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This article reports on a new composite gypsum binder (CGB) with nanostructured silica-based admixture (NSS). NSS is obtained by a wet ultrafine milling of quartz sand resulting in the formation of an inorganic polydisperse binding system, which has a high concentration of active nanoscale phase (about 10%). Developed CGB contains hemihydrate gypsum and nano-component based on quartz sand. It is observed that the addition of 15–20 % of NSS improves the rheological properties of gypsum systems through the formation of solvate shells hindering the access of water to gypsum particles; this process also retards the setting of binder.The experimental program used infrared IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) to reveal the contribution of NSS. The porosity of CGB is analyzed by the kinetics of water adsorption and BET. The XRD and IR investigations determined the formation of a new sulfosilicate phase, hydroxyellestadite during the hydration of CGB. With the addition of NSS an overall reduction in pore volume, as well as the shifts in macro-, meso- and nano- porosity values are observed.Analysis of CGB microstructure reveals that in the presence of the NSS the size and morphology of crystals are changed contributing to the formation of dense fine-grained structure. Experimental studies have demonstrated that the composite gypsum binders with NSS are characterized by reduced water absorption and increased density, as well as improved mechanical performance especially, higher compressive strength.

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Many of the aqueous drilling muds used in the field are prepared with bentonite and treated with sodium hydroxide and quebracho. In view of limitations of published literature on such systems, extensive tests were conducted to show the effects, singly and in combination with each other, of sodium hydroxide and quebracho in a 4.8% SUBpension of bentonite. In addition, this study summarizes the eKect of sodium chloride, which is frequently encountered as a contaminant, and of sodium carboxymethylcellulose, which is used to achieve low water-loss values and to facilitate control of the physical properties.QUEOUS drilling fluids for field operations are generally pre-A pared by the addition of clays to water. Of the clays used in preparing muds, bentonite is the most common. This clay is also introduced into the mud during penetration of certain shales. Because of its highly colloidal nature, it is of particular value in producing systems having a low water-loss value. To achieve water-loss values even lower than those that may be obtained with clay suspensions, various additives, usually organic materials of high molecular weight (gums, starches, cellulose, and their modifications), have been employed.In addition to treatment for control of water loss, a treatment is necessary for control of the rheological properties-viscosity and gel strengths. To control these properties, several alternatives are available. One, dilution with water, is applied particularly when the solids content of the mud is high. This procedure is not universally applicable, because the dilution reduces the density of the mud and may involve expenditure of an excessive amount of weighting agent. A second alternative is to treat the mud with the so-called "viscosity reducers." The chemicals most frequently added for this purpose include sodium silicate, phosphates, quebracho (tannates), and products related to the tannates.In the treatment of aqueous drilling fluids the effect of contamination due to electrolytes which may be introduced during drilling must be known. Of these sodium chloride, calcium sulfate, and cement are the most common: Despite the numerous problems pertaining to these contaminants, a survey of the literature revealed that much of the information is limited or general rather than specific in nature. This may in part be attributed to the fact that each operation involves a mud that is slightly different from that involved in another operation; and the problems with each system are different. However, as a result of various studies in this laboratory, it appeared highly desirable to obtain extensive information on the most common treatments which are used to control the physical propertieswater loss, viscosity, and gel strengths-and to study the effect of electrolytes on these treatments. In order to utilize the results of this study most fully, the experiments were conducted with a simple system-a 4.8% suspension of bentonite-because this clay is usually present in field muds. This report covers that part of the study relati...