Presentation on theme: "National Highway Institute Federal Highway Administration"— Presentation transcript:
1 National Highway Institute Federal Highway Administration CONCRETE PAVEMENT DESIGN DETAILS AND CONSTRUCTION PRACTICES A Training CourseThis course is intended to provide the latest guidance on concrete pavement design details and construction practices--that is, elements of concrete pavement design that are critical to performance but often overlooked or selected from a design standard.Sponsored by the FHWA/NHI, the intent of the course is to provide practical guidance on the selection and use of these design elements.Findings from many recent research and performance studies provide the foundation for this course. These will be referenced throughout the course and are referenced throughout the Technical Digest, which serves as the reference or technical manual for this course.National Highway InstituteFederal Highway Administration
2 SESSION 1OverviewWe’ll start right in with chapter 1 in the Technical Digest. This chapter gives an overview of the course and provides a general overview of the information to be covered.
3 Introduction Focus of concrete pavement design: SLAB THICKNESS Does slab thickness solve all concrete pavement performance problems?Those familiar with concrete pavement design recognize that most pavement design procedures focus almost exclusively on the determination of slab thickness.But does additional slab thickness solve all concrete pavement performance problems? Many of the distresses that develop on concrete pavements are not due to deficiencies in slab thickness, but to other design deficiencies.
4 Distress Type?For example, what is this distress? What causes it? What effect does slab thickness have on this distress? What is the most efficient way of addressing this distress?(Pumping caused by erosion or loss of support beneath slab corners. For pumping to occur we need: 1. heavy loads 2. pump susceptible base/subbase and 3. free moisture)
5 Distress Type?Here’s another example. What is this distress? What causes it? What effect does slab thickness have on this distress? How is it related to the previous distress?(Transverse joint faulting caused by poor or inadequate load transfer and/or loss of support)
6 Distress Type?What is this distress? What causes it? Will additional slab thickness solve this problem?(Corner break caused by loss of support/erosion beneath corners)
7 Distress Type?What distress is this? What is the suspected cause? Will slab thickness prevent this? How do we prevent this from occurring?(Joint spalling caused by incompressibles in the joints preventing the slab from expanding during warm summer months)..
8 Distress Type?Now here is a distress that can be affected by slab thickness. What is it? What are some of the causes?(Cracking in JPCP. Can be caused by repeated traffic loading, thermal and shrinkage forces, excessive joint spacing, late sawing, or locking up of transverse joints)
9 Distress Type?What distress is this? What causes it? This is a materials related distress, really beyond the scope of this course. In pavement design, it is assumed that we are using durable paving materials.(D-cracking of JCP caused by susceptible coarse aggregate that holds water and cracks under repeated freeze-thaw repetitions)
10 Distress Type?Similarly, this is another materials related distress. What is it? What causes it? Again, it is assumed in design that we are using durable materials. This course presumes that durable materials are being used (material durability problems are an entirely separate topic and more information can be found in concrete materials courses and textbooks).(ASR due to a chemical reaction between the aggregate and alkalies in cement paste)
11 Comprehensive Concrete Pavement Design More than just slab thicknessDirect consideration of other design elements, e.g.,Joint spacingLoad transferShoulder designDesign pavement as a systemSo we have seen that many slab distresses are not related to inadequate slab thickness. Thus, concrete pavement design should not just focus on slab thickness but must also look at other design elements important to pavement performance.However, these design elements must not be designed independently but should be designed as part of the system (many of the design features are not independent, e.g., slab thickness and joint spacing)How are these designed or selected within your agency? (Have state pavement designer give updates)
12 Overall Course Objectives Recognize effect of design features on performanceSelect appropriate design featuresIdentify construction practices critical to performanceThis course is intended to provide guidance on the selection and design of these design features, as is shown in the overall coarse objectives listed here. The focus of the course is on jointed plain concrete pavements because it is the most common type being constructed today.What are the types of concrete pavement being constructed by your agency?Focus is on jointed plain concrete pavements
13 Concrete Pavement Design and Construction Process General Design ConsiderationsTraffic Design LifeSubgrade ReliabilityClimate CostsOther FactorsSelect Concrete Pavement TypeSpecific Concrete Pavement Design ElementsSubgrade CharacterizationDrainage DesignBase Selection and DesignThickness DesignJoint DesignShoulder DesignSpecial Design and Construction Considerations for Reinforced PavementsThis is figure 1 on page 3 in the Technical Digest. It shows the general process followed in concrete pavement design and construction, and closely mirrors the flow of material for this class (briefly walk through figure as these topics are essentially repeated on the following page).Construction
14 Course Content DAY ONE Course Introduction Concrete pavement type selectionSubgrade characterizationThe course content mirrors that shown in the previous figure. The material is introduced in a logical sequence, beginning with the course introduction, then concrete pavement type selection, and moving on to subgrade characterization…(go to next slide)
15 Course Content DAY TWO Drainage considerations Base selection and designThickness designJoint designShoulder considerationsOn the second day looking at foundation considerations (drainage, base), thickness design, joint design, and shoulder considerations…(go to next slide)
16 Course Content (cont’d) DAY THREEConstruction considerationsSpecial considerations for reinforced pavements (optional)And wrapping up on the third day with construction considerations. The last module is on special considerations for reinforced pavements and is optional.What areas are a concern here? How are some of these features determined or selected by your agency? Is there interest here on reinforced pavements?
17 Course Format Lecture/discussion Workshops Protocol: Informal Questions are encouragedClass participation is essentialMost of the information will be presented in lecture/discussion format. However, we will also feature several workshops to help apply some of the concepts presented and drive home some of the important points.We want the course to be as informal as possible. We encourage questions and class participation so that the course is tailored to the needs of the group.
18 Workshops Opportunity to apply course concepts Most are computer-oriented:Selection of k-valueBase and drainage selectionPreliminary thickness designFinal pavement designCost-effectiveness evaluationThe workshops are a key part of the class. It provides the participants an opportunity to apply course concepts and procedures to example problems. Workshops are included on k-value selection, base and drainage type selection, preliminary thickness design, final pavement design, and cost effectiveness evaluation.
19 Course Reference Materials Concrete Pavement Design Details and Construction Practices — Technical DigestConcrete Pavement Design Details and Construction Practices — Participant’s WorkbookThere are two course reference materials that will be useful to the participants. The Technical Digest contains most of the technical information that will be presented in this course, although it does not contain a lot of details. The Participant’s Workbook contains information for the participant to follow along during the presentations. An annotated bibliography at the back of the Technical Digest provides additional references on the various topics.
20 Related NHI Courses http://www.nhi.fhwa.dot.gov Techniques for Pavement Rehabilitation (No )Portland Cement Concrete Materials (No )Pavement Subsurface Drainage Design (No )Construction of Portland Cement Concrete Pavements (No )Pavement Distress Identification (No )There are several related courses sponsored by the NHI that may be of interest to participants. While we will touch on parts of these subjects in this course, a more complete treatment of the subject can be found in these NHI courses:--Techniques for Pavement Rehabilitation--PCC Materials--Subsurface Drainage--PCC Construction--Distress Identification
21 Summary Comprehensive pavement design More than just slab thickness Selection/incorporation of design featuresOverview of courseCourse contentFormatReference materialsThis module has introduced the concept of a comprehensive approach to concrete pavement design, in which the focus is not just on slab thickness but on all factors known to contribute to pavement performanceAn overview of the course is presented, including a review of the course content, a discussion of the format, and a review of the course reference materials.