Abstract:
This study was carried out in order to investigate the effect of binder composition on fresh and mechanical properties of self-compacting concrete (SCC). Total of eight different concrete mixtures have been produced. All mixes had a total binder powder content of 550 kg/m3. One of these was a control mix with only cement and no powder replacement. The other seven had varied percentages (5, 10, 27, and 36 per cent) of fly ash (FA), silica fume (SF) and limestone powder (LP) replacing Portland cement in the mix. In the fresh state, mixes were tested according to the self-compactability criteria tests; such as flow table, Utube, V-funnel, L-box and visual segregation rating. The mechanical tests consisted of compressive strength, splitting tensile strength, lollipop pullout. Another set of results was obtained from pullout, compression, ultrasound, and rebound hammer tests applied on specimens sawn from different sections of full size columns (10x20x200 cm). The cut surfaces of these columns also allowed the investigation of variations in concrete microstructure with changing depth along the column length. The concrete-steel interface was also examined using video-microscope techniques. The durability properties were assessed using water absorption, sorptivity, rapid chloride permeability, deicing salt scaling, carbonation, sulfate resistance and drying shrinkage tests performed on different number of specimens for each mix. In the fresh state, all the mixes exhibited satisfactory self-compactability and resistance to segregation which was also credited for the homogeneity of the full size columns properties. The results showed that the combined use of SF and FA replacement of cement improved the mechanical and durability properties of the SCC, where as the LP especially in large percentages reduces these properties. The only exception is the drying shrinkage, which is reduced by LP and increased by SF replacement of cement.
