Experimental analysis of Pressed Adobe Blocks reinforced with Hibiscus cannabinus fibers

WOS:000331424400009International audienceThere is an intense on-going search for less polluting materials and technologies, which consume little energy in their production, construction and/or utilization. Attention of the researchers has turned to materials, which found applications in engineering in pre-industrial times: local vegetable fibers and earth composites are one of the promising materials. This paper presents the results of an investigation in establishing the physical and mechanical properties of Hibiscus cannabinus fibers which have been used in the fabrication of Pressed Adobe Blocks (PABs). The PABs have been reinforced with 0.2-0.8 wt.% of 30 mm and 60 mm lengths of H. cannabinus fibers. The microstructural characteristics of the PABs composites were investigated using X-ray diffraction (XRD), thermal gravimetric analyses (TGA), scanning electronic microscopy (SEM) and video microscopy. It was established that the addition with 0.2-0.6 wt.% of 30 mm long fibers reduced the dimensions of the pores in the PABs with the improvement of their mechanical properties. However, the addition of 0.8 wt.% of 60 mm fibers had negative effects on the compressive strength. The elaborated Pressed Adobe Blocks specimens were suitable as building material with contribution for thermal comfort. (C) 2013 Elsevier Ltd. All rights reserved

Formulation of low cost eco-repair mortar based on dune sand and Stipa tenacissima microfibers plant

Mortar for patch repair of damaged concrete elements by corrosion or honeycombing are extensively used. However, they are quite expensive and they frequently incorporate low volume of synthetic fibers. This paper presents an experimental study on the development of an eco-repair mortar based on dune sand and microfibers plant. The vegetable fibers are 3–5 mm long Alfa microfibers plant (Stipa tenacis-sima L.) and are used with different volume ratios. The physical and mechanical properties are compressive strength, flexural strength, shrinkage and bonding strength. The durability of mortar was evaluated through gas permeability and capillary water absorption tests. The results obtained show an enhancement of the mechanical and physical properties of mortars with natural microfibers compared to those of mortars without natural fibers. A lower sorptivity and a lower gas permeability were also obtained for the repair mortar reinforced with microfibers plant

Behavior of FRP Bars-Reinforced Concrete Slabs under Temperature and Sustained Load Effects

The large temperature variation has a harmful effect on concrete structures reinforced with fiber reinforced polymer (FRP) bars. This is due to the significant difference between transverse coefficient of thermal expansion of these bars and that of the hardened concrete. This difference generates a radial pressure at the FRP bar/concrete interface, and may cause splitting cracks within concrete. This paper presents results of an experimental and analytical study carried out on FRP-reinforced concrete slabs subjected, simultaneously, to thermal and mechanical loads. The analytical model based on the theory of linear elasticity consists to evaluate combined effects of thermal and mechanical loads on the transverse expansion of FRP bars. Parameters studied in this investigation are the concrete cover thickness, FRP bar diameter, and the temperature variation. The thermal cycles were varied from −30 to +60 °C. Comparisons between analytical and experimental results show that transverse strains predicted from the proposed model are in good correlation with experimental results