• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.1
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• pp.50-57
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• 2015

Portland cement production is under critical review due to high amount of $CO_2$ gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. Many researchs on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. Instead, the sources of material such as fly ash, that are rich in Silicon(Si) and Aluminium(Al), are activated by alkaline liquids to produce the binder. Hence concrete with no cement is effect reduction of $CO_2$ gas. In this study, we investigated the influence of the fluidity, air content and compressive strength of mortar on alkaline activator in order to develop cementless fly ash and ground granulated blast-furnace slag based alkali-activated mortar with superplasticizer. In view of the results, we found out that Pn of fluidity and compressive strength is the best in four type of superplasticizer, and PNS of powder type of fluidity is better than that of liquid type in the case of AA.

• Resources Recycling
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• v.19 no.4
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• pp.19-28
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• 2010

Attempts to increase the utilization of a by-products such as fly ash and blast furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. However, most study deal only with alkali-activated blast furnace slag or fly ash, as for the combined use of the both, little information is reported. In this study, we investigated the influence of mixture ratio of fly ash/slag, type of alkaline activator and curing condition on the workability and compressive strength of mortar in oder to develop cementless alkali-activated concrete. In view of the results, we found out that the mixture ratio of fly ash/slag and the type of alkaline activator always results to be significant factors. But the influence of curing temperature in the strength development of mortar is lower than the contribution due to other factors. At the age of 28days, the mixture 50% fly ash and 50% slag activated with 1:1 the mass ratio of 9M NaOH and sodium silicate, develop compressive strength of about 65 MPa under $20^{\circ}C$ curing.