Alkali-activated fly ash/slag cements

Puertas, Francisca; Martínez-Ramírez, S.; Alonso, Santiago; Vázquez, T.

doi:10.1016/s0008-8846(00)00298-2

Cited by 713 publications

(103 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The binary system, FA/GBFS, was prepared with equal proportions of fly ash and blast furnace slag, which earlier studies showed to be optimal (31)(32)(33). The liquid/solid ratio (L/S) given in the table was found taking L to be the water in the sodium silicate plus the amount added to the mix, and S to be the FA and GBFS plus the solid phase in the activating solution (SS or RHA and NaOH).…”

Section: Systems Prepared and Working Conditionsmentioning

confidence: 99%

Ceniza de cascarilla de arroz como fuente de sílice en sistemas cementicios de ceniza volante y escoria activados alcalinamente

Mejía¹,

Gutiérrez²,

Puertas³

2013

Mater. construcc.

View full text Add to dashboard Cite

This study assesses the viability of using an agro-industrial by-product, rice husk ash (RHA) from a Colombian rice company's combustion facility, as a total replacement for the commercial sodium silicate ordinarily used in alkaliactivated binders. Fly ash (FA), granulated blast furnace slag (GBFS) and binary 50FA:50GBFS blended pastes were activated with a mix of sodium hydroxide and either sodium silicate or one of two types of RHA. The pastes were characterised for strength, mineralogy and microstructure. The findings showed that the agro-industrial by-product can be used to yield alkali-activated materials with 7-day mechanical strengths on the order of 42 MPa. The study confirmed that both amorphous silica and part of the crystalline silica present in RHA participate in the alkaline activation process, providing the alkalinity is suitably adjusted.

show abstract

Section: Systems Prepared and Working Conditionsmentioning

confidence: 99%

Ceniza de cascarilla de arroz como fuente de sílice en sistemas cementicios de ceniza volante y escoria activados alcalinamente

Mejía¹,

Gutiérrez²,

Puertas³

2013

Mater. construcc.

View full text Add to dashboard Cite

show abstract

“…Moreover, the construction industry is presently very keen on developing new cements and construction materials, whose manufacture would be less energy-intensive and entail the emission of less polluting gas (primarily CO 2 ) than conventional Portland cement manufacture. These cements are obtained by mixing amorphous silico-aluminates such as blast furnace slag, fly ash, metakaolin or volcanic rock, or blends of two or three of these materials, with highly alkaline solutions (NaOH, Na 2 CO 3 or alkaline silicate hydrates) (12)(13)(14)(15)(16)(17)(18). Inorganic polymer binders provide an alternative to traditional cements up to 80% less CO 2 emissions, and are derived from industrial waste materials (19,20).…”

Section: Introductionmentioning

confidence: 99%

Sodium silicate solutions from dissolution of glasswastes. Statistical analysis

Torres-Carrasco¹,

Palomo²,

Puertas³

2014

Mater. construcc.

View full text Add to dashboard Cite

It has studied the solubility process of four different waste glasses (with different particle sizes, <45 µm and>125 µm) in alkaline solutions (NaOH and NaOH/Na 2 CO 3 ) and water as a reference and under different conditions of solubility (at room temperature, at 80°C and a mechano-chemical process). Have established the optimal conditions of solubility and generation of sodium silicates solutions, and these were: the smaller particle size (<45 µm), with NaOH/Na 2 CO 3 solution and with temperature during 6 hours of stirring time. The statistical analyses of the results give importance to the studied variables and the interactions. Through 29 Si NMR MAS it has confirmed the formation after dissolution processes of monomeric silicate, suitable for use as an activator in the preparation of alkaline cements and concretes. RESUMEN: Disoluciones de silicato sódico procedentes del tratamiento de residuos vítreos Estudio estadístico.Se ha estudiado el proceso de solubilidad de cuatro diferentes residuos vítreos (con distintas granulometrías, <45 µm y >125 µm) en disoluciones alcalinas de NaOH y NaOH/Na 2 CO 3 y agua como medio de referencia y bajo distintas condiciones de solubilidad (a temperatura ambiente, a 80°C y con un proceso mecano-químico). Se han establecido las condiciones óptimas de solubilidad y generación de disoluciones de silicato sódico, y estas son: menor tamaño de partícula del residuo vítreo (inferior a 45 µm), con la disolución de NaOH/Na 2 CO 3 y tratamiento térmico a 80°C durante 6 horas de agitación. El análisis estadístico realizado a los resultados obtenidos da importancia a las variables estudiadas y a las interacciones de las mismas. A través de 29 Si RMN MAS se ha confirmado la formación, tras los procesos de disolución, de un silicato monomérico, apto para su utilización como activador en la preparación de cementos y hormigones alcalinos.

show abstract

“…There are however a few obstacles preventing the adoption of AAFA cements, which include the variability in the chemical and mineralogical composition of fly ashes (Fernández-Jiménez and Palomo, 2003), and, despite the fact that the alkali activation of fly ash is an exothermic reaction (Palomo et al, 1999), slow strength development at ambient temperatures (Puertas et al, 2000;Somna et al, 2011). Dry or steam heat curing in a wide range of temperatures is normally used to accelerate the alkali activation process in order to obtain an adequate early age compressive strength for AAFA cements and concretes (Bakharev, 2005;Kovalchuk et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Direct electric curing of alkali-activated fly ash concretes: a tool for wider utilization of fly ashes

Kovtun

Shekhovtsova

Kearsley

2016

Journal of Cleaner Production

View full text Add to dashboard Cite

Utilization of the fly ashes is a major problem in many developing countries and in South Africa only about 7% of the fly ash produced annually by coal-fired power stations, has being utilized. Although, fly ashes can be used as an alternative binder in alkali-activated concretes, strength development of these concretes at room temperature is slow limiting application of the material. Direct electric curing is proposed for heat curing of alkali-activated fly ash concrete which will open new opportunities for in-situ applications of these concretes in the construction industry thus increasing the amount of beneficially utilized fly ash. Alkaliactivated fly ash concretes containing unclassified low calcium fly ash, sodium hydroxide and sodium silicate solutions were cured at 60 ºC by means of direct electric curing. The electric resistivity and compressive strength development of the concretes were investigated. The resistivity strongly depends on the type of activator used. Compressive strength up to 33.8 MPa and 48.5 MPa at 2 and 28 days respectively, can be achieved after a short period of 2 direct electric curing. This opens new opportunities for wider application of alkali-activated fly ash concretes and for more extensive utilization of fly ash.

show abstract

Alkali-activated fly ash/slag cements

Cited by 713 publications

References 12 publications

Ceniza de cascarilla de arroz como fuente de sílice en sistemas cementicios de ceniza volante y escoria activados alcalinamente

Ceniza de cascarilla de arroz como fuente de sílice en sistemas cementicios de ceniza volante y escoria activados alcalinamente

Sodium silicate solutions from dissolution of glasswastes. Statistical analysis

Direct electric curing of alkali-activated fly ash concretes: a tool for wider utilization of fly ashes

Contact Info

Product

Resources

About