The bagasse (raw material) used came from a sugar and alcohol factory in the
State of Rio de Janeiro (Brazil). It was washed in the laboratory with distilled water
and dried at 45 C in a ventilated oven to remove impurities. Subsequently, the
bagasse samples were burnt in an aired electric oven with a 10 C/min heating rate,
first at 350 C for 3 h, and then at different temperatures ranging from 400 to
800 C, at increments of 100 C, for another 3 h. The ashes are designated as
SCBA-T, where T is the maximum temperature. The ratio of sample to internal
chamber volumes was maintained at 0.036 for all burning processes. The burning
was performed in two steps in accordance with the efficient results obtained by
Sugita [10] with RHA.
After calcination and cooling inside the oven, the samples were subjected to dry
grinding using a planetary mill (Restch PM-4) with alumina jar operating with
300 rpm and 25% filling of alumina spheres as grinding media. Particle sizes were
measured using a laser diffraction analyzer (Mastersizer 2000, Malvern Instruments)
and the loss on ignition (LOI) was determined by heating the sample up
095to 1000 C according to ASTM C-114 recommendations [11]. X-ray diffraction patterns
(powder method) were taken using a Rigaku Miniflex diffractometer with
Cu–Ka radiation. The chemical composition was determined by X-ray fluorescence
(XRF) using a Phillips PW2400 spectrometer and the specific surface area was measured
according to the N2 adsorption (BET) using a Gemini 2375V5. The density was
determined using an Accupic Micromeritics helium picnometer. The morphology of
SCBA particles was investigated using scanning electron microscope (Jeol JXA840-
A) images coupled to microanalysis by energy-dispersive spectroscopy (EDS). The
samples were carbon-coated under vacuum.
The reactivity of the SCBAs was evaluated by two methods: mechanical test
(pozzolanic activity index) and chemical analysis (Chapelle method). The principle
of determining the pozzolanic activity index is to compare the compressive
strength of an ISO mortar with that of a mortar where 35% of the cement volume
is replaced by SCBA, as described in Brazilian Standard NBR 5752 [12]. The ISO
mortar was prepared with sand–cement and water–cement ratios of 3 and 0.52
(in mass), respectively. The pozzolanic activity was also determined based on CaO
fixation by ash in the Chapelle method [13]. The test consisted of heating a solution
of 1.0000 g of CaO, 1.0000 g of ash and 250.0 g of water up to 90 C and keeping this
temperature constant for 16 h. The free CaO amount was then measured by titration
and the fixed CaO was estimated.
The bagasse (raw material) used came from a sugar and alcohol factory in theState of Rio de Janeiro (Brazil). It was washed in the laboratory with distilled waterand dried at 45 C in a ventilated oven to remove impurities. Subsequently, thebagasse samples were burnt in an aired electric oven with a 10 C/min heating rate,first at 350 C for 3 h, and then at different temperatures ranging from 400 to800 C, at increments of 100 C, for another 3 h. The ashes are designated asSCBA-T, where T is the maximum temperature. The ratio of sample to internalchamber volumes was maintained at 0.036 for all burning processes. The burningwas performed in two steps in accordance with the efficient results obtained bySugita [10] with RHA.After calcination and cooling inside the oven, the samples were subjected to drygrinding using a planetary mill (Restch PM-4) with alumina jar operating with300 rpm and 25% filling of alumina spheres as grinding media. Particle sizes weremeasured using a laser diffraction analyzer (Mastersizer 2000, Malvern Instruments)and the loss on ignition (LOI) was determined by heating the sample up095to 1000 C according to ASTM C-114 recommendations [11]. X-ray diffraction patterns(powder method) were taken using a Rigaku Miniflex diffractometer withCu–Ka radiation. The chemical composition was determined by X-ray fluorescence(XRF) using a Phillips PW2400 spectrometer and the specific surface area was measuredaccording to the N2 adsorption (BET) using a Gemini 2375V5. The density wasdetermined using an Accupic Micromeritics helium picnometer. The morphology ofSCBA particles was investigated using scanning electron microscope (Jeol JXA840-A) images coupled to microanalysis by energy-dispersive spectroscopy (EDS). Thesamples were carbon-coated under vacuum.The reactivity of the SCBAs was evaluated by two methods: mechanical test(pozzolanic activity index) and chemical analysis (Chapelle method). The principleof determining the pozzolanic activity index is to compare the compressivestrength of an ISO mortar with that of a mortar where 35% of the cement volumeis replaced by SCBA, as described in Brazilian Standard NBR 5752 [12]. The ISOmortar was prepared with sand–cement and water–cement ratios of 3 and 0.52(in mass), respectively. The pozzolanic activity was also determined based on CaOfixation by ash in the Chapelle method [13]. The test consisted of heating a solutionof 1.0000 g of CaO, 1.0000 g of ash and 250.0 g of water up to 90 C and keeping thistemperature constant for 16 h. The free CaO amount was then measured by titrationand the fixed CaO was estimated.
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