Louisiana Accelerated Pavement Research Facility Zhong Wu, Ph.D., P.E. Louisiana Transportation Research Center (LTRC) Louisiana Department of Transportation and Development (LADOTD) Louisiana State University (LSU) 4/14/2019 Project status

APT Devices ALF (9,750 – 18,950 lb; Uni-directional loading) ATLaS (0 – 30,000 lb; Bi-directional loadig)

Recent APT Projects Evaluation of Bonded Concrete Overlay over Asphalt under Accelerated Loading (on-going) Accelerated Load Testing of Geosynthetic Base Reinforced Test Sections (on-going) Roller Compacted Concrete over Soil Cement under Accelerated Loading (completed)

Bonded Concrete Overlay The Louisiana DOTD has great interest in determining if thin bonded concrete overlays (usually 2-6 in.) are a suitable and cost-effective alternative to the current practice for medium- to high-volume roadway maintenance, which consists of an existing asphalt concrete layer over a PCC or cement- stabilized soil base.

Bonded Concrete Overlay Sections Detailed layered information of test sections Section 2 Section 3 Section 1 Three sections constructed Section 2 (4’’) completed Section 3 (2’’) standby Section 1 (6’’) under testing

Test Results of Section 2 (4” PCC) Load sequence Cracking area 9 kips 16 kips Pumping Cracking

Crack Mapping of Section 2 0.7M EASL 1M EASL 1.1M EASL 1.3M EASL 1.4M EASL 1.5M EASL

Section 1 (6” PCC) under Testing Load sequence 9 kips 16 kips After approximately 500,000 varied ATLaS wheel loading, No cracking found yet!

Accelerated Load Testing of Geosynthetic Base Reinforced Test Sections

Objectives Evaluate the benefits of geosynthetics for subgrade stabilization and reinforcement of base aggregate layer in flexible pavements built on soft subgrade soils; Evaluate the effect of pre-rut of unpaved sections on mobilization of geosynthetics, their benefits and performance; Evaluate the design parameters of geosynthetic reinforced flexible pavement for incorporation them into the context of 1993 AASHTO pavement design and M-E pavement design guide.

Heavy clay (A-7-6), Mexico Limestone, Level 1 Superpave Test Lane Sections Six test lanes of different reinforcement configurations were constructed, The dimensions of each section: 80 ft. long and 13 ft. wide. 10 in. 18 in. 6 in. TENCATE RS-580i Tensar TX-5 12 in. Sand 3 inch Heavy clay (A-7-6), Mexico Limestone, Level 1 Superpave

Results of ALF Test Lane Sections Accumulated surface permanent deformation Testing Criteria: All sections will be loaded to ¾” rut depth. Experimental studies by different researchers indicated 10 in. 18 in. 6 in. RS-580i TX-5 12 in. Sand 10 in.

In-Box Cyclic Plate Load Tests Cross-Section Complete Test Set-up Experimental studies by different researchers indicated

Results of In-Box Paved Test Sections 6 1 3 2 Testing Criteria: All sections will be loaded to ¾” rut depth. 4 5 Accumulated surface permanent deformation 10 in. 18 in. 6 in. RS-580i TX-5 12 in. Sand 10 in.

Roller Compacted Concrete over Soil Cement under Accelerated Loading (completed) Final report will be available soon.

Accelerated Load Testing Facility (ALF) About 100-ft long, 40-ft wheel path, Adjustable axle load: 9,750 lb to 18,950 lb Nominal speed: 10.5 mph, Wander covering 30’’ transverse distance.

Pre-rut Testing - Phase I Section 1 Section 2 Section 3 Section 4 Section 5 Section 6