Chemical admixtures/agents

Their physical properties are listed in Table 4. FA and SF were also used as mineral admixtures. The physical properties of each admixture are listed in Table 5 and 6. For the chemical admixtures, polycarboxylate-based superplasticizer and negative ion type AE agent were used. 

In most instances these agents are intermixed with the fresh concrete mix as chemical admixtures however, it is also possible to interblend or intergrind some of them with the cement in the comse of its manufacture. 

Wood consists of 40-50% cellulose, 20-30% hemi-celluloses, 21-23% lignin, 0.2-0.5% protein, and 1-5% mineral matter, which is left behind as ash when the wood is burned. Besides its straightforward use as timber, much wood is pulped for use in papermaking. Lignin is extracted in the process by either sulfonation or chlorination. Sulfonation produces lignosulfonates, which are widely used as dispersing agents, for example as chemical admixtures for concrete to disperse the cement particles (see the section on Cement and Concrete Admixtures, below). 

Development of highly sensitive and reliable techniques for determination chemical warfare agents subjected to destruction, including technological admixtures and decomposition products ... 

The improvement is based on in-situ mixing of soil with admixtures, which chemically react with the soil and/or the groundwater. Generally the resulting stabilised soil mass has a higher strength, lower permeability and lower compressibility than the native soil. For environmental treatment, admixtures can be enriched with chemical oxidation agents or other reactive materials to immobilise or neutralise contaminants (Moseley et al, 2004). 

Superplasticisers Also called water-reducing agents-, chemical admixtures used to disperse particles homogeneously. In concrete or mortar... 

This closeness of 0 to zero explains the existence of a gas-oversaturated solution area in the polymer melt, when P < Pg, but the entire volume of gas remains in the solution. The degree of oversaturation, particularly upon free foaming (not in flow) can be 2- to 3-fold. In real polymer compositions, there are always solid admixtures, which have poor wetting areas. This reduces the degree of oversaturation at the interface melt-molding tool. Moreover, bubble nuclei can result from fragmentation of gas bubbles in the polymer [16]. Another factor that promotes the formation of bubble nuclei is the presence of localized hot points in the polymer melt they act as nuc-leation centres. Hot points appear either after a chemical reaction in the melt polymer [17], or in overheated areas on the surface of metal equipment [18]. Density of nucleation can be improved via introduction of various agents that reduce tension of the polymer [19]. 

Upon the formation of CdS colloids, at the point when the colloidal particles stop their growth and the system reaches the quasiequilibrium state, the total amount of cadmium is distributed over CdS particles and the aqueous phase of the solution, where it appears both as activated Cd2+ ion and as the compounds with complexing admixtures. One may assume the thermodynamic equilibrium is reached between the different possible forms of cadmium occurrence. Assuming the presence of only one complexing agent L, which participates in a stepwise complexing, we may describe the above equilibrium by a system of chemical equations ... 

Water reducers and superplasticizers. Admixtures aimed at increasing the workability of concrete are chemical substances that improve the mobihty of the particles in the fresh concrete mix by increasing the effectiveness of the mixing water. They contain surface-active agents that are adsorbed on the surface of solid particles and modify their electrical surface charge, so that they do not tend to flocculate, and thus are more dispersed, and the water can better lubricate the mix. 

Abstract. Polyvinylalcohol (PVA) is a polymer soluble in hot water, it has the property of film formation and it can improve the concrete performance. The effects of PVA modified with nano clay on the cement hydration reaction have been investigated by means of semiadiabatic calorimeter, FTIR spectroscopy and SEM. FTIR spectroscopy was employed to monitor chemical transformation of cement. The morphology of the different samples was compared by means of SEM micrographs. With the semiadiabatic calorimeter the hydration kinetic was measured to compare the heat rate of the admixtures materials. Fixing the water-cement ratio, w/c, in 0,45, the ratio of polymer to cement (p/c) was 2 wt% and the ratio of clay to polymer was 4 wt% (0.8wt.% related to cement). The polymer and modified polymer admixtures produced a retardation effect on the kinetic of cement hydration, but the clay acts as nucleating agent. The increase of the temperature with time was measured and a new model with four parameters was employed and the kinetic parameters were determined for each sample. 

Hubei Aging Chemical Company China Lignosulfonates Additives for concrete admixtures, feed, leather reinforcing agents for refractory material asnd ceramics Dispersants for fertilizers, pesticides... 

Uses Dispersant, wetting agent for wettable powds., agric. chems., concrete admixtures, dyes, gypsum wallboard, high-strength cements, pigment slurries and disps., and water treatment chemicals... 

As mentioned, refractory castables are combinations of refractory aggregates, matrix components, bonding agents, and admixtures. The proportions of each component used vary in each castable composition to achieve the desired physical and chemical properties and characteristics for the intended castable application. The general range of component quantities in a refractory castable is shown in Table 2. 

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