Abstract
Conventional concrete production that uses ordinary Portland cement (OPC) as a binder seems unsustainable due to its high energy consumption, natural resource exhaustion and huge carbon dioxide (CO2) emissions. To transform the conventional process of concrete production to a more sustainable process, the replacement of high energy-consumptive PC with new binders such as fly ash and alkali-activated slag (AAS) from available industrial by-products has been recognized as an alternative. This paper investigates the effect of curing conditions and steel fiber inclusion on the compressive and flexural performance of AAS concrete with a specified compressive strength of 40 MPa to evaluate the feasibility of AAS concrete as an alternative to normal concrete for CO2 emission reduction in the concrete industry. Their performances are compared with reference concrete produced using OPC. The eco-efficiency of AAS use for concrete production was also evaluated by binder intensity and CO2 intensity based on the test results and literature data. Test results show that it is possible to produce AAS concrete with compressive and flexural performances comparable to conventional concrete. Wet-curing and steel fiber inclusion improve the mechanical performance of AAS concrete. Also, the utilization of AAS as a sustainable binder can lead to significant CO2 emissions reduction and resources and energy conservation in the concrete industry.
Highlights
Concrete is the most widely used construction material and uses a great amount of cement
Yang et al [2] derived the relationship between the CO2 and binder intensities of different concretes from a regression analysis of a comprehensive database in Korea. Their applicability was hindered because the activated slag (AAS) concretes obtained with sodium silicate activators exhibit higher drying shrinkage rates than in ordinary Portland cement (OPC)
Fiber inclusion is commonly accepted as the way to improve shrinkage behavior of AAS concrete [3,4]
Summary
Concrete is the most widely used construction material and uses a great amount of cement. Yang et al [2] derived the relationship between the CO2 and binder intensities of different concretes from a regression analysis of a comprehensive database in Korea Their applicability was hindered because the AAS concretes obtained with sodium silicate activators exhibit higher drying shrinkage rates than in ordinary Portland cement (OPC). Bernal et al [5] concluded that alkali-activated slag concrete reinforced with steel fibers shows three times higher flexural toughness than Portland cement concretes at early ages of curing. The aim of this study is to improve the mechanical performance of Ca(OH)2-based AAS concrete by incorporation of steel fibers because it has been found from other previous research results that microfiber such as polyethylene (PE) or polyvinyl alcohol (PVA) is useful for improving tensile performance of a cementitious composite without coarse aggregate. The utilization of AAS in concrete will be helpful in reducing environmental problems and greenhouse gas emissions associated with the Portland cement production, and in conserving existing natural resources
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