From technology to policy, the US is thinking about construction differently. The federal government is motivated to address the aging infrastructure across the country, and policy proposals are surfacing that seek green methods of performing this construction. This paper reviews the current status of concrete technology and policy to provide insight into the current state of the art. The scale of CO2 emissions from concrete production and use is elucidated. Current embodied emissions reduction methods show that action can be taken today in small and large projects alike. Additionally, developing concrete technologies offers pathways to reuse and rely on concrete for longer service lifetimes and reduce their lifetime embodied emissions. These concrete technologies must be implemented, and public procurement proves a unique tool to develop a nationwide demand signal for low embodied carbon building materials. Local governments closely interact with concrete producers, state governments oversee large infrastructure projects, and the federal government invests massively in construction. All three levels of government must coordinate for the effective rollout of low embodied carbon construction practices. Disparate policy approaches show successes and pitfalls to developing an effective construction policy that is aligned with climate. Importantly, approaches to addressing the twin challenge of climate change and crumbling infrastructure must consider the whole lifetime of the concrete. Throughout this paper, we examine the sector to highlight current practices and provide a vision for effective implementation.

A combined experimental and Large-Eddy Simulation (LES) study of molecular radiation is presented for combustion in a homogeneous pre-mixed spark-ignition engine. Molecular radiation can account for ~10% of the engine heat loss and could have a noticeable impact on the local conditions within the combustion chamber. The Transparent Combustion Chamber (TCC) engine, a single-cylinder two-valve research engine with a transparent liner and piston for optical access, was used for this study. High-speed infrared emission spectroscopy and radiative post-processing of LES calculations have been performed to gain insight into the timescales and magnitude of radiative emissions of molecular gases during the combustion process. Both the measurements and simulations show significant Cycle-to-Cycle Variations (CCV) of radiative emission. There is agreement in the instantaneous radiative spectrum of experiment and simulation, but the crank-angle development of the radiative spectrum shows disagreement. The strengths and limitations of the optical experiments and radiative simulations are seen in the results and suggest pathways for future efforts in characterizing the influence of molecular radiation. In particular, focusing on the relative changes of the spectral features will be important as they contain information about the thermochemical properties of the gas mixture.

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