In a groundbreaking study published in “Case Studies in Construction Materials,” researchers have unveiled a promising framework for sustainable coastal infrastructure, leveraging seawater and marine sand to produce durable, low-carbon geopolymer concrete (GPC). This innovation addresses critical global challenges, including freshwater scarcity and the depletion of river sand, offering a viable alternative for coastal construction.
The research, led by Phu Dao Van from the University of Agriculture and Forestry at Hue University in Vietnam, explores the use of seawater and marine sand in GPC production. Traditional Portland cement is a significant source of carbon emissions, and the study highlights the potential of GPC as a sustainable alternative. “Our findings demonstrate that seawater and marine sand can be effectively used in GPC, providing a robust and eco-friendly solution for coastal construction,” Van explained.
The study prepared mixes with varying proportions of seawater and marine sand, testing their mechanical properties and analyzing the resulting microstructures. Key to their approach were three newly defined indices: the amorphous gel fraction (λ), the stability-to-interference ratio (γ), and the Gel Stability Index (GSI). These indices capture the delicate balance between gel continuity and crystalline disruption, crucial for the material’s strength and durability.
At 35% replacement of freshwater with seawater, the researchers observed a stable hybrid network of sodium-alumino-silicate-hydrate (N-A-S-H) and calcium-(alumino)-silicate-hydrate (C-(A)-S-H), leading to significant strength gains. Interestingly, complete seawater use resulted in the highest compressive strength, attributed to sodium-induced gelation and delayed zeolitic reinforcement. However, 70% replacement led to oversaturation and premature strength loss due to early brucite–halite precipitation.
The Gel Stability Index (GSI) emerged as a composite indicator of gel integrity and long-term stability, tracking both compressive and flexural strength. “GSI provides a mechanistic descriptor for durability-relevant behavior, including chloride ingress, sulphate/magnesium attack, and sorptivity,” Van noted. This index could revolutionize the way engineers assess the long-term performance of GPC in coastal environments.
The implications for the energy sector are substantial. As coastal infrastructure projects proliferate, the demand for sustainable and durable construction materials will grow. This research offers a blueprint for developing low-carbon concretes that can withstand the harsh conditions of coastal environments, reducing the environmental footprint of construction activities.
Moreover, the study’s findings could pave the way for further innovations in material science, particularly in the realm of geopolymer concretes. By understanding the intricate interplay between ion chemistry, gel evolution, and structural performance, researchers can optimize the use of alternative resources, contributing to a more sustainable future.
As the world grapples with the challenges of climate change and resource depletion, this research provides a beacon of hope. By harnessing the power of seawater and marine sand, we can build resilient coastal infrastructure that stands the test of time, all while minimizing our impact on the environment. The journey towards sustainable construction has taken a significant step forward, and the future looks promising.