Hydraulic cement concrete overlays made with latex-modified concrete (LMC) and silica fume concrete (SFC) are typically used to extend the life of bridge decks because the overlays reduce the infiltration of water and chloride ions. Rapid concrete overlays can be used to reduce lane closure time and associated traffic congestion and road user costs. LMC prepared with very early hardening cement (LMC-VE) has been used as a rapid overlay for bridge decks in Virginia since 1997. This paper compares the performance of LMC-VE overlays to that of conventional LMC and SFC overlays. Results indicate that LMC-VE overlays are performing as well or better than LMC and SFC overlays. LMC-VE has become a standard overlay for situations in which lane closures cause major traffic congestion. The higher cost of materials for LMC-VE overlays can be off set by lower costs for traffic control. Including user cost savings make LMC-VE overlays even more cost effective.

Polymer modified concrete (PMC) was introduced to address some of the disadvantages of normal concrete such as low tensile strength and vulnerability to chloride penetrability. Latex-modified concrete (LMC), a type of PMC where latex-based polymers are used, is usually utilized in special applications that require some of PMC’s advantageous properties. Approximately 10% of all latex paint purchased in the United States becomes unused. This waste latex paint (WLP) contains volatile organic compounds (VOC), which makes it difficult and expensive to recycle. Using WLP in concrete as a replacement for styrene-butadiene rubber (SBR) has been found to produce a PMC comparable to LMC. WLP could produce a cost effective PMC as it can replicate the improved properties of LMC. Bridge overlays use LMC due to its durability under environmental conditions and traffic loads. Bridge overlays are subjected to chloride ion ingress, which may result in corrosion of the reinforcement and surface scaling of concrete. In this study, four concrete mixtures were evaluated. These mixtures consisted of a control mixture of normal concrete, one with SBR, and two with WLP. The experimental program included fresh properties as well as hardened properties. Results showed that a WLP mixture can meet the requirements for LMC bridge overlays. The success of the proposed technique can result in a total of one to two million cubic yards of inexpensive LMC produced in the United Sates yearly, with a substantial recycling of WLP.

Maintaining satisfactory moisture content in concrete during its early ages is very important to develop required properties. Retaining free water of the mixture for a longer period will have a beneficial effect similar to that of curing. Self-curing mixtures will be very beneficial especially in regions where water is not adequately available. Polymers in concrete have received considerable attention over the past two decades. This study investigates using laboratory synthesized water-soluble polymers: polyethylene glycol (PEG) and polyacrylamide (PAM) as self-curing agents and its effect on the degree of hydration, water absorption, permeable pores and microstructural characteristics of Portland cement mixtures without and with 8% silica fume replacement. Portland cement mixtures including PEG or PEG+PAM as self-curing agents showed a better quality compared to that of the non-cured mixtures. Mixtures incorporating 8% silica fume including a mixture of PEG and PAM as self-curing agent had a better quality compared to that of the mixture including only PEG especially at later ages.

This research examines the significance of using carbon nanotubes (CNTs) on the mechanical characteristics and microstructural features of latex modified mortar (LMM). CNTs have been introduced recently as a new nanoscale material with excellent mechanical properties. This work examines the ability of various CNTs’ contents to alter the mechanical properties of latex modified mortars. Compression and tension tests were performed on LMM specimens with and without CNTs at 7 and 28 days of age. The experimental investigations showed that CNTs can enhance the strength and deformation characteristics of LMM. Microstructural investigations showed CNTs to be well dispersed and bonded to the polymer latex matrix. It is concluded that CNTs can be a useful alternative to enhance the mechanical characteristics of polymer modified cement composites.

Thin polymer concrete overlays (TPCOs) consist of a polymer binder and aggregates with a thickness of 1 inch (25 mm) or less. They have been widely used for providing long-lasting wearing surfaces for bridge decks. Their advantages include adding little dead load; very fast cure; shallow depths that eliminate raising approach slabs and permitting the transition from overlaid lane to non-overlaid lane during construction; excellent bond to concrete; very low permeability; and excellent skid resistance. Over 2200 have been installed in the U.S. and Canada, and they have become a recognized method for extending the lives of bridges. The state of practice has become well established. Evaluation of the substrate, repair of the substrate, and surface preparation are essential to having a sound surface for applying the TPCOs. The three types of overlays normally used are multiple layer, slurry and premixed. Epoxies are the most widely used resins although methacrylates and polyester styrenes are used for some applications. Resin application rates and aggregate gradings and application rates are also quite important.