Use of synthetic resins for grouting when repairing structures and performing antiseepage and strengthening works

Abstract

Technologies of grout sealing and strengthening of soils and concretes by synthetic resins -epoxy and polyurethane -have become widespread during the past 10-20 years in world construction practice. For example, the technology of structural restoration of concrete (SCB) by injection of epoxy resins made it possible to restore the concrete structural members of coke ovens without extinguishing them in the Netherlands. The use of polyurethane foams for soil stabilization at coal mines in Germany, Japan, and other countries, including the Commonwealth of Independent States, is displacing traditional methods of supporting mine workings. The "Podur" technology is being used successfully by the Soletanche company for repairing a number of concrete dams in European countries. Our own specialists successfully used epoxy resins for repairing structures of the Volga-Baltic canal as far back as 1967-1971. Many research and industrial institutions of our country are engaged in problems of the synthesis, study, and use of epoxy and polyurethane resins. Polyurethane foam (PUF) materials PUF-328 and PUF-329 were developed by the "Polimersintez" research and industrial association (by I. R. Metlyakova) for strengthening weakened rocks by the grouting method. The consumption of polyurethanes for strengthening mine workings at Donbas mines was at the level of 3500 tons/yr in 1985-1990 [1].Experience in the area of the synthesis and use of hydrophilic isocyanate prepolymers [2] showed that by manipulating a limited quantity of initial substances (hydrophilic polyether, isocyanates) it is possible to obtain a broad spectrum of hydrophilic urethane-isocyanate oligomers able to form polyurethane ureas with hardening by a large but not strictly controllable quantity of water. The hydrophilic polyurethane foams of the Aquisol type created by our specialists on contact and mixing with water (including with ground and seepage waters) react with it, "solidify" the water, and in so doing increase in volume (due to liberation of gas during the reaction). The degree of expansion of the chemical foam forming reaches 5-30 (100) depending on the type of PUF material, relationship with water, and certain other factors. The use of analogous American-made PUFs on the Buchanan dam [3] was extremely effective. After numerous and ineffective attempts to reduce seepage on this dam over the course of many years, an effective method of eliminating seepage by injecting solutions foaming on mixing with water was found and realized. It was established that the foamed solution has great flexibility, mobility, and seals joints and cracks well despite their periodic opening and closing in accordance with the temperature and shrinkage deformations in the dam.At present considerable experience has been gained in using PUFs on many objects in our country and abroad. An analysis of this experience indicates that it is quite effective and economical in the case of grouting in media where the pressure of the ground and seepage waters is within limits up to 0.3-0....

Experimental Study of Epoxy Resin Repairing of Cracks in Fractured Rocks

“…The strength reduction ratio of strength is depended by the proportion of mixing water. Although numerous studies have been conducted concerning the application of epoxy grouts for cracks repairing in fractured rocks 8,12 , there is not clearly about the efficacy of epoxy resin grouts on fractured rock strengthening and especially on the filling situation of epoxy grouts in cracks and pores.…”