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The objective of this course is to introduce and explain by case studies a new document, “211.7R-15: Guide to Proportioning Concrete Mixes with Ground Limestone and Mineral Fillers”. This main objective is to propose that a blended portland limestone cement (PLC) with supplementary cementitious material (SCM) cement blend can provide an effective synergy to produce a comparable concrete to a portland cement. This course will provide studies that show different ways that PLC and SCM concretes can attain adequate compressive strength and durability to be used in many concrete applications.

Commitment to reducing the environmental impact of concrete is of great importance nowadays. In case of self-consolidating concrete (SCC), this is of critical significance given the fact that the binder content of such concrete needed to ensure the required rheological properties is normally high. The present study aims to propose an appropriate design approach for producing SCC of low carbon footprint (Eco-SCC) for building applications. The presentation elaborates the step-by-step methodology to develop the Eco-SCC including packing density approach to optimize the volumetric proportions of sand and coarse aggregate to achieve an ideal particle gradation curve. The water content is adjusted to provide the necessary minimum paste volume to obtain self-consolidating properties. The powder composition is determined according to rheological optimizations of pastes to reduce the water demand while satisfying mechanical properties and durability considerations. Such design method is found to be effective for obtaining Eco-SCC. Mixtures with total powder content ranging from 280 to 310 kg/m3 are shown to exhibit satisfactory workability characteristics and 28-day compressive strengths in the range of 25 to 30 MPa and low drying shrinkage for building applications.

Due to the increasing threat posed by climate change, there is a growing interest in reducing greenhouse gas (GHG) emissions throughout the economy. Considerable focus has been placed on the use of concrete, as Portland cement-based concrete is responsible for roughly 1.5% of the GHG emissions in the United States, with some estimating it is responsible for up to 8% of the world's anthropogenic GHG emissions. Concrete airfield pavements offer an opportunity for our industry to immediately reduce our GHG emissions through improved material selection and proportioning without compromising longevity or economic life cycle costs. Currently available strategies will be discussed as will emerging technologies that may offer additional savings. The presentation will conclude with a discussion on assessment and the need to use a standardized approach to quantify environmental impact as a means to ensure real improvement.

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The large volume o Rui He f the using of Portland cement makes the industry a large emitter of CO2 despite it has a relatively low carbon footprint compared to most other construction materials. The CO2 curing has been found to be an effective method to achieve carbon neutrality of cementitious materials. In this work, cementitious materials with the addition of nano-silica were cured by CO2. The carbon footprint of cementitious materials with and without the addition of nano-silica was calculated. The mechanical performance of cementitious materials cured by CO2 is tested. The chemical composition of cementitious materials cured by CO2 incorporated with various dosage of nano-silica is characterized by thermogravimetric analysis (TGA) and X-ray powder diffraction (XRD). The pH value change of cementitious materials after CO2 curing is measured. The pore structure of cementitious materials is characterized by mercury intrusion porosimetry (MIP) and 3D X-ray microscopy (Micro-CT) techniques. The morphology of CO2 curing products is also characterized by scanning electron microscope (SEM) analysis. The results indicates that the CO2 curing method can significantly reduce the car-bon footprint of cementitious materials. The addition of nano-silica can improve the mechanical performance and result in a dense microstructure of cementitious materials.

An important part of improving the embodied carbon of the built environment is reducing the carbon emissions associated with concrete. The beneficial use of carbon dioxide (CO2) in ready mixed concrete production has been developed and installed as a retrofit technology with industrial users. An optimum dose of CO2 added to concrete as an admixture leads to the in-situ formation of mineralized calcium carbonate (CaCO3) and can increase the concrete compressive strength. The improved performance can be leveraged to design concrete mixture proportions for a more efficient use of portland cement along with the use of CO2 to reduce the carbon footprint of concrete. The physicochemical aspects of CO2 mineralization, the fresh and hardened concrete performance, durability performance and life cycle impacts will be discussed.