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Atterberg limits (Plastic limit “PL”, Liquid limit  Atterberg limits (Plastic limit “PL”, Liquid limit 

Atterberg limits (Plastic limit “PL”, Liquid limit  - PDF document

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Atterberg limits (Plastic limit “PL”, Liquid limit  - PPT Presentation

Plasticity 37 Plasticity decrease in the maximum dry density The bellshaped compaction curves compaction curves see Appendixes 10 11 12 In the case of tertiary clay the maximum dry d ID: 450768

Plasticity 37 Plasticity decrease the maximum

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Plasticity 37 Atterberg limits (Plastic limit “PL”, Liquid limit “LL”, and Plasticity index “PI” = LL-PL) play an important role in soil identification and classification. These parameters indicate to some of the geotechnical problems such as important and principle aims of this study was to liquid, plastic limits, and plasticity index with addition of lime, fly ash, and lime/fly ash together to the three studied soils. To achieve this objective, Atterberg limits test conducted on both natural soils and different lime-, fly ash-, and lime/fly for the three studied soils according to consistency test PL and LL of the different soil-lime, -fly ash, -lime/fly ash mixtures were determined after 1 day curing according to DIN 18 122-1 and TPBF-StB, part B 11.5, 1991. The results of the tests were calculated using GGU-software program. Figure 3.1 (a, b, & c) illustrates both liquid limit (LL), plastic limit (LL), and plasticity index (PI) of tertiary clay, organic silt, and weathered soil, respectively with different chemical additives. that the addition of lime, fly ash, and lime/fly ash together, in case of the three studied soils, led to an increase in both the liquid limit and the plastic limit. The increase of the plastic limit is greater than that of the liquid limit. This resulted in a reduction of the plasticity index [PI = The geotechnical properties of soil (sucmpressive strength, CBR, permeability, and compressibility etc) are dependent on the moisture and density at which the soil is compacted. Generally, a high level of parameters of the soil, so that achieving the ve compaction necessary to meet specified or desired properties of soil is very important (Nicholson et al., 1994). The aim of the proctor test (moisture-density test) was to determine the optimum moisture contents of both untreated compacted and treated stabilized soil-mixtures. Standard proctor software program. Figure 3.2 (a, b, & c) illustrates the moisture-den The curves show the physical changes thlay) during lime, fly ash, and lime/fly ash treatment. In general, the addition of lime, fly ash, and lime/fly ash together, for the three studied soils, led to an increase in the optimum moisture content and to a Plasticity decrease in the maximum dry density. The bell-shaped compaction curves compaction curves (see Appendixes 10, 11, & 12). In the case of tertiary clay, the maximum dry density due to fly ash addition decreased with continuous increase in fly ash content. In the case of organic silt and weathered soil, the maximum dry density decreased with the fly ash addition, and with continuous increase in fly ash content, it increased relatively. This may be due to the different mineralogical composition, where tertiary clay contains montmorost with the chemical additives (lime & fly ash) in comparison to kaole addition of lime and e maximum dry density compared to the addition of lime and fly ash separately. In the case of boof lime and fly ash together resulted in a more decrease of the maximum dry density compared to the addition of fly ash alone. Fig. (3.1, a) Effect of lime-, fly ash-, and lime/fly ash-addition on consistency limits of tertiary clayNatal soil4.5% Lime6.5% Limeashashashashash8%FL+16%L+16%L+16%Percent admixtureMoisture content (%) Liquid limit (%) Plastic limit (%) Plasticity index (%) Plasticity 39 Fig. (3.1, b) Effect of lime-, fly ash-, and lime/fly ash- addition on consistency limits of organic siltoil3%Li5%Lime7%Lime8% Fly as Fly Fly as Fly as2%L12%F2%L20%F5%LPercent admixtureMoisture content (%) Liquid limit (%) Plastic limit (%) Plasticity index (%) Fig. (3.1, c) Effect of lime-, fly ash-, and lime/fly ash-addition on consistency limits of weathered soilPercent admixtureMoisture content (%) Liquid limit (%) Plastic limit (%) Plasticity index (%) Plasticity 40 Fig. (3.2, a ) Moisture-density relationship for tertiary clay is an evidence of the physical changes (after 2-hr delay) during lime-, fly ash-, and lime/fly ash-treatment1.21.251.31.351.41.451.515202530354045Moisture content (%)Dry density (g/cm³) Natural soil 4.5%L 6.5%L 8.5%L 8%F 12%F 16%F 20%F 25%F 2.5%L/8%F 2.5%L/16%F 4.5%L/16%F 6.5%L/16%F Fig. (3.2, b) Moisture-density relationship for organic silt is an evidence of the physical changes (after 2-hr delay) during lime-, fly ash-, and lime/fly ash-treatment1.281.31.321.341.361.381.41.421.441.461.48152025303540Moisture content (%)Dry density (g/cm³) Natural soil 3%L 5%L 7%L 8%F 12%F 16%F 20%F 25%F 2%L/12%F 2%L/20%F 3%L/20%F 5%L/20%F Compressive strength of a soil is a significant factor to estimate the design criteria for the use as a pavement and construction material. The lime- and fly ash-stabilization of soil, the soil. Therefore, lime and fly ash become cost-effective and efficient material for use in road construction, embankment, and earth fills. Plasticity 41 Fig. (3.2, c ) Moisture-density relationship for weathered soil is an evidence of the physical changes (after 2-hr delay) during lime-, fly ash-, and lime/fly ash-treatment1.151.21.251.31.351.41.451.51.5515202530354045Moisture content (%)Dry density (g/cm³) Natural soil 5%L 7%L 9%L 8%F 12%F 16%F 20%F 25%F 35%F 3%L/20%F 3%L/35%F 5%L/35%F 7%L/35%F zed soil is primarily caused by the formation of various calcium silicate hydrates and calcium aluminate hydrates. The exact products formed, however, depend on the type of clay mineralogy and the reaction conditions including temperature, moisture, and curing Unconfined compression tests were conducted to characterize the strength of soils and their mixtures with lime, fly ash and lime/fly ash. The test procedures and the preparation of the specimens were performed according to the procedures in chapter 2.4.1 and 2.5, respectively. Unconfined compressive strengths of the three studied soils, compacted at optimum water content and without chemical a2.8, 3.1, 3.2, and 3.3. Unconfined compressive strengweathered soil were measured after carrying out All the specimens were prepared using a standard proctor test. Untreated compacted soil specimens (without chemical additives) of te(compacted at optimum water content) had unconfined compressive strengths of 131.21, 136.91, and 173.25 KN/mcompacted soils need to be interpreted in the context of the general relationship between the unconfined compressive strength and the consistency (quality) of the soils used in pavement applications according to Das, 1994 (see chapter 2.4.1). Unconfined compressive strength Plasticity ranging from 100 to 200 Kpa (KN/m) is considered as a stiff consistency. This means that the three tested untreated compacted soils are stiff consistency due to compaction process at the optimum water content and without chemical additives (lime & fly ash). Unconfined compressive strength of treated stabilized soils Unconfined compressive strength of different soil-lime, soil-fly ash and soil-lime/fly ash mixtures prepared at optimum water contunconfined compressive strength was measured afthe three studied stabilized soils. Soil-lime mixtures of the three tested soils were prepared at the optimum lime content, 2%, and 4% above the optimum lime content (compacted at optimum water content) and illustrated in Tables 3.1, 3.2, & 3.3 and in Figures 3.3 a & 3.4. Soil-fly ash mixtures were prepared at 8, 12, 16, 20, and 25% fly ash for both the tertiary 5, and 35% fly ash for the weathered soil. All the mixtures were compacted at the optimum water content, two hours after mixing with water to simulate the construction delay that typically occurs in the compaction due to construction operations, Soil-fly ash mixtures of tertiary clay, organic silt and weathered soil were prepared (at optimum water contents) at the optimum fly ash content curing on the unconfined compressive strength Soil-lime/fly ash mixtures were prepared (at optimum water contents) at the optimum lime/fly ash contents, according organic silt (2%L/12%F), and for weathered soil (3%L/20%F). All the mixtures were cured for 7 days. Other mixtures were prepared at the optimum fly ash content with different lime percentages to evaluate the influence of the increase in the lime and the lime/fly ash ratio on the lime/fly ash-stabilizati Plasticity Table (3.1) Unconfined compressive strength (CBR-value), and CBR-gain of untreated compacted Admixture mixing Curing time qu- value qu- gain CBR- value CBR- gain L (%) FA (%) Days kN/m² - (%) - 0 131.214.6 4.5* 6.5 8.5 0 0 1034.001147.801221.707.888.759.3161.862.313.0013.4313.54 0 0 0 0 0 8 12 16* 20 180366.88594.90820.381459.271660.641791.371064.97950.002.804.536.2511.1212.6613.658.127.2421.936.639.473.877.094.961.151.64.767.968.5716.0416.7420.6313.2811.22 2.5* 1.5 2.5 4.5 6.5 8* 16 16 16 180905.591424.421476.282256.573081.503505.231363.751159.566.9010.8611.2517.2023.4926.7110.398.8446.859.787.2109168.3234.281.879.510.1712.9818.9623.7036.5950.9117.7817.28 L = Lime content qu = Unconfined compressive strengthtreated stabilized soil/CBR of untreated compacted of treated stabilized soil/qu of untreated compacted soil Optimum content according to pH Soil-lime/fly ash mixtures of tertiary clay (2.5%L/16%F), organic silt (2%L/20%F), and weathered soil (3%L/35%F) were prepared at the optimum fly ash content with small percentages of lime (see chapter 2.5.3) and at the optimum water contents. The mixtures were cured for 7, 28, 56, and 180 days to estimate the influence of curing time on the unconfined compressive strength and on the lime/fly ash-stcompressive strength are illustrated in Tables 3.1, 3.2, & 3.3 and in Figures 3.3 c, 3.4 & 3.5. Plasticity Table (3.2) Unconfined compressive strength (CBR-value), and CBR-gain of untreated compacted- Admixture mixing Curing time qu- value qu- gain CBR- value CBR- gain L (%) FA (%) Days kN/m² - (%) - 0 136.913.2 3* 5 7 0 0 439.49634.40628.033.214.634.5916.823.423.45.257.317.31 0 0 0 0 0 8 12 16 20* 180322.29532.48620.38685.351331.261385.551738.98964.332.353.894.535.019.7210.1212.707.0414.728.745.858.294.4105.047.84.598.9711.5614.3118.1929.5032.8114.94 2* 2 3 5 * 12 20 20 180729.65866.431348.781648.442148.35871.88796.115.336.339.8512.0415.696.375.8235.238.461.180.4103.140.227.411.0012.0019.0925.1332.2212.568.56 Table (3.3) Unconfined compressive strength (CBR-value), and CBR-gain of untreated compact Admixture mixing Curing time qu- value qu- gain CBR- value CBR- gain L (%) FA (%) Days kN/m² - (%) - 0 173.255.4 5* 7 9 0 0 309.55329.90298.091.791.901.7217.117.616.83.173.263.11 0 0 0 0 0 0 8 12 16 20 25 35* 180294.27301.54335.50389.81526.12938.851151.071184.211412.791.701.741.942.253.045.426.646.848.1615.317.522.826.443.550.251.062.995.32.833.244.224.898.069.309.4411.6517.65 3* 3 5 7 8 20* 35 35 35 180713.391327.301619.811751.112297.161421.541416.491376.684.127.669.3510.1113.268.218.187.9544.579.284.4103.3115.080.276.672.48.2414.6715.6319.1321.3014.8514.1913.41 Plasticity h-, and lime/fly ash-stabilization The general effect of lime-, fly ash-, and lime/fly ash-stabilization process on the three The addition of optimum lime content led to an increase in the unconfined compressive strength for the three different studied soils. Lime-tertiary clay mixtunconfined compressive strength values and lime-weathered soil mixtures have the lowest ing lime content (2 and 4% above the optimum lime content). and weathered soil with lime is weak according to reactivity test (see chapter 2.5.1). The lime-organic silt mixtures have unconfined compressive strength values relatively higher than the values of lime-weathered soil mixtures. The unconfined compressive strengths of both lime-organic silt and -weathered soil mixtures increased with increase in the lime content (2% above the optimum lime content) and decreased slightly with continuous increasing the lime content (4% above the optimum lime content). The ratio of the unconfined compressive strength of the lime-, fly ash-, and lime/fly ash-stabilized soil to that of the untreated compacted soil is known as (see factor, due to optimum lime content, of and 1.79 (time), respectively. The final consistency (quality) of the mixtures is ha respectively (see Table The addition of fly ash contents resulted in an increase in the unconfined compressive strength for the three tested soils. Fly ash-tertiary clay mixtures havecompressive strength values and fly ash-weathered soil mixtures have the lowest values, at the same fly ash contents. The unconfined compressive strength values increased with continuous the unconfined compressive streiary clay mixture decreased. The qu-values of both fly ash-organic silt and -weathered soil mixtures are lower than the values of fly ash-tertiary clay mixtures, at the same fly ash contents. Fly ash-organic silt mixtures have unconfined compressive strength valuan the values of fly ash-weathered soil mixtures, at the same fly ash contents. The unconfined compressive and -weathered soil mixtures increased with Plasticity The strength gain factor of optimum fly ash-tertiary clay, optimum fly ash-organic silt, and optimum fly ash-weathered soil mixtures is Fig. (3.3, a) Unconfined compressive strength (qu-value) of untreated compacted and treated stabilized soil with lime200400600800100012001400012345678910Lime content (%)qu-value ( KN/m²) Tertiary clay 7 days Organic silt 7 days Weathered soil 7 days Fig. (3.3, b) Unconfined compressive strength (qu-value) of untreated compacted and treated stabilized soil with fly ash200400600800100012000481216202428323640Fly ash content (%)qu-value (KN/m²) Tertiary clay 7 days Organic silt 7 days Weathered soil 7 days Plasticity 47 Fig. (3.3, c ) Unconfined compressive strength (qu-value) of untreated compacted and treated stabilized soil with lime/fly ash 0L/0F8L/35F6.5L/16F4.5L/16F2.5L/16F1.5L/16F2.5L/8F5L/20F3L/20F2L/20F2L/12F0L/0F7L/35F5L/35F3L/35F3L/20F0L/0F2004006008001000120014001600Lime/fly ash content (%)qu-value (KN/m²) Tertiary clay 7 days Organic silt 7 days Weathered soil 7 days The strength gain factor of weathered soil is relatively higher than the gain factor of organic silt, this may be, since the optimum fly greater than the optimum fly ash of the three mixtures is hard (see Table 3.4). The addition of lime and fly ash together led to an increase in the unconfined compressive strength values for the three studied soils strongly compared to the addition of lime and fly ash separately. Lime/fly ash-tertiary clay mixtures have unvalues higher than the values of both lime/fly ash-weathered soil and lime/fly ash-organic silt mixtures. The reactivity of tertiary clay with lime and fly ash together is stronger than the in factors (due to addition of the optimum lime/fly ash content, according to the pH-test) of tertiary clay, organic silt, and of the optimum fly ash with small percent of lime) of tertiary clay ((2%L/20%F), and weathered soil (3%L/35%) of the three mixtures is halime and fly ash together is stronger than the reaction with lime and fly ash separately. The unconfined compressive strength values of the three studied soils increased with increasing the lime/fly ash ratio. The optimum lime/fly asclay, organic silt, and weathered soil is 0.16, 0.15, and 0.14, respectively (see Fig. 3.5). Above nic silt (about 1 lime: 6 Plasticity the case of weathered soil (about 1 lime: 7 fly ash by weight), qu-value of the mixtures decreased. of both untreated compacted- and treated stabilized- soils (according to Das, 1994 & Bowles, 1992). Soil type Type and percent of chemical additives Curing time (days) qu- value (kN/m²) Quality after qu-value, Das (1994) CBR- value (%) Quality after CBR-value, Bowles (1992) Organic silt 3% Limestiff Tertiary clay4.5% Limestiff Weathered soil 5% Limestifffair Plasticity 49 Fig. (3.4) Strength gain factors of untreated compacted and treated stabilized soilsT.clayO.siltW.soilMixturesStrength gain factor Untreated compacted Optimum lime content Optimum fly ash content Optimum L/F content Lime/optimum fly ashcontent Fig. (3.5) Response of qu-value to variable lime/fly ash ratios400600800100012001400160000.050.10.150.20.250.30.350.40.450.5Lime/fly ash ratioqu-value (KN/m² ) Tertiary clay 7 days Organic silt 7 days Weathered soil 7 days Soil-fly ash and soil-lime/fly ash mixtures were prepared, for the estimate how curing time affects unconfined compressive strength of the stabilized soils. Unconfined compressive strength tests were performed on the specimens after carrying out 2.5%L/16%F 2%L/20 3%L/35 Plasticity All the specimens were prepared at the optimum water content. The effect of long-term curing on the unconfined compressive strength of soil-fly ash and soil-lime/fly ash mixtures is shown lime/fly ash mixtures increased with long-term curing. Unconfined compressive strength values of soil-lime/fly ash mixtures were strong-term curing compared to the strength values of soil-fly ash mixtures. Unconfined compressive strength values of tertiary clay-optimum fly ash mixtures increased strongly with curing time compared to ganic silt-optimum fly ash mixtures. Unconfined compressive strengthd soil-optimum fly ash mixtures increased slightly with curing time. Unconfined compressive strength value of tertiary clay-lime/fly ash mixtures increased dramatically with long-term curing compared to silt-lime/fly ash mixtures (s Figure 3.8 (a, b, & c) shows stre = zero, for the three studied soils at different soil-chemical additives with different curing time (7, 28, and 180 days). All the specimens were compacted at optimum water csignificantly influenced by both lime- and fly ash-addition. Unconfined compressive strength, elasticity modulus at the first loading (E), failure axial either the separate or the joined effects of lime and fly ash contents. By comparing the curves, for all the three tested soils, showed where the unconfined compressive strength equal to stress-value at 20% strain (according to DIN 18 136). The untreated compacted soils have relatively similar behavior, which means that the compaction process for the natural soils at optimum water content and without chemical additives, does not affect the stress-stain behavior to large amplittertiary clay and the weathered soil and remained quite similar in case of the organic silt (see Plasticity 51 Fig. (3.6) Effect of curring time on unconfined compressive strength of fly ash- and lime/fly ash-treated stabilized soils5001000150020002500300035004000728497091112133154175196Curing time (days)qu-value (KN/m²) Tertiary clay 16% F Organic silt 20% F Weathered soil 35% F Tertiary clay 2.5%L/16%F Organic silt 2%L/20%F Weathered soil3%L/35%F Fig. (3.7) Photos of specimens after unconfined compressive strength illustrated the development of the mechanical behavior from ductile to brittle due to the stabilization process and the curing time. A1= Natural clay, A2= Untreated compacted clay, A3= Clay+16%ash 7 days, A4= Clay+2.5%lime+16%ash 7 days, A5= Clay+2.5%lime+16%ash 180 days. B1= Natural organic silt, B2= Untreated compacted organic silt, B3= Organic silt+20%ash 28 days, B4= Organic silt+2%lime+20%ash 7 days, B5= Organic silt+2%lime+20% ash 180 days. C1= Natural weathered soil, C2= Untreated compacted weathered soil, C3= Weathered soil+35%ash 180 days, C4= Weathered soil+3%lime+20%ash 7 days, C5= Weathered soil+3%lime+35%ash 180 days Plasticity 52 Fig. (3.8, a) Stress-strain curves of tertiary clay200400600800100012001400160018002000220024002600280030003200340036000.02.55.07.510.012.515.017.520.0Strain (%)Stress (KN/m²) Natural soil Untreated, compacted 4,5%L7 16%F7days 16%F28days 16%F180days 2,5%L8%F7days 2,5%L16%F7days 2,5%L16%F28days 2.5%L16%F180days Fig. (3.8, b) Stress-strain curves of organic silt200400600800100012001400160018002000220024000.02.55.07.510.012.515.017.520.0Strain (%)Stress (KN/m²) natural soil Untreated, compacted 3%L7days 20%F7days 20%F28days 20%F180days 2L12F7days 2L20F7days 2L20F28days 2L20F180days The addition of both optimum lime content and optimum fly ash contenan increment of the Esecant and a decrement of the failure axial strain () for the three studied soils. The increase in Eand the reduction of the failure axial strain () were relatively high with the addition of optimum fly ash content compared to the addition of optimum lime Plasticity 53 Fig. (3.8, c) Stress-strain curves of weathered soil2004006008001000120014001600180020002200240026000.02.55.07.510.012.515.017.520.0Strain (%)Stress (KN/m²) Natural soil Untreated, compacted 5%L7days 35%F7days 35%F28days 35%F180days 3%L20%F7days 3%L35%F7days 3%L35%F28days 3%L35%F180days Fig. (3.9) Elasticity modulus (Esecant) of treated stabilized soils with curing time200400600800100012001400728497091112133154175196Curing time (days)Secant (MPa) Clay+16% fly ash Clay+2.5%L+16%F O.silt+20% fly ash O.silt+2%L+20%F W.soil+35% fly ash W.soil+3%L+35%F In the case of soil-fly ash mixtures, Eilure axial strain (decreased through the long-term curi soils (with the exception of the weathered soil-fly ash mixture, where the general direction of the development of these Plasticity two parameters (Esoil-lime/fly ash mixtures, unconfined compressive strength qu-value and E increased and the failure axial strain (ong-term curing for the three different soils especially in the case of lime/fly ash-stabilized tertiary clay, where the change was dramatic. Finally, the soil-lime/fly ash mixtures showed an extremely brittle through the long-term curing in comparison to the soil-fly ash mixtures which showed relatively smaller change (see Tabland elasticity modulus (E) of untreated compacted- and treated stabilized-soils at different mixtures and curing time. Soil type Mixtures qu-value (KN/m f (%) Esecant (MPa) Tertiary clayUntreated compacted4.5% lime 7 days16% fly ash 7 days16% fly ash 28 days16% fly ash 56 days16% fly ash 180 days2.5% lime/ 8% fly ash72.5% L/16% fly ash 72.5% L/16% fly ash 282.5% L/16% fly ash 562.5% L/16%fly ash180131.211034.00820.381459.271660.641791.37905.591476.282256.573081.493505.236.101.371.200.930.920.781.461.331.190.840.701011013003006001002017018821157 Untreated compacted3% lime 7 days20% fly ash 7 days20% fly ash 28 days20% fly ash 56 days20% fly ash 180 days2% lime/12% fly ash 72% L/20% fly ash 72% L/20% fly ash 282% L/20% fly ash 562% L/20% fly ash 180136.91439.49685.351331.261385.551420.12729.65866.431348.781648.442148.352.511.401.331.001.721.521.200.910.67101169201100101200370642 Untreated compacted5% lime 7 days35% fly ash 7 days35% fly ash 28 days35% fly ash 56 days35% fly ash 180 days3% lime/20% fly ash 73% L/35% fly ash 73% L/35% fly ash 283% L/35% fly ash 563% L/35% fly ash 180173.25309.55938.851151.071184.211412.79713.391327.301619.811751.112297.168.912.081.331.191.381.201.201.271.221.380.48100100101200201299709 Plasticity 55 Fig. (3.10 ) Failure axial strain (f) of treated stabilized soils with curing time 0,40,91,41,92,42,9728497091112133154175196Curing time (days)Strain, f (%) Clay+16% fly ash Clay+2.5%L+16%F O.silt+20% fly ash O.silt+2%L+20%F W.soil+35% fly ash W.soil+3%L+35%F The stabilized soils must be subjected toconditions especially in the rainy season, where the soil becomes completeted, to estimate the strength loss due to the water saturati(water-soaking) tests were conducted (loosely based on ASTM C593) on soil-fly ash mixtures of tetertiary clay (2.5% lime+16% fly ash), organic silt (2% lime+20% fly ash), and of weathered soil (3% lime+35% fly ash). The mixtures were compacted after standard proctor test and cured to 7 days (25°C temperature & 98% humide set of the samples nd the corresponding sample set was vacuum Unconfined compression test (according to DIN 18 138, see chapter 2.4.1) was performed, after soaking, on the two sample sets. The resuFigure 3.11. Both fly ash- and lime/fly ash-organic silt mixtures had the lowest strength loss me/fly ash-weathered soil mixtures had the highest strength loss. Soil-fly ash mixtures of tertiary clay (16%F), organic silt (20%F), and weathered soil (35%F) and soil-lime/fly ash mixtures of tertiary clay (2.5% lime+16% (2% lime+20% fly ash), and of weathered soil (3% lime+35% fly ash) were prepared after standard compaction test and cured to 7 days (25°C temperature & 98% humidity). They were Plasticity subjected to wetting/drying-, and freezing/thawing-durability tests according to ASTM D559 of wetting/drying and 12 cycles of similar to the procedures of the standards test methods for compacted cement mixtures except wire brushing after each cycle is omitted (U.S. Army, Air force, and Navy, 2005). Each test consists of twelve two-day cycles of wetting/drying or freezing/thawing, which means th24 days to complete. Stabilized soil mixtures, that satisfy strength requirements, are required to pass these tests to prove their ability to withstand environmentaof the durability test were expressed in terms weigh loss criteria and the durability test results of the stabilized soils after 12 cycles are shown in Tables 3.7 and 3.8, respectively. In the case of freezing/thawing durability test, all the mixtures passed successively. In the case of wetting/drying durability test, three mixtures passed successively (tertiary clay-lime/fly ash, -lime/fly ash mixtures) while the other three mixtures failed (sTable (3.6) Unconfined compressive strength, ststabilized soils under different conditions Unconfined compressive strength after 7 days curing (under 25°C temperature & 98 % humidity) Unsoaked Plain soaked loosely based on (ASTM C593) Vacuum saturated soaked loosely based on (ASTM C593) qu-value at different conditions Samples qu-value (KN/m²) Strength gain qu- value (KN/m²) Strength gain Strength loss (%) qu-value (KN/m²) Strength gain Strength loss (%) Clay 16% F Clay 2.5% L/ 16%F Silt 20% F Silt 2% L/ 20% F W.soil 35% F W.soil 3% L/ 35% F Table (3.7) Durability test weight loss criteria (Durability requirements) according to (ASTM Type of soil stabilized Maximum allowable weight loss after 12 wet-dry or freeze-thaw cycles percent of initial specimen weight Granular, PI 11 �Granular, PI 10 8 Silt 8 Clay 6 Plasticity ity test results. Durability test results Specimens Numbers of specimens Wet-Dry Freeze-Thaw T.clay+16% fly ash 7days T.clay+2.5% lime+16% fly ash7fail O.silt+20% fly ash 7days O.silt+2% lime+20% fly ash 7 W. soil+ 35% fly ash 7days W. soil+ 3% lime+35%fly ash 7failfail Fig. (3.11) Unconfined compressive strength of stabilized soils after 7 days under different conditions2004006008001000120014001600ay2.5L%/16%F silt 20% Fw.soil 5% Fw.soil 3%L/5% Perecent admixturequ-value (KN/m²) Unsoaked Plain soaked Vaccum saturated soaked * The addition of lime, fly ash, and lime/fly ash to* The addition of lime, fly ash, and lime/fly ash to the studied soils resulted in an increase in the optimum moisture content and a decrease in the maximum dry density. The moisture-density curves of the stabilized * In the case of lime-stabilization process, the optimum lime content of the tertiary clay, Plasticity reactive with lime and the unconfined compressiincrease in the lime content. Both the weathered soil and the organic silt failed in the sed at the optimum lime content and 2% above the optimum compared to the strength of the untreated compacted specimens. The continuous increase in the lime (4% above the optimum lime content) led to a decrease in the unconfined compressive strength. * In the case of fly ash-stabilization process, the optimum fly ash content (according to pH-method) of the tertiary clay, organic silt, and weathered soil is 16, 20, and 35%, respectively. The unconfined compressive strength increased the organic silt and weathered soil. In case of the tertiary clay, the unconfined compressive strength increased with increasing fly ash content (from 8 to 20%) and decreased with mixtures have lower qu- and strength gain-values compared to flmixtures. These values are satismixtures. * In the case of lime/fly ash-stabilization process, the optimum lime/fly ash content (according to pH-method) of tertiary clay, organic silt, and weathered soil is (2.5%L+8%F), respectively. The addition of lime and fly ash together increased the unconfined compressive strengthstudied soils strongly compared to the addition of lime and fly ash separately. Lime/fly ash-tertiary clay mixtures have lime/fly ash-organic silt and –weathered soil mixtures. in both the lime and the fly ash contents, but this increase has upper limit at the optimum lime/fly ash ratio. The optimum ratio of tertrespectively (about 1 lime: 6 fly ash by weight) a1 lime: 7 fly ash by weight). elasticity modulus (E) increased and the failure axial strain (of either the separate or the joined effects of lime increased and the failure axial strain () decreased dramatically with the addition of both lime and fly ash together, especially in the case of tertiary clay. The mechanical be was changed from ductile to brittle. This development was relatively weak for the acidic weathered soil. Plasticity The development of the mechanical behavior from ductile to brittle of the three stabilized soils was dramatic through the long-term curing, * In the case of durability (water-soaking) test, both fly ash- and lime/fly ash-organic silt mixtures had the lowest strength loss. Fly ash- and lime/fly ash-weathered soil mixtures had All the tested stabilized mixtures passed successively in the freeze-thaw durability test. Three mixtures (lime/fly ash-tertiary clay and fly ash- and lime/fly asmixtures) passed successively in the wet-dry durability test and the other three mixtures (fly ash-tertiary clay and fly ash-and lime/fly ash-weathered soil mixtures) failed. Lime/fly ash-tertiary clay mixtures are more durable than fly ash-tertiary clay mixtures. Both fly ash- and lime/fly ash- organic silt mixtures are durabh fly ash-and lime/fly ash-weathered soil mixtures failed.