Investigations on Improving the Compressive Strength of Sand Column with Cement Grout and Chemical Admixture

M Samuel Thanaraj, Et Al

doi:10.17762/turcomat.v12i2.1522

Abstract

Grouting is one of the most commonly adopted technique for soil improvement and strengthening. Adding super plasticizers, accelerators, antifreezes, air entraining agent improves the performance of the cement grout. The performance of the grout while injecting in the sand column mainly depends on its fluidity property. Keeping it in mind about the water cement ratio, the strength of the sand column is studied in two sets of experiments one by sand column with cement grout only and another set by sand column with cement grout added with super plasticizers by varying the water cement ratios. Strength parameters like angle of internal friction and cohesion were obtained be direct shear test and unconfined compressive strength test on the specimens by varying the water content. An increase of 15.2kPa to 60.33 kPa was observed in the cohesion value for specimens with 10% water content and 13.8 kpa to 47.2kPa cohesion value observed in the specimens with 20% water content. The angle of internal friction was decreased from 360 to 160 for 10% water content whereas 300 to 100 for 20% water content. A series of experiments were conducted on the sand column grouted with cement and for different water cement ratios as 1.5, 2.0 and 2.5. Another set of experiments were repeated by adding 2%super plasticizer Sulphonated Melamine Formaldehyde (SMF). The experiment results revealed that at lower water cement ratio higher value of compressive strength was observed. It was also observed that the strength increases with curing period.

Highlights

Grouting technique is adopted very widely in various purposes especially in soil strengthening by injecting the grout to seal voids, filling fissures and cavities in rocks
Grouting has a wide application in modern civil engineering world (Nonveiller 1989) to strengthen the dam structures, increasing the strength of the soil under the foundation, fixing and sealing of soil nailing adopted in slope stability works, fixing reinforcing elements in pre-stressed concrete structures, Repair and rehabilitation of deteriorated structures and buildings, Fill voids between rock and tunnel linings, rehabilitate and reinforce old defective masonry of historical buildings (Yeon and Han, 1997)
Whereas for 20 % water content, there is a change in the values of angle of internal friction from 360 for 2% cement and 220 for 8% cement mixed specimens

Summary

Introduction

Grouting technique is adopted very widely in various purposes especially in soil strengthening by injecting the grout to seal voids, filling fissures and cavities in rocks . Grouting has a wide application in modern civil engineering world (Nonveiller 1989) to strengthen the dam structures, increasing the strength of the soil under the foundation, fixing and sealing of soil nailing adopted in slope stability works, fixing reinforcing elements (e.g. cables) in pre-stressed concrete structures, Repair and rehabilitation of deteriorated structures and buildings, Fill voids between rock and tunnel linings (yasilinacur, 2003), rehabilitate and reinforce old defective masonry of historical buildings (Yeon and Han, 1997). Sand column being one of the methods of installing vertical drains to reduce the water table, could be adapted to strengthening measures for weak soil stabilization by injecting cement or lime as grout by increasing its compressive strength and by increasing the surrounding soil on installation. To study the improvement in the compressive strength of sand column with grout by varying the water – cement ratios for its fluidity characteristics to ease injection. To bring out the extent of improvement in adding super plasticizer

Properties of Sand

Sample preparation for UCC test

Results and Discussions

Summary and Conclusion