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- Razouki, Sabah, et al.
(författare)
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Behaviour of Fine-Grained Gypsum-Rich Soil under Triaxial Tests
- 2021
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Ingår i: Proceedings of the Institution of Civil Engineers. - : Institution of Civil Engineers (ICE). - 1747-650X .- 1747-6518. ; 174:5, s. 240-248
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Tidskriftsartikel (refereegranskat)abstract
- This study presents the unconsolidated undrained (UU) and consolidated undrained (CU) behaviour of a compacted gypsum-rich sandy lean clay with a total soluble salt content of 35% and a gypsum content of 33%. The compaction curve of the soil exhibits a double peak indicating two maximum dry densities and two optimum moisture content (OMC) values for the standard American Association of State Highway and Transportation Officials (Aashto) compaction effort. For triaxial testing, soil specimens were compacted at the wet OMC. UU triaxial tests on both unsoaked and 120 d soaked specimens in fresh water indicate a significant decrease of soil cohesion and angle of internal friction due to long-term soaking. An increase of compaction effort from that of standard Aashto to that of modified Aashto improved both soil strength parameters. CU triaxial tests were carried out on specimens compacted at standard Aashto compaction in a manufactured mould to prepare the triaxial soil specimens. The test results revealed that the stress paths for the tested samples differ markedly from those displaying the behaviour of overconsolidated soils, as discussed in detail in this paper.
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| 2. |
- Razouki, Sabah, et al.
(författare)
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Compaction and Design of Gypsiferous Fill for Hot Desert Road Pavements
- 2011
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Ingår i: Proceedings of the Institution of Civil Engineers. - 1747-650X .- 1747-6518. ; 164:1, s. 3-11
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Tidskriftsartikel (refereegranskat)abstract
- A comparative study between a homogeneous road embankment constructed of gypsiferous soil and compacted throughout its full height at the dry optimum moisture content (DOMC) and an exactly similar embankment but with improved active zone (top 50 cm of the embankment compacted at the wet optimum moisture content WOMC), is presented. Two soils A and B were examined. Soil A was sandy lean clay (CL) containing about 35% total soluble salt (TSS) of which 33% was gypsum; soil B had a 28% TSS and a gypsum content of 25·6%. California bearing ratio (CBR) soil samples, prepared at DOMC and WOMC for soil A and at WOMC for soil B, showed serious reductions in soil strength and stiffness due to soaking, especially when the soil had been compacted at DOMC. A soaking period of 4 days was considered very reasonable and conservative for hot dry regions. Swelling of the soil during soaking was observed, especially when the soil was compacted at DOMC. For pavement design, it appears to be more economical to introduce an active zone compacted at WOMC instead of DOMC. The cost of the additional water required for compaction at WOMC instead of DOMC is much less than the savings in cost of sub-base material due to increased subgrade soil strength. It is concluded that the gypsiferous soil which occurs widely in the Middle East can be used to build embankments for hot desert road pavements.
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| 8. |
- Razouki, Sabah, et al.
(författare)
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Effect of Long-Term Soaking on the Distribution of Moisture and Total Soluble Salts in Compacted Gypsiferous Soils
- 2001
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Ingår i: Iraqi Journal of Civil Engineering. - Baghdad. - 7428-1992. ; :1, s. 263-271
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Tidskriftsartikel (refereegranskat)abstract
- Presented in this paper is a study of the effect of long-term soaking on the distribution of moisture hence on the dissolution of total soluble salts (T.S.S.) and its distribution along compacted CBR samples of gypsiferous soil.The soil tested is a fat clay of CH grouping according to ASTM specification and A-7-6 (42) according to AASHTO soil classification system, with about 34.5 % T.S.S. and about 33 % gypsum content.For this purpose, sixteen CBR samples were prepared at 95 % relative modified AASHTO compaction and 17 % optimum moisture content. For each soaking period of 0,4,7,15,30,60,120 & 180 days, two samples were prepared and loaded by 40 lb (178N) surcharge load.The paper reveals that the moisture content along the CBR soil samples increased with increasing soaking period. This increase is more pronounced at the top of CBR soil samples than that at the bottom, while little increase in moisture content took place at the mid-depth of CBR samples even after 180 days soaking period. This phenomenon is in good agreement with the distribution of T.S.S. and gypsum content along the CBR soil samples for different soaking periods.An empirical equation is introduced in this paper that enables the determination of T.S.S. at the top of CBR samples after different soaking periods from the initial T.S.S. content.
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| 9. |
- Razouki, Sabah, et al.
(författare)
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Effect of Soaking Period and Surcharge Load on Resilient Modulus and California Bearing Ratio of Gypsiferous soils
- 2004
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Ingår i: Quarterly journal of engineering geology and hydrogeology. - : Geological Society of London. - 1470-9236 .- 2041-4803. ; 37, s. 155-164
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Tidskriftsartikel (refereegranskat)abstract
- A clay of CH group according to the unified soil classification system (or CV clay according to BS 5930) with about 33% gypsum content was tested in the laboratory for the resilient modulus using the ultrasonic wave propagation technique. Forty-eight California bearing ratio (CBR) soil samples were compacted at the optimum moisture content and 95% of modified AASHTO compaction. For each soaking period of 0, 4, 7, 15, 30, 60, 120 and 180 days, three pairs of samples were loaded at 45, 178 and 312 N surcharge load, respectively. The resilient modulus (MR of the gypsiferous soil tested was determined using CBR soil samples before and after each soaking period, and the following observations were made: (1) soaking results in a progressive decrease in MR with increasing soaking period; (2) after 180 days soaking the resilient modulus decreased by 92%, 85% and 80% relative to the unsoaked condition for CBR samples under surcharge loads of 45, 178, and 312 N, respectively. Furthermore, a strong linear correlation between the resilient modulus and soaked CBR was found. An empirical equation has been developed relating MR, at any soaking period to the unsoaked condition, taking into account the effect of soaking period and surcharge load.
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| 10. |
- Razouki, Sabah, et al.
(författare)
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Improving Fine Grained Gypsiferous Soil by Increased Compaction
- 2012
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Ingår i: The international journal of pavement engineering. - : Informa UK Limited. - 1029-8436 .- 1477-268X. ; 3:1, s. 32-38
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Tidskriftsartikel (refereegranskat)abstract
- Presented in this paper is a study of the effect of compactive effort (CE) and long-term soaking on the strength characteristics of a clayey gypsiferous subgrade soil. The tested soil is A-6 (6) soil according to American Association of State Highway and Transportation Officials (AASHTO) soil classification system. To study the effect of CE and long term soaking on the properties of the tested soil, various California bearing ratio soil samples were prepared and compacted at optimum moisture content of the modified AASHTO compaction, but using four different chosen CEs of 12, 25, 56 and 70 blows/layer and then soaked for 0, 4, 7, 15, 30 and 120 days. The California bearing ratio (CBR) tests indicate that the CBR increases significantly in a nonlinear manner with increasing CE for all soaking periods, indicating improvement in soil strength with increased compaction. The rate of increase dies out with increasing CE. The CBR tests reveal also that there is a serious drop in the CBR due to soaking for all CEs.
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