Adhesion in repair systems is one of the most important factors affecting their durability. Elaboration of a reliable nondestructive test method to perform an adhesion mapping is one of the most important tasks. A majority of NDT methods applicable for the assessment of concrete structures are based on the propagation of various types of stress waves. In this paper, the influence of the repair material type (polymer-cement or polymer) and quality of the concrete substrate (roughness, microcracking, not cleaned surface) upon propagation of stress waves in a repair system was studied in view of developing a reliable NDT procedure for the field assessment of bond quality in concrete repairs.
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In the field experiment no relation between organic matter content (0-83%) in substrates provided and Chironomus plumosus (L.) abundance was found. Numbers of larvae and their age structure were usually similar on the mineral substrate and various bottom sediments but sometimes differed up to 2-3 times (at the same site and date of sampling); there was howerver no correlation with the quality of substrate. This indicates that the feeding of Chironomus plumosus did not depend on the bottom deposit the larwae lived in, but mostly on sedimenting tripton, which formed a thin layer on the top of substrates provided. Also mutual relations of individuals and the period of exposure of the sediment (from 3 weeks to few months) did not matter. Very high abundance of Ch. plumosus (up to 90 thousands ind. m^-2) found already after 3 weeks exposition in the sediment initially without that species indicates a very high growth potential of the Chironomus population at the study site.
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