Effect of Precast Concrete Pavement Albedo on the Climate Change Mitigation in Spain

Radiative Cooling Properties of Portlandite and Tobermorite: Two Cementitious Minerals of Great Relevance in Concrete Science and Technology

Although concrete and cement-based materials are the most engineered materials employed by mankind, their potential for use in daytime radiative cooling applications has yet to be fully explored. Due to its complex structure, which is composed of multiple phases and textural details, fine-tuning of concrete is impossible without first analyzing its most important ingredients. Here, the radiative cooling properties of Portlandite (Ca(OH)2) and Tobermorite (Ca5Si6O16(OH)2·4H2O) are studied due to their crucial relevance in cement and concrete science and technology. Our findings demonstrate that, in contrast to concrete (which is a strong infrared emitter but a poor sun reflector), both Portlandite and Tobermorite exhibit good radiative cooling capabilities. These results provide solid evidence that, with the correct optimization of composition and porosity, concrete can be transformed into a material suitable for daytime radiative cooling.

Precast Assembled Road Paving Technology: Progress and Prospects

This article presents a systematic review of the most cutting-edge research on precast pavement technology for the first time. Firstly, precast pavement is divided into two categories, precast cement concrete pavement and precast carpeted flexible pavement, according to the application of precast technology in pavement engineering. Subsequently, the structural characteristics, advantages, and disadvantages of various precast pavement systems are compared and analyzed; technical problems in precast pavement systems are explained; and future development directions are identified. In addition, the text specifically mentions the great contribution of precast carpeted flexible pavement technology in reducing the harmful effects of asphalt fumes on humans and the environment. This work will promote the application of prefabrication in road engineering and provide suggestions and references for subsequent research.

Investigation of Parking Lot Pavements to Counteract Urban Heat Islands

Urban heat islands (UHI) are one of the unequivocal effects of the ongoing process of climate change: anthropized areas suffer extreme heat events that affect the human perception of comfort. This study investigated the effects of road pavements as a passive countermeasure by comparing the air temperature (AT) and the predicted mean vote (PMV) for different surface materials used to pave a historical square in Rome, Italy. The software ENVI-met has been used to compare, for the whole year 2021, the performances of the existing asphalt pavement with five alternative solutions composed of light concrete, bricks, stone, wood, and grass. This paper proposed a new methodology to summarize the multi-dimensional results over both temporal and spatial domains. The results of the simulations in the evening of the hottest month showed the existing asphalt pavement gives the worst performance, while the light concrete blocks and the grass pavement ensure the coolest solutions in terms of AT (the average AT is 32 °C for the asphalt pavement and 30 °C for the modular one) and PMV (the maximum PMV value is 4.6 for the asphalt pavement and 4.4 for the modular and grass ones).

Precast Concrete Pavements of High Albedo to Achieve the Net “Zero-Emissions” Commitments

Pavements store heat, which is subsequently released into the atmosphere, heating the surrounding air. Therefore, this process contributes to climate change and global warming. For this reason, the use of high-solar-reflectance (albedo) pavements is seen as one of the potential mitigation methods for climate change. Concrete pavements have a much higher albedo than asphalt due to their light gray color compared with black pavements. Accordingly, the widespread utilization of highly reflective concrete pavements will improve local climate change mitigation. Nevertheless, concrete albedo slightly decreases over time because of weathering. Albedo and solar reflectance index (SRI) measurements were taken on actual precast concrete pavements made with different mixes. The methodology applied for this project is based on the comparison between the asphalt and concrete pavements’ reflectivity. Conventional concrete mix designs can provide cool pavements with SRI higher than 29. Replacement of black pavements by highly reflective concrete pavements appeared to be a cost-effective and easily implemented measure to combat climate change. Finally, multidisciplinary studies considering factors such as building materials’ albedo, among other mitigation measures, should be performed to provide more precise and reliable guidance to policymakers, stakeholders, decision makers and urban planners.