Self-compacting concrete (SCC) is undoubtedly a promising ecological cement matrix composite of new generation. However, it is not easy to achieve the required combination of properties in fresh SCC mixes. SCC is also particularly sensitive to any changes in the laboratory and at the job site. Choice of constituents for SCC, especially cement and superplasticiser which are able to collaborate in the correct way, has a signi-1279;cant effect on SCC performance. In this investigation considered in qualitative way, four cements, varying in physical and chemical properties and phase composition were used to check their compatibility with a new generation superplasticiser, taking into account the properties of fresh and hardened self-compacting concretes. Results revealed some differences although it is impossible to answer de-1279;nitely which cement performs with the superplasticiser in the best way.
INVESTIGATION OF THE TIME AND SPATIAL MACRO-SCALE OF TURBULENCE IN A COMPOUND CHANNEL
Autor
Adam P. Kozioł
Pages
15–23
Keywords
open channel, compound channel, turbulence, eddy, measurements
Abstract
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Investigations of the time and spatial macro-scale of the present paper are based on the measurements of instantaneous velocities in a two-stage trapezoidal channel under three various depth in the channel. These investigations have shown the following: the values of time macro-scale have changed in range since 0.07 to 1.15 s; in all three tests the distributions of the sizes of the eddies reveal stable regularity; the relative length of eddies are bigger on the flood plains and achieve value of 0.1 to 2.5 of the flow depths on the flood plains, whereas in the main channel the sizes of largest eddies do not exceed the value of 1 of the total water depth.
INFLUENCE OF USE OF VARIOUS METHODS TO ESTIMATE INSTANTANEOUS UNIT HYDROGRAPHS (IUH) ON THE ACCURACY OF EVALUATION OF PARAMETERS FOR AN URBAN CATCHMENT
Autor
Kazimierz Banasik, Anna Sikorska
Pages
25–39
Keywords
rainfall-runoff process, urban catchment, IUH, Nash model, Służew Creek in Warsaw
Abstract
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The main goal of this article was comparison of estimated Instantaneous Unit Hydrograph – IUH calculated with four methods: on the basis of recorded data, SCS formula, with Rao, Delleur and Sarma equations and hydrological analogy with the use of IUH transformation from the adjoining stream gauge. The object of case study was Służew Creek catchment, located in Warsaw (Poland). The IUH based on the Nash model was used to transform effective rainfall into direct runoff, moreover the comparison of four methods was based on Nash model characteristics: tp – time to peak of IUH, and up – peak of IUH, estimated for each method. The measured IUH has been chosen as a reference standard of IUH for the others methods. Conducted analysis has shown that IUH estimated with the use of Rao, Delleur and Sarma equation has been the closest one to measured IUH. Therefore, in situation of limited information, this method could be useful to calculate and predict flood flows in urban catchments with relation to designing hydro-engineering objects.