When a new bonding agent using coal ash is utilized as a substitute for cement, it has the advantages of offering a reduction in the generation of carbon dioxide and securing the initial mechanical strength such that the agent has attracted strong interest from recycling and eco-friendly construction industries. This study aims to establish the production conditions of new hardening materials using clean bottom ash and an alkali activation process to evaluate the characteristics of newly manufactured hardening materials. The alkali activator for the compression process uses a NaOH solution. This study concentrated on strength development according to the concentration of the NaOH solution, the curing temperature, and the curing time. The highest compressive strength of a compressed body appeared at 61.24MPa after curing at 60˚C for 28 days. This result indicates that a higher curing temperature is required to obtain a higher strength body. Also, the degree of geopolymerization was examined using a scanning electron microscope, revealing a micro-structure consisting of a glass-like matrix and crystalized grains. The microstructures generated from the activation reaction of sodium hydroxide were widely distributed in terms of the factors that exercise an effect on the compressive strength of the geopolymer hardening bodies. The Si/Al ratio of the geopolymer having the maximum strength was about 2.41.

이 연구에서는 단일 활성화제로 활성화시킨 슬래그 기반 섬유보강 복합재료의 초기재령에서 인장거동을 조사하였다. 실험 결과, 활성화제 종류에 따라 재령 7일에서 균열강도, 인장강도, 인장변형성능에 차이가 있었으며, 규산나트륨을 활성화제로 사용한 배합이 가장 큰 인장변형성능을 나타내었다.

본 연구는 혼합 활성화제에 의한 알칼리 활성화 슬래그 시멘트(AASC)의 역학적 특성에 관한 연구이다. 사용된 활성화제는 황산칼슘(CaSO4, 이하 CS), 황산나트륨(Na2SO4, 이하 SS) 및 수산화나트륨(NaOH)이다. 황산염은 슬래그 중량의 2.5, 5.0, 7.5 및 10.0%로 치환하여 사용하였으며, NaOH는 2M 및 4M 농도의 수용액으로 사용하였다. 본 연구에서는 황산염(CS 및 SS) 치환율에 따른 배합(4가지 배합)과 2M 및 4M의 각각의 NaOH 수용액에 치환된 황산염을 혼합하여 시험체를 제작하였다. 시험체는 총 24가지의 배합에 따라 페이스트로 제작되었으며, 물－결합재 비는 0.5로 하였다. 경화된 시험체에 대해서 압축강도, 휨강도, 초음파속도(UPV), 흡수율 및 XRD 분석을 수행하였다. CS의 활성화제를 사용한 경우는 7.5% CS 치환율, 2M NaOH 수용액+ 5.0% CS 치환율 및 4M NaOH 수용액+ 5.0% CS 치환율의 시험체에서 최고의 압축강도를 나타내었다. 또한, SS의 활성화제를 사용한 경우는 10.0% SS 치환율, 2M NaOH + 7.5% SS 치환율 및 4M NaOH + 2.5% SS 치환율에서 최고의 압축강도 발현을 나타내었다. 휨강도, UPV 및 흡수율은 압축강도 발현 결과와 유사한 경향을 나타내는 것을 알 수 있었으며, XRD 분석결과 시험체 내에 생성된 반응물질은 ettringite, CSH 및 실리케이트계 수화물인 것으로 나타났다. AASC에서 황산염과 NaOH의 혼합 사용은 황산염의 단독 사용의 경우와 비교하여 일정 수준의 농도 범위에서 강도를 향상시키고 조직을 치밀화 시키는 등의 긍정적인 영향을 미치는 것으로 판단된다.

In this study, it was developed eco-friendly alkali-activated slag fiber reinforced concrete using ground granulated blast furnace slag, alkali activator (water glass, sodium hydroxides), and steel fiber. Eight reinforced concrete beam using alkali-activated slag concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, mixed/without of steel fiber. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The reinforced concrete beams using the eco-friendly alkali-activated slag fiber reinforced concrete was failed by the flexure or flexure-shear in general. In addition, the maximum strength increased with the adding the mol of sodium hydroxide, and the specimen reinforced the steel fiber showed the value of maximum strength which is increased by 15.8% through 25.9%. It is thought that eco-friendly alkali-activated slag fiber reinforced concrete can be used with construction material and product to replace normal concrete. If there is applied to structures such as precast concrete member and production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

This study is based on developing a free-cement. The Setting time of 100% GGBS(Ground Granulated Blast furnace Slag) admixed alkali-activators is measured, the influence of cation of alkali-activators on setting time is assessed. As a result, in case of mixing KOH or NaOH, setting time is getting shorter, although, GGBS admixed Ca(OH)2 has similar setting times regardless of concentration of alkali-activators.

In the previous result, the flexural strength of geopolymer prepared was affected by the evaporation of water content or the shrinkage rate in the curing process of specimen. We investigated the effect of SiO2/H2O ratio on the physical property of geopolymer prepared in this research. The specimen of geopolymer tile was made from mine tailing and melting slag. The maximum flexural strength was obtained at SiO2/H2O ratio of 0.21 under our experimental condition. And the lowest was obtained at SiO2/H2O 0.41. EDS analysis was acted to elucidate this cause. According to the results, it was due to the extent of geopolymerization at the inside and outside of specimen.

본 연구는 알칼리 활성화 슬래그에서 혼합 활성화제에 관한 것이다. 본 연구에서는 수산화나트륨(NaOH, A Case), 수산화칼슘(Ca(OH)2, B Case), 수산화마그네슘(Mg(OH)2, C Case), 수산화알루미늄(Al(OH)3, D Case), 그리고 수산화칼륨(KOH, E Case)의 5가지 수산화계열 활성화제를 사용했다. 이 5가지 수산화계열 활성화제와 탄산나트륨(Na2CO3)를 혼합하였다. 5가지 수산화계열 활성화제의 농도는 3M로 하고, 탄산나트륨은 1M, 2M, 3M로 하였다. 플로우와 응결 특성은 탄산나트륨의 혼합에 따라 감소하는 결과가 나타났다. 그러나 압축응력은 탄산나트륨의 혼합 농도에 따라 증가하는 결과를 나타내었다. 이것은 수산화계열 활성화제와 탄산나트륨의 혼합은 알칼리 활성화 슬래그 모르타르의 특성에 효과적인 것으로 판단된다.

Investigated the factors to effect on the flow of geopolymer mortar based on on ground granulated blast furnace slag in order to develop cementless alkali-activated concrete GGBS.