Water Resistance Of Samples Research Articles

Study on properties of foamed concrete with EPS as coarse aggregate

Foamed concrete was prepared using lightweight coarse aggregate (EPS) and composite cementitious materials consisting of flue gas desulphurization gypsum (FGD), fly ash (FA), ordinary Portland cement (OPC) and steel slag (SS). The effects of activator and epoxy resin on mechanical properties, thermal conductivity and water resistance of samples were researched and analysed. The experimental data indicated that density of samples was chiefly affected by EPS and epoxy resin. The flexural strength, compressive strength and water resistance could be improved by the addition of activator. Moreover, epoxy resin played a beneficial role in improving mechanical properties, thermal insulation performance and water resistance due to the improvement of pore structure.

Preparation of porous silica nanocomposites from montmorillonite using sol-gel approach

The object of research is montmorillonite, which due to its properties and structure shows high sorption characteristics. However, the significant barrier to its use in industrial water purification technologies is the tendency of montmorillonite to be self-dispersed in aqueous solutions on elementary structural layers and to form stable suspensions. It creates difficulties with separating the solid and liquid phases after the sorption process. The authors used the sol-gel method for the synthesis of nanocomposite materials based on montmorillonite using tetraethoxysilane as a gelling agent. The synthesis involves the hydrolysis reaction of tetraethoxysilane and the subsequent polycondensation of silica molecules with hydroxyl groups of montmorillonite. The obtained samples inherit good sorption properties from a layered mineral and a solid frame structure from silica. Such a structure of synthesized nanocomposites is ensured by the presence of siloxane bonds, which help to bound together the elementary particles of montmorillonite. This, in turn, improves the water resistance of samples. Based on the results of rheological studies, it has been shown that the basic processes of the structure formation in the initial water-alcohol suspensions of the hydrolysis products of tetraethoxysilane and montmorillonite occur at a concentration of 1 % silica, which is due to the colloidal and chemical properties of the investigated systems. It has been shown that the treatment of montmorillonite with tetraethoxysilane hydrolysis products leads to the formation of a material with lower ability to swell and with better separation of liquid and solid phases. The optimum content of silica in the sample, which is in the range of 0.1 to 14 %, makes it possible to reduce the optical density of solutions by 2.5 times compared with the original montmorillonite. It has been shown that the synthesized materials retain a sufficiently high sorption capacity to remove the cationic dye methylene blue (up to 158 mg/g), which rises with increasing clay mineral content. And has been having a higher selectivity (up to 3.4 dm 3 /mg).

THE EFFECT OF WEATHERING ON VARIOUS ROTPROOFING TREATMENTS APPLIED TO COTTON TENTAGE DUCK

Cotton tentage duck treated with ferric oxide–chromic oxide ('mineral khaki'), copper carbonate–ferric oxide ('copper–iron'), cuprammonium, cutch–cuprammonium, copper 8-quinolinate, copper glyoxime, 2,2′-dihydroxy-5,5′-dichlorodiphenylmethane, zinc dimethyldithiocarbamate, copper naphthenate, copper hydroxynaphthenate, zinc naphthenate, and mercuric naphthenate, showed varying degrees of breaking strength loss when subjected to outdoor weathering during the summer months. The losses were in no case greater than that of the untreated fabric, and certain treatments, such as mineral khaki and cutch–cuprammonium, gave considerable protection against loss in breaking strength. With copper naphthenate, copper hydroxynaphthenate, and mercuric naphthenate the degree of chemical degradation as measured by cuprammonium fluidity was somewhat greater than that of the untreated fabric. The presence of a waterproofing treatment consisting of a mixture of petroleum-base waxes in addition to the rotproofing treatments usually resulted in increased breaking strength loss. The water resistance of the waxed samples showed a slight to pronounced increase on weathering. In general there was considerable loss of rotproofer as a result of weathering; with the copper compounds this loss was of the order of 37 to 90%, but was reduced to 6 to 44% by the presence of wax. Weathering produced an almost complete loss of the two zinc compounds, 2,2′-dihydroxy-5,5′-dichlorodiphenylmethane, and mercuric naphthenate. Losses of metal from chromium–iron proofings were negligible even in the absence of wax proofing. The degree of rot resistance as judged by soil burial was greatest in the fabrics treated with copper, and was increased by the presence of wax. The water resistance of samples subjected to soil burial was frequently decreased before the occurrence of any marked loss in breaking strength; this indicates microbiological attack on the wax coating prior to attack on the cotton fabric.