Percussion and laboratory cone penetration are two different methods employed for the determinati... more Percussion and laboratory cone penetration are two different methods employed for the determination of liquid limit of the soil. The empirical nature, advantages and limitations of these methods in determining liquid limit of the soil has been discussed in detail in the literature. One of the most important observations is that the soils with high liquid limit exhibits higher discrepancy between the two methods. There is a need to understand the reason for this discrepancy and to obtain identical values for all ranges of liquid limit. As an initial attempt, the present study reviews the possible reasons for the discrepancy in liquid limit values obtained by the two methods. Further, a re-evaluation of the cone penetration method has been done and a modified penetration limit is proposed based on the free swell index of the soil. The cone penetration liquid limit was re-calculated by employing the modified penetration limit, and compared with the percussion liquid limit. It is noted that the modified penetration limit based on free swell property of the soil minimizes the difference in liquid limit values obtained by using both the methods. It is further emphasized that the observations obtained from the present study cannot be compared with the field cone penetration results. The details of the experimental scheme adopted are described in detail in this technical paper.
Fly ash has many bulk applications; but Class 'F' fly ash being non-cohesive, has to be strengthe... more Fly ash has many bulk applications; but Class 'F' fly ash being non-cohesive, has to be strengthened or reinforced when used in structural fills. Portland cement and lime are the usual additives for strengthening fly ash. The strength from such additions comes from pozzolanic reactions. In this study, bentonite was used to augment pozzolanic reactions of fly ash with lime, producing very high unconfined compressive strength exceeding 7000 kPa. The strength increased by 88% because of 20% addition of bentonite at the optimum lime content of 13% by weight. There was no adverse effect in terms of swell after adding bentonite. The addition of bentonite also increased the elastic modulus of fly ash-lime combine.
Percussion and laboratory cone penetration are two different methods employed for the determinati... more Percussion and laboratory cone penetration are two different methods employed for the determination of liquid limit of the soil. The empirical nature, advantages and limitations of these methods in determining liquid limit of the soil has been discussed in detail in the literature. One of the most important observations is that the soils with high liquid limit exhibits higher discrepancy between the two methods. There is a need to understand the reason for this discrepancy and to obtain identical values for all ranges of liquid limit. As an initial attempt, the present study reviews the possible reasons for the discrepancy in liquid limit values obtained by the two methods. Further, a re-evaluation of the cone penetration method has been done and a modified penetration limit is proposed based on the free swell index of the soil. The cone penetration liquid limit was re-calculated by employing the modified penetration limit, and compared with the percussion liquid limit. It is noted that the modified penetration limit based on free swell property of the soil minimizes the difference in liquid limit values obtained by using both the methods. It is further emphasized that the observations obtained from the present study cannot be compared with the field cone penetration results. The details of the experimental scheme adopted are described in detail in this technical paper.
Fly ash has many bulk applications; but Class 'F' fly ash being non-cohesive, has to be strengthe... more Fly ash has many bulk applications; but Class 'F' fly ash being non-cohesive, has to be strengthened or reinforced when used in structural fills. Portland cement and lime are the usual additives for strengthening fly ash. The strength from such additions comes from pozzolanic reactions. In this study, bentonite was used to augment pozzolanic reactions of fly ash with lime, producing very high unconfined compressive strength exceeding 7000 kPa. The strength increased by 88% because of 20% addition of bentonite at the optimum lime content of 13% by weight. There was no adverse effect in terms of swell after adding bentonite. The addition of bentonite also increased the elastic modulus of fly ash-lime combine.
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