Influence of the kenaf fiber length on the mechanical and thermal properties of Compressed Earth Blocks (CEB)

International audienceThe association of natural fibers and raw land soil has many advantages (thermal control, sound insulation, mechanical behavior, etc.). However, the major issue with the use of these materials is the lack of knowledge regarding their reliability and durability. In this work, we have evaluated the influence of kenaf fiber length on the mechanical and thermal properties of compressed earth blocks (CEB). Fibers with length 10, 20 or 30 mm were used at mixing rate of 1.2% dry weight of soil; with the aim to enhance the mechanical and thermal properties of CEB fabricated starting from a plastic clayey soil mined in Benin. Analysis of the mechanical behavior of different Soil/Fiber formulations in terms of flexural strength demonstrated the beneficial effect of the fibers. However, the mechanical strength of CEB obtained by immersing fibers till saturation prior to incorporation into the soil greatly diminished. The higher flexural strength was obtained with fibers 30 mm long. The thermal conductivity of CEB decreased when the fiber length was raised. The results showed the real possibility to improve CEB mechanical and thermal properties by using fibers for reinforcement

Influence of the kenaf fiber length on the mechanical and thermal properties of Compressed Earth Blocks (CEB)

International audienceThe association of natural fibers and raw land soil has many advantages (thermal control, sound insulation, mechanical behavior, etc.). However, the major issue with the use of these materials is the lack of knowledge regarding their reliability and durability. In this work, we have evaluated the influence of kenaf fiber length on the mechanical and thermal properties of compressed earth blocks (CEB). Fibers with length 10, 20 or 30 mm were used at mixing rate of 1.2% dry weight of soil; with the aim to enhance the mechanical and thermal properties of CEB fabricated starting from a plastic clayey soil mined in Benin. Analysis of the mechanical behavior of different Soil/Fiber formulations in terms of flexural strength demonstrated the beneficial effect of the fibers. However, the mechanical strength of CEB obtained by immersing fibers till saturation prior to incorporation into the soil greatly diminished. The higher flexural strength was obtained with fibers 30 mm long. The thermal conductivity of CEB decreased when the fiber length was raised. The results showed the real possibility to improve CEB mechanical and thermal properties by using fibers for reinforcement

INSECTICIDAL ACTIVITIES OF ESSENTIAL OILS EXTRACTED FROM THREE SPECIES OF POACEAE ON ANOPHELES GAMBIAE SPP, MAJOR VECTOR OF MALARIA

In this paper, the insecticidal activities on Anopheles gambiae spp of the essential oils (EO) extracted from the dry leaves of some species collected in Benin were studied. The essential oil yields are 2.8, 1.7 and 1.4�0respectively for Cymbopogon schoanenthus (L.) Spreng (CS), Cymbopogon citratus Stapf. (CC) and Cymbopogon giganteus (Hochst.) Chiov (CG). The GC/MS analysis showed that the EO of CS had a larger proportion in oxygenated monoterpenes (86.3�20whereas those of the sheets of CC and CG are relatively close proportions (85.5�0and 82.7�0respectively) with. The piperitone (68.5� 2-carene (11.5� and -eudesmol (4.6�20are the major components of the EO of CS while trans para-mentha-1(7),8-dien-2-ol (31.9� trans para-mentha-2,8-dien-1-ol (19.6� cis para-mentha-2,8-dien-1-ol (7.2� trans piperitol (6.3�20and limonene (6.3�20prevailed in the EO of CG. The EO of CC revealed a rich composition in geranial (41.3� neral (33� myrcene (10.4� and geraniol (6.6� The biological tests have shown that these three EO induced 100�0mortality of Anopheles gambiae to 1.1, 586.58 and 1549 µg•cm-2 respectively for CC, CS and CG. These effects are also illustrated by weak lethal concentration for 50�0anopheles population (CC: 0.306; CS: 152.453 and CG: 568.327 µg•cm-2) in the same order of reactivity. The EO of CC appeared most active on two stocks (sensitive and resistant) of Anopheles gambiae

Antifungal Properties of Pimenta racemosa (Mill.) and Mentha x piperita (L.) Essential Oils against Fusarium oxysporum Causing Tomato Fruit Rot

peer reviewedFungal pathogens are responsible for the rot of tomatoes and cause health hazards to consumers as well as economic loss. The aims of this study were to evaluate the efficacy of essential oils from Pimenta racemosa (Mill.) and Mentha x piperita (L.) leaves as plant-based fungicide against Fusarium oxysporum strains associated with tomato rot. The chemical composition of the essential oils was determined by GC-MS analysis. Antifungal effects of essential oils against strain of F. oxysporum obtained from rotted tomato, were evaluated through the determination of Minimal Fungicide Concentration (MFC) and the Minimal Inhibitory Concentration (MIC). Results indicated that β-myrcene (19.48%), chavicol (15.39 %), and eugenol (46.65%) were the major components of the essential oil of Pimenta racemosa (Mill.). L-menthone (17.19 %), menthol (24.79%), and menthofuran (26.78 %) were the major components of the essential oil of Mentha x piperita (L.). Essential oil of Pimenta racemosa (Mill.) exhibited the highest antifungal activity against the growth of Fusarium oxysporum strain tested with a MIC and MFC of 0.75 and 1.25 μl.ml-1 respectively. These results provide an experimental basis for further research on the use of these plant extracts in the development of eco-friendly preservatives against fungi causing rots of tomato in post-harvest