Using GGBOS as the alkali activators in GGBS and GGBOS blended cements

Tsai, Chia-Jung; Huang, Ran; Lin, Wei‐Ting; Chiang, Hsiang-Wei

doi:10.1016/j.conbuildmat.2014.08.011

Cited by 12 publications

(18 citation statements)

References 11 publications

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“…The EDS analysis showed the major elements are Ca, Si with O and Ca, Si, Al with O, which, thus, infers those elements are a colloid of C-S-H and C-A-S-H. Based on previous study [3], C-S-H and C-A-S-H are the key factors in producing strength in cementitious materials. This is shown in Figure 7C and Figure 7D, based on previous reports [3,6]. Thus, it was confirmed the main reason for the strength production of CF5G5 came from C-S-H and C-A-S-H.…”

Section: Resultssupporting

confidence: 86%

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Recycling of Sustainable Co-Firing Fly Ashes as an Alkali Activator for GGBS in Blended Cements

Huang

Tsai

et al. 2015

Materials

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This study investigates the feasibility of co-firing fly ashes from different boilers, circulating fluidized beds (CFB) or stokers as a sustainable material in alkali activators for ground granulated blast-furnace slag (GGBS). The mixture ratio of GGBS and co-firing fly ashes is 1:1 by weight. The results indicate that only CF fly ash of CFB boilers can effectively stimulate the potential characteristics of GGBS and provide strength as an alkali activator. CF fly ash consists of CaO3 (48.5%), SiO2 (21.1%), Al2O3 (13.8%), SO3 (10.06%), Fe2O3 (2.25%) and others (4.29%). SA fly ash consists of Al2O3 (19.7%), SiO2 (36.3%), Fe2O3 (28.4%) and others (15.6%). SB fly ash consists of Al2O3 (15%), SiO2 (25.4%), Zn (20.6%), SO3 (10.9%), Fe2O3 (8.78%) and others (19.32%). The mixtures of SA fly ash and SB fly ash with GGBS, respectively, were damaged in the compressive strength test during seven days of curing. However, the built up strength of the CF fly ash and GGBS mixture can only be maintained for 7–14 days, and the compressive strength achieves 70% of that of a controlled group (cement in hardening cement paste). The strength of blended CF fly ash and GGBS started to decrease after 28 days, and the phenomenon of ettrigite was investigated due to the high levels of sulfur content. The CaO content in sustainable co-firing fly ashes must be higher than a certain percentage in reacting GGBS to ensure the strength of blended cements.

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Section: Resultssupporting

confidence: 86%

“…In SEM, after mixing GGBS with GGBOS with an optimal proportion of 50%:50% during 7 days and 28 days of curing, hexagonal platelets of C-A-S-H colloid were found [6]. This finding is in line with the reactions in CF5G5 (50% CF fly ash: 50% GGBS) at 28 days age whereby Ca(OH) 2 reacted with SiO 2 and Al 2 O 3 of GGBS powder forming C-A-S-H.…”

Section: Introductionmentioning

confidence: 99%

Recycling of Sustainable Co-Firing Fly Ashes as an Alkali Activator for GGBS in Blended Cements

Huang

Tsai

et al. 2015

Materials

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“…This reaction creates the alkaline environment, which is similar to only using Portland cement [10]. The referenced papers [11,12] reported that mixing ground-granulated basic oxygen slag (GGBOS) with ground-granulated basic blast furnace slag (GGBS) as blended cement in compliance with ASTM C-595M-13 that GGBOS is feasible to use as an alkali activator for GGBS with optimal mixing ratio is 40%:60% for generating strength.…”

Section: Introductionmentioning

confidence: 92%

“…Table 3 shows the compressive strength test results of mortar made from each of the seven mixtures of CFFA and GGBS blended The test results found the materials of CFFA and GGBS mixing together can react with water and produce strength that varies with the ratio. Refer to the paper [11,12], the blended material of GGBS and GGBOS, which contains a certain amount of CaO mixes with water produces both an alkali-activated reaction and pozzolanic reaction leading to the desired strength. Table 2 displays 37.8% CaO content of the CFFA component, which can be speculated to be one of reasons.…”

Section: Panalytical X'pert Promentioning

confidence: 99%