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Alkali-activated binders

The alkaline activators include sodium or potassium hydroxide, silicate, and carbonate. The rate of setting and hardening of alkali-activated binders and the quality and quantity of the resulting reaction products depend on a variety of factors, including the quality of the starting aluminosilicate, the quality and amount of alkaline activator, and the temperature of reaction. [Pg.249]

Commercially produced alkali-activated binders have been introduced on the market in the United States under the name Pyrament and in France under the names Geopolymite and PZ-Geopoly. [Pg.251]

Hybrid systems will continue to be the subject of future research on the development of ultra-high-performance fibre-reinforced concrete for many applications. However, two other research topics on FRC have emerged in recent years (1) utilization of waste fibres as reinforcement, and (2) development of fibre-reinforced alkali-activated binders (also known as geopolymers). [Pg.571]

Bemal, S. A., R. San Nicols, R. J. Myers, R. Mejia de Gutierrez, F. Puertas, J. S. J. Van Deventer and J. L. Provis (2014). MgO content of slag controls phase evolution and structural changes induced by accelerated carbonation in alkali-activated binders . Cement and Concrete Research 57 33—43. [Pg.501]

In alkali-activated fly ash binders a fly ash is eombined with an alkali metal eompound, preferably sodium silieate, which will secure a high alka-linity (pH=13-14) of the liquid phase. The alkaline activator may be blended with the ash prior to mixing with water, or— preferably—dissolved in the mixing water before mixing with the ash. [Pg.136]

The binder may be suitable for applications in which high chemical corrosion, including acid attack, is likely. It has also been suggested that alkali-activated fly ash binders should be used for fixation of hazardous waste, including radioactive wastes (Brough ei a/., 1995 Roy efo/., 1995). [Pg.137]

Other fast-setting cements not mentioned so far include alkali-activated slag cement (see section 8.5), alkali-activated fly ash binder (see section 9.1), geopolymeric cement (see section 15.7.1), zinc phosphate cement (see section 12.4), magnesium oxychloride and oxysulfate cement (see section 15.1), and alkali silicate binder(see section 15.3). [Pg.267]

Solutions of alkali hydroxides generally do not exhibit a corrosive action towards pastes of hardened Portland cement and related binders. Only at very high concentrations may a moderate corrosion become apparent, probably owing to degradation of the hydrated aluminate phases. Also highly resistant to alkaline solution are alkali-activated slag binders (see section 8.5). In contrast, hydrated calcinm aluminate cement may be attacked by high-pH solutions. [Pg.283]

As an alternative to Portland cement, alkali-activated blended cements (see section 8.5 and 9.1.5) have also been suggested as a binder in wood-based materials (Lin et al, 1994). The hardening of these binders is little affected by the quality of the wood employed. [Pg.343]

Lehn and Sauvage deliberately designed compounds that they expected to be three-dimensional alkali metal binders. They succeeded in this with compounds that were similar to those Pedersen had isolated but bicycUc rather than mono-cyclic [3]. The development of these two classes of related compounds caused an explosion of activity both on the synthetic [4] and the analytical fronts [5]. As structures became more elaborate, new binding selectivilies anerged, as did previously undocumented binding interactions (Fig. 8.1). [Pg.235]

A. Femandez-Jimenez and A. Palomo, Composition and microstructure of alkali activated fly ash binder Effect of activator Cem. Conor. Res., 35,1984-1992(2005)... [Pg.268]

Multicomponent alloys of nickel and aluminum activated by Ti, Mo are most widespread and wide by used materials for hydrogen electrodes of low temperature alkaline fuel cells. To make hydrogen electrodes skeletal nickel prepared by alkali-soluble of alloy with composition 50 %Ni -i- 47 % A1 -i-3 % Ti is used. Raney catalyst is processed by 20 % suspense of Fluoroplast F-4 D with following drying in vacuum at 50 °C that permits pyrophoric catalyst to protect against self combustion and serves hydrophobic binder to form electrodes [5]. [Pg.182]

Group 1 alkali metals (including potassium) are poisons for cobalt catalysts but are promoters for iron catalysts. Catalysts are snpported on high-surface-area binders/supports such as silica, alumina, and zeolites (Spath and Dayton, 2003). Cobalt catalysts are more active for FTS when the feedstock is natnral gas. Natnral gas has a high H2 to carbon ratio, so the water-gas-shift is not needed for cobalt catalysts. Iron catalysts are preferred for lower quality feedstocks such as coal or biomass. [Pg.724]

Zinc phosphates are widely used in many binders, including oil-based binders, alkyds, and epoxies [41-50]. Their low solubility and activity make them extremely versatile they can be used in resins, such as alkyds, where more alkali pigments pose stability problems. Typical loading levels are 10% to 30% in maintenance coatings. [Pg.31]

The alkali silicates is one of the raw materials classically used in the formulation of new materials like geopolymers. Geopolymers are amorphous three-dimensional aluminosilicate binder materials which are synthesized at ambient temperature by the alkaline activation of silica solution and aluminosilicates derived from natural minerals, calcined clay or industrial byproducts. Previous study focused on the aluminosilicate sources have shown that the presence of impurities and the reactivity of the metakaolin (aluminosilicate source) can lead to the formation of one or several networks in geopolymers materials [1]. Indeed, the different sources of metakaolins conduct to the presences of various siliceous species in the solution which react with alumina. These multiple combinations lead to the formation of different networks (then various properties of geopolymers). To understand the formation of these various networks, studies relative to the neutralization of siliceous species in solution have been done. Parmentier [2] showed that the ammonium molybdate could react with silica to create silicomolybdic compounds. More recent studies demonstrated that ammonium molybdate could also react with these species in an alkaline environment [3]. These analyses showed that ammonium molybdate could react not only with monomers and dimers, but also with larger molecules. According to this, molybdate can permit to complex siliceous species and to modify polymerization reactions. The aim of the study is to study the influence of the ammonium molybdate addition on the kinetics of the polycondensation reaction as well as on the formation of several networks. [Pg.60]

Binder and others [230] found that Raney platinum was the best single catalyst for electrochemical oxidation of hydrocarbons. Data obtained by Bianchi [231], Grubb [232], and Cairns and Mclnemey [203], who compared the catalytic activities of various platinum blacks in the anodic oxidation of propane, are consistent with this conclusion. As found by Petrii and Marvet [100], the oxidation rate of methane decreases sharply on changing from platinum to other platinum catalysts. Bockris and Dahms [192] showed that the oxidation rate of ethylene decreases in the series Pt > Rh > Ir and Pd > Au, where platinum is considerably more active than palladium. It was found in [233] that the oxidation rate of propane in alkali decreases in the order Pd > Pt > Ag, and those of ethane ethylene, propylene, and n-butane decrease in the order Pt > Pd... [Pg.361]


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Active binders

Alkali-activated fly ash binder

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