الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Increasing technology results in an increase of environmental problems due to the accumulation of waste materials. Many researchers come out to explain how to use the waste materials in a safe way. Some waste materials have been use for many applications for the civil engineering as soil improvement and road construction works. The present work aims to study the use of different wastes in the form of additives e.g. CKD, cement, dune sands, to reduce swelling characteristics and improve the behavior of problematic soils such as swelling soil and soft clay. The swelling soil is obtained from Toshka area, southeastern corner of western desert of Egypt. The soft clay is obtained from Sahl El- Tina area, North Sinai governorate. The tested mixtures were classified to ten groups. Four groups (A, E, F, K) contain various percentages of soil mixed with constant ratios of CKD equal to 10%, 20%, 30%, 40% respectively were used to determine the Atterberg limits, free swelling, compaction and CBR. Three groups (G, S, H) contain various percentages of soil mixed with constant ratios of CKD equal to 35%, 30%, 20% and constant ratios of sand equal to 10%, 20%,30% respectively were used to determine the Atterberg limits, free swelling. Three groups (B, C, D) contain various percentages of soil mixed with constant ratios of CKD equal to 20%, 30%, 40% and small ratios of cement equal to 6%, 9%, 12% respectively were used to determine UCS, XRD, SEM and SEM/EDAX. The results showed that the plasticity properties and the free swelling of the soil after mixing decreased compared with the soil before mixing and the soil mixtures considered more stable. All mixtures of group (D) obtained the highest values in UCS all over other groups, although the best mixtures in UCS for each cement ratio was mix B6-12% cement, mix B5-9% cement and mix B6-6% cement. The cement ratio 6% obtained the lowest values of UCS in all three groups, ranging between 21 to 156.3 KN/m2 (after 90 days curing time).While 9% cement ratio obtained high values of UCS in all groups ranging between 209.9 to 257.6 KN/m2 (after 90 days curing time).Whereas 12% cement ratio obtained highest values of UCS in all groups ranging between 314 to 389.8 KN/m2 (after 90 days curing time).The addition of CKD resulted in an increase in the OMC and a decrease in the MDD comparing with soils before mixing. The MDD increases with the increase of CKD ratio to 30% so group (F) shows the maximum dry density 1. 74gm/cm3 and the optimum moisture content 20.19%. group (F) shows increasing in the CBR values in all mixtures, comparing with untreated soil. The increase of CKD ratio to 30% increases the CBR values and these mixtures gain higher strength. XRD and SEM analyses after treatment showed that all clay minerals are transformed to new cementitous compounds, such as (C-A-H),( C-S-H), and (C-A-S-H), which has a more complex crystalline structure, as curing time increase. Salinity and pH causing flocculation process, the increase in pH values is responsible for separation of silica causing cementation. The pH values for 6 % cement-treated clay samples for all groups increasing as the curing time increase, the pH value increases with the rise in cement content (9 % and 12%) for all groups. Also the results showed that, the SiO2 slightly increase as the curing time increases in all groups, causing formation of strong inter particle bond that improves the strength and reduce swelling,
Keywords: Cement kiln dust, Soil stabilization, Cement, Problematic soils.