Sand columns stabilized with cement-lime mixture embedded in soft clay

Dissertant

al-Hasnawi, Nur Safa al-Din

Thesis advisor

al-Suudi, Namir K. S.

University

University of Technology

Faculty

-

Department

Department of Building and Construction Engineering

University Country

Iraq

Degree

Master

Degree Date

2013

English Abstract

Sand columns or sand compacted piles are an alternative technique to the widely used stone columns.

The primary functions of these inclusions in soft saturated soil are to improve the carrying capacity, control the settlement within tolerable limits and accelerate the consolidation process.

Geotechnical engineers working in the field of soil improvement are more familiar and have more experienced with stone columns as this technique proved to be successful worldwide for more than four decades.

One of the main defects of stone columns is the limited stiffness provided by the large crushed stone particles filling the holes during the construction process.

The filling process based on gradual throwing of the crushed stone from the ground level into the holes revealing a specific placement unit weight that provide a specific stiffness.

Several techniques have been proposed to increase the stiffness of stone columns by inserting special rings along the length of the columns or encasing with geogrid to suppress the material from lateral deformations and increase their stiffness.

Recently sand columns started to get more attention as the sand is easy to compact as compared to the crushed stone and it is more cheaper than stone.

A second advantage of sand columns is the availability of different additives that can be mixed with sand to increase the stiffness of the sand columns and hence increase its performance.

From this point the idea of the current research started, both cement and lime were mixed with sand in predetermined percentages and were used as backfill material in the construction of columns in soft saturated bed of soil.

A testing program was set for evaluating both floating and bearing sand columns was set.

Beds of saturated soft clay of average undraind shear strength 17 kN/m2 were prepared inside steel containers of dimensions 600x600x500 mm, four holes of diameter 50 mm and length 300mm and 300mm c.c were excavated and backfilled with ordinary sand and/ or sand stabilized with different percentages of cement/lime and cured for 7 and 28 days following that a model footing 64.6 mm in diameter was placed on each column and loaded incrementally up to failure.

Best results were obtained with optimum additive content of (6%cement+4%lime) and (10%cement+0%lime) for floating type stabilized sand columns.

On the other hand models performed on bearing stabilized columns demonstrated increasing trend with increasing additive content within the limits used in the investigation.

A hypothetical mechanism is also proposed for the analysis of sand columns stabilized with cement/lime mixture.

This proposal is listed in the recommendation for future work.

Main Subjects

Engineering & Technology Sciences (Multidisciplinary)

Topics

• Cement
• Building materials
• Concrete
• Adhesives

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-418317