Design of a rigid pavement (jpcp & crcp)
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The document details the design of two types of rigid pavements, Jointed Plain Concrete Pavement (JPCP) and Continuously Reinforced Concrete Pavement (CRCP), utilizing the AASHTOware pavement ME software. JPCP consists of three layers and includes features like contraction joints to control cracking, while CRCP is a four-layer structure that eliminates the need for transverse joints, resulting in a smoother surface. The analysis includes user-defined inputs for traffic and climate factors, leading to predictions of distress levels and pavement performance over a 30-year period.
Design of a rigid pavement (jpcp & crcp)
- 1. Design of a Rigid pavement Team : 1) Ahsan ullah Hussaini Syed 2) Ahmed Towfeequllah Siddiqui
- 2. Introduction The project involved designing of two different types of Rigid pavements using the AASHTOWare Pavement ME software. 1) JPCP (Jointed Plain Concrete Pavement) : It was designed as a three layered structure, the layer distribution being as follows: Layer 1 – PCC – 16 inch Layer 2 – NonStabilized (Crushed gravel) – 8 inch Layer 3 – Subgrade (A-1a) – Semi Infinite Jointed plain concrete pavement uses contraction joints to control cracking and uses reinforcing steel in form of dowel bars. Transverse joint spacing is selected such that temperature and moisture stresses do not produce intermediate cracking between joints. This typically results in a spacing no longer than about 6.1 m (20 ft.). 2) CRCP (CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS) : It was designed as a 4 layered structure, the layer distribution being as follows: Layer 1 – PCC – 11.3 inch Layer 2 – Stabilized – 4 inch Layer 3 – NonStabilized – 8 inch Layer 4 – Subgrade – Semi infinite CRCP is concrete pavement reinforced with continuous steel bars throughout its length. Its design eliminates the need for transverse joints (other than at bridges and other structures) and keeps cracks tight, resulting in a continuous, smooth-riding surface.
- 3. AASHTOWARE PAVEMENT ME DESIGN USER INPUTS The Pavement ME Design program utilizes the user-defined inputs to conduct a CRCP and JPCP mechanistic analysis to predict the expected incremental distress levels based on a national calibration. As the Pavement ME Design program represents a fundamental change in design philosophies in CRCP and JPCP design, it requires much greater knowledge of design parameters affecting design including layer materials, climate, and traffic characterization. For users new to the program, the following section outlines a basic overview of the program’s format and design parameters. The Figure shows the main input screen of the Pavement ME Design program. General input categories are viewed in the left of the screen while specific input parameters are viewed and entered in the middle of the screen. Figure 2 : Layer Structure & material properties – CRCP Figure 1: Design user inputs for CRCP & JPCP – AASHTOWare ME.
- 4. Figure 3 Layer structure & material properties - JPCP Traffic To characterize the volume, the total amount of truck traffic is input as average annual daily truck traffic (AADTT), including the expected lane and directional distribution factor for the facility. Figure 4: Quarterly ADT distribution for Naples, Fl. Ref : https://www.colliergov.net/modules/showdocument.aspx?documentid=58143 The AADT of Naples, FL was used to design the JPC pavement (With Dowel Bars), likewise the AADT of Chicago, IL was used in the designing of the CRCP (Ref: https://goo.gl/3OtCIY)
- 5. CLIMATE A key improvement to the CRCP design process is accounting for site-specific climate. The Pavement ME Design program models account for daily and seasonal fluctuations in temperature and moisture profiles in the CRCP and soil layer, respectively, through site- specific factors such as percent sunshine, air temperature, precipitation, wind, and water table depth. There are several hundred weather stations across North America from which the user can select the nearest one to the project site, or the user can create a “virtual weather station” by allowing the program to interpolate nearby weather data to the user’s specific project site. Figure 5 : Ideal station can be picked to input Climate information The pavement is then analyzed for : a) IRI and Punchout in case of CRCP b) Cracking, faulting & IRI in case of JPCP. Post analysis, thickness is determined (Trial & error) for both the pavements. Figure 6-7: Climate data for both the pavements.
- 6. Result for JPCP As far as terminal IRI is considered, Distress reliability of 122.56 was predicted from the analysis against the targeted 172 which was well below the threshold. Similarly Joint Faulting and Transverse cracking reliability criterion were satisfied. The graphs above illustrate the achieved data for Cracking, Faulting and IRI and prediction for a period of 30 years ahead. By trial & error the thickness of the slab was found to be 16 inches.
- 7. Result for CRCP: Distress Type Distress @ Specified Reliability (%) Criterio n SatisfiedTarget Predicted Target Achieved Terminal IRI (in./mile) 172.00 143.15 90.00 99.29 Pass CRCP punchouts (1/mile) 10.00 3.99 90.00 99.95 Pass As far as terminal IRI is considered, Distress reliability of 143.15 was predicted from the analysis against the targeted 172 which was well below the threshold. Similarly punchouts achieved a satisfactory 99.95% reliability. The graphs above illustrate the achieved data for IRI & Punchout and prediction for a period of 30 years ahead. By trial & error the thickness of the slab was found to be 11.3 inches.
- 8. KENPAVE An analysis was carried out both the pavement types for Maximum stress using Kenpave. CRCP Slab thickness: 11.3 in ; Dimensions: 12 x 12 ; Reinforcement: 0.7% Nodes : X : 0, 7, 14, 26, 50, 85, 120 Y : 0, 12, 36, 54, 78, 120 MAXIMUM STRESS (SMAX) IN LAYER 1 IS -95.112 ( NODE 2 ) MAXIMUM STRESS IN X DIRECTION = 0.0 ( NODE 0 ) MINIMUM STRESS IN X DIRECTION = 34.4 ( NODE 22 ) MAXIMUM STRESS IN Y DIRECTION = -95.1 ( NODE 2 ) MINIMUM STRESS IN Y DIRECTION = 13.4 ( NODE 5) JCPC Slab thickness: 16 in ; Dimensions: 12 x 12 ; Dowel bar: Dia: 1.25 in; Joint Spacing: 17ft Nodes : X : 0, 7, 14, 26, 50, 85, 120 Y : 0, 12, 36, 54, 78, 120 MAXIMUM STRESS (SMAX) IN LAYER 1 IS -67.833 ( NODE 2 ) MAXIMUM STRESS IN X DIRECTION = 0.0 ( NODE 0 ) MINIMUM STRESS IN X DIRECTION = 24.2 ( NODE 43 ) MAXIMUM STRESS IN Y DIRECTION = -67.8 ( NODE 2 ) MINIMUM STRESS IN Y DIRECTION = 5.6 ( NODE 6 )
- 9. Conclusion JPCP For a period of 30 years cracking is shown to be constant and gives a possibility of the pavement life extending through 40-50 years as far as cracking is concerned. The faulting rose from 0.02 during construction to 0.09 over a period of 30 years and may only breach the threshold value after 40-45 years which again is well beyond the design life. The IRI curve shows a linear relation for 25 years and the curve begins to flatten out hence indicating an extended life than what it was being designed for. CRCP The IRI at the 30 year threshold is 143.15 (172 Max) and it keeps ascending and will breach the target value round about the 45-50 year mark which is well ahead of our target design life. The punchout starts at 2.2 and the curve ascends to about 3.99 till 15 years and henceforth remains constant till the target design life of 30 years and may breach the limit well beyond the 50 year mark.