Pavement Basics CIMT 210 I History of PCC

Pavement Basics - CIMT 210 I. History of PCC Pavements: • Legislation • Equipment • Interstates • Design Procedures • Jointing II. Basics of PCC Pavement • Pavement Types • Basic Components of Concrete Pavement • Design Methods

Topics covered in this Course *PAVEMENT HISTORY http: //www. pavement. com/Concrete_Pavement/About_Concrete/100_Years_of_Innovation/index. asp

First Legislation • 1916 President Woodrow Wilson Directed Federal gov’t to cooperate 50/50 with the state (he signed the first “Federal-Aid Highway Act) • 1956 President Eisenhower “National System of Interstate and Defense Highways” (signed the “Federal-Aid Highway Act of 1956)

Equipment • 1946 James W. Johnson and Bert Myers conceptualized the slip form paver • 1949 The Iowa Highway Dept. constructed the first slipformed roadway • 1955 Quad City Construction developed an improved self-propelled, track mounted slipform paver • At that time on-site mixing was replaced with hauling

Interstate • 1956 Introduction of the interstate • 41 Billion Dollars • 41, 000 miles • Largest road construction in US history • AASHTO- American Association of State Highway and Transportation Officials was formed to conduct studies • 1976 Congress funded the 3 R program Restoration, Rehabilitation, and Resurfacing • 1981 the fourth R of Reconstruction was added for Interstate projects

Design Procedures • 1920 s were the beginning of the “Mechanistic. Empirical” Design Procedure (Related pavement thickness to traffic loading) • The Critical stress was found in slab corners • Mechanistic –Based on computed pavement response • Empirical – Calibrated to observe pavement performance • A design thickness was limited to the stress of ½ the concrete’s Modulus of Rupture (MOR) • Edges of the concrete were thickened • 1930 s Westergaard’s equation was adopted • 1933 PCA (Portland Cement Association) procedure introduced fatigue

Jointing Practices • Expansion joints were used to relieve compression stresses in heat • From 1925 to 1945 Contraction joints and transverse expansion joints were employed • Results of this combination was that expansion joints closed up causing contraction joints to open • Skewed joints were employed in 1906 and 1918 not allowing wheels to cross joints at the same time • Skewed Joint Roadway became a common practice for undoweled pavements • Randomized joint spacing became the standard practice for major roadways due to resonating car vertical responses

Jointing Practices • Expansion Joint (Not Good Practice with Good Design of Contraction Joint ) • Contraction Joint reinforced slab

Jointing Practices (1) Transverse Contraction Joint - a sawed, formed, or tooled groove in a concrete slab that creates a weakened vertical plane. It regulates the location of the cracking caused by dimensional changes in the slab, and is by far the most common type of joint in concrete pavements. (2) Longitudinal Joint - a joint between two slabs which allows slab warping without appreciable separation or cracking of the slabs. (3) Construction Joint - a joint between slabs that results when concrete is placed at different times. This type of joint can be further broken down into transverse and longitudinal joints. (4) Expansion Joint - a joint placed at a specific location to allow the pavement to expand without damaging adjacent structures or the pavement itself.

Jointing Practices • Missing Contraction Joints

Jointing Practices • Contraction Joints

Jointing Practices • Skewed Contraction Joints Axle with Two Wheels

Jointing Practices • Longitudinal and Transverse (Construction Joints )

II. Basics of PCC Pavement • Pavement Types • Basic Components of Concrete Pavement • Design Methods

Pavement Types

Pavement Types • Jointed Plain • Undoweled • Doweled • Jointed Reinforced • Continuously Reinforced • Prestressed

Pavement Types • Jointed Plain (JPCP) • Undoweled • Doweled 15 -20 ft. Dowels

Pavement Types • Jointed Reinforced (JRCP) 25 -30 ft. Mesh Dowel

Pavement Types • Continuously Reinforced (CRCP) 1. 5 -6. 0 ft.

II. Basics of PCC Pavement • Pavement Types • Basic Components of Concrete Pavement • Design Methods

Basic Components of Concrete Pavement

II. Basics of PCC Pavement • Pavement Types • Basic Components of Concrete Pavement • Design Methods

Pavement Design • Empirical Design Procedures (The 1993 AASHTO Guide for Design of Pavement Structures. ) Based on observed performance AASHO Road Test • Mechanistic Design Procedure (The 2002 AASHTO Guide for Design of Pavement Structures) Employs the Finite Element Method Based on mathematically calculated pavement responses PCA Design Procedure (PCAPAV) New windows based Street. Pave • MEPDG Procedure Mechanistic-Empirical Pavement Design Guide (uses both procedure mentioned above)

Pavement Design Empirical Design Equation and Procedures Therefore, the slab depth (D) is required to determine the number of ESALs to design for before the pavement is ever designed. The iterative design process usually proceeds as follows: 1. 2. 3. 4. 5. 6. 7. Determine and gather rigid pavement design inputs (ZR, So, DPSI, pt, Ec, S'c, J, Cd and keff). Determine and gather rigid pavement ESAL equation inputs (Lx, L 2 x, G) Assume a slab depth (D). Determine the equivalency factor for each load type by solving the ESAL equation using the assumed slab depth (D) for each load type. Estimate the traffic count for each load type for the entire design life of the pavement and multiply it by the calculated ESAL to obtain the total number of ESALs expected over the design life of the pavement. Insert the assumed slab depth (D) into the design equation and calculate the total number of ESALs that the pavement will support over its design life. Compare the ESAL values in #5 and #6. If they are reasonably close (say within 5 percent) use the assumed slab depth (D). If they are not reasonably close, assume a different slab depth (D), go to step #4 and repeat the process.

Design Criteria

READING ASSIGNMENT /REFERENCES Training Workshop Modules_Rigid Pavement Types Training Workshop Modules_Rigid Pavement Basics Reading Material _NCPTC