TY - JOUR
T1 - Production of geopolymeric binder from blended waste concrete powder and fly ash
AU - Ahmari, Saeed
AU - Ren, Xin
AU - Toufigh, Vahab
AU - Zhang, Lianyang
N1 - Funding Information:
This work is supported by the Environmental Research and Education Foundation (EREF). The authors gratefully acknowledge the Salt River Materials Group in Phoenix, Arizona for providing the fly ash used in this investigation.
PY - 2012/10
Y1 - 2012/10
N2 - Recycling and utilization of waste concrete is a significant contribution to environment and sustainable development. In current practice, the recycling of waste concrete is mainly limited to the use of crushed aggregates in low-specification applications. Few researchers have investigated complete recycling of waste concrete. These complete recycling methods, however, need to re-clinker the hydrated cement using the standard cement kiln procedures and thus consume significant amount of energy and release large quantity of CO 2. To completely recycle and utilize waste concrete in a sustainable and environmentally-friendly way, a method that does not need re-clinkering at high temperature should be used. This paper studies the production of geopolymeric binder from ground waste concrete (GWC) powder mixed with class F fly ash (FA), which can then be used with recycled concrete aggregates to produce new concrete. Specifically, the effect of composition and concentration of the alkaline solution and the content of GWC on the unconfined compressive strength (UCS) of the produced geopolymeric binder is investigated. SEM/EDX, XRD, and FTIR analyses are also performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the produced geopolymeric binder and the effect of calcium (Ca) on them. The results indicate that utilization of GWC together with FA can increase the UCS of the geopolymeric binder up to 50% GWC content. Further increase of GWC decreases the UCS of the geopolymeric binder. So with proper combination of GWC and FA, the geopolymeric binder with required strength can be produced.
AB - Recycling and utilization of waste concrete is a significant contribution to environment and sustainable development. In current practice, the recycling of waste concrete is mainly limited to the use of crushed aggregates in low-specification applications. Few researchers have investigated complete recycling of waste concrete. These complete recycling methods, however, need to re-clinker the hydrated cement using the standard cement kiln procedures and thus consume significant amount of energy and release large quantity of CO 2. To completely recycle and utilize waste concrete in a sustainable and environmentally-friendly way, a method that does not need re-clinkering at high temperature should be used. This paper studies the production of geopolymeric binder from ground waste concrete (GWC) powder mixed with class F fly ash (FA), which can then be used with recycled concrete aggregates to produce new concrete. Specifically, the effect of composition and concentration of the alkaline solution and the content of GWC on the unconfined compressive strength (UCS) of the produced geopolymeric binder is investigated. SEM/EDX, XRD, and FTIR analyses are also performed to investigate the micro/nano-structure, morphology and phase/surface elemental compositions of the produced geopolymeric binder and the effect of calcium (Ca) on them. The results indicate that utilization of GWC together with FA can increase the UCS of the geopolymeric binder up to 50% GWC content. Further increase of GWC decreases the UCS of the geopolymeric binder. So with proper combination of GWC and FA, the geopolymeric binder with required strength can be produced.
KW - CSH gel
KW - Fly ash
KW - Geopolymer
KW - Micro/nano structure
KW - Unconfined compressive strength
KW - Waste concrete
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U2 - 10.1016/j.conbuildmat.2012.04.044
DO - 10.1016/j.conbuildmat.2012.04.044
M3 - Article
AN - SCOPUS:84861595762
SN - 0950-0618
VL - 35
SP - 718
EP - 729
JO - Construction and Building Materials
JF - Construction and Building Materials
ER -