LTPP Data Analysis: Influence of Design and Construction Features on the Response and Performance of New Flexible and Rigid Pavements (2005)

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14 CHAPTER 2 - DESCRIPTION OF SPS 1, 2 AND 8 EXPERIMENTS 2.1 INTRODUCTION This chapter includes description of Specific Pavement Studies (SPS) experiments 1, 2 and 8, in terms of their respective goals, experimental designs, and associated factors (design and construction). A separate section is included for the Dynamic Load Response (DLR) experiment, which constitutes a subset of the SPS-1 and -2 experiments. 2.2 STRATEGIC STUDY OF STRUCTURAL FACTORS FOR FLEXIBLE PAVEMENTS—SPS-1 The SPS-1 experiment is focused on the strategic study of structural factors for flexible pavements, and was intended to study the effect of specific design and construction features on pavement response and performance. As the test sections in the experiment are monitored since inception, the experiment provides an opportunity to determine the relative influence of the key pavement design and construction elements that affect pavement performance. 2.2.1 Experiment Design The fractional factorial design for the SPS-1 experiment is shown in Table 2-1 . The overall experiment consists of 192 factor level combinations, which consist of 8 site-related (subgrade soil and climate) and 24 pavement structure combinations. The experiment design requires that “48 test sections representing all structural factor and subgrade type combinations in the experiment are to be constructed in each of the climatic zones, with 24 test sections to be constructed on fine-grained soil and 24 test sections to be constructed on coarse-grained soil”[1]. The SPS-1 experiment examines the effects of both site and structural factors. The site factors include: climatic region, subgrade soil (fine- and coarse-grained), and traffic rate (as a covariate) on pavement sections incorporating different levels of structural factors. The structural factors include: • drainage (presence or lack of it), • asphalt concrete (AC) surface thickness – 102 mm (4-inch) and 178 mm (7-inch), • base type – dense-graded untreated aggregate base (DGAB), dense-graded asphalt-treated base (ATB) and a combination of both,

15 • base thickness – 203 mm (8-inch) and 305 mm (12-inch) for un-drained sections; and 203 mm (8-inch), 305 mm (12-inch) and 406 mm (16-inch) for drained sections. The study design stipulates a traffic load level in excess of 100,000 Equivalent Single Axle Loads (ESALs) per year for the study lane [2]. According to the experiment design, twelve test sections were constructed at a given project location (site). Each section is represented by either XX-0101 to XX-0112 or XX-0113 to XX-0124, where XX denotes the state ID. Six sections have a target HMA surface thickness of 4-inch (102 mm) and the remaining six have a target HMA surface thickness of 7-inch (178 mm). Out of 12 sections, 5 have 203 mm (8-inch) base layer, 5 have a 305 mm (12-inch) base layer and the remaining 2 have a 406 mm (16-inch) base layer. Also 2 test sections have dense- graded aggregate base (DGAB), 2 sections have asphalt treated base (ATB), 2 sections have a combination of ATB/DGAB, 3 sections have permeable asphalt treated base (PATB) over DGAB, and 3 sections have ATB over PATB. In-pavement drainage is provided only for sections with PATB as the base.

16 Table 2-1 SPS-1 Experiment Design Matrix Pavement Structure Climatic Zones, Subgrade WET DRY FREEZE NO FREEZE FREEZE NO FREEZE Fine Coarse Fine Coarse Fine Coarse Fine Coarse Drainage Base Type Base Thickness (mm) HMA Thickness (mm) J K L M N O P Q R S T U V W X Y 102 113 113 113 113 113 113 113 113 203 178 101 101 101 101 101 101 101 101 102 102 102 102 102 102 102 102 102 DGAB 305 178 114 114 114 114 114 114 114 114 102 103 103 103 103 103 103 103 103 203 178 115 115 115 115 115 115 115 115 102 116 116 116 116 116 116 116 116 ATB 305 178 104 104 104 104 104 104 104 104 102 105 105 105 105 105 105 105 105 203 178 117 117 117 117 117 117 117 117 102 118 118 118 118 118 118 118 118 No ATB/4" DGAB 305 178 106 106 106 106 106 106 106 106 102 107 107 107 107 107 107 107 107 203 178 119 119 119 119 119 119 119 119 102 120 120 120 120 120 120 120 120 305 178 108 108 108 108 108 108 108 108 102 121 121 121 121 121 121 121 121 PATB/DGAB 406 178 109 109 109 109 109 109 109 109 102 122 122 122 122 122 122 122 122 203 178 110 110 110 110 110 110 110 110 102 111 111 111 111 111 111 111 111 305 178 123 123 123 123 123 123 123 123 102 112 112 112 112 112 112 112 112 Yes ATB/PATB 406 178 124 124 124 124 124 124 124 124

17 2.2.2 Current Status of the Experiment (Release 17 of DataPave) The SPS-1 experiment includes eighteen sites with twelve sections each, with a total of 216 sections located at all four LTPP climatic regions. The Wet-Freeze (WF) and the Wet-No- Freeze (WNF) zones contain the majority of the sections. This is in line with the common wisdom that WF and WNF conditions critically affect flexible pavement performance. The geographical distribution of sites within the SPS-1 experiment is presented in Figure 2-1 . The full factorial design for SPS-1 experiment design requires that a total of thirty-six similar designs be replicated across eight (8) soil-climate combinations. The thirty-six designs were reduced to twenty-four designs in each soil-climate combination making the experiment design a fractional factorial. However, it was considered that the construction of twenty-four test sections at each site would require a greater effort on the part of the participating agencies [1]. Therefore, to reduce the cost of construction the experiment was developed so that only 50% of the possible combinations of factors (i.e. 12 test sections) will be built at each site. The experiment, designed in a factorial manner to enhance implementation practicality, permits the construction of twelve test sections (0101 through 0112 or 0113 through 0124) at one site with the complementary twelve test sections to be constructed at another site within the same climatic region on a similar subgrade type [2]. The LTPP NIMS data (DataPave 3.0) shows that the site populations within the SPS-1 experiment design are not equally distributed. This deviation is partly because of the cutoff values of precipitation and freeze index used for categorizing the “wet/dry” and “freeze/non- freeze” climates. The current status of the factorial design, along with the current distribution of sites in each climatic zone, is shown in Table 2-2 . As these deviations are expected to seriously affect the results of the analysis (the experimental design is unbalanced), this issue will be further discussed in Chapter 3 under design versus actual construction. It can also be seen from Table 2-2 , that there is no replication available for sites in DF zone for different subgrade types. Therefore, the subgrade effects in DF zone cannot be estimated. Similarly, the results may be seriously hampered due to the small number of sites in Dry zones. A discussion on the current status of the experiment for each can be found in Appendix A1.

18 MT NV AZ OK KS NM NE IA AR LA TX AL MI WI OH VA DE FL Figure 2-1 Geographical location of SPS-1 sites Table 2-2 SPS-1 site factorial — From DataPave 3.0 Weta Dryb Subgrade Type Designs Freezec Non-Freezed Freeze Non-Freeze Total 0101-0112 IA (19) OH (39) KS (20) AL (1) - NM (35) Fine 0113-0124 MI (26) NE (31) LA (22) VA (51) - - 9 0101-0112 AR (5) DE (10) FL (12) NV (32) - Coarse 0113-0124 WI (55) OK (40) TX (48) MT (30) AZ (4) 9 Total 8 6 2 2 18 Note: a. Wet Regions — Average Annual Rainfall > 20 inches (508 mm) b. Dry Regions — Average Annual Rainfall < 20 inches (508 mm) c. Freeze Regions — Average Annual Freezing Index > 83.3 oC-day (150 oF-day) d. Non-Freeze Regions — Average Annual Freezing Index < 83.3 oC-day (150 oF-day)

19 2.2.3 Construction Guidelines for SPS-1 Experiment The study of the SPS-1 experiment has specific objectives; mainly the experiment was designed to study the influence of design and construction features on the response and performance of new flexible pavements. Therefore the focus of the experiment is on the main factors (HMA and base thicknesses, base type and presence or absence of drainage). The designs were repeated across 18 states in order to study the effect of different climates and subgrade soils. To study the specific objectives of the SPS-1 experiment, it is essential to control for other sources of variability, which can mask the effects of the main factors. These factors may include differences in construction quality, material properties and traffic levels across sites. Therefore, each SPS-1 project had to meet certain construction criteria. To approach uniformity across projects, there were limitations on the methods and materials used in construction, as well as requirements for testing and continued monitoring. These guidelines are outlined below. Construction Requirements Construction requirements were provided in the “Construction Guidelines” section of the SHRP-LTPP Specific Pavement Studies: Five-Year Report[2, 3]. The overall length of each section was required to be 183 m (600 ft) with 152.4 m (500 ft) for monitoring and 15.25 m (50 ft) on each side for material sampling. The distance between each of these sections had to be long enough to allow sufficient space (transition) for changes in materials and thicknesses during construction. The suggested length for these transitions was 30.5 m (100 ft). Subgrade Requirements The finished subgrade elevations could not vary from the design by more than 12 mm (0.5-inch). This could be determined using rod and level readings taken on the lane edge, outer wheel path, mid lane, inner wheel path and inside lane edge at 15 m (50 ft) intervals throughout the length of the project. Surface irregularities could not exceed 6 mm (0.5-inch) between two points in any direction in a 3.05 m (15 ft) interval. Modifiers may be used to provide a stable working platform for construction but not to increase subgrade strength.

20 Base Layers Two types of bases are included in each SPS-1 project — drained and un-drained. The drained bases include a permeable asphalt treated base with edge drains. The un-drained bases consist of dense graded materials. Two types of dense graded bases were specified for the sections without drainage. The un-drained bases were used in sections 101-106 and 113-118 and were defined as dense graded aggregate base (DGAB), asphalt treated base (ATB), or a combination of these two materials. The drained base was used in sections 107-112 and 119-124 with a combination with DGAB and ATB base types. The requirements for each base type are as follows: Dense graded aggregate base (DGAB) • Minimum 50% retained on the No. 4 sieve. • Top-size aggregate was specified as 38 mm (1.5-inch). • Less than 60% passing the No. 30 sieve and less than 10% passing the No. 200 sieve. • Liquid limit less than 25 and plasticity index less than 4 for fraction passing No. 40 sieve. • In L. A. Abrasion Test, the loss must not exceed 50% at 500 revolutions. • The compacted lift thickness must not exceed 200 mm (8 inches). • The DGAB must be compacted to at least 95% of maximum density. • In-place density of DGAB should be determined prior to the application of an asphalt prime coat. • The base surface must be primed with low-viscosity asphalt and allowed to cure prior to placement of the asphalt concrete surface. • The finished DGAB elevations should not vary from design by more than 12 mm (0.5 inches). Asphalt treated base (ATB) • The aggregate used in the ATB layer must meet the same requirements as the aggregate for DGAB layer. • Asphalt emulsions should not be used in ATB. • Experimental modifiers were allowed only in the supplemental sections. • No recycled HMA was allowed in ATB.

21 • For the Hveem mix design procedure, the following requirements were required for the ATB: Swell 0.7 mm Stabilometer Value 35 min Moisture Vapor Susceptibility 25 Design Air Voids 3 to 5 percent • For the Marshal mix design procedure, the following requirements were required for the ATB: Compaction blows 50 Flow 3 to 5 mm Stability 4.4 KN Design Air Voids 3 to 5 percent • The maximum compacted lift thickness for the ATB layer should be limited to a maximum of 200 and 100 mm (8- and 4-inch) for the first and subsequent lifts, respectively. • The minimum compaction requirement was 90% of the maximum theoretical specific gravity for the first lift and 92% for subsequent lifts. • The finished surface of the ATB base should not vary from the design more than 12 mm, as measured using rod and levels. • The base layer thickness should not vary from design by more than 6 mm (0.25-inch). Permeable asphalt treated base (PATB) The drained base was used in sections 107-112 and 119-124 with a combination of DGAB and ATB base types. Each of these sections included a PATB layer with edge drains to permit water to drain out of the pavement structure. The requirements for the PATB layer were as follows: • An asphalt emulsion was not allowed as binder for PATB base layer. • The gradation for the PATB layer should be within the following ranges: Sieve No. % Passing 38 mm (1.5 inch) 100 % 25 mm (1 inch) 95 – 100 % 13 mm (0.5 inch) 25 – 60 % No. 4 0 – 10 % No. 8 0 – 5 % No. 200 0 – 2 % • More than 90% of the aggregate has at least one crushed face. • No recycled HMA should be used in PATB. • Compaction should be performed by using static wheel roller applying 0.5 to 1.0 ton of force per foot of roller width. • No portion of the PATB should be day-lighted.

22 HMA Layer The HMA surface layers were required to meet the following minimum requirements. • For the Hveem mix design procedure, the following requirements were required for the HMA mix: Swell (maximum) 0.7 mm Stabilometer Value (minimum) 37 min Air Voids 3 - 5% • For the Marshal mix design procedure, the following requirements were required for the HMA mix: Compaction blows 75 Flow 2 to 4 mm Stability 8 KN • No recycled materials were permitted in HMA mixtures. • The aggregates should have a minimum of 60% retained on the No. 4 sieve with at least two fractured faces, and a minimum sand equivalent of 45. • The asphalt grade and characteristics should be selected based on normal agency practice. • The use of modifiers should be discouraged in the main sections. • Lift thickness could not exceed 102 mm (4-inch) and compacted thickness of any single layer had to be at least 51 mm (2-inch). • Longitudinal joints should be staggered between successive lifts to avoid vertical joints. • All transverse joints should be placed outside the main sections. • The thickness of the HMA layer (surface and binder) should be within 6 mm (0.25-inch) of the thickness specified by the experiment design. • The as-constructed finished surface should have a profile index of less than 158 mm per km (10 inches per mile) as measured by the California-type profile-graph. Shoulders • The shoulders placed on these projects should have a minimum width of 1.2 m (4-ft) and have the full pavement structure across their width. • If possible, the shoulders should be paved full-width with the surface course to eliminate longitudinal joints. If not, then the shoulders should be paved such that the longitudinal joint is at least 205 mm (12-inch) outside the travel lane. Drainage Materials Filter fabric (or geo-textile) was required on sections that included a PATB layer. This was specified to prevent the clogging of the PATB layer due to migration of fine material from the subgrade. The filter fabrics used should meet the American Association of State Highway and Transportation Officials-American Building Contractors-American Road and Transportation Builders Association (AASHTO-ABC-ARTBA) Task Force 25 recommendations, which include the following requirements for the geo-textiles:

23 • In order to separate the base layer from the subgrade non-woven and woven geo-textile materials that conform to Class A requirements should be used. • The geo-textile material conforming to Class B requirements could be used in the edge drains. • Geo-textiles should be overlapped a minimum of 610 mm (2 ft) at all longitudinal and transverse geo-textile joints. • Filter fabrics should be installed in accordance with the manufacturer’s specifications. • For the sections where the PATB layer was placed on DGAB, the filter fabrics should extend around each edge drain and wrap around the outer edge of the PATB layer. • Exposure time of the geo-textile to elements between lay down and cover should be limited to a maximum of 3 days. Edge drains were to be installed on sections containing a PATB layer to collect water draining from the permeable base. The requirements on these drains were as follows: • Inside and outside edge drains should be constructed for crowned pavements. • Edge drains should be at least 914 mm (3 ft) away from the edge of the travel lane. • The PATB was recommended for backfill around the edge drains; however, other open graded materials could be used as backfill materials if approved. • Collector pipes (slotted) should be at least 76 mm (3-inch) diameter. • Outlet pipes (un-slotted) should be rigid plastic pipes with a minimum diameter of 76 mm (3- in). • Drainage pipes should be sized for the expected discharge determined as part of design. • Discharge outlet pipe should be placed at a maximum interval spacing of 76.2 m (250-ft). Material Sampling and Testing Sampling and testing were required for each of the material used for the construction of sections. The material characterization is necessary to evaluate the differences between the as- constructed sections within a site and between different sites within the experiment. These measured parameters are used mostly in the design procedures as well as to assess important performance characteristics of the materials. A general sampling and testing plan was created for use as a guideline[3]. These guidelines were then used to develop the sampling and testing plan specific to each site. These plans were created prior to the construction of each project and the location of each sample was predetermined. The following types of samples should be taken from each project: • Bulk samples from the upper 305 mm (12-inch) of the subgrade. • Thin-walled tube samples of the subgrade to a depth of 1.2 m (4 ft). • Jar samples for subgrade.

24 • Bulk samples for the DGAB. • Jar samples for the DGAB. • Bulk samples for PATB. • Bulk samples for ATB. • Bulk samples for the asphalt mixes used in the surface and binder course. • Bulk sample of asphalt mixes used in all mixes. • Cored samples for bound bases and surface asphalt layers. In addition to these samples, bulk samples were to be taken for the asphalt cement, aggregates and un-compacted HMA mixes. These samples were to be stored for long term. A series of auger probes should be performed in the shoulder of each test section up to a depth of 6 m. This allows for the determination of the stiff layer depth. Finally, as part of the construction activity, nuclear density and moisture testing should be conducted at the location of the bulk sampling areas for the subgrade and on the top of each layer in every test section. The type and number of tests per layer are given elsewhere [3]. Monitoring Requirements The monitoring of the sections at each site includes several types of data. These include distress surveys, deflection measurements, transverse profiles and longitudinal measurements. Each of these measurements has different frequency requirements, which can be revised over time. Distress Surveys A distress survey was to be performed on each section within 6 months of construction. A manual distress survey should be performed on the sections biennially, with the exception of “weak” sections (2, 5, 7 and 13 in SPS-1 projects where distress surveys should be more frequent). The survey could be postponed by a year if necessary. Deflection Surveys Deflection measurements should be collected using a falling weight deflectometer (FWD) from 1 to 3 months after the construction of the project. The deflection survey of these projects is to be completed biennially except of the “weak” sections (2, 5, 7 and 13 in SPS-1 projects

25 where distress surveys should be more frequent). This testing also could be postponed up to 1 year if necessary. Transverse Profile Transverse profile measurements should be taken at the same frequency and at the same time, as the distress surveys. Longitudinal Profile Longitudinal profiles should be taken on the sections within 3 months after construction. These measurements can be postponed up to 3 additional months. The “weak” sections (2, 5, 7 and 13 in SPS-1 projects) should be monitored every 6 months but monitoring can be postponed up to 6 additional months. The other sections should be monitored biennially and can be postponed by 1 year if necessary. Traffic Data Traffic data should be collected on each site. The current requirement states that weigh- in-motion (WIM) data should be continuously collected on all SPS-1 sections. Continuous data collection has been defined as the “use of a device that is intended to operate throughout the year and to which the SHA commits the resources necessary to both monitor the quality of the data being collected and to fix problems quickly upon determination of any fault” [2]. WIM devices are to be calibrated biannually. This level of data collection is necessary to assess accurate traffic loading measurements. Climatic Data Each SPS-1 site was required to install an automatic weather station (AWS). The AWS should be located close enough to each of the sites to provide weather data that is representative of the climate on each site. The equipment installed at these locations should measure the following weather components: • Rain • Humidity • Wind speed • Temperature

26 All the data collected should be stored by a data-logger. The data should be downloaded from the data-logger at least every 6 months. In addition to AWS used to collect weather data, weather data should also be obtained from the four or five closest National Oceanic and Atmospheric Association (NOAA) weather stations. The data should be averaged using the weighting procedure, with the weights based on the distance of the weather station from the particular site. The data collected from NOAA stations should include information about the temperatures, rainfall, wind and solar radiation levels. 2.3 STRATEGIC STUDY OF STRUCTURAL FACTORS FOR RIGID PAVEMENTS — SPS-2 The primary objective of the SPS-2 experiment is to determine the relative influence and long-term effectiveness of design features and site conditions on the performance of doweled jointed plain concrete pavement (JPCP) sections with and uniformly spaced transverse joints. As the test sections in the experiment are monitored since inception, the experiment provides an opportunity to estimate, more precisely, the relative influence of the key pavement elements that affect pavement performance. 2.3.1 Experiment Design The design factorial for the SPS-2 experiment is shown in Table 2-3. The overall experiment consists of 192 factor level combinations comprising of 8 site-related (subgrade soil type and climate, also referred to as site factors) combinations and 24 pavement structure combinations (design factors). The experiment was developed such that 12 sections should be built, with only half of the possible combinations of design factors, at each of the 16 sites. It was planned that “48 test sections representing all structural factor and subgrade type combinations in the experiment are to be constructed in each of the climatic zones, with 24 test sections to be constructed on fine-grained soil and 24 test sections to be constructed on coarse-grained soil” (see Table 2-3). Moreover, for each climatic zone and soil type combination, 12 sections are to be constructed at one site and the other 12 sections at the other site [4].

27 Table 2-3 SPS-2 Experiment Design Matrix Pavement Structure Climatic Zones, Subgrade PCC WET DRY FREEZE NO FREEZE FREEZE NO FREEZE Fine Coarse Fine Coarse Fine Coarse Fine Coarse Drainage Base Type Thickness (mm) 14-day Flexural Strength (MPa) Lane Width (m) J K L M N O P Q R S T U V W X Y 3.7 201 201 201 201 201 201 201 201 3.8 4.3 213 213 213 213 213 213 213 213 3.7 214 214 214 214 214 214 214 214 203 6.2 4.3 202 202 202 202 202 202 202 202 3.7 215 215 215 215 215 215 215 215 3.8 4.3 203 203 203 203 203 203 203 203 3.7 204 204 204 204 204 204 204 204 No DGAB 279 6.2 4.3 216 216 216 216 216 216 216 216 3.7 205 205 205 205 205 205 205 205 3.8 4.3 217 217 217 217 217 217 217 217 3.7 218 218 218 218 218 218 218 218 203 6.2 4.3 206 206 206 206 206 206 206 206 3.7 219 219 219 219 219 219 219 219 3.8 4.3 207 207 207 207 207 207 207 207 3.7 208 208 208 208 208 208 208 208 No LCB 279 6.2 4.3 220 220 220 220 220 220 220 220 3.7 209 209 209 209 209 209 209 209 3.8 4.3 221 221 221 221 221 221 221 221 3.7 222 222 222 222 222 222 222 222 203 6.2 4.3 210 210 210 210 210 210 210 210 3.7 223 223 223 223 223 223 223 223 3.8 4.3 211 211 211 211 211 211 211 211 3.7 212 212 212 212 212 212 212 212 Yes PATB 279 6.2 4.3 224 224 224 224 224 224 224 224

28 The structural factors included in the experiment are: • Drainage (presence or lack of drainage), • Base type (DGAB, LCB, and PATB), • PCC slab thickness (203 mm and 279 mm), • PCC flexural strength (3.8 MPa and 6.2 MPa, at 14-day), and • Lane Width (3.66 m and 4.27 m). The site factors included in the experiment are: • Subgrade soil type (fine-grained and coarse-grained, based on Unified system), • Climate (Wet Freeze, Wet No Freeze, Dry Freeze and Dry No Freeze), and • Traffic (considered as a covariate). At each site, 6 sections have a target PCC slab thickness of 8-inch (203 mm) and the remaining 6 have a target PCC slab thickness of 11-inch (279 mm). The 76 mm difference between the lower and upper levels of PCC slab thickness was believed to be necessary to demonstrate the effect of PCC slab thickness and its interaction with other factors on performance [4]. The other factors with two levels (PCC flexural strength and lane width) have 6 test sections corresponding to each level. Also 4 test sections have dense-graded aggregate base (DGAB), 4 sections have lean concrete base (LCB), and the other 4 sections have permeable asphalt treated base (PATB) over DGAB. In-pavement drainage is provided only to the sections with PATB as the base. Other features common to all SPS-2 sections are as follows [2]: • The monitored part of a test section is 152.4 m (500 feet) long with a transition zone of at least 15.2 m (50 feet) on each side for material sampling and other destructive testing. • A uniform joint spacing of 4.6 m (15 feet) is maintained for all test sections. • All the sections with 203 mm (8-inch) as the target PCC slab thickness are built with dowel bars of 32 mm (1.25-inch) diameter. The sections with the target PCC slab thickness of 279 mm (11-inch) are built with dowel bars of 38 mm (1.5-inch) diameter. Also, all the dowels are 457 mm (18-inch) long and placed at slab mid- depth with a center-to-center spacing of 305 mm (1 ft). • The HMA or PCC shoulders are not tied to the mainline pavement of the test sections. • Longitudinal joints are tied using 762 mm (30-inch) long, No. 5 epoxy-coated deformed steel bars of grade 40 steel and spaced 762 mm (30-inch) center-to- center. • All structural repairs are performed on the test sections before opening to traffic. In addition, all joint sealing is completed prior to opening to traffic.

29 Though a major factor, traffic is not addressed like other design factors, in that, only a lower limit was specified for traffic volume in terms of ESALs per year. A SPS-2 test site must have a minimum estimated traffic loading of 200,000 rigid ESAL per year in the design lane [2, 4]. Traffic will thus vary from site to site and will therefore be treated as a covariant in the study. Based on the average annual precipitation and the average annual Freezing Index, the sites in the experiment have been categorized into different climatic zones using the thresholds defined by LTPP program. In the experiment, the 12 sections at a given site are represented by either XX- 0201 through XX-0212, or XX-0213 through XX-0224, where XX denotes the site code. The number 02 indicates the SPS experiment number and the last two digits represent the sequential numbering of the sections. 2.3.2 Current Status of the Experiment A total of 14 sites with 167 test sections are in the experiment according to the latest data (from Release 17 of DataPave). The geographical distribution of the sites within the SPS-2 experiment is presented in Figure 2-2. The full factorial design for SPS- 2 experiment design requires that a total of 48 similar designs be replicated across 8 soil- climate combinations. However, the 48 designs were reduced to 24 designs in each soil- climate combination making the experiment design a fractional factorial. Later, it was considered that the construction of 24 test sections at each site would require a greater effort on the part of the participating agencies [4]. Therefore, to reduce the cost of construction the experiment was developed so that only 50% of the possible combinations of factors (i.e. 12 test sections) will be built at each site. The experiment, designed in a factorial manner to enhance implementation practicality, permits the construction of 12 test sections (0201 through 0212 or 0213 through 0224) at one site with the complementary 12 test sections to be constructed at another site within the same climatic region and on a similar subgrade soil type [2].

30 The status of the design factorial is shown in Table 2-4. There are six cells within the table that are missing from the factorial, indicating a loss of 6/16 or 37.5% of the overall experiment population. Though the experiment was designed to have 4 sites in each climatic zone, there are only 2 sites each in Wet No Freeze and Dry No Freeze climatic zones, and 3 sites in the Dry Freeze climatic zone. The majority of sites (7 of 14) have been constructed in the Wet Freeze zone making the current SPS-2 design unbalanced. The experiment design also called for half of the sites to be constructed on coarse- grained soils and the other half to be constructed on fine-grained soils. In addition to this, it was required that all the sections within a site be constructed on the same type of soil (coarse or fine). Of the 14 sites, 5 sites were constructed on coarse-grained subgrade soils (see Table 2-4). In 3 of the 4 climatic zones the number of sites constructed on fine- grained and coarse-grained soils is not the same. Moreover in AR (5), CO (8), CA (6) and NV (32), not all the sections within the site were constructed on the same type of soil. A discussion on the current status of the experiment at site-level can be found in Appendix B1.

31 Table 2-4 Status of the design factorial Wet Dry Subgrade Type Designs Freeze Non Freeze Freeze Non Freeze Total 0201-0212 KS (20) OH (39) NC (37) WA (53) NV (32)* Fine- grained 0213-0224 MI (26) IA (19) ND (38) CO (8)* 9 0201-0212 DE (10) CA (6) Coarse- grained 0213-0224 WI (55) AR (5)* AZ (4) 5 Total 7 2 3 2 14 Note: * Two sections in NV and five sections in CO are coarse-grained while two sections in AR are fine-grained. a. Wet Regions — Average Annual Rainfall > 20 inches (508 mm) b. Dry Regions — Average Annual Rainfall < 20 inches (508 mm) c. Freeze Regions — Average Annual Freezing Index > 83.3 oC-day (150 oF-day) d. Non-Freeze Regions — Average Annual Freezing Index < 83.3 oC-day (150 oF-day) Figure 2-2 Geographical location of SPS-2 sites 2.3.3 Construction Guidelines for SPS-2 Experiment The SPS-2 experiment requires construction of multiple test sections with similar details and/ or materials at several sites distributed throughout the country. Construction variability that may arise from this large project can potentially affect the results from analysis of the data. Therefore, construction uniformity at all sites was deemed important for the success of the experiment. In light of this, guidelines were developed to help

32 participating highway agencies. The guidelines addressed those items that should be considered by the participating agencies to ensure adherence to the study requirements. Adherence to the criteria will ensure that any difference in performance between test sections constructed with similar experimental parameters at different locations is mainly due to difference in climatic conditions and traffic levels. The salient aspects of the guidelines have been summarized in the section below. Further details of the guidelines can be obtained from the relevant SHRP report [2]. Subgrade Requirements The requirements for preparation and compaction of the subgrade are the same as those for the SPS-1 experiment explained above. Base Layers Dense Graded Aggregate Base (DGAB) The requirements for DGAB are essentially the same as those described for the SPS-1 experiment. However, the lift thickness must be 102 and 152 mm for the test sections with and without PATB, respectively. Also the DGAB should be kept uniformly moist prior to the placement of PCC surface layer, using a procedure that will avoid formation of puddles of water. Lean Concrete Base (LCB) The general requirements for the LCB are as follows: • A slump (Slip-form method of concrete placement) of 25 to 76 mm. • Target compressive strength 3.5 MPa at 7 days of (maximum is 5.2 MPa). • An air content of 4 to 9%. • Portland Cement (Type I or II) and aggregates confirming with the AASHTO specifications M85 and M80, respectively,. The recommended aggregate size is AASHTO Size No. 57. • The LCB shall be constructed such that it extends to the outside edge of the shoulders. When in reconstruction projects, LCB shall extend at least 914 mm outside the edge of the travel lanes. • The LCB should be finished to a smooth surface without texturing. • No traffic shall be allowed on LCB.

33 Permeable Asphalt Treated Base (PATB) The drained base structure in the SPS-2 is similar to that described for SPS-1 experiment above. The 102 mm thick PATB layer should be constructed over an equally thick DGAB layer. Filter fabric (or geotextile) should be used only in edge drains and transverse interceptor drains. Portland Cement Concrete The guidelines stipulate that the concrete mix design be done according to the procedures and specifications followed by the participating agency. The slip-form method is recommended for concrete placement. The main requirements are as follows: • Use Type I or II Portland cement (meeting requirements of AASHTO specifications M85). Fly ash of Class C or F can be used to replace up to 15% (by weight) of cement. Use of silica fume or additives to accelerate strength gain is prohibited. • Crushed gravel or stone should be used as coarse aggregate and the aggregate should confirm to requirements in AASHTO specification M80. Fine aggregate should a fineness modulus between 2.3 and 3.1 and should meet the requirements of AASHTO specification M6. • Flexural Strength: 3.8 or 6.2 MPa average, at 14 days, depending on the test section. For high strength concrete (6.2 MPa) the guidelines require the conduct of a well-planned laboratory testing of trial mixes. • Slump: 25.4 to 63.5 mm. • Air Content: 6.5 + 1.5 % for freeze-thaw areas. • The as-placed concrete thickness should be within 6.4 mm from the target value. Construction Operations Specifications were also developed regarding the construction operations of the pavement. The salient features are: • The slip-form machine should vibrate the concrete for the full depth and width of the concrete. • All joints should be sawn with an initial saw cut of one-third the slab thickness and a second saw cut to provide a sealant reservoir of 9.5 mm width and 25.4 mm depth. • Silicone sealant is to be used for sealing of joints. • Liquid curing compound should be placed within 15 minutes after surface texturing but no later than 45 minutes after concrete placement. • High pavement areas with a vertical deviation greater than 10.2 mm in 7.6 m should be removed by diamond grinding or multiple-saw devices as approved by the agency.

34 Data Collection Requirements To ensure uniform and consistent data collection, detailed procedures have been developed for the experiment. Most of the requirements are similar to the ones applicable to SPS-1. The requirements that are applicable to SPS-2 are briefly listed below. 1. Inventory and construction data: Includes items necessary to identify the test sections, describe geometric details, and material properties. Most of this data is obtained from the participating agency. Construction data pertains to the as-built thickness and properties of different layers. 2. Materials and testing data: This data is obtained from field sampling and laboratory testing. The data should help characterize pavement material properties that may influence performance. For SPS-2, testing is to be done on field samples obtained from PCC layer to determine compressive strength, split tensile strength, coefficient of thermal expansion, static modulus of elasticity, unit weight, core condition and thickness, air content of hardened concrete, and flexural strength. In addition to tests on field samples from the as-built pavement, properties of as-delivered PCC are determined from samples taken from ready-mix truck. For unbound granular base layer or PATB, tests are performed as in the case of SPS-1. For LCB, tests are performed to determine core condition and thickness, compressive strength and split tensile strength. For the subgrade, tests are performed in the same way as in SPS-1. Testing on samples obtained from LCB and PCC obtained from pavements at different ages is also done. 3. Traffic data: This data includes estimated, and monitored data. Continuous weigh- in-motion data is also required, as for SPS-1. 4. Distress data: Distress data to be collected are described in the SHRP Distress Identification Manual for Long-term Pavement Performance Studies [5]. 5. There are 16 types of distresses for jointed plain concrete pavements. The frequency of collection of distress data, profile data and deflection data suggested by the LTPP guidelines is summarized at the end of this section. 6. Profile data: Profile measurements are made using profilometers conforming with the method laid out in the manual for profile measurements.

35 15 ft 15 ft 12 ft or 14 ft J1 J3/J8 J2/J7 J4 J5 Direction of Traffic Figure 2-3 Deflection test locations on the pavement slabs Table 2-5 Details of FWD testing locations and potential use of testing Lane No. Location on slab Type of test section Potential use of the data J1 Midslab Sections with 3.7 or 4.3 m lane width Used with J3 to compute the D-ratio or the edge support factor Used to analyze the response of the PCC layer J2 Corner Sections with 3.7 m lane width Used to estimate void potential J3 Midslab-Edge Sections with 3.7 m lane width Used with J1 to compute the D-ratio or the edge support factor J4 Wheelpath, Leave Slab Sections with 3.7 or 4.3 m lane width Used with J5 to compute LTE J5 Wheelpath, Approach slab Sections with 3.7 or 4.3 m lane width Used with J4 to compute LTE J7 Corner Sections with 4.3 m lane width Used to estimate void potential J8 Midslab-Edge Sections with 4.3 m lane width Used with J1 to compute the D-ratio or the edge support factor Table 2-6 Data Collection Frequency guidelines Long-term Monitoring Frequency Data type Post construction monitoring In effect before 10/1/99 In effect after 10/1/99 Longitudinal profile <6 months is permitted Biennially, but may be postponed up to one year Annually Deflection <6 months is permitted Biennially and responsive Biennially and responsive Manual distress <3 months Biennially, but may be postponed up to one year Annually

36 7. Deflection data: Deflection measurements are performed using Dynatest FWD. Figure 2-3 is a plan view showing locations of FWD testing. Table 2-5 is a summary of FWD testing locations and potential use of the data obtained from testing. ‘Lane No.’ is the number given to the location of testing and has been explained in the table. 8. Climatic data: The requirements are similar for SPS-2 and SPS-1. An Automated Weather Station (AWS) should be installed on every site if representative weather stations are not located in proximity to the test site. Maximum, minimum, and mean daily temperatures, daily precipitation, and daily snowfall are considered essential data that must be obtained for each site. 9. Maintenance data: Maintenance can be done for safety or other reasons, and information about this need to be collected. 10. Rehabilitation data: No rehabilitation activity should be performed on the SPS test sites. If rehabilitation is performed for any reason, the section will be considered no longer part of the experiment. However, data needs to be collected about the rehabilitation. Monitoring Requirements Based on the LTPP directives a summary of data collection guidelines have been prepared and are presented in Table 2-6. Monitoring of sections is to be continued until one of the following conditions is satisfied:” the LTPP program concludes, application of rehabilitation construction event, or test section goes out-of-study”.

37 2.4 SPS-8 EXPERIMENT The SPS-8 experiment evaluates environmental effects in the absence of heavy traffic loads. The study examines the effect of climatic factors and subgrade type (frost- susceptible, expansive, fine, and coarse) on pavement sections incorporating different designs of flexible and rigid pavements, which are subjected to very limited traffic as measured by ESAL accumulation. Pavement structure includes two levels of structural design for each class of pavements. Flexible pavement sections consist of 102 mm (4- inch) and 178 mm (7-inch) HMA surfaces on 203 mm (8-inch) and 305 mm (12-inch) layers of DGAB, respectively. Rigid pavement test sections consist of 203 mm (8-inch) and 279 mm (11-inch) doweled JPCP slabs on 152 mm (6-inch) DGAB. The study design stipulates the traffic volume in the study lane be at least 100 vehicles per day but not more than 10,000 ESALs per year. The combination of study factors results in four possible section combinations, two flexible and two rigid. The flexible and rigid sections may be constructed at the same or at different sites. Table 2-7 shows the experiment design matrix for SPS-8. For flexible pavements in SPS-8 experiment, the sections are identified as XX- 0801 to XX-0806, while for rigid pavements they are identified as XX-0807 to XX-0812, where ‘XX’ is the state code and ‘08’ stands for SPS-8 experiment. The sections with SHRP ID that ends with an odd number have target HMA thickness of 102 mm or PCC slab thickness of 203 mm, while the others have HMA thickness of 178 mm or PCC slab thickness of 279 mm thickness. In the section ID, an alphabet is introduced before the SHRP ID in case a second site is constructed in the same state. 2.4.1 Current Status of the SPS-8 Flexible Pavements Table 2-8 shows the flexible pavement sites in the SPS-8 experiment. There are fifteen sites constructed for SPS-8 flexible pavement sections with the largest number of sites (7) located in the WF climatic zone. The details of test sections for flexible pavements according to SPS-8 experiment design are given in Table 2-9. In total, 32 flexible pavement sections have been constructed in the 15 sites. There are a limited number of test sections in the Dry zones with no pavements on fine subgrade in DF or active subgrade in DNF zones.

38 2.4.2 Construction Guidelines for SPS-8 Flexible Pavements Construction guidelines were provided to ensure uniformity and consistency among the test sites. The requirements for preparation and compaction of the subgrade for flexible sections are the same as for the SPS-1 experiment. The construction guidelines stipulated the use of DGAB; the requirements for the materials and construction of the base layers are also the same as those of the SPS-1 experiment. Similarly, the guidelines for the materials and construction of asphalt layers are similar to the un-drained sections included in the SPS-1 experiment, which require DGAB.

39 Table 2-7 SPS-8 Experiment Design Matrix WF WNF DF DNF Pavement Type AC/PCC Thickness Base Thickness A F C A F C A F C A F C 4 8 x x x x x x x x x x x x Flexible 7 12 x x x x x x x x x x x x 8 6 x x x x x x x x x x x x Rigid 11 6 x x x x x x x x x x x x A: Active subgrade soil (either frost susceptible or swelling type relative to climatic zone) F: Fine-grained subgrade soil C: Coarse-grained subgrade soil Table 2-8 Distribution of SPS-8 flexible pavements sites by subgrade type and climatic zone Weta Dryb Subgrade Type Freezec Non-Freezed Freeze Non-Freeze Total Fine AR (5) MO (29) NJ (34) OH (39) MS (28) TX (48) SD (46) NM (35) 8 Coarse NY (36) WA (53) WI (55) NC (37) MT (30) UT (49) CA (6) 7 Total 7 3 3 2 15 Note: a. Wet Regions — Average Annual Rainfall > 20 inches (508 mm) b. Dry Regions — Average Annual Rainfall < 20 inches (508 mm) c. Freeze Regions — Average Annual Freezing Index > 83.3 oC-day (150 oF-day) d. Non-Freeze Regions — Average Annual Freezing Index < 83.3 oC-day (150 oF-day)

40 Table 2-9 Distribution of SPS-8 flexible pavements sections by design, subgrade type and climatic zone Pavement Structure Moisture, Temperature and Subgrade Type Wet Dry Freeze No-Freeze Freeze No-Freeze Active* Fine Coarse Active Fine Coarse Active Fine Coarse Active Fine Coarse Pavement Type Surface Thickness inches DGAB Thickness inches 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 4 8 2 2 3 1 1 2 1 0 2 0 1 1 Flexible 7 12 3 0 4 1 2 1 2 0 1 0 1 1 Note: DGAB= Dense-graded aggregate base. *Active soil can be either frost-susceptible or swelling (expansive) type. Each no. indicates presence of sections fulfilling the criteria of the cell

41 2.4.3 Current Status of SPS-8 Rigid Pavements Table 2-10 shows the distribution of rigid pavement sections in the actual SPS-8 experiment, as per Release 17 of DataPave. While the minimum required number of rigid pavement sections to fulfill the proposed experiment criteria is 24, only 14 rigid pavement sections are currently in the experiment, spread over 6 states. There are 2 sites [Missouri (29) and Ohio (39)] in Wet Freeze zone, 2 sites [Arkansas (5) and Texas (48)] in Wet No Freeze zone, and 2 sites [Colorado (8) and Washington (53)] in Dry Freeze zone. There are no sites in the Dry No Freeze zone. An active subgrade can be coarse-grained or fine-grained. A section that is ‘active’ is not categorized under ‘fine’ or ‘coarse’ but is taken just as ‘active’. Table 2-10 Distribution of rigid pavement sections in the SPS-8 experiment Pavement Structure Factors Moisture, Temperature and subgrade soil type Wet Dry Freeze No Freeze Freeze No Freeze PCC slab thickness, mm DGAB thickness, mm Active Fine Coarse Active Fine Coarse Active Fine Coarse Active Fine Coarse 203 X X X X X X 279 152 X X X X X X Each ‘X’ indicates presence of one or more sections fulfilling the criteria of the cell 2.4.4 Construction Guidelines for SPS-8 Rigid Pavements Each section is constructed as uniformly as is practical over a length of 183 m to allow 152 m for monitoring purposes and 15 m at each end for destructive testing. The guidelines also stipulate that an asphalt concrete, untied PCC, or bituminous surface-treated aggregate shoulder be constructed as part of the test section. The concrete used for the surface layer has to have a target average 14-day flexural strength of 3.8 MPa. Moreover, no subsurface drainage is to be provided to the pavements in the experiment. The other construction guidelines for the experiment are the same as for the SPS-2 experiment. 2.5 INSTRUMENTED SPS TEST SECTIONS The Strategic Highway Research Program (SHRP) has included two projects with instrumented test sections as part of the SPS-1 and SPS-2 experiments. This subset of sections constitutes the Dynamic Load Response (DLR) experiment. The sections are located in Ohio and North Carolina. The Ohio test sections include both flexible and rigid pavements while the North Carolina test sections include only rigid pavements. The objective of this experiment is to support the development of mechanistic-empirical design procedures for flexible and rigid pavement systems.

42 More specifically, it can be used to investigate the relationship between pavement response and performance, and to validate pavement response and performance prediction models. In addition to standard FWD, profile and distress measurements, pavement dynamic response parameters are being measured in these test sections including: • Vertical deflections in the surface layer, base and subgrade; • Horizontal strains in the pavement; • Vertical pressure at layer interfaces; and • Joint opening in PCC pavements. The seasonal parameters being measured include: • Temperature within the pavement layers including base and subgrade; • Frost depth in base and subgrade; • Soil suction in the subgrade; • Water table elevation; and • Moisture in the subgrade. In addition to measurements within the pavement system, the loads being applied on the pavement are measured using weigh-in-motion (WIM) scales. Several series of controlled vehicle tests at different speeds and non-destructive load tests have been conducted to measure the pavement response. 2.5.1 SPS-1 Sections The instrumented flexible pavement sections are located in the SPS-1 site Ohio (39). These sections were instrumented with strain gauges, pressure cells and linear variable differential transformers (LVDT) to conduct the controlled loading experiments. The experiment targeted four core sections for the installation of sensors to monitor dynamic pavement response during controlled vehicle testing. These sections include 39-0102, 39-0104, 39- 0108 and 39-0110. Tests were to be performed with a single axle and tandem axle dump truck. The rear axle on the single–axle truck was loaded to approximately 18 kips (40 kN) and 22 kips (49 kN) while the total load on the rear axles of the tandem-axle dump truck were 32 kips (142 kN) and 42 kips (187 kN), respectively. Both trucks ran over the instrumented sections at 50(30), 65(40) and 80(50) km/hr (mph) in the morning and in the afternoon.

43 Experiment Setup The details of the instrumented flexible pavement sections are given in Table 2-11. Tests were conducted in the morning and in the afternoon to gather information on how temperature differences in the pavement layers affect response. Table 2-12 shows the instrumentation details of all the strain gauges and LVDTs for each instrumented section. This information is taken from Report No. FHWA/OH-94/019 by Ohio University, as this data was not available in the DataPave Release 17.0.

44 Table 2-11 Details of instrumented sections for flexible pavements Section ID HMA Thickness (inches) Base Thickness (inches) / Base Type Drainage Comments 39-102 4 12 DGAB No Strain gauges at 4” 39-104 7 12 ATB No Strain gauges at 7” and 19” 39-108 7 4 PATB 8 DGAB Yes Strain gauges at 7” 39-110 7 4 ATB 4 PATB Yes Strain gauges at 7” and 11” Note: DGAB ─ Dense graded aggregate base, ATB ─ Asphalt treated base, PATB ─ Permeable asphalt treated base Table 2-12 Instrumentation details for all the SPS-1 sections in Ohio Section ID Strain Gauge Designation Location LVDT Designation 39-102 DYN7 ─ Transverse DYN8 ─ Longitudinal DYN9 ─ Transverse DYN10 ─ Longitudinal DYN11 ─ Transverse DYN12 ─ Longitudinal All strain gauges are installed at the bottom of AC, 4” deep from the surface LVDT1 ─ Deep1 LVDT2 ─ Shallow2 LVDT3 ─ Shallow LVDT4 ─ Deep 39-104 DYN10 ─ Transverse DYN11 ─ Longitudinal DYN12 ─ Transverse DYN13 ─ Longitudinal DYN14 ─ Transverse DYN15 ─ Longitudinal DYN16 ─ Longitudinal DYN17 ─ Longitudinal DYN18─ Longitudinal DYN10 to DYN15 are located at bottom of AC, 7” deep from the surface These three strain gauges are installed at the bottom of ATB, at 19” deep from the surface LVDT1 ─ Deep LVDT2 ─ Shallow LVDT3 ─ Shallow LVDT4 ─ Deep 39-108 DYN10 ─ Transverse DYN11 ─ Longitudinal DYN12 ─ Transverse DYN13 ─ Longitudinal DYN14 ─ Transverse DYN15 ─ Longitudinal All strain gauges are installed at the bottom of AC, 7” deep from the surface LVDT1 ─ Deep LVDT2 ─ Shallow LVDT3 ─ Shallow LVDT4 ─ Deep 39-110 DYN10 ─ Transverse DYN11 ─ Longitudinal DYN12 ─ Transverse DYN13 ─ Longitudinal DYN14 ─ Transverse DYN15 ─ Longitudinal DYN16 ─ Longitudinal DYN17 ─ Longitudinal DYN18─ Longitudinal DYN10 to DYN15 are located at bottom of AC, 7” deep from the surface These three strain gauges are installed at the bottom of ATB, at 11” deep from the surface LVDT1 ─ Deep LVDT2 ─ Shallow LVDT3 ─ Shallow LVDT4 ─ Deep 1 The deep referenced LVDT is anchored at 10 ft depth from the surface 2 The shallow referenced LVDT is anchored at bottom of base layer for each section from the surface Source: Report No. FHWA/OH-94/019

45 2.5.2 SPS-2 Sections Two projects with instrumented test sections were included as a part of the SPS-2 experiment in Ohio and in North Carolina. Four sections (0201, 0205, 0208, and 0212) at each of the sites have been instrumented with strain gauges and LVDTs (Linear Variable Differential Transformers) for measurement of longitudinal strains and vertical deflections, respectively, of the PCC slab. Instrumentation was installed in 2 slabs in the transition zone of each section. The design features of the four sections are summarized in Table 2-13. A brief description of the DLR experiments in Ohio and North Carolina follows. Ohio DLR Sections The longitudinal strain in the PCC slab and the vertical deflection of the PCC slab are the structural response parameters that are measured in the experiment using embedded strain gauges and LVDTs, respectively. The details of the instrumentation setup are described below. Information about the set-up of the experiment has been obtained from reports “Development of an instrumentation plan for the Ohio SPS test pavement”, “Coordination of load response instrumentation of SHRP pavements- Ohio university” and “Continued Monitoring of Instrumented Pavement in Ohio” [6] apart from the data (Release 17 of DataPave). Setup of strain gauges In the Ohio sections, strain gauges were installed to measure longitudinal strain along the wheel path at 25.4 mm from the top and 25.4 mm from the bottom of the PCC slab. Figure 2-4 is the plan view showing the locations of strain gauges. The numbering used for strain gauges in the LTPP data has been used in this report. The spatial coordinates of the gauge locations are summarized in Table 2-14. Figure 2-5 is a sketch showing the locations of the strain gauges in cross-section. Setup of LVDTs LVDTs (Linear Variable Differential Transformers) were used to measure the vertical deflection of the PCC slab. Two types of LVDTs have been installed: shallow-reference and deep- reference. The shallow-reference LVDTs have their reference in the subgrade layer while the deep- reference LVDTs are founded in the roadbed soil. The LVDTs that are located at the edge of the slab have been anchored in the shoulder. Deep-reference LVDTs give ‘total’ deflections as they are

46 referred to a depth where measurable deflections are not likely and shallow-reference LVDTs represent the difference in deflection between pavement surface and the depth of the anchor. The shallow-reference LVDTs are the ones that give deflections that are nearer (magnitude-wise) to deflections of the slab. The locations of the various LVDTs in the plan view, according to DataPave are shown in Figure 2-6. Test setup The testing procedure adopted for SPS-1 and SPS-2 sections is identical. Two types of trucks, a single-axle and a tandem-axle, were used to ‘load’ the sections. On each testing day, twelve runs were made by each of the trucks by varying speed and loading for different runs. The rear load of the single-axle truck was 80.3 kN or 98.1 kN, while the total load on the tandem-axle dump truck was 142.7 kN or 187.3 kN, respectively, for different runs. For the same rear axle load, the speeds of the truck varied between 50, 65 and 80 km/hr. The trucks were run such that the right rear tires either pass over or straddle the sensors.

47 Table 2-13 Design details of instrumented sections PCC slab details Section ID Thickness, mm Average 14-day flexural strength, MPa Base Course details Drainage 0201 203 3.8 152 mm DGAB No 0205 203 3.8 152 mm LCB No 0208 279 6.2 152 mm LCB No 0212 279 6.2 102 mm PATB over 102 mm DGAB Yes 0 0.5 1 1.5 2 2.5 3 3.5 0 1 2 3 4 5 6 7 8 9 'X' coordinate, m 'Y ' c oo rd in at e, m 1, 2 7, 84 5Wheelpath Figure 2-4 Plan view of locations of strain gauges 1 2 4 5 8 7 Figure 2-5 Slab cross-section at wheel path showing typical strain gauge locations Table 2-14 Spatial locations of strain gauges in the PCC slabs Gauge ID ‘X’+ coordinate, m ‘Y’+ coordinate, m ‘Z’+ coordinate, mm DYN1 2.1 0.8 25.4 (from top) DYN2 2.1 0.8 25.4 (from bottom) DYN4 5.2 0.8 25.4 (from top) DYN5 6.1 0.8 25.4 (from bottom) DYN7 6.9 0.8 25.4 (from top) DYN8* 6.9 0.8 25.4 (from bottom) * In section 0208 the gauge is in the top one-inch of the PCC slab, + ’X’ is the distance along the traffic from the entry slab corner; ‘Y’ is the distance from the longitudinal joint; and ‘Z’ is the depth-wise location

48 North Carolina DLR In addition to the embedded strain gauges and LVDTs, surface-mounted strain gauges were instrumented in the DLR test sections of North Carolina. The details of the instrumentation setup are as follows. Information about the set-up of the experiment has been obtained from “Pavement Instrumentation Program for SPS-2 Experiments Instrumentation Details” (April 1994), apart from the data (Release 17 of DataPave). Setup of strain gauges The embedded strain gauges were installed to measure longitudinal strains in the PCC slab. Three gauges at the mid-slab edge location and one gauge at the mid-slab wheel path location were installed in one slab of each of the instrumented sections (see Figure 2-7). The surface-mounted gauges were installed at the slab surface at mid-slab edge (about 25.4 mm from edge) and mid-slab wheel path locations. Twelve surface-mounted gauges were installed in each instrumented section before testing and were later removed after the completion of the test. Figure 2-8 shows of the locations of surface-mounted gauges in plan view. Setup of LVDTs Two types of LVDTs have been installed in the NC DLR sections; one for the measurement of subgrade deflections and another for measurement of PCC slab deflections. The LVDTs installed for measuring deflections of PCC slab have been considered in this study. Figure 2-9 illustrates in plan the locations of the 8 LVDTs installed in these sections. The LVDTs were installed at corner, mid-slab edge and mid-slab wheel path locations of both the instrumented slab panels in each test section. Testing setup The testing procedure adopted for NC DLR experiment is similar to the one adopted for the OH DLR experiment. Two types of trucks, a single-axle and a tandem-axle, were used to ‘load’ the sections. On a typical testing day, the rear axle of each truck was loaded to a certain pre-determined level and the sections were tested with the trucks at various speeds. The single-axle truck was loaded with 79.1 kN or 89 kN. The tandem-axle truck was loaded with 142.4, 160.3, or 168.2 kN, respectively. For a particular load level, speeds varied between 48, 64 and 80 km/ hr. The trucks were run such that the right rear tires either pass over or straddle the sensors.

49 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 'X' coordinate, m ' Y ' c o o r d i n a t e 7 1 8 5 2 9 10, 11 3 4 12 13 14 6 15, 16 Wheelpath Figure 2-6 Location of LVDTs (plan-view, OH) 0.0 1.0 2.0 3.0 0.0 1.0 2.0 3.0 4.0 'X' coordinate, m ' Y ' c o o r d i n a t e , m 1 2 3 4 Figure 2-7 Strain gauge location (plan view, NC) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 'X' coordinate ' Y ' c o o r d i n a t e 1 2 3 4 5 6 10 11 12 7 8 9 Figure 2-8 Location of surface-mounted strain gauges (NC) 0 1 2 3 0 1 2 3 4 5 6 7 8 9 'X' coordinate, m ' Y ' c o o r d i n a t e , m Wheelpath 1A, 1B 2T 3T 4T 5T 6A, 6B Figure 2-9 Location of LVDTs (plan view, NC)