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This study introduces the results of an experimental investigation on the behavior of the circular columns of concrete under a load of axial compression, confined by an envelope of composite materials (carbon fiber and glass fiber). The composite used is a FRP glued in surface with epoxy resin. The specific objectives of this study are: verifying the applicability of this method of reinforcement of the columns to improve the behavior of concrete from the point of view strength and ductility, seeing the influence of composite materials type used, and confronting the experimental results acquired with different models developed on one hand and on the other hand with empirical formulas developed by other researches. Two models were developed to represent the structural behavior of the tested samples based on the calibration of the experimental results and criterion of Mohr—Coulomb failure. The validity of the results acquired numerically is based on a comparison with experimental results as well as with empirical formulas developed.

The aim of this study is to explore the possibility of recycling a waste material that is now produced in large quantities, while achieving an improvement of the mechanical properties and durability of the mortar. This study examines the mechanical properties and the durability parameters of mortars incorporating plastics bag wastes (PBW) as fine aggregate by substitution of a variable percentage of sand (10, 20, 30 and 40 %). The influence of the PBW on the, compressive and flexural strength, drying shrinkage, fire resistance, sulfuric acid attack and chloride diffusion coefficient of the different mortars, has been investigated and analyzed in comparison to the control mortar. The results showed that the use of PBW enabled to reduce by 18-23 % the compressive strength of mortars containing 10 and 20 % of waste respectively, which remains always close to the reference mortar (made without waste). The replacement of sand by PBW in mortar slows down the penetration of chloride ions, improves the behavior of mortars in acidic medium and improves the sensitivity to cracking. The results of this investigation consolidate the idea of the use of PBW in the field of construction.

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This paper presents the results of an experimental study which investigates the effect of the use of marble powder (MP), as partial cement substitution, on the fresh and hardened properties of fibre-reinforced self-compacting concrete (FRSCC) of nonuniform size (length) and aspect ratio of fibres used. For each length of steel fibre (25, 30 and 50 mm), three percentages (.5, .8 and 1%) were used to improve the performance of FRSCC. All mixtures of concrete specimens prepared with 30% of MP were evaluated. Slump flow time and diameter, sieve stability and L-Box were performed to assess the fresh properties of the (FRSCC). Compressive strength, splitting tensile strength, flexural strength and ultrasonic pulse velocity of the FRSCC and self-compacting concrete (SCC) were determined for the hardened properties. The results were compared with ordinary concrete (without steel fibre) containing 30% of MP (SCC). The results suggest that the incorporation of steel fibre in the SCC requires the use of high volume of superplasticiser to overcome the workability loss resulting from the elongated shape and large surface area of fibres. The sieve stability, Slump flow diameter, L-Box and Slump flow time for RSCC dropped to 1, 10, 12 and 65%, respectively. The workability loss is significant in the case of 1% and 50 mm length fibre which revealed the highest length and percentage. On the other hand, the use of steel fibre and MP has a significant effect on the mechanical performances. The increase in ultrasonic pulse velocity, compressive strength, splitting tensile strength and flexural strength reaches 2, 8, 16 and 29%, respectively. The addition of fibre enhanced the ductility significantly. The optimum volume fraction and aspect ratio of fibre for better performance in terms of strength was found to be .8% and 30 mm, respectively. The results indicated that high volume of MP can be used to produce FRSCC.