This study aims to analyze the possibility of valorizing rubber waste in roller-compacted concrete pavement (RCCP) mixes as aggregates. The rubber particles were added to the mix as partial replacement of the total volume of gravels at different rates (5, 10, 15, 20, 25, 30%). The experimental approach followed in this research consisted of studying the effects of the incorporated rubber on the mechanical properties of RCCP. The obtained results show that the incorporation of rubber changes the behavior of RCCP mixes. In presence of rubber, the RCCP became more ductile. The principal disadvantage of rubber incorporation was the decrease in the mechanical properties of RCC. To remedy this problem, the rubber particles were subjected to a treatment and silica fume was added to the mix. The obtained results showed that the performance of RCCP can be improved by modifying the surface roughness of rubber particles. Therefore, a large part of strength losses were corrected.
This paper reports on an experimental investigation using either rubber aggregates or steel fibres recycled from waste tires in the production of self-consolidating concrete composite (SCCC). Ten mixes are designed, one of them is the reference concrete. The natural aggregates are substituted by rubber particles by volume at 5, 10, 15, 20 and 30%. Recycled steel fibres are separately added to SCC mixes at volume fraction of 0.5, 0.8, 1 and 1.5%. The tested rheological properties of SCCC are slump flow diameter, T500 slump flow time, V-funnel flow time, L-box ratio, and the segregation resistance test. The compressive strength, the flexural strength, and total shrinkage are also measured on the 28 days. The experimental results show that the addition of recycled steel fibre is favorable for the SCC by means of increasing the flexural strength and reducing the shrinkage and the risk of cracking. Keywords: Self-consolidating concrete composite; Waste tires; Rubber; Steel fibers; Rheology, Strength
The present work is aimed mainly to investigate and compare the antibacterial activities of methanolic, diethyl ether and ethyl acetate extracts of retama on Escherichia coli, Salmonella, Proteus mirabilis and Staphylococcus aureu using well difusion method.The results of study showed a significant effect on all bacterial species except Proteus mirabilis. The preliminary test of retama constituents revealed the presence of active material : Resins, Volatil oils, Coumarins, Terpenes, Phenols, Tannins, Alkaloids, Saponins, Cardiac glycosides, and Flavons. The highest Inhibition rate of Salmonella is 16 mm at the concentration 100 mg/ml, while the lowest inhibition rate was 8 mm for Escherichia coli at concentration 1 mg/ ml in methanolic extract. The results obtained in the present study suggest that the retama stalks (broom broom) can be used in treating deseases caused by the tested organisms. Further chemical and pharmacological investigations may be carried out to isolate and identify the chemical constituents in the selected plants responsible for the antimicrobial activity.
Used tyre rubber wastes present a serious environmental problem of pollution and storage. The recycling of this waste in the industry of construction could be an appropriate solution to produce an eco-concrete and could contribute to the improvement of some of its properties. This paper aims to study the possibility of using tyre rubber waste as fine aggregate replacement in self-compacting concrete (SCC). Fines rubber particles of 0-2 mm of waste tyres were added SCC mixtures as a partial substitution of the total volume of sand at different percentages (5, 10, 15, 20 and 30%). The influence of fines rubber of used tyres on fresh and hardened properties of the SCC was investigated. The fresh properties of SCC were performed by using slump-flow, T50 flow time, L-box, V-funnel and segregation resistance tests. Characteristics of the hardened state were obtained by compressive strength and thermal conductivity. The experimental results showed that the inclusion of fines rubber in SCC decreases the workability, reduced its passing capacity and increases the possibility of blocking. A decrease in compressive strength is observed with the increase in rubber content. On the other hand, the incorporation of the rubber fines aggregates enhances in a remarkably way the thermal conductivity.
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