To improve the eco-efficiency and sustainability of concrete, the cement and concrete industry can exploit many byproducts in applications that could, in some cases, outperform conventional materials made with traditional ingredients. This Special Publication of the American Concrete Institute Committee 555 (Concrete with Recycled Materials) is a contribution towards improving the sustainability of concrete via using recycled materials, such as scrap tire rubber and tire steel wire fiber, GFRP waste, fluff, reclaimed asphalt pavements, recycled latex paint, and recycled concrete aggregate. Advancing knowledge in this area should introduce the use of recycled materials in concrete for applications never considered before, while achieving desirable performance criteria economically, without compromising the quality and long-term performance of the concrete civil infrastructure.

The fresh and mechanical properties as well as the durability of the polyvinyl alcohol (PVA) fiber-reinforced rubber mortar were evaluated in this study. The mini-slump test showed that the workability of the cement mortar was decreased with the both added rubber aggregates and PVA fibers. The mechanical strength was reduced in rubberized mortar compared with the plain cement mortar. The added PVA fiber with optimized content improved the compressive strength of the rubberized mortar. The ultrasonic wave velocity test showed that the dynamic modulus of the rubberized mortar was lower than that of plain mortar. In addition, the fiber reinforcement can enhance dynamic modulus (shown as the increased ultrasonic wave velocity) in the rubberized mortar mixtures. The drying shrinkage of the cement mortar was reduced by using the low content of the rubber aggregate as well as applying the PVA fiber reinforcement.

In the U.S. and around the world, large amounts of waste latex paint are generated annually, which creates a significant challenge in terms of disposal in an economic manner. Paint contains some chemicals that may be harmful to the environment if recycled as it contains volatile organic compounds. However, waste latex paint can be used to produce an economic latex-modified pervious concrete that is similar or superior to regular pervious concrete. Previous studies investigated recycling waste latex paint in concrete applications such as sidewalks. This study investigates the use of waste latex paint in producing pervious concrete and the effect of using different ratios of paint addition on the properties of the studied mixtures. The properties evaluated included physical, mechanical and hydraulic properties. Results show that while waste latex paint recycling in pervious concrete can slightly reduce its mechanical properties at 5% polymer to cement content, it can still be a viable option to prevent paint disposal in landfills.

Statistics show an increase in the use of fly ash in concrete to improve both sustainability and performance. However, concrete incorporating high volume fly ash has encountered an issue with incompatibility between fly ash and air entraining admixture (AEA). This study investigates using ground recycled rubber (GRR) as an eco-friendly alternative to AEA to improve the freeze-thaw performance of mortar mixtures incorporating two different types and ratios of fly ash. Two different sizes and ratios of GRR were used in this study. The results were compared with mixtures having two different types and dosages of AEA as well as a reference mortar mixture having neither GRR nor AEA. Foam indices were determined for both types of fly ash and compared with cement. The compressive strength retention values of mortar cubes after exposing them to 36 freeze-thaw cycles were determined and linked to the air content of each mixture. This study revealed that the GRR outperformed the AEA in terms of the freeze-thaw durability where all mixtures retained their compressive strengths. However, the performance of mixtures including AEA was inconsistent depending on the chemical composition of the fly ash, fly ash replacement ratio, and AEA dosage.

Due to their unique mechanical characteristics, glass fiber reinforced polymer (GFRP) composite materials are difficult to recycle at the end of their service lives. In the present work, a specific approach of recycling GFRP waste for use in concrete is investigated. Scrap from GFRP rebar and waste from a GFRP wind turbine blade shell were processed into slender elements, referred to as “needles,” with a length of 100 mm and used in concrete to replace 5% and 10% of natural coarse aggregate. The results of testing various concrete specimens revealed that the incorporation of needles with longitudinally aligned glass fibers increased the splitting tensile strength of concrete significantly. Both types of recycled needles, regardless of the source of waste and orientation of glass fibers, increased the tensile toughness of concrete significantly. In addition, it was observed that incorporating needles did not reduce concrete’s slump, due to the relatively high specific surface area of the needles. The findings suggest that recycling GFRP waste into needles as concrete reinforcement may be a viable GFRP waste management strategy and deserves further research.