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Abstract

Moisture-sensitive or collapsible soils are materials with high porosity that under the loads transmitted by the superstructure or even under its own weight present additional settlements once the soil is saturated. This category includes loess deposits and other high silt content soils with uneven porosity. A method often used for foundation on these soils is the realization of local loessoid material compacted columns. This paper presents, on one hand, the experimental laboratory programs aiming to achieve some optimal mixtures of local material (loess) and different other materials (sand, bentonite, cement) in order to improve the values of the mechanical parameters of the soil and so, to limit the settlements. On the other hand, it presents a lot of settlement calculations for different case scenarios.

Abstract

One of the main threats to constructions made from rammed earth is destruction due to exposure to water. The way to limit this dangerous phenomenon is to supplement the local soil mixtures with stabilizing agents. The main component used is Portland cement. This article analyses the results of research which focused on the resistance of rammed earth to water erosion. Because of the lack of national standards regarding the method of examining the durability of rammed earth, the research was based on the New Zealand standard NZS 4298: 1998. The results confirm the possibility of using rammed earth stabilized by cement in a temperate climate.

Abstract

Here we describe the effects of the well-characterized, commercial plant growth-promoting rhizobacteria (PGPR) strain Pseudomonas sp. DSMZ 13134 (Proradix®) on plant growth, root morphology, and nutrient acquisition of a maize mutant (rth2) with impaired root hair production as compared with the corresponding wild type line, to study the importance of root hairs for the interaction of the PGPR strain with the host plant. The study was conducted in rhizobox culture with a sand–soil mixture and moderate P supply. Root hair development of the mutant was clearly impaired, reflected by slower growth and limited elongation as compared with the wild type line. This defect was compensated by more intense root growth and fine root production of the mutant which was particularly expressed after inoculation with Proradix®. By contrast, PGPR inoculation had no effect on root hair length. The beneficial effects of Proradix® on root growth were reflected in higher shoot contents of the macronutrients P and K. Interestingly, negative effects on shoot accumulation of the micronutrients Zn and Cu were observed. These findings support proposed PGPR effects of this strain but also show limitations that may be explained by additional strain-specific properties. Possible implications of these findings are discussed.

CBR Test”, Journal of Civil Engineering Research 2 (1): 34-40, 2012. [11] Fabio Santos, Lin Li, Yadong Li, Farshad Amini, “Geotechnical Properties of Fly Ash and Soil Mixtures for Use in Highway Embankments” in Proc. of the World of Coal Ash (WOCA) Conference, Denver, USA: 125-136,2011. [12] IRC 37: 2001: Guildelines for the Design of Flexible Pavement. [13] IRC: SP 58: 1999: Bureau of Indian Standards: Guidelines for Use of Fly Ash In Road Embankments. [14] IS: 2720:2001: Bureau of Indian Standards: Methods of Test for Soils. [15] A. Marto, A.R. Awang, A.M. Makhtar

percentages of thermally treated clay and 6% lime. Distilled water was used in the mixtures. The soil mixtures, with or without additives, were thoroughly mixed for 1 h prior to compaction. v) Free swelling and swelling pressure of the soil mixtures were measured using the oedometer device in accordance with ASTM D4645 [ 17 ] and ASTM D2435 [ 18 ]. The samples were compacted in the ring of the oedometer device according to the maximum dry unit weight ( γ dmax ) and optimum water content ( W opt ) obtained from the standard proctor compaction test. Distilled water was added

. Mamatha, P. Soumyashree, N. Sushyam, T. P. Bharatha, and R. W. Vivekan, “Laboratory characterization of tyre crumbs soil mixture for developing low cost damping materials,” IJEE 4(6), 63–66(2011). Anbazhagan P. Mamatha M. Soumyashree P. Sushyam N. Bharatha T. P. Vivekan R. W. “Laboratory characterization of tyre crumbs soil mixture for developing low cost damping materials,” IJEE 4 6 63 66 2011 [6] M. Ehsani, N. Shariatmadaria, and S. M. Mirhosseini, “Experimental study on behavior of soil-waste tire mixtures,” Scientia Iranica. Transaction A, Civil Eng 24(1), 65

. Effects of chitosan soil mixture treatment in the seedling stage on the growth and flowering of several ornamental plants, J. Jpn. Soc. Hortic. Sci. , 2004, 73(1), 66. Ohta K., Suzuki M., Matsumoto S., Hosoki T., Kobayashi N. Effect of nitrogenous organic compaunds on growth and flowering in Eustoma grandiflorum, HortScience , 2004, 39(1), 1438. Du, C., Zhou, J. Supported slow-release fertilizer and its preparation process, CN 1470485, China, 2004. Cho, Y. J. Production of chitosan for coating slow release chemical fertilizer and coating method, KR 2003058804, S

. - Hussain, M. (2012) Lime stabilization of soils: Reappraisal. Journal of Materials in Civil Engineering, ASCE, 24, 707-714. Degirmenci, N. - Okucu, A. - Turabi, A. (2007) Application of phosphogypsum in soil stabilization. Building and environment, 2007, 42(9), 3393. Herrin, M. - Mitchell, H. (1961) Lime-soil mixtures. Bulletin No. 304, Highway Research Board, Washington, D.C., 99-138. Hilt, G. H. - Davidson, D. T. (1960) Lime fixation on clayey soils. Bulletin No. 262, Highway Research Board, Washington, D.C., 20-32. IRC: 37 (2001) Guidelines for the design of flexible

References Al-Wahab, R. M. – El-Kedrah, M. M. (1995) Using fibres to reduce tension cracks and shrink/swell in compacted clays. Geoenvironment 2000, Geotechnical Special Publication No. 46, Y. B. Acar and D. E. Daniel, eds., ASCE, Reston, Va, 1: 791-805. Andersland, O. B. – Khattak, A. S. (1979) Shear strength of kaolinite/fibre soil mixtures. In: Proceedings of Int. Conf. on Soil Reinforcement, Paris, France, 1: 11-16. Babu, G. L. S. – Vasudevan, A. K. (2008) Strength and stiffness response of coir fibre-reinforced tropical soil. Journal of Materials in Civil

://iti.northwestern.edu/cement/monograph/Monograph5_4_3.html Thompson, M. R. (1967). Factors Influencing the Plasticity and Strength of Lime Soil Mixtures. University of Illunois Bulletin, Vol. 64, No. 100, pp. 1–19. Tremblay, H., - Duchesne, J., - Locat, J., - Leroueil, S. (2002). Influence of the nature of organic compounds on fine soil stabilization with cement. Canadian Geotechnical Journal, Vol. 39, No. 3, pp. 535–546. Wang, D., - Edine, N., - Zentar, R. (2013). Strength and deformation properties of Dunkirk marine sediments solidified with cement, lime and fly ash. Engineering Geology, Vol. 166, pp. 90