The study attemps to determine the optimal recipes based on cement, fly ash and two superplasticisers of new generation which would be able to fulfill space between the pipes in renovation of pipelines by relining. Inject recipes were selected taking into account the most favourable rheological properties of injects. There were flow time from the viscometer, time of spread at the distance of 100 cm, time needed to achieve the maximum spread. Moreover, initial setting time, shrinkage and compressive strength after 28 days were determined. It was found that the type and amount of superplasticiser and cementto-fly ash ratio affect the rheological properties of the injects. Relatively easy laboratory methods used for measurements of rheological properties made it possible to select optimal recipes of injects which in technical scale fulfill space between the pipes successfully.

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