Techniques for Improving Soil Properties in Civil Engineering

This report delves into various soil improvement techniques crucial in civil engineering. It begins by discussing the injection of polymers under load clay, highlighting the benefits of high clay intercalation, exfoliation, and dispersion achieved through polymer reinforcement, and the use of injection molding for molecular orientation and enhanced mechanical properties. The report then explores methods like stabilization of reactive subgrades via cementitious slurry injection, detailing the process of injecting reactive slurry to modify soil characteristics, including soil strength, and addressing the limitations of this technique. Multiple grout injection, including compensation grouting, is examined, focusing on its role in offsetting subsidence during excavation and tunneling. The report also covers soft ground improvement methods, categorizing techniques into compaction, reinforcement, and fixation methods, and discussing the use of expanding polyurethane for remediating differential settlement issues. Finally, it addresses factors affecting the long-term efficiency of soil properties, such as grout bleeding and solid penetration, and explores methods to mitigate these issues. This report provides a comprehensive overview of soil improvement strategies, offering valuable insights into the practical applications and effectiveness of different techniques.

INJECTION OF POLYMER UNDER LOAD CLAY.
INJECTION OF POLYMER UNDER LOAD CLAY.
NAME OF THE STUDENT
NAME OF THE INSTITUTION

INJECTION OF POLYMER UNDER LOAD CLAY.
Introduction
According to Constantino et al. (2012), high levels of intercalation, exfoliation and dispersion of
clay are achieved when the clay is reinforced with polymers. A huge period of time is required
for the intercalation of the clay. Injection molding technique is a conventional way based on the
concept of in-mould shear manipulation of the melt during polymer solidification phase. The
injection method , results in excellent molecular orientation as a result of excellent shears. The
technique therefore, achieves high levels of clay exfoliation and orientation, improving the
mechanical properties of the soil.
Stabilization of Reactive Subgrades by Cementitious Slurry Injection.

INJECTION OF POLYMER UNDER LOAD CLAY.
The method involves inserting the reactive slurry in the soil strata allowing it to react with the
elements present in the soil, therefore, modifying the mechanical characteristics of the soil such
as the soil`s strength Wilkinson et al. (2004). This technique involves use of a hi-rail rig that
injects the slurry. During injection, high pressures are developed as a result of resistance caused
by friction inside the rig`s surfaces. The pressures must be controlled and kept below 1450k Pa.
This injection leads to a layer that is laterally filled with the cementitious slurry that reacts with
the soil to improve its properties Wilkinson et al. (2004). The common additives in the slurry that
make it reactive are calcium carbonate lime as well blasted slugs Wilkinson et al. (2004). Both of
these slurry are mixed with water and act to reduce moisture reactivity characteristics, reduce
permeability of subgrade soils and to improve the engineering properties like the strength of the
soil. However, the limitation of this technique is that it becomes a challenge to show whether
there is an improvement in the soil`s` engineering. Therefore, many geologists find it hard to use
this technique in their research studies Wilkinson et al. (2004).

INJECTION OF POLYMER UNDER LOAD CLAY.
Wilkinson, A., Haque, A., Kodikara, J., Christie, D. and Adamson, J. (2004) Stabilization of
Reactive Subgrades by Cementitious Slurry Injection- A Review, Australian Geomechanics,
39(04)

INJECTION OF POLYMER UNDER LOAD CLAY.
Multiple Grout Injection.
Multiple Grout Injection technique involves a large number of grout injections carried out at a
specified place. Each injection alters the in-situ stress state of the neighboring sites that have
undergone injections, hence, affecting the grout behavior, and leading to deformation of the
surrounding soil. An example of this technique is the compensation grouting. Compensation
grouting offsets the subsidence caused during underground excavation and bored tunneling S.K.
Au et al.(1994), it involves injecting grouts in the zone between the tunnel and the overlying
buildings to compensate for the ground loss and stress relief induced by underground excavation.
The effectiveness of compensation grouting is a function of ground conditions, grout rheology
and the injection methods used. However, the primary function is the ground rheology. From
experiments, multiple injections which involves injecting small amounts of the grout from
multiple locations, has proved to be better than single injection that involves injecting the whole
volume of grout from a single location.

INJECTION OF POLYMER UNDER LOAD CLAY.
Au, K., Soga, K., Jafari, M., Bolton, M. and Komiya, K. (2004) Laboratory Investigation of
Multiple Grout Injection into Clay. Geotechnique, 54(2)
Soft Ground Improvement Methods.

INJECTION OF POLYMER UNDER LOAD CLAY.
According to James D. Hussin, (2006), the soft ground improvement techniques chosen are
chosen based on their cost effectiveness and ability to greatly improve the soil structure. Cost
effective methods like surface compaction and geotextile placement are mostly used. The
engineers normally follow a decision making process in selecting the technique that will provide
an optimum type of foundation to the soil. These techniques are classified into three main
categories: compaction of the soil in situ, reinforcement of the soil without necessarily changing
the soil properties and fixation techniques that bind particles to improve the soil`s strength. Some
of the compaction techniques used are like the compaction grouting and surcharging of the soils.
Compaction grouting densifies the soils by the injection of low mobility and low slump mortar
grout, hence improving the soft grounds. This is because it is effective in free draining of
granular soils and low sensitivity soils. Surcharging on the other hand involves the use of
prefabricated vertical drains (PVD). Soft grounds are easy to penetrate using the drains and
hence, the structure of the grounds are made better with the PVDs. Reinforcement techniques
involve the use of stone columns, vibro concrete columns, soil nailing and micropiles. Lack of
soil reinforcement especially in soil that has undergone a long-term deformation, may lead to a
failure in improving the soil`s capacity (Kerner, R 1994). After the reinforcement, fixation
follows. It could either be by permeation grouting or jet grouting.

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INJECTION OF POLYMER UNDER LOAD CLAY.
Hussin, J (2006) Methods of Soft Ground Improvement. Taylor and Fiona`s Group LLC

INJECTION OF POLYMER UNDER LOAD CLAY.
Hussin, J (2006) Methods of Soft Ground Improvement. Taylor and Fiona`s Group LLC
Use of Expanding Polyurethane.
According to Oliver Buzzi, Stephen Fityus and Scott W. Sloan, (2010), injection of expansive
polyurethane can be used to remediate differential settlement issues. The polymer is desirable as
it hardens within few minutes therefore paving way for quick analysis of its effect on the
foundation. In addition, the resin is considered to be stable because it is only sensitive to ultra
violet radiation and some synthetic chemicals which are absent in the soils. The injection of these
resin affects the size and shape of the soil spaces. The spaces are among the properties that
determine the mechanical characteristics of the soil. The resins therefore improve the spacing
enhancing the soil mechanical properties.

INJECTION OF POLYMER UNDER LOAD CLAY.
Bazzi, O., Fityus, S. and Sloan, S. (2010) Use of Expanding Polyurethane Resin to Remediate
Expansive Soil Foundations, Can Geotech, (47)