Sustainability in Geotechnical Construction to Reduce Environmental Impacts
Sustainable geotechnical practices can reduce environmental impacts by using energy-efficient designs, low-carbon materials, alternate fuels & equipment and waste reduction strategies.
Dr. V. R. Raju - Senior Advisor, Sustainability at Keller plc, and Professor of Practice, IIT Madras
Sustainability involves balancing environmental, social, and economic dimensions for long-term health and prosperity. Human activities like burning fossil fuels and deforestation have warmed the atmosphere, land, and water, impacting weather, sea levels, and biodiversity. The construction industry contributes 40% of global emissions, with foundation industries accounting for 15-23% of a building’s embodied carbon (Deamer 2023).
Figure 1: Comparison of Original Driven Piling Solution Vs Sustainable Alternative GI Solution
Emission Scopes and Carbon Hierarchy
As per the Greenhouse Gas Protocol (Ranganathan et al., 2004), emissions are categorized into three scopes: Scope 1 (direct emissions), Scope 2 (indirect emissions from energy production), and Scope 3 (indirect emissions from the value chain). Cement, concrete, and steel are major Scope 3 contributors. The carbon hierarchy suggests avoiding carbon-heavy foundations, optimizing efficiency, substituting with lower-carbon options, and offsetting emissions as a last resort.
Avoid Heavy Foundations and Use Alternate Techniques (Eliminate)
Jurong Island in Singapore hosts major oil and gas refinery plants. A traditional piling approach for one such plant involved 8,900 driven spun piles, covering 147,000 m², but faced challenges like high cement and steel consumption, long transportation demands, and waste generation. An alternative ground improvement (GI) approach using vibro compaction for sand layers and vibro stone columns for soft clay was proposed (Figure 1). This hybrid solution densified loose sands and reinforced clayey subsoils, eliminating traditional driven piles and reducing environmental impact. The GI approach cut carbon emissions by 92%, saving 20,100 tCO2e, from 22,000 tCO2e to 1,900 tCO2e (Figure 2).
Figure 2: Carbon Reductions Achieved by Adopted GI Solution (Vibro Techniques)
Design Optimization (Reduce)
Design optimization is key to reducing carbon emissions. A case study of an electric arc furnace rebar mill under construction in Punjab aimed to produce net zero steel. Located in earthquake Zone IV with a shallow groundwater table, the soil was susceptible to liquefaction. The innovative solution involved vibro compaction to mitigate liquefaction and designing piles assuming no loss of capacity during earthquakes (figure 3). This reduced the number of piles and pile diameter, saving 60% of concrete and 65% of steel, cutting emissions by 35,000 tCO2e.
Figure 3: Keller Innovative Design in Foundation Construction for a Project In Punjab, India
Additionally, optimizing the concrete mix design with Portland pozzolana cement saved 3,000 tCO2e, and reducing cementitious content saved another 50 tCO2e. Replacing Bentonite with synthetic polymer in BCIS piling saved 100 tCO2e. Efficient machinery use, and mass transportation further reduced emissions by 2,700 tCO2e and 150 tCO2e, respectively. These measures collectively demonstrate significant carbon savings and highlight the importance of sustainable practices in construction (Figure 4).
Figure 4: Stages of Carbon Reduction from Foundation Construction Project
Alternate Fuel Types and Equipment (Substitute)
Using alternative fuels like biodiesels and HVO is a promising early decarbonization strategy, as they can be used without modifying existing equipment. HVO, a biofuel from waste food or plants, can replace diesel directly, while biodiesel must be blended with standard diesel. HVO significantly reduces particulate matter (PM) and nitrogen oxide (NOx) emissions. UK trials showed HVO reduced emissions by 97.6 tCO2e, a 98.4% saving, despite higher (HVO) fuel consumption.
Electric construction equipment, such as piling rigs from Bauer and Liebherr, is becoming globally available. For a metro project in Oslo, electric rigs were used to install secant piles using city power, which are from Norway's near-zero emission electricity due to hydro power.
Conclusion
In the Anthropocene, where human impact on the planet is undeniable, sustainable geotechnical construction is not just a choice but a necessity. Construction contributes to global greenhouse gas emissions; but also offers reduction opportunities. Adding sustainability lens to conventional design fosters innovation and carbon savings. Following the carbon hierarchy (Avoid, Reduce, Substitute, Offset) systematically maximizes impact, with material reduction or substitution offering the greatest savings.
