بررسي خواص مكانيكي خاك ماسه اي تثبيت شده با بيوپليمركازئين و الياف پلي‌پروپيلن

چكيده انگليسي :

113An investigation into the mechanical properties of sandy soil stabilized by casein bio polymer and polypropylene fibers Shabnam Keshvari s keshvari@cv iut ac ir January 16 2019 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Dr M A Rowshanzamir mohamali@cc iut ac irAdvisor Dr S M Hejazi hejazi110@cv iut ac irAbstractThe Improvement of problematic soils has long been regarded as a main concern by civil engineers Dunesands are considered as main common problematic soils due to their uniform gradation and lack of cohesion So far various methods have been used for the soil modification In this research a combination of casein andpolypropylene fibers has been used to improve the strength parameters of a typical dune sand To prepare thestabilized soil samples resin amounts of 1 1 5 and 2 and 12 mm length fibers of 0 05 0 1 and 0 15 relative to dry weight of the soil were used Direct shear tests were employed at three levels of normal stressesof 50 100 and 150kPa to determine the strength parameters of the stabilized samples provided with a treatmenttime of 3 days The results of the experiments showed that increasing the amount of casein resin increases thesoil strength Adding the fiber up to 0 1 caused more strength enhancement Thus under a normal stress of100kPa the shear strength of pure sand sample as well as samples stabilized with 1 1 5 and 2 of the resin incombination with 0 1 fibers were 67 75 107 53 329 82 and 474 75kPa respectively It is observed that theshear strength has increased by increasing the amount of resin so that at the additive content of 2 resin and0 1 fiber the shear strength has reached to 5 8 times of the pure sand strength The effect of wetting on thestrength of the stabilized samples was also investigated As the strength of the stabilized samples decreasedunder wetting conditions small amounts of hydrated lime was used to maintain the strength of the samples inthe presence of water The results showed that the addition of lime increases the resistance of samples underwetting conditions The optimum amount of lime required to maintain the sample strength was determined tobe about 0 5 of dry weight of the soil samples The CBR standard tests have also been used to investigate theperformance of the stabilized soil as a subgrade layer In this context the CBR tests were conducted on thesamples stabilized with 2 casein resin and 0 1 fibers as optimum additive mixture under both dry andsaturated conditions Similar tests were also conducted on samples stabilized with 2 resin as well as puresand samples In dry conditions the specimens were cured at laboratory environment for 3 days To achievesaturation conditions the samples were immersed in a water sink for 4 days The highest CBR values of 34 and 22 were obtained for samples with optimum additive content respectively for dry and saturatedconditions It is observed that even in saturation conditions the CBR value of the soil stabilized by 2 resinand 0 1 fiber is close to the CBR value of the soil stabilized by 2 resin in dry conditions i e 23 Finally scanning electron microscopy SEM images were used to determine how to improve the bond betweenparticlesKey words dune sands casein resin polypropylene fibers direct shear test CaliforniaBearing Ratio tests electron microscopy images

كشوري، شبنم

بررسي خواص مكانيكي خاك ماسه اي تثبيت شده با بيوپليمركازئين و الياف پلي‌پروپيلن

خاك ماسه بادي , رزين كازئين , الياف پلي‌پروپيلن , آزمايش برش مستقيم , آزمايش نسبت باربري كاليفرنيا , تصاوير ميكروسكوپ الكتروني