Use of Microcracking to Reduce Shrinkage Cracking in Cement-Treated Bases

2005 ◽  
Vol 1936 (1) ◽  
pp. 2-11 ◽  
Author(s):  
Stephen Sebesta
Keyword(s):  
Cement Hydration ◽  
Water Infiltration ◽  
Falling Weight Deflectometer ◽  
Shrinkage Cracking ◽  
Crack Control ◽  
Pavement Distress ◽  
Pavement Damage ◽  
Falling Weight ◽  
Periodic Crack ◽  
Construction Practice

Shrinkage cracking occurs in cement-treated bases because of desiccation and cement hydration; eventually these cracks start to reflect through the pavement surfacing. Although initially considered cosmetic, these cracks open the pavement to water infiltration and increase the likelihood of accelerated pavement distress. Numerous options exist for minimizing the amount of reflective cracks that appear; microcracking is a promising approach. The microcracking concept can be defined as the application of several vibratory roller passes to the cement-treated base at a short curing stage, typically after 1 to 3 days, to create a fine network of cracks. In addition to the microcracked test sites, the contractor constructed moist-cured, dry-cured, and asphalt membrane–cured sites for comparison. Researchers used falling weight deflectometer (FWD) tests to control the microcracking process, periodic crack surveys to monitor crack performance, and FWD tests through time to track base moduli. Microcracking proved quite effective at reducing shrinkage cracking problems in the base; applying the procedure with three passes of the roller after 2 to 3 days of curing resulted in the best performance. In addition, researchers observed that, without microcracking, excessively high cement contents resulted in problematic cracking in the base even if they were cured according to good construction practice. Microcracking did not result in pavement damage or diminished inservice modulus; thus, microcracking should be considered a viable and inexpensive option to incorporate shrinkage crack control into the construction of cement-treated bases.

Mechanistically Based Flexible Overlay Design System for Idaho

1996 ◽  
Vol 1543 (1) ◽  
pp. 10-19 ◽  
Author(s):  
Fouad M. Bayomy ◽  
Fawzi A. Al-Kandari ◽  
Robert M. Smith
Keyword(s):  
Design Procedure ◽  
Failure Criteria ◽  
The State ◽  
Design System ◽  
Falling Weight Deflectometer ◽  
Overlay Design ◽  
Pavement Damage ◽  
Critical Strains ◽  
Falling Weight ◽  
User Friendly

A study was conducted on a mechanistically based overlay design procedure that incorporates the in situ pavement layer modulus values evaluated by deflection-based nondestructive testing using falling weight deflectometer data. The proposed overlay design procedure addresses the seasonal variation in the state of Idaho and adjusts the modulus values accordingly. The performance of the pavement is calculated in terms of critical strains based on the elastic multilayer theory. The study adopts the Asphalt Institute fatigue and rutting failure criteria to calculate the life of the pavement. Damage analysis is performed based on the past and expected future traffic to calculate the required overlay thickness. The procedure developed has been implemented in an event-driven, user-friendly computer program FLEXOLAY, which runs in the DOS environment. The program was tested and compared with other overlay design methods using pavement sections from the state of Idaho. The overlay thickness determined by FLEXOLAY was found to be close to some of the existing methods and far from others, depending on the existing pavement conditions.

Parks Highway Load Restriction Field Data Analysis: Case Study

1998 ◽  
Vol 1615 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Lutfi Raad ◽  
Eric Johnson ◽  
Dave Bush ◽  
Stephan Saboundjian
Keyword(s):  
Field Data ◽  
Traffic Data ◽  
Falling Weight Deflectometer ◽  
Department Of Transportation ◽  
Truck Traffic ◽  
Weigh In Motion ◽  
Pavement Damage ◽  
Field Data Analysis ◽  
Falling Weight ◽  
Thaw Period

The loss of pavement strength during spring thaw could result in excessive road damage under applied traffic loads. Damage assessment associated with the critical thaw period is essential to evaluate current load restriction policies. The Alaska Department of Transportation and Public Facilities proposed a plan that will provide an engineering analysis of field conditions with 100-percent loads on the Parks Highway for 1996. Extensive data were collected and analyzed in an effort to monitor pavement damage during the spring of 1996 and to determine loss of pavement strength. Field data included truck traffic data from scalehouse and weigh-in-motion (WIM) stations, pavement temperature data, profilometer data for roughness and rutting, and falling weight deflectometer data. Analyses were performed to compare WIM and scalehouse traffic data and to determine the fraction of overweight axle-loads and corresponding pavement damage during spring thaw. Northbound and southbound truck traffic and its effect on pavement damage were considered. Ground temperature measurements were analyzed to determine when thaw initiates and how long seasonal load restrictions are required. In addition, comparisons of remaining life with and without load restrictions using mechanistic methods were conducted.

Application of Falling Weight Deflectometer Data for Analysis of Superheavy Loads

1996 ◽  
Vol 1540 (1) ◽  
pp. 83-90 ◽  
Author(s):  
Dar-Hao Chen ◽  
Emmanuel Fernando ◽  
Michael Murphy
Keyword(s):  
Falling Weight Deflectometer ◽  
Pavement Condition ◽  
Percent Confidence Level ◽  
Significant Difference ◽  
Before And After ◽  
Transport Vehicle ◽  
Pavement Damage ◽  
The Cost ◽  
Falling Weight ◽  
Surface Deflections

Permitting superheavy loads may increase the rate of pavement damage and the cost of maintenance. An analysis of a proposed superheavy load route (FM519) to evaluate the potential pavement damage caused by a planned superheavy load move is presented. Falling weight deflection (FWD) tests and backcalculations of layer moduli were performed on the FM519. FWD tests and backcalculation of layer moduli were performed on the pavement before and after the superheavy load was moved. ELSYM5 and BISAR were used to evaluate the pavement responses using the backcalculated layer moduli from FWD data. The predictions of surface deflections from ELSYM5 and BISAR were close to (within 10 percent of) the measured deflections from FWD tests. The FWD data and analyses show that the existing pavement structure is adequate for the planned superheavy load move. Finally, the permit was issued with the condition that the transport vehicle should be kept within the travel lanes and away from the shoulder whenever possible. FWD tests were conducted after the superheavy load move and comparisons with before superheavy load move were made. T-tests were performed to check for significant difference at the 95 percent confidence level. T-tests showed that there is no significant difference between before and after superheavy load move. Also, no significant distresses due to this superheavy load were observed after the move, and the pavement condition is consistent with the analysis performed to issue the permit.

Pavement Distress Under Accelerated Trafficking

1998 ◽  
Vol 1639 (1) ◽  
pp. 120-129
Author(s):  
Dar-Hao Chen
Keyword(s):  
Asphalt Concrete ◽  
Grid Size ◽  
Pavement Performance ◽  
Falling Weight Deflectometer ◽  
Pavement Distress ◽  
Structural Capacity ◽  
Surface Deflection ◽  
Load Simulator ◽  
Falling Weight ◽  
Asphalt Concrete Pavement

A test pad was closely monitored for a 6-month period, with 640,000 axle load repetitions applied to the test pavement. The load was applied by the Texas Mobile Load Simulator, a full-scale accelerated loading device. Pavement performance data, such as rutting and cracking, were collected at intervals of 0; 2,500; 5,000; 10,000; 20,000; 40,000; 80,000; 160,000; 320,000; and 640,000 axle repetitions. Falling weight deflectometer (FWD) tests were performed at these same data collection intervals to characterize the structural capacity of the pavement system. Although there is a trend indicating that locations with higher FWD deflection result in higher rutting, a unique relation to predict rutting accurately from the surface deflection alone was not found in the study. The back-calculated asphalt concrete pavement moduli were reduced by 50 percent of the original value at the end of 320,000 repetitions. However, the test was not terminated until 640,000 repetitions, when moduli were reduced to 40 percent of the original values. Both FWD deflection and percent of cracked area share the same trend; the left wheelpath had higher initial FWD deflections and later yielded a higher percentage of cracked area. Approximately 50 percent of the wheelpath area was cracked at the end of 80,000 repetitions, as measured by counting the number of cracked squares on a 100 mm by 100 mm grid. However, most of the cracks were hairline cracks. The percentage of cracked area is strongly related to the grid size used. A grid size of 100 mm by 100 mm has been recommended by other researchers and was adopted in this study. Eighty-five percent and 90 percent of the area in the wheelpaths was cracked at the end of 320,000 and 640,000 repetitions, respectively. These numbers are higher than those adopted by the Asphalt Institute, which defines failure as 45 percent cracking in the wheelpath.

scholarly journals PERENCANAAN LAPIS TAMBAH PERKERASAN PADA RUAS JALAN LAMBARO – BATAS PIDIE

2018 ◽  
Vol 1 (3) ◽  
pp. 31-38
Author(s):  
Rizaldi Fachrun ◽  
Muhammad Isya ◽  
Sofyan M. Saleh
Keyword(s):  
Resilient Modulus ◽  
Flexible Pavement ◽  
Falling Weight Deflectometer ◽  
National Highway ◽  
Pavement Damage ◽  
Falling Weight

Lambaro - Batas Pidie is a highway that located in Aceh Besar District, and has important function as a national highway. This highway is connecting from Aceh Besar District to Pidie District, started from Ingin Jaya District to Lembah Seulawah District. There is pavement damage that needs overlay activity in the highway, so the pavement is needed to maintain. This study is performed to find the overlay thick of pavement by using Falling Weight Deflectometer (FWD) and Benkelman Beam (BB) tools. Overlay thick design is based on Design of Overlay Thick of Flexible Pavement by Deflection Method (Pd T-05-2005-B). The segment of this study is in Jalan Lambaro - Batas Pidie highway, the data that taken is from the same point between FWD and BB. This is from STA 14+250 to STA 16+300. To design the overlay, this investigation need the testing result deflection of FWD and BB, then the value result is corrected. After the obtain corrected deflection value, the next process is calculating uniformty factor (FK), representative deflection (Dsbl ov), design deflection (Dstl ov), overlay thick (Ho), factor of overlay thickness (Fo), and corrected overlay thick (HT). The result of this study is the overlay thick from FWD and BB, it is 7 cm for FWD and 9 cm for BB. From the study result, the conclution is the FK value is under 30% and used overlay pavement is concrete asphalt layer with 2,000 MPa Resilient Modulus and minimum stability of Marshall Value is 800 kg.

scholarly journals Flexible pavement damage during spring thaw: A field study using the falling weight deflectometer

2018 ◽  
Vol 45 (3) ◽  
pp. 227-234 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré
Keyword(s):  
Fatigue Damage ◽  
Load Reduction ◽  
Falling Weight Deflectometer ◽  
Material Condition ◽  
Structural Capacity ◽  
Vehicle Loading ◽  
Pavement Response ◽  
Pavement Damage ◽  
Falling Weight ◽  
Performance Conditions

Spring thaw creates critical performance conditions for pavement networks. The increase of water content in the pavement environment is significant during spring thaw. Combined with poor drainage conditions, material condition variations are triggering factors that accentuate the effect of heavy vehicle loading on pavement response and damage. Two experimental pavement sections were monitored in 2014 and 2015 for temperature and deflections. The section with the lowest structural capacity was found to be more sensitive to thaw weakening. Fatigue damage calculated for this section was found to be 31% higher than the section with the highest structural capacity. Moreover, it was shown that a load reduction in the range of 20% can decrease the total yearly damage by about 7 to 10% for the considered test sections. In general, fatigue damage was found to increase from spring onset to the warmest conditions of the yearly cycle, in July.

Field Evaluation of Geocell Use in Flexible Pavements

2000 ◽  
Vol 1709 (1) ◽  
pp. 26-35 ◽  
Author(s):  
Imad L. Al-Qadi ◽  
John J. Hughes
Keyword(s):  
High Density Polyethylene ◽  
Resilient Modulus ◽  
Field Evaluation ◽  
Falling Weight Deflectometer ◽  
Pavement Distress ◽  
The Road ◽  
Delaware County ◽  
Confinement System ◽  
Falling Weight ◽  
Good Possibility

Wheel rutting in excess of 100 mm occurred within 7 days after reconstruction of a section of Route 30 in Delaware County, Pennsylvania, an urban roadway with high average daily traffic. The road was reconstructed on a weak subgrade, and soil tests produced California bearing ratio values between 1.5 and 6.5 percent. A geocell confinement system was used to stabilize the subgrade and solve this problem. The geocell used was constructed of high-density polyethylene. Each geocell panel was fabricated using 60 strips 3.3 m long and 100 mm thick. The panels were 2.4 m × 6.1 m when expanded and created a honeycomb-patterned cellular confinement system. The geocell system was used in combination with other geosynthetics (geogrid or geotextiles, or both). The findings indicated that the geocell system used in this project performed very favorably. The roadway has not shown any pavement distress (alligator cracking, rutting, etc.) during the 3-year evaluation period. To date, falling weight deflectometer data, initially collected after construction, have since been collected annually for 2 years. Analysis suggests that the geocell, in combination with a geosynthetic layer, provides a significant improvement to the pavement structure capacity when built over a weak subgrade. The resilient modulus of the 150-mm-thick aggregate layer was improved almost twofold. There is a good possibility that this increase was caused by the aggregate confinement resulting from the geocell and the separation provided by another geosynthetic layer.

Primary Results for the First Texas Mobile Load Simulator Test Pad

1997 ◽  
Vol 1570 (1) ◽  
pp. 30-38 ◽  
Author(s):  
Dar-Hao Chen ◽  
Ken Fults ◽  
Mike Murphy
Keyword(s):  
Permanent Deformation ◽  
Falling Weight Deflectometer ◽  
Pavement Condition ◽  
Pavement Distress ◽  
Moisture Contents ◽  
Load Simulator ◽  
The Right ◽  
Falling Weight ◽  
Simulator Test

The pavement behavior under 630,000 axle repetitions from the Texas Mobile Load Simulator (TxMLS) was studied. During the course of TxMLS testing, nondestructive testing and in situ instrumentation (pressure cell, strain gauge, and multidepth deflectometers) were applied to monitor and assess the pavement condition. In addition, pavement distress data, such as measurements of permanent deformation, rutting, and cracking, were collected and analyzed. At the end of 630,000 axle repetitions, the maximum permanent deformation was approximately 22 mm. A forensic study was then performed by cutting a 1.8-m by 3-m trench in the middle of the test pad and three nuclear density gauge (NDG) tests were performed on top of each layer to determine the densities and moisture contents. It was found that the lime-treated gravel base (LTB) layer contributed the most to rutting. The axle-load applications increased the density of the LTB layer in the pit area, which caused the pavement structure to settle and consolidate. The highest rate of rutting was observed at the early stages of loading, between 10,000 and 20,000 axle repetitions. The higher deflections on the left wheelpath as observed from falling weight deflectometer data were probably due to the higher moisture content and the instrumented pit. NDG data showed that the LTB, lime-stabilized subgrade (LTS), and subgrade in the left wheelpath all had higher moisture contents than those in the right wheelpath.

scholarly journals NON-DESTRUCTIVE MODULUS TESTING AND PERFORMANCE EVALUATION FOR ASPHALT PAVEMENT REFLECTIVE CRACKING MITIGATION TREATMENTS

2018 ◽  
Vol 13 (1) ◽  
pp. 46-53 ◽  
Author(s):  
Can CHEN ◽  
Shibin LIN ◽  
Ronald Christopher WILLIAMS ◽  
Jeramy Curtis ASHLOCK
Keyword(s):  
Surface Wave ◽  
Pavement Performance ◽  
Wave Method ◽  
Falling Weight Deflectometer ◽  
Reflective Cracking ◽  
Pavement Distress ◽  
And Performance ◽  
Falling Weight ◽  
Surface Wave Method ◽  
Non Destructive

Reflective cracking is a common type of pavement distress, which manifests as cracks in an underlying layer propagating through to the surface of a pavement structure. To minimize reflective cracking of asphalt layers in composite pavements, four treatments are commonly used: standard/full rubblization, modified rubblization, crack and seat, and rock interlayer. The four types of treatment were evaluated to determine their effectiveness in mitigating reflective cracking via non-destructive Falling Weight Deflectometer tests and Surface Wave Method tests to measure layer modulus, along with field pavement performance surveys. It is found that moduli measurements from Surface Wave Method tests have reduced uncertainty comparing to those from Falling Weight Deflectometer tests, (2) the moduli of thin rock interlayers were captured by Surface Wave Method, but missed by Falling Weight Deflectometer. In addition, the Surface Wave Method results show that (1) crack and seat treatments provide the highest moduli, followed by modified rubblization, and (2) standard rubblization and rock interlayers provide moduli that are slightly lower than the other two treatments. Pavement performance survey was also conducted concurrently with the in-situ modulus tests. Based on the results of this study, modified rubblization and rock interlayer treatments are recommended for mitigation of reflective cracking.

Sign in / Sign up

Export Citation Format

Share Document