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High development of civilisation leads to incremental growth of produced municipal wastes. Despite of introducing restrictions related to municipal selective waste management still great amount of wastes is being landfilled. In countries like India or Philippines engineers started to utilize plastic wastes in extraordinary way using it as an alternative aggregate in cementitious composites. Many researchers tried to improve properties of concrete containing artificial aggregate. This paper analyses various treatment of PET flakes before adding to the mortar mix. Main aim was to modify the surface of PET flakes in order to obtain improved adhesion between artificial aggregate and cement matrix. Mortar mixes contained boiled, stored in alkali and acid solutions and regular plastic particles. This paper presents the results of flexural and compressive strength after 28 days and SEM analysis. Replacing natural aggregate in mortars with 5% PET flakes resulted in decreasing the compressive strength by 7%. Although the surface of PET flakes modified by alkali and acid solutions appeared to become rougher there was no improvement in compressive strength, moreover decreased in comparison to control sample. [ABSTRACT FROM AUTHOR]

The rheological properties of fresh ordinary concrete are closely affected by temperature and time. The paper presents the study of consistency of fresh concrete mixtures made with Portland cement and cement with calcareous fly ash. Two types of admixtures were used. It was proven that the temperature has a clear effect on workability and compressive strength concrete. Influence on workability can be reduced by selecting the appropriate superplasticizer and cement. [ABSTRACT FROM AUTHOR]

The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting. [ABSTRACT FROM AUTHOR]

The paper presents a study on self-compacting concrete with two types of steel fibres. Under consideration was the effect the method of forming of beam elements has on the distribution of steel fibres. Formed we beams of dimensions 120×15×15 cm3 and 180×15×15 cm3. The self-compacting mixture contained steel fibres of varying lengths (35 and 50 mm) and varying levels of their volume ratio in the mix (0.5% - 1.0% - 1.5%). [ABSTRACT FROM AUTHOR]

The paper presents an analysis of cross-sections of beams made of Steel Fiber Reinforced High Performance Self-Compacting Concrete (SFRHPSCC). The analysis was performed by two methods, using our own computer program (destructive method), and computed tomography (non-destructive method). Statistical analysis showed that the orientation of the fibers exhibit exponential distribution. The tests confirmed the correct formation of concrete, maintaining the uniformity of steel fibre distribution. [ABSTRACT FROM AUTHOR]