January 2020 Issue of National Concrete Consortium Newsletter Is Now Available

The NCC E-News is issued by the National Concrete Pavement Technology Center. The following are covered in more detail with links to research and other reports.

• The January 2020 MAP Brief, Development and Deployment of the Next Generation Concrete Surface describes the Next Generation Concrete Surface (NGCS) and the latest innovation in concrete texture.

• Implementation of a Testing Protocol for Approving Alternative Supplementary Cementitious Materials (SCMs): Natural Minerals and Reclaimed and Remediated Fly Ashes - Supplementary cementitious materials (SCMs) provide many benefits to concrete mixtures in terms of cost, strength and durability. Class F fly ash is the most widely used SCM in Texas, but its availability is dwindling while demand is increasing. Given the importance of Class F fly ash as a means to improve concrete durability, it is important to find alternative materials that can maintain the high quality and durability of concrete required in Texas.

• Construction of Crack-Free Bridge Decks (April 2017) - The goal of the study described in this final report “Construction of Crack-Free Bridge Decks” for Transportation Pooled-Fund Program Project No. TPF-5(174) was to implement the most cost-effective techniques for improving bridge deck life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the construction of 17 bridge decks in Kansas that were let under Low-Cracking High-Performance Concrete (LC-HPC) specifications. The report documents the performance of the decks based on crack surveys performed on the LC-HPC decks and matching control bridge decks.

• Proposed Enhancements to Pavement ME Design: Improved Consideration of the Influence of Subgrade and Unbound Layers on Pavement Performance (2019) - The American Association of Transportation Officials’ (AASHTO) pavement mechanistic-empirical (ME) design software, AASHTOWare Pavement ME Design, and the AASHTO Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) provide a methodology for the analysis and performance prediction of pavements and overlays. The performance of flexible and rigid pavements is known to be closely related to properties of the base, subbase and/or subgrade. However, some recent research studies indicated that the performance predicted by this methodology shows a low sensitivity to the properties of underlying layers and does not always reflect the extent of the anticipated effect so the procedures contained in the Pavement ME Design need to be evaluated.

• Impact of Joint Spacing on Bonded Concrete Overlay of Existing Asphalt Pavement in the AASHTOWare Pavement ME Design Software - This paper describes the impact of joint spacing or panel size on the performance and relative cost of short jointed bonded concrete overlay of asphalt (SJPCP) pavement using the AASHTO Pavement ME Design procedure. Joint spacing, or panel dimension, is a critical design issue that greatly affects both performance and cost of the SJPCP as well as conventional jointed plain concrete pavement (JPCP) overlays. In fact, pavement performance is more dictated by the panel size than thickness. Three factors that greatly affect the performance of SJPCP include (1) traffic (truck) volume, (2) wheel load placement and panel size, and (3) layer bonding of portland cement concrete (PCC) to asphalt concrete (AC). This paper focuses on the second point, wheel placement or panel size, which defines the location of critical stresses, location of fatigue damage along the transverse joint and initiation of corner, longitudinal and transverse fatigue cracking.

• Impact of Water/Cementitious-Based Concrete Mix Design Specification Changes on Concrete Pavement Quality (July 2018) - This research investigated the impact of Minnesota DOT implementing a w/cm-based specification for concrete pavements. Pavement sections constructed before and after the specification implementation were examined to assess permeability, compressive strength and air-void system parameters. Pavement management system data was examined to identify changes in ride quality associated with the specification change.

• Relationship Between Erodibility and Properties of Soils (2019) - The goal of this project is to develop reliable and simple equations quantifying the erodibility of soils based on soil properties. The reliability must take into account the accuracy required for erosion-related projects while the simplicity must consider the economic aspects of erosion-related projects. Different soils exhibit different erodibility (sand, clay); therefore, erodibility is tied to soil properties. However, many researchers have attempted to develop such equations without much success. One problem is that erodibility is not a single number but a relationship between the erosion rate and the water velocity or the hydraulic shear stress. This erosion function is a curve and it is difficult to correlate a curve to soil properties. Another problem that needs to be solved is associated with the availability of several erosion testing devices.

• Effect of Fiber Characteristics on Fresh Properties of Fiber-Reinforced Concrete with Adapted Rheology - The influence of fiber type and volume on fresh properties of fiber-reinforced self-consolidating concrete (FR-SCC) and fiber-reinforced super-workable concrete (FR-SWC) was investigated. These mixtures were developed for infrastructure construction and repair, respectively, and the fibers were incorporated to reduce cracking and enhance service life of concrete structures.

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