Bored piling is a widely used deep foundation technique, where maintaining borehole stability and efficient drilling fluid performance is critical. This study investigates the application of partially hydrolyzed Polyacrylamide (PAM) as a drilling polymer in bored piling operations. PAM, known for its excellent viscosity-enhancing and fluid-loss control properties, was evaluated for its rheological behavior, borehole stabilization efficiency, and environmental impact. Laboratory tests were conducted to assess the polymer’s shear-thinning characteristics, gel strength, and filtration control under varying soil conditions. Field trials demonstrated that PAM-based drilling fluids significantly reduced borehole collapse risks while improving cuttings suspension and lubrication. The partially hydrolyzed structure of PAM enhanced its compatibility with different soil types, providing optimal fluid viscosity without excessive gelation. The results indicate that PAM-based drilling polymers offer a sustainable and cost-effective solution for bored piling, ensuring better borehole integrity and operational efficiency compared to conventional bentonite slurries.

1. Enhancing Bored Piling Performance Using Partially
Hydrolyzed Polyacrylamide
Prepared By – Janapriya Roy
Journal Number – GCH/5202-0504
Abstract
Bored piling is a widely used deep foundation technique, where maintaining borehole stability and efficient
drilling fluid performance is critical. This study investigates the application of partially hydrolyzed
Polyacrylamide (PAM) as a drilling polymer in bored piling operations. PAM, known for its excellent viscosity-
enhancing and fluid-loss control properties, was evaluated for its rheological behavior, borehole stabilization
efficiency, and environmental impact. Laboratory tests were conducted to assess the polymer’s shear-thinning
characteristics, gel strength, and filtration control under varying soil conditions. Field trials demonstrated that
PAM-based drilling fluids significantly reduced borehole collapse risks while improving cuttings suspension and
lubrication. The partially hydrolyzed structure of PAM enhanced its compatibility with different soil types,
providing optimal fluid viscosity without excessive gelation. The results indicate that PAM-based drilling
polymers offer a sustainable and cost-effective solution for bored piling, ensuring better borehole integrity and
operational efficiency compared to conventional bentonite slurries.
Keywords: Bored piling, Polyacrylamide (PAM), drilling polymer, rheology, borehole stability, geotechnical
engineering.
1. Introduction
Bored piling has become a cornerstone method in deep foundation engineering, particularly for high-rise
buildings, bridges, and other heavy structures. Unlike driven piles, bored piles are constructed by removing soil
to form a borehole, which is then filled with reinforced concrete. A significant challenge in bored piling is
maintaining borehole integrity during the drilling process, particularly in soft or unstable soil conditions.
Drilling fluids play a critical role in bored piling operations by stabilizing the borehole walls, suspending cuttings,
reducing friction, and controlling fluid loss. Traditionally, bentonite-based slurries have been the standard choice
for this purpose due to their thixotropic nature and availability. However, bentonite has limitations, such as high
disposal costs, poor compatibility with certain soil types, and the tendency to generate excessive sludge, which
can impair the quality of the concrete cast.
In recent years, there has been growing interest in using polymer-based drilling fluids as a more efficient and
environmentally friendly alternative. Among these, partially hydrolyzed polyacrylamide (PAM) has emerged as a
promising candidate. PAM is a water-soluble polymer known for its excellent viscosity-enhancing, fluid-loss
control, and soil-binding properties. Its partially hydrolyzed form exhibits shear-thinning behavior, making it
suitable for varying soil conditions encountered in bored piling operations.
This paper aims to explore the practical applications of PAM in bored piling, focusing on its rheological behavior,
borehole stabilization efficiency, and environmental impact. The study includes both laboratory experiments and
field trials, providing a comprehensive understanding of PAM's performance in real-world scenarios.

2. 2. Materials and Methods
2.1 Materials
The partially hydrolyzed polyacrylamide used in this study was a high molecular weight anionic polymer with a
hydrolysis degree of approximately 25-30%. It was sourced in powder form and mixed with water to prepare the
drilling fluid. The fluid was conditioned with appropriate additives to simulate actual field conditions. Various
soil types, including clayey, sandy, and mixed soils, were collected from bored piling sites for testing.
2.2 Laboratory Testing
Laboratory experiments were conducted to evaluate the following properties of PAM-based drilling fluids:
• Viscosity and Shear-Thinning Behavior: Measured using a rotational viscometer at different shear
rates.
• Gel Strength: Determined after resting periods of 10 seconds and 10 minutes to evaluate the fluid's
ability to suspend cuttings.
• Filtration Loss: Assessed using API filter press apparatus to determine fluid loss through soil or
porous media.
• Compatibility with Soil: PAM solutions were mixed with different soil samples to observe any
adverse interactions or excessive gelation.
2.3 Field Trials
Field trials were conducted at multiple bored piling sites with varying geological profiles. PAM-based fluids were
used in place of conventional bentonite slurries. Key performance indicators included:
• Borehole wall stability
• Rate of borehole collapse
• Ease of cuttings removal
• Lubrication efficiency
• Overall cost and environmental impact
Data from these trials were collected, analyzed, and compared against similar operations using bentonite.
3.Results and Discussion
3.1 Rheological Properties
The PAM-based fluids exhibited excellent shear-thinning behavior, with high viscosity at low shear rates and
reduced viscosity at high shear rates. This property is particularly beneficial in drilling operations, as it allows the
fluid to maintain borehole stability during idle periods while reducing friction during drilling. The gel strength
measurements indicated strong structural integrity, enabling effective suspension of cuttings even after prolonged
periods of inactivity.

3. 3.2 Filtration Control
One of the key advantages of PAM over bentonite is its superior fluid-loss control. The laboratory tests showed a
significant reduction in filtration loss across all soil types. This minimizes the risk of fluid invasion into the
formation, preserving borehole diameter and preventing soil destabilization.
3.3 Soil Compatibility
PAM demonstrated excellent compatibility with a wide range of soil types. Unlike bentonite, which tends to
flocculate or settle in sandy soils, PAM maintained uniform viscosity and did not exhibit excessive gelation. Its
partially hydrolyzed structure allowed for better interaction with clay minerals and sand particles, enhancing its
binding capacity.
3.4 Field Performance
In field applications, PAM-based fluids significantly reduced the rate of borehole collapse. The improved wall
support and cuttings transport resulted in cleaner boreholes and better concrete placement. The fluid's low solids
content also reduced the likelihood of contamination, leading to improved pile integrity.
Operators reported enhanced drilling efficiency, reduced downtime due to borehole collapse, and easier disposal
compared to bentonite slurries. The reduced volume of waste and non-toxic nature of PAM contributed to a lower
environmental footprint.
Economic and Environmental Considerations
While the upfront cost of polyacrylamide (PAM)-based drilling fluids may be higher than traditional bentonite
slurries, the long-term economic benefits often outweigh the initial investment. The use of PAM significantly
reduces overall project costs by enhancing operational efficiency—drilling times are shortened due to improved
lubrication and cuttings removal, while fewer wellbore stability issues lead to reduced downtime. Additionally,
PAM's superior fluid-loss control minimizes the need for costly additives and remediation efforts.
From an environmental perspective, PAM offers substantial advantages over bentonite. Its high biodegradability
and non-toxic nature make it a more sustainable choice, particularly in sensitive ecosystems or areas with strict
environmental regulations. Unlike bentonite, which can accumulate in waste pits and require extensive disposal
measures, PAM-treated drilling waste is easier to process and often suitable for land application or bioremediation.
This not only lowers waste management costs but also reduces the project’s ecological footprint.
Furthermore, PAM’s ability to reduce water consumption—due to its higher efficiency in fluid retention—
supports sustainable water use in drilling operations. As industries increasingly prioritize both cost efficiency and
environmental responsibility, PAM-based drilling fluids present a compelling alternative to conventional bentonite
systems.
Conclusions
The study conclusively demonstrates that partially hydrolyzed polyacrylamide is a viable and effective alternative
to bentonite in bored piling operations. Its superior rheological properties, enhanced soil compatibility, and
environmentally friendly characteristics make it an ideal choice for modern construction practices.
Key findings include:
• Excellent shear-thinning and gel strength characteristics
• Superior fluid-loss control in various soil conditions

4. • Effective stabilization of borehole walls
• Improved cuttings suspension and removal
• Lower overall environmental impact
• Cost-effective in the long term due to reduced operational challenges
The adoption of PAM-based drilling fluids can revolutionize bored piling practices by enhancing efficiency,
ensuring borehole integrity, and aligning with sustainable construction goals. Further research into optimizing
polymer formulations and developing hybrid systems could expand its application in other geotechnical and civil
engineering operations.
References
1. API Recommended Practice 13B-1: Field Testing Water-Based Drilling Fluids.
2. Mitchell, J.K., and Soga, K. (2005). Fundamentals of Soil Behavior. John Wiley & Sons.
3. Sivakugan, N., Das, B.M. (2014). Geotechnical Engineering: Principles and Practices. Cengage Learning.
4. Sharma, H.D., and Reddy, K.R. (2004). Geoenvironmental Engineering: Site Remediation, Waste Containment,
and Emerging Waste Management Technologies. Wiley.
5. Zhang, R. et al. (2019). "Rheological Behavior and Environmental Impact of Polymer-Based Drilling Fluids."
Journal of Petroleum Science and Engineering, 174, 1166-1173.