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The U.S. Environmental Protection Agency (EPA) announced the selection of 38 grant recipients across the country, totaling nearly 160 million USD, to support efforts to report and reduce climate pollution from the manufacturing of construction products. The grants will be awarded to businesses, universities, and nonprofit organizations serving all 50 states and will help disclose the environmental impacts associated with manufacturing concrete, asphalt, glass, steel, wood, and other materials.

The shortage of high-quality fine aggregate as an essential component of concrete has become an emerging worldwide concern for the construction industry. Concrete typically comprises up to 30% fine aggregate, which largely influences the strength and durability of the final product. Therefore, finding suitable substitutes for natural fine aggregate has become an important aspect of current concrete research.

In this study, we investigated the suitability of using remediated thermal-treated soil and tar-containing asphalt as secondary raw materials in a self-compacting concrete (SCC) mixture. The remediated materials were used as both (1) fine aggregate replacement to replace all the river sand and (2) partial filler/supplementary cementitious material (SCM) replacement. The modified Andreasen and Andersen (A&A) particle packing model was used to determine the optimal replacement level. Based on the optimal mixture design, the impact of the replacement on the fresh and mechanical properties of SCC was evaluated. Additionally, the pozzolanic reactivity of the fine fraction (<125 μm) within the secondary sand was assessed and compared to that of limestone powder. Our findings confirm that using remediated thermal-treated soil and tar-containing asphalt can produce a more circular, sustainable SCC by replacing high-quality natural sand and limestone filler and reducing the environmental impact of conventional SCC. This study contributes to finding viable alternatives to natural fine aggregate and promotes the use of recycled materials in construction.

The use of recycled aggregates allows for reducing the environmental impact of concrete materials, by reducing the amount of waste and limiting the consumption of natural resources. Recycled asphalt pavement (RAP) is a granular material that comes from the milling of road pavements whose size and distribution make it suitable as aggregate for concrete. The environmental benefits of the replacement of natural aggregate with RAP need to be assessed with a better understanding of the long-term behavior of RAP concrete, considering the evolution of its performance in time and its ability to guarantee an adequate service life when exposed in operating conditions. This note presents the preliminary results of research on the effect of RAP on concrete properties. The addition of RAP aggregate affects concrete properties in a fresh and hardened state. Some parameters showed clear trends with the percentage of RAP, however, also other factors (e.g. w/c ratio and curing time) seem to play a role. Compressive strength and dynamic modulus of elasticity of RAP concrete were always lower compared to reference concrete, while the electrical resistivity did not show a clear trend. Further investigations will be carried out to clarify the role of RAP aggregate.

The milling of road pavements produces a granular material (called recycled asphalt pavement, RAP) whose size and distribution are suitable for its use as aggregate in concrete. The use of RAP as aggregate in concrete would have a twofold beneficial effect: reducing the amount of wasted asphalt and limiting the consumption of natural aggregates. In view of an assessment of the actual environmental benefits of concrete made with RAP aggregate, a thorough evaluation of its performance needs to be carried out, both on the short term (e.g., workability, shrinkage) and on the long term (e.g., resistance to aggressive environment and protection of embedded reinforcement from corrosion). Structural and mechanical properties (e.g., compressive strength, modulus of elasticity) also need to be assessed. This note presents the preliminary results of laboratory tests aimed at the characterization of RAP as aggregate to produce concrete. The characterization included analyses of size distribution by sieving, assessment of fine, chloride content, ESEM observations and XRD analyses, moisture content, and water absorption. Tests were performed on batches of RAP coming from different production plants to assess the variability and also, for comparison, on natural limestone aggregate. Results show a particle size distribution with a good replicability within the same site; all particle size fractions seem to be covered and the maximum diameter is around 21-22 mm. Regarding the microstructure of the aggregates, this is practically the same as for natural aggregates, except for the bituminous coating. The chloride content was negligible. Water absorption is higher compared to values of natural aggregates, probably because of surface dust layers and various impurities, which soak more water.

Asphaltic concrete pavements are generally repaired using cold patch and hot mix products. While cold patch material can be applied quickly and is low in cost, it is not durable. Because hot mix repair products are applied like newly paved surfaces, they are high in cost and are typically used for larger repairs. The article discusses a new type of a cementitious repair material suitable for asphalt and concrete pavements that is easy to apply and durable.