Implementing the LWD for MoDOT Construction Acceptance of Unbound Material Layers

MoDOT project # TR202103Conventional density-based methods of compaction quality assurance (QA) using nuclear density gauges (NDG) have been the practice for many years. However, NDG testing becomes less desirable because of safety, regulatory, and cost concerns. In addition, density is not a direct input to the structural design of the pavements and is not directly linked to pavement performance. In recent years, modulus-based compaction QA of unbound materials is gaining attention, as it can not only result in a better constructed product but also provide the engineering properties critical for better understanding of the connection between pavement design and long-term pavement performance. Moisture content is one of the main factors influencing soil modulus and should also be performed concurrent with field modulus measurement. However, existing LWDs do not have the function to measure moisture content. In this study, a national survey on acceptance of LWD and a substantial literature review were firstly carried out to study the current status of LWD application. Then, four types of representative soils from two projects provided by MoDOT were selected to investigate the implementation of LWD for construction acceptance of unbound materials. Four LWD devices including three Zorn ZFG 2000 and one Zorn ZFG lab 3.0, were used in laboratory and field tests. Furthermore, two moisture content analyzers including Aggrameter and Ohaus MB120 were chosen to evaluate their practicability of quick moisture content measurement in the field. Based on the results of considerable laboratory and field tests, it was concluded that the modulus-based construction quality assessment method using LWD and moisture content analyzer Ohaus MB120 worked well at four construction sites. In addition, a guideline was created for the use of the modulus-based method in the appendix

Performance of Cost-Effective Non-Proprietary UHPC in Thin-Bonded Bridge Overlays

MoDOT project # TR202121The constructability and performance of non-proprietary thixotropic UHPC for thin bonded bridge deck overlay construction was investigated. Task 1 reviewed literature on UHPC for thin bonded overlays and non-proprietary UHPC. Crack monitoring of experimental slabs cast with UHPC thin bonded overlay (MoDOT project TR201704) and pull-off bond strength and flexural behavior for 16 composite overlay slabs cast with UHPC were determined