Abstract
Clinker production is very energy-intensive and responsible for releasing climate-relevant carbon dioxide (CO2) into the atmosphere, and the exploitation of aggregate for concrete results in a reduction in natural resources. This contrasts with infrastructure development, surging urbanization, and the demand for construction materials with increasing requirements in terms of durability and strength. A possible answer to this is eco-efficient, high-performance concrete. This article illustrates basic material investigations to both, using eco-friendly cement and recycled aggregate from tunneling to produce structural concrete and inner shell concrete, showing high impermeability and durability. By replacing energy- and CO2-intensive cement types by slag-pozzolanic cement (CEM V) and using recycled aggregate, a significant contribution to environmental sustainability can be provided while still meeting the material requirements to achieve a service lifetime for the tunnel structure of up to 200 years. Results of this research show that alternative cements (CEM V), as well as processed tunnel spoil, indicate good applicability in terms of their properties. Despite the substitution of conventional clinker and conventional aggregate, the concrete shows good workability and promising durability in conjunction with adequate concrete strengths.
Highlights
The concrete industry acts as one of the main contributors to CO2 emissions accounting for approx. 5 to 7% of global anthropogenic CO2 emissions, whereby Portland cement production accounts for approx
CO2 emission during cement production is derived from two sources, having a similar share: (1) Process-related CO2 accounting for the energy demand by the use of fuels and electric energy mainly for drying, grinding, and mostly from clinker burning; (2) the emission of embodied CO2 (ECO2 ) during CaCO3 decomposition during heating, when the chemically bound CO2 from the carbonate rock is degassing [2,5]
In the case of CEM V cements, early strength is naturally reduced by the pozzolanic reaction of SiO2 and Al2 O3 from fly ash or natural pozzolana and the latent hydraulic reaction of blast furnace slag, and is not suitable for fast-track construction
Summary
The demand for concrete—the worlds most used construction material—continues to remain at a high level notwithstanding recent global economic fluctuations. CO2 emission during cement production is derived from two sources, having a similar share: (1) Process-related CO2 accounting for the energy demand by the use of fuels and electric energy mainly for drying, grinding, and mostly from clinker burning; (2) the emission of embodied CO2 (ECO2 ) during CaCO3 decomposition during heating, when the chemically bound CO2 from the carbonate rock is degassing [2,5]. As a very central point with regard to embodied CO2 , the usage of alternative raw materials with the absence of carbonates in their mineral content is effective This means the reduction in the portion of Portland cement replacing the clinker by alternative binder compositions (e.g., fly ash, furnace slag, or natural pozzolans) producing blended or—when using more than one blending material—so-called composite cements [18,19,20]. The approach of slag-pozzolanic cements (CEM V) according to [22] is pursued
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
