Determination of amorphous silica in rice husk ash by a rapid analytical method

Payá, J.; Monzó, J.; Borrachero, M.V.; Mellado, A.; Ordónez, Luis M.

doi:10.1016/s0008-8846(00)00466-x

Cited by 110 publications

(61 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The particle size distribution of the RHAs was measured as described above; their amorphous silica content of the RHAs was measured by a rapid analytical method developed by Payá et al [25], and the Ca(OH) 2 consumption of the RHAs was determined through the modified Chapelle method based on Raverdy et al work [26]. For a material to be classified as pozzolanic, a minimum consumption of 330 mg CaO/g is required.…”

Section: Methodsmentioning

confidence: 99%

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Rêgo

Nepomuceno

Figueiredo

et al. 2015

Construction and Building Materials

View full text Add to dashboard Cite

Section: Methodsmentioning

confidence: 99%

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Rêgo

Nepomuceno

Figueiredo

et al. 2015

Construction and Building Materials

View full text Add to dashboard Cite

“…For this purpose, there are some specific methods in the literature [24,25]. One of them established that the degree of amorphous form of silica is estimated by the 'silica activity index' , which is determined by calculating the percentage of valuable silica dissolved in an excess of boiling 4 M KOH in a 3-min extraction period [24].…”

Section: Characterizationmentioning

confidence: 99%

Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

et al. 2012

View full text Add to dashboard Cite

Rice husk (RH), an inexpensive waste material, was used to produce nanosilica. Acid treatment of RH followed by thermal combustion under controlled conditions gave 22.50% ash of which 90.469% was silica. Various chemical treatments in varied conditions for controlled combustion were investigated in order to produce highly purified nanosilica. The structural properties (such as X-ray diffraction, Brunauer-Emmett-Teller, Fourier transform infrared spectroscopy, and transmission electron microscopy) of the silica were studied. The method was optimized, and the chemical composition of the product was determined by X-ray fluorescence and carbon, hydrogen, and nitrogen analysis. Lime reactivity of the ashes was determined. At optimized conditions, a nanosized, highly purified silica (98.8 mass percentage) was produced with a high surface area, high reactivity, and 99.9% amorphous in form. Strength and number of acidic sites were measured by potentiometric titration. This nanosilica showed strong and a large number of acidic sites in comparison with commercial silica, making it as a good support for catalysts. This economic technology, as applied to waste material, also provides many benefits to the local agro-industry.

show abstract

“…Table 2 shows the particle size distribution and amorphous silica content for tested pozzolans. The amorphous silica content was performed using the selective chemical analysis proposed by Payá et al (15).…”

Section: Methodsmentioning

confidence: 99%

New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

Tashima¹,

Soriano²,

Monzó³

et al. 2014

Mater. construcc.

View full text Add to dashboard Cite

A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide:pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH) 2 in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 °C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels. RESUMEN:Nuevo método para evaluar la reactividad puzolánica de adiciones minerales por medio de medidas de pH y conductividad eléctrica en suspensiones cal:puzolana. En este trabajo se propone un método simple basado en medidas de conductividad eléctrica y pH. Se determinaron los valores de conductividad eléctrica y pH de suspensiones acuosas de hidróxido cálcico:puzolana. En las suspensiones, había inicialmente Ca(OH) 2 en estado sólido, de manera que dichas suspensiones estaban, por tanto, saturadas respecto a ese reactivo. Se seleccionaron tres temperaturas de trabajo (40, 50 and 60 °C). En las experiencias, el hidróxido cálcico fue mezclado con agua desionizada, generando una suspensión saturada en cal. La adición de puzolana silícea (se ensayaron dos tipos de ceniza de cáscara de arroz y dos tipos de humo de sílice densificado) a la suspensión saturada de cal puede producir la insaturación del sistema, dependiendo del tiempo, temperatura y reactividad de la puzolana. Cuando se alcanza la insaturación, la pérdida de conductividad eléctrica fue mayor a 30% y la variación de pH fue mayor que 0.15 unidades. Estos valores umbral fueron seleccionados para caracterizar la reactividad de las puzolanas por medio de una plantilla propuesta al efecto, clasificando la puzolana en tres niveles de reactividad diferentes.

show abstract

Determination of amorphous silica in rice husk ash by a rapid analytical method

Cited by 110 publications

References 3 publications

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Microstructure of cement pastes with residual rice husk ash of low amorphous silica content

Optimization of synthesis and characterization of nanosilica produced from rice husk (a common waste material)

New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

Contact Info

Product

Resources

About