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“Can We Build with Sea Sand and Sea Water? A Historical and Modern Perspective in Civil Engineering”

🌊 “Can We Build with Sea Sand and Sea Water? A Historical and Modern Perspective in Civil Engineering”




A Historical and Modern Civil Engineering Perspective

As the global demand for concrete continues to rise, the construction industry faces two increasingly urgent challenges: the shortage of natural river sand and the scarcity of potable water. These materials are fundamental to conventional concrete production. In response, engineers and researchers are now exploring alternatives once considered unsuitable—sea sand and sea water.

Traditionally rejected due to their high salt content and the risk of steel reinforcement corrosion, these marine resources are now being re-evaluated through the lenses of modern technology, sustainability, and regional necessity. But can we really build with sand and water from the sea? The answer lies in a blend of historical insight, material science, and engineering innovation.

🕰️ A Brief History of Marine Materials in Construction





Ancient Civilizations

Use of marine materials isn’t new. The Romans, for example, created long-lasting harbor structures using a blend of volcanic ash, lime, and seawater. This mixture formed a chemically robust concrete that still exists today in structures like Portus Julius, surviving two millennia of exposure to saltwater. The secret? A chemical reaction between sea water and volcanic ash created calcium-aluminum-silicate hydrates (C-A-S-H), a compound more durable than modern Portland cement concrete (Jackson et al., 2017, PNAS).

Wartime Practices

During World War II, military engineers often had to improvise using local materials in remote or coastal regions. The U.S. Navy Seabees and Japanese construction crews sometimes used sea water and coral aggregates for building bunkers and airstrips. These structures were functional in the short term but deteriorated rapidly due to chloride-induced corrosion, especially in reinforced concrete elements.

These failures led post-war engineering codes—such as those from ACI, BSI, and NSCP—to explicitly prohibit the use of sea sand and sea water in reinforced concrete without extensive treatment or modification.

🌍 The Modern Challenge: Sand and Water Scarcity




The Global Sand Crisis

  • According to the UNEP (2022), humanity consumes over 50 billion tons of sand each year, making it the most-extracted solid material on Earth.

  • Excessive mining of river sand leads to riverbank erosion, habitat destruction, and lower groundwater levels.

  • Cities like Dubai—despite being surrounded by desert—import sand because desert sand is too smooth and round to use in concrete.

Water Scarcity in Construction

  • Freshwater is a critical resource, and its use in concrete competes with agriculture and drinking water needs.

  • Arid regions such as the Middle East, North Africa, and Australia face increasing pressure to conserve potable water, making sea water an attractive alternative—if its risks can be managed.

⚙️ The Science: What Happens When We Use Sea Materials?

Sea Water in Concrete

Sea water contains about 3.5% dissolved salts, mainly chlorides (NaCl, MgCl₂) and sulfates. While these salts can actually accelerate early strength gain in concrete, they pose a serious risk to steel reinforcement by promoting electrochemical corrosion.

Effects:

  • Accelerates rusting in steel

  • Causes expansion, cracking, and eventual failure

  • May impair long-term durability

Solutions:

  • Use of non-metallic reinforcement (e.g., GFRP, BFRP, stainless steel)

  • Corrosion inhibitors and protective coatings

  • Blended cements (e.g., fly ash, GGBFS, silica fume) that bind chlorides and reduce permeability

Sea Sand in Concrete

Sea sand usually has:

  • High chloride content

  • Rounded grains (less interlock)

  • Possible organic impurities and shells

Concerns:

  • Weak bond with cement paste

  • High porosity and reduced strength

  • Corrosion if salts are not removed

Solutions:

  • Washing and grading to remove salts and fines

  • Blending with crushed stone or river sand

  • Restricting use to non-load-bearing or unreinforced applications

✅ Where and How It Works Today

Suitable Applications

Sea sand and sea water can be used in:

  • Plain concrete or mass concrete (e.g., retaining walls, revetments, concrete blocks)

  • Marine structures like breakwaters and seawalls

  • Precast units, bricks, and paving slabs

  • Remote or disaster-relief construction when materials are limited

Unsuitable Applications

Avoid using untreated sea materials in:

  • Reinforced concrete (especially buildings and bridges)

  • Prestressed concrete

  • Critical infrastructure without specialized design measures

🏗️ Global Case Studies and Regional Practices

🇸🇬 Singapore

Singapore has limited natural resources and imports most of its sand. It uses washed sea sand for land reclamation and precast non-structural concrete. The National University of Singapore (NUS) is leading studies on sea water-sea sand concrete (SWSSC), aiming to create sustainable mixes using marine materials and SCMs (NUS News, 2020).

🇨🇳 China

China’s rapid coastal development includes research into sea water concrete for island construction and harbor infrastructure. Tests confirm acceptable performance when fly ash and silica fume are incorporated to counter chloride penetration.

🇯🇵 Japan

Japan’s earthquake-prone coastlines demand highly durable infrastructure. Sea water is allowed in mass concrete where reinforcement is absent or protected. Japan is also a leader in durability-driven design, ensuring that marine structures achieve 50–100 years of service life.

🇸🇦 Middle East

With abundant coastlines and limited freshwater, Gulf nations like Saudi Arabia and UAE explore using sea water for non-structural applications and concrete roads, often combining it with desalinated mixing water or corrosion-resistant design.

📚 Engineering Standards and Academic Support

Standard

Summary

ACI 318-19

Prohibits use of sea water for reinforced concrete but allows it for plain concrete with restrictions.

NSCP 2015

Aligns with ACI; restricts chloride exposure in concrete to avoid steel corrosion.

EN 206

European code specifying maximum allowable chloride contents based on exposure class.

ASTM C94

Requires water used in concrete to meet chemical purity limits, including chloride concentration.

Notable Studies:

  • Jackson et al. (2017), PNAS: Roman marine concrete’s resilience due to pozzolanic reaction in seawater.

  • Shaikh (2016), Construction and Building Materials: Sea water exposure in geopolymer concrete showed minimal corrosion.

  • Mehta & Monteiro (2014): Advised use of SCMs to improve marine concrete durability.

  • Neville (2011): Documented effects of chlorides on concrete microstructure and reinforcement.

🧭 Final Thoughts: A Responsible Path Forward

While sea sand and sea water have been traditionally discouraged in mainstream construction, modern advancements in material technology, durability design, and sustainable practices are helping us reconsider. Their use is context-sensitive—what works in marine breakwaters or remote island housing may not apply to high-rise urban structures.

✔️ Use them when:

  • The structure is unreinforced or properly protected

  • Freshwater and natural aggregates are scarce

  • Sustainability is prioritized and mitigations are in place

❌ Avoid them when:

  • Steel reinforcement is not corrosion-protected

  • Long-term structural integrity is critical

  • National codes explicitly prohibit it without treatment

📣 Join the Conversation

Have you encountered sea materials in your civil engineering projects? Are you interested in helping develop sustainable concrete practices? Share your experience in the comments below or connect for a deeper dive.

🔖 References

  1. ACI Committee 318. (2019). Building Code Requirements for Structural Concrete. American Concrete Institute.

  2. NSCP 2015. National Structural Code of the Philippines. ASEP.

  3. Mehta, P.K., & Monteiro, P.J.M. (2014). Concrete: Microstructure, Properties, and Materials. McGraw-Hill.

  4. Neville, A.M. (2011). Properties of Concrete. Pearson.

  5. Jackson, M.D. et al. (2017). “Roman marine concrete durability explained by synchrotron X-ray microdiffraction.” PNAS, 114(28).

  6. Shaikh, F.U.A. (2016). “Sea water effect on corrosion of reinforced geopolymer concrete.” Construction and Building Materials, Elsevier.

  7. NUS News. (2020). Making Concrete More Sustainable with Sea Water and Sea Sand. Link

  8. UNEP (2022). Sand and Sustainability: 10 Strategic Recommendations. United Nations Environment Programme.

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