Researching the effects of stabilization of cohesive soils by using lime on cbr value

ivRESEARCHING THE EFFECTS OF STABILIZATION OF COHESIVESOILS BY USING LIME ON CBR VALUE(M.Sc. Thesis)İnci SÜTGAZİ UNIVERSITYINSTITUTE OF SCIENCE AND TECHNOLOGYMay 2006ABSTRACTSoils that have problems such as inadequate bearing capacity, highplasticity, low workability, high swelling potential and etc. needimprovement to be used as subsoils for superficial structures such asairports, aprons, parking areas and roads. Weak subsoils, that are notreplaced with controlled fills, have typically been stabilized by eithermechanical methods (compaction) or by adding chemical stabilizers.However, compaction alone is generally not enough and not possible inevery situation. Mechanical compaction does add some strength butnot prevent the shrinkage and the swelling of the soil as a result ofwater content that changes in an unstable manner. In addition it may bedifficult to run mechanical compaction at desired water content.Especially for cohesive soils that have high plasticity and high claycontent, lime is an effective stabilizer since the reactions that occurbetween clay minerals and lime. These reactions provide some short-term and long-term benefits. Short-term benefits occur as a result ofcation exchange and flocculation-agglomeration. Long-term benefitsare related with pozzolanic reactions. Due to the rapid cation exchangeand flocculation-agglomeration phenomenon, soil-lime mixture shows,reduction in plasticity, improved workability, immediate strengthincrease and reduced volume change potential. The gain in strengthvalso occours due to the pozzolanic reactions that progress slowly. Inthis study, sieve analysis, hydrometric analysis, Atterberg limits,specific gravity, organic content, pH, compaction, unconfinedcompressive strength, triaxial (UU) and CBR tests were performed onnatural soil and mixtures. Clay with high plasticity (CH) is mixed withdifferent percentages of hydrated lime (2%, 4%, 6% and 8% of dryweight of the soil). Bearing capacity and swell potential values that varydue to the increasing amount of the hydrated lime are observed.Optimum lime quantity is determined by evaluating the CBR andunconfined compressive strength results together.Science Code : 911.1.050Key Words : Cohesive soil, clay, lime, improvement, CBRPage Number : 110Adviser : Dr. dipl. ing. Ünsal SOYGÜR