation of Hot Mix Asphalt Moisture Sensitivity Using the Nottingham Asphalt Test Equipment, July 2005

Moisture sensitivity of Hot Mix Asphalt (HMA) mixtures, generally called stripping, is a major form of distress in asphalt concrete pavement. It is characterized by the loss of adhesive bond between the asphalt binder and the aggregate (a failure of the bonding of the binder to the aggregate) or by a softening of the cohesive bonds within the asphalt binder (a failure within the binder itself), both of which are due to the action of loading under traffic in the presence of moisture. The evaluation of HMA moisture sensitivity has been divided into two categories: visual inspection test and mechanical test. However, most of them have been developed in pre-Superpave mix design. This research was undertaken to develop a protocol for evaluating the moisture sensitivity potential of HMA mixtures using the Nottingham Asphalt Tester (NAT). The mechanisms of HMA moisture sensitivity were reviewed and the test protocols using the NAT were developed. Different types of blends as moisture-sensitive groups and non-moisture-sensitive groups were used to evaluate the potential of the proposed test. The test results were analyzed with three parameters based on performance character: the retained flow number depending on critical permanent deformation failure (RFNP), the retained flow number depending on cohesion failure (RFNC), and energy ratio (ER). Analysis based on energy ratio of elastic strain (EREE ) at flow number of cohesion failure (FNC) has higher potential to evaluate the HMA moisture sensitivity than other parameters. If the measurement error in data-acquisition process is removed, analyses based on RFNP and RFNC would also have high potential to evaluate the HMA moisture sensitivity. The vacuum pressure saturation used in AASHTO T 283 and proposed test has a risk to damage specimen before the load applying.

Spatial planning to the test of property rights in Switzerland : an innovative land management approach to coordinate spatial planning goals with property rights interests

In Switzerland, the land management regime is characterized by a liberal attitude towards the institution of property rights, which is guaranteed by the Constitution. Under the present Swiss constitutional arrangement, authorities (municipalities) are required to take into account landowners' interests when implementing their spatial planning policy. In other words, the institution of property rights cannot be restricted easily in order to implement zoning plans and planning projects. This situation causes many problems. One of them is the gap between the way land is really used by the landowners and the way land should be used based on zoning plans. In fact, zoning plans only describe how landowners should use their property. There is no sufficient provision for handling cases where the use is not in accordance with zoning plans. In particular, landowners may not be expropriated for a non-conforming use of the land. This situation often leads to the opening of new building areas in greenfields and urban sprawl, which is in contradiction with the goals set into the Federal Law on Spatial Planning. In order to identify legal strategies of intervention to solve the problem, our paper is structured into three main parts. Firstly, we make a short description of the Swiss land management regime. Then, we focus on an innovative land management approach designed to implement zoning plans in accordance with property rights. Finally, we present a case study that shows the usefulness of the presented land management approach in practice. We develop three main results. Firstly, the land management approach brings a mechanism to involve landowners in planning projects. Coordination principle between spatial planning goals and landowners' interests is the cornerstone of all the process. Secondly, the land use is improved both in terms of space and time. Finally, the institution of property rights is not challenged, since there is no expropriation and the market stays free.

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.

Evaluation of the Buena Vista IBRD Bridge: A Furthering of Accelerated Bridge Construction in Iowa, February 2012

The need to construct bridges that last longer, are less expensive, and take less time to build has increased. The importance of accelerated bridge construction (ABC) technologies has been realized by the Federal Highway Administration (FHWA) and the Iowa Department of Transportation (DOT) Office of Bridges and Structures. This project is another in a series of ABC bridge projects undertaken by the Iowa DOT. Buena Vista County, Iowa, with the assistance of the Iowa Department of Transportation (DOT) and the Bridge Engineering Center (BEC) at Iowa State University, constructed a two-lane single-span precast box girder bridge, using rapid construction techniques. The design involved the use of precast, pretensioned components for the bridge superstructure, substructure, and backwalls. This application and demonstration represents an important step in the development and advancement of these techniques in Iowa as well as nationwide. Prior funding for the design and construction of this bridge (including materials) was obtained through the FHWA Innovative Bridge Research and Deployment (IBRD) Program. The Iowa Highway Research Board (IHRB) provided additional funding to test and evaluate the bridge. This project directly addresses the IBRD goal of demonstrating (and documenting) the effectiveness of innovative materials and construction techniques for the construction of new bridge structures. Evaluation of performance was formulated through comparisons with design assumptions and recognized codes and standards including American Association of State Highway and Transportation Officials (AASHTO) specifications.

Ammonium Phosphate/Fly Ash Road Base Construction, HR-294, 1993

The objective of this research project was to evaluate the construction and service performance of ammonium phosphate/fly ash (APFA) treated base courses of crushed fines and/or unprocessed sand. Specific test results related to construction of the test sections were included in the 1987 construction report by Iowa State University. The performance of the experimental sections is dealt with in this final report. This 1986 project demonstrated that in all cases the control sections utilizing a Type B base experienced dramatically less cracking in the surface than the APFA treated base sections. The cost per mix and subsequent surface maintenance costs for the APFA base sections, especially those having a substantial amount of limestone, were higher than the Type B base control sections. This type of construction may prove to be economical only when petroleum product costs escalate.

Innovative Leak Test for Pavement Joint Seals, Progress Report, HR-318, 1993

Premature failure of concrete pavement contraction joint seals is an ongoing and costly problem for the Iowa Department of Transportation. Several joint seal test sections consisting of variations in sawing methods, joint cleaning techniques, sealant installation, and sealant types have been established over the past few years. Laboratory analysis and field inspections were done as a part of the tests, and core samples were taken for laboratory adhesion pull tests. Such methods often cover specifically small areas and may not expose hidden failures. Some tests are also labor-intensive and destructive, especially that of coring. An innovative, nondestructive, broad coverage joint seal tester that yields quick results has been designed and developed for evaluation of pavement joint seal performance. The Iowa vacuum joint seal tester (IA-VAC) applies a low vacuum above a joint seal that has been spray-covered with a foaming water solution. Any unsealed area or leak that exists along the joint will become quickly and clearly visible by the development of bubbles at the leak point. By analyzing the results from the IA-VAC tests, information on the number and types of leaks can be obtained; such information will help identify the source of the problem and direct efforts toward a solution.

A Study of the Reliability of the ASTM C-666 Freeze-Thaw Test, MLR-72-01 and R-252, 1972

The Iowa State Highway Commission purchased a Conrad automatic freeze and thaw machine and placed it in operation during October 1961. There were a few problems, but considering, the many electrical and mechanical devices used in the automatic system it has always functioned quite well. Rapid freezing and thawing of 4"x4"xl8" concrete beams has been conducted primarily in accordance with ASTM C-29l (now ASTM C-666 procedure B) at the rate of one beam per day. Over 4000 beams have been tested since 1961, with determination of the resulting durability factors. Various methods of curing were used and a standard 90 day moist cure was selected. This cure seemed to yield durability factors that correlated very well with ratings of coarse aggregates based on service records. Some concrete beams had been made using the same coarse aggregate and the durability factors compared relatively well with previous tests. Durability factors seemed to yield reasonable results until large variations in durability factors were noted from beams of identical concrete mix proportions in research projects R-234 and R-247. This then presents the question "How reliable is the durability as determined by ASTM C-666?" This question became increasingly more important when a specification requiring a minimum durability factor for P.C. concrete made from coarse aggregates was incorporated into the 1972 Standard Specification for coarse aggregates for concrete.

Thin Bonded Overlay Evaluation, Construction Report, HR-559, 1999

In recent years, ultra-thin whitetopping (UTW) has evolved as a viable rehabilitation technique for deteriorated asphalt cement concrete (ACC) pavement. Numerous UTW projects have been constructed and tested, enabling researchers to identify key elements contributing to their successful performance. These elements include foundation support, the interface bonding condition, portland cement concrete (PCC) overlay thickness, synthetic fiber reinforcement usage, joint spacing, and joint sealing. The interface bonding condition is the most important of these elements. It enables the pavement to act as a composite structure, thus reducing tensile stresses and allowing an ultra-thin PCC overlay to perform as intended. Although the main factors affecting UTW performance have been identified in previous research, neither the impact that external variables have on the elements nor the element interaction have been thoroughly investigated. The objective of this research was to investigate the interface bonding condition between an ultra-thin PCC overlay and an ACC base over time, considering the previously mentioned variables. Laboratory testing and full scale field testing were planned to accomplish the research objective. Laboratory testing involved monitoring interface strains in fabricated PCC/ACC composite test beams subjected to either static or dynamic flexural loading. Variables investigated included ACC surface preparation, PCC thickness, and synthetic fiber reinforcement usage. Field testing involved monitoring PCC/ACC interface stains and temperatures, falling weight deflectometer (FWD) deflection responses, direct shear strengths, and distresses on a 7.2 mile Iowa Department of Transportation (Iowa DOT) UTW project (HR-559). The project was located on Iowa Highway 21 between Iowa Highway 212 and U.S. Highway 6 in Iowa County, near Belle Plaine, Iowa. Variables investigated included ACC surface preparation, PCC thickness, synthetic fiber reinforcement usage, joint spacing, and joint sealing. This report documents the planning, equipment selection, and construction of the project built in 1994.

Asphalt Rubber Cement Concrete Webster County, HR-555, Construction Report, 1993

Discarded tires have become a major disposal problem in the U.S. Different techniques of recycling these discarded tires have been tried. The state of Iowa is currently evaluating the use of discarded tires ground into crumb rubber and blending it with asphalt to make asphalt rubber cement (ARC}. This was the sixth project this process has been used in. This project is located on US 169 from the east junction of IA 175 west and north to US 20. Only the binder course was placed this year with the surface course to be let at a later date. There are four test sections, two sections with conventional mixtures and two with ARC mixtures.