Lignosulfonates effect

Chromium lignosulfonates are the biggest contributions to heavy metals in drilling fluids. Although studies have shown minimal environmental impact, substitutes exist that can result in lower chromium levels in muds. The less used chromium lignites (trivalent chromium complexes) are similar in character and performance with less chromium. Nonchromium substitutes are effective in many situations. Typical total chromium levels in muds are 100-1000 mg/1. 

Acid flooding can be successful in formations that are dissolvable in the particular acid mixture, thus opening the pores. Hydrochloric acid is common, in a concentration of 6% to 30%, sometimes also with hydrofluoric acid and surfactants added (e.g., isononylphenol) [130,723]. The acidic environment has still another effect on surfactants. It converts the sulfonates into sulfonic acid, which has a lower interfacial tension with oil. Therefore a higher oil forcing-out efficiency than from neutral aqueous solution of sulfonates is obtained. Cyclic injection can be applied [4,494], and sulfuric acid has been described for acid treatment [25,26,1535]. Injecting additional aqueous lignosulfonate increases the efficiency of a sulfuric acid treatment [1798]. 

Some lignosulfonic acids are used as a tanning auxiliary. The tanning effect is due to the sulfonic acid groups and not to the phenolic hydroxyls in the product there is only about one free phenol group in every third Cg unit in hgnin and many of these may be sterically inaccessible. Leather tanned with lignosulfonates is therefore not water-proof. 

Fig. 1.16 Effect of hydration time on the adsorption of calcium lignosulfonate on C3A hydrates (Rossington).

Table 1.10 Effect of calcium lignosulfonate on C3A reaction (after Chatterji)... 

In the case of lignosulfonate water-reducing agents, the effectiveness in reducing the water-cement ratio diminishes with an increase in either the the C3A or alkali content. In a comparative experiment with three... 

Products based on hydroxycarboxylic acid salts are more effective than lignosulfonates in reducing the water-cement ratio as illustrated in Table 1.15 [75],... 

The recorded data on lignosulfonate water-reducing agents indicate that, as far as freeze-thaw durability is concerned, because of the low water-cement ratios possible, an enhancement to the durability will invariably be obtained. When the admixtures are used to effect a reduction in the cement content, there are strong indications that a considerable enhancement of durability is obtained, presumably due to a reduction in the cement matrix which is the part of the concrete susceptible to frost damage. The higher aggregate content would therefore allow easier dissipation of stresses. 

The data presented in this section illustrate that, with the exception of those accelerating water-reducing admixtures containing calcium chloride, there is an abundance of evidence to support the conclusion that water-reducing admixtures of lignosulfonate chemical form certainly will not accelerate any kind of corrosion with reinforcement and, when used to reduce the water-cement ratio, will form a more permeable and durable protective cover for the reinforcement. In view of the chemical nature of the other types of materials such as the hydroxycarboxylic acids and hydroxylated polymers, it seems most likely that these materials too would have no deleterious effect in this respect. 

Table 1.28 Effect of a lignosulfonate-based water-reducing agent on reinforcement bond under an appiied external voltage (after Kondo)...

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