Journal of Building Materials and Structures

Number 2, 2014

40-46
Effect of the heat curing on strength development of ultra-high performance fiber reinforced concrete (UHPFRC) containing dune sand and ground brick waste

Authors: Brahim Safi, Amel Aboutair, Mohammed Saidi, Youcef Ghernouti, Chahrazade Oubraham

Abstract

View in PDF

Number of views: 645

This work aims to investigate the strength development of ultra-high performance fiber reinforced concrete (UHPFRC) containing ground dune sand (GDS) and ground brick waste (GWB) as a substitutions of cement and dune sand (DS) as an aggregate. The variables are the nature of addition (GDS and GWB) in the binder and the heat curing at different temperatures (20°C and 60°C) at 7 days of curing. Two temperatures 20°C and 60 °C were applied to samples with intermediate levels for 8 hours in total. In this study, two types of cements (CEMI and CEMII) were used to prepare UHPFRC. The GWB was replaced by GDS at levels of 10, 20 and 30% by weight. The results show that the obtained concretes develop a high mechanical performance with a suitable heat treatment according to the cement type and the used fiber. The compressive strength at 7 days of UHPFRC has increased with heat curing (at 60 °C) compared to that obtained at 28 days and measured at 20 °C. Results show also that values of compressive strength of concrete containing DS are close to those obtained by the control concrete. This study has showed that the dune sand can be used in UHPRC, and that the substitution of the GWB by GDS can provide concretes with acceptable mechanical performance.

47-57
Strengthening of concrete beams by CFRP: Experimental study and finite element analysis

Authors: Youcef Ghernouti, Bahia Rabehi, Ali Benhamna, Adda Hadj Mostefa

Abstract

View in PDF

Number of views: 742

This work presents an experimental study on the mechanical behavior of structural concrete reinforced by carbon fiber reinforced polymer (CFRP). The main purpose of this study is to test the applicability of this method of reinforcement in the beams to improve the behavior of concrete: strength and ductility. An experimental characterization of mechanical behavior by tensile test by three point bending is achieved, namely, the reinforcement of the lower part of the beam (15x15x75) cm3 with composite material, Based on the ANSYS simulation, a model was developed to validate the different results obtained experimentally. The experimental results show that the reinforced concrete offered a great improvement in strength and ductility; in effect an influence directly on the failure mode is observed and then read by the value of strength and ultimate deformation. The tensile bending of beams reinforced by CFRP is more than 295% in comparison with that of non-reinforced beams. The gain maximum of ductility is 247%. The experimental results have been compared with the theoretical models, a good correlation was obtained.

58-64
Thermophysical characterization of earth blocks stabilized by cement, sawdust and lime

Authors: Sylvere Azakine Sindanne, Guy Edgar Ntamack, Roger Pierre Lemanle Sanga, Claude Armand Moubeke, Eric Sylvain Kelmamo Sallaboui, Hamid Bouabid, Khalifa Mansouri, Saad Charif D’ouazzane

Abstract

View in PDF

Number of views: 731

Several buildings throughout the world are built with blocks of compressed and stabilized ground. These blocks do not commonly have the same thermal properties necessary for their use. If the incorporation of stabilizer in these blocks like lime or cement increases the mechanical properties, it is not the case for the thermophysical properties. In this paper, the evolution of the thermal properties of earth blocks according to the rates of stabilizer and their nature was discussed. The experimental method of “hot iron” was applied. Results indicate that thermal conductivity increases when percentages of cement and lime increase. However, it decreases when the rates of the sawdust increase. Moreover, thermal resistance decreases according to the percentages of lime and cement, and increases according to the percentages of the sawdust.

65-76
The effect of hybrid steel fiber on the properties of fresh and hardened self-compacting concrete

Authors: Haddadou N, Chaid R, Ghernouti Y and Adjou N

Abstract

View in PDF

Number of views: 623

Self-compacting concrete (SCC) offers several economical and technical benefits, the use of steel fibers extends its possibilities. This study was performed to compare the properties of SCC and fiber reinforced self-compacting concrete (FRSCC) with high volume of mineral addition. Six mixtures were elaborated in this study. The content of the cementitious materials and the water/cementitious materials ratio were kept constant, 500 kg/m3 and 0.34 respectively. The self-compacting mixtures have been prepared with a cement replacement of 30% by weight of marble powder. Two different types of steel fibers were used in combination with different lengths (50 mm and 30 mm), keeping the total fiber content constant at 60 kg/m3. Slump flow time and diameter, sieve stability, and L-Box were performed to assess the fresh properties of the SCC and FRSCC. Compressive strength, splitting tensile strength, flexural strength and ultrasonic pulse velocity were determined for the hardened properties. A marginal improvement in the ultimate strength was observed. The addition of steel fiber enhanced the ductility significantly and the results indicated that high-volume of marble powder can be used to produce FRSCC, even though there is some decrease in the compressive strength because of the fiber geometry which affects the properties of SCC mixtures not only in the fresh state but also in the hardened state.