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As established above, the interaction of algae and concrete in environmental conditions produces degradation and weakening. However, some experimentation has shown that using algae as a filler in the concrete synthesis process results in concrete with characteristics that are more beneficial in certain structural categories. Intentional incorporation of algae into concrete pastes and mixtures has been investigated for sustainability and ability to reduce carbon emissions from manufacturing. Such methods of algae incorporation may involve use of raw, dry, untreated algae, heat-treated algae that forms a [[biochar]], and algae grown in a photobioreactor in order to [[Upcycling|upcycle]] cement kiln dust, a waste product created from traditional concrete processing methods. Some species of algae used for algae concrete production are ''[[Chlorella|Chlorella kessler]]i, [[Sargassum]]'' [[Sargassum|sp]]., and [[Lobophora (alga)|''Lobophora'' sp]].

== Fabrication Methods ==

As established above, the interaction of algae and concrete in environmental conditions produces degradation and weakening. However, some experimentation has shown that using algae as a filler in the concrete synthesis process results in concrete with characteristics that are more beneficial in certain structural categories. Intentional incorporation of algae into concrete pastes and mixtures has been investigated for sustainability and ability to reduce carbon emissions from manufacturing. Such methods of algae incorporation may involve use of raw, dry, untreated algae, heat-treated algae that forms a biochar, and algae grown in a photobioreactor in order to upcycle cement kiln dust, a waste product created from traditional concrete processing methods. Some species of algae used for algae concrete production are ''[[Chlorella|Chlorella kessleri]]'', ''[[Sargassum|Sargassum sp]]''., and [[Lobophora (alga)|''Lobophora sp''.]]

Raw, untreated algae and heat-treated algae have been incorporated into calcium sulfoaluminate cement via replacement at varying percentages by mass{{Cite web |url=https://pubs.acs.org/action/cookieAbsent |access-date=2026-04-21 |website=pubs.acs.org |doi=10.1021/acssuschemeng.4c01007}}. Heat-treatment of ''C. kessleri'' was performed to ensure full thermal decomposition to remove functional groups, leaving behind a stable carbon-rich [[biochar]]. [[Superplasticizer|Superplasticizers]] such as poly(carboxylate ether) and retardants such as citric acid can also be added to ensure proper workability and increase hydration time. Calcium sulfoaluminate-based concrete with algal inclusions still must be stored in humid environments after mixing to facilitate proper hydration, forming [[ettringite]].

== Cultivation and Fabrication Methods ==

Brown algae, specifically ''Sargassum sp.'' and ''Lobophora sp.'' have been investigated for incorporation into magnesium oxychloride cement mixtures. Brown algae are highly abundant in aquatic environments and can be processed into fine powders via drying, grinding in a mortar, and then milling{{Cite journal |last=Mellado-Lira |first=Emireth A. |last2=Luévano-Hipólito |first2=Edith |last3=Torres-Martínez |first3=Leticia M. |date=2025-04 |title=Brown algae: Sargassum sp. and Lobophora sp. incorporation in magnesium oxychloride cement |url=https://linkinghub.elsevier.com/retrieve/pii/S2352554125000671 |journal=Sustainable Chemistry and Pharmacy |language=en |volume=44 |pages=101969 |doi=10.1016/j.scp.2025.101969}}. Like with algae-incorporated calcium sulfoaluminate concrete, processed brown algae was used to replace some of the MgO and MgCl₂ used in magnesium oxychloride cement. The mixture was then poured into molds and left to cure for seven days, demonstrating a use case for the problem of brown algae overabundance.

== Characterization ==

[[Fourier-transform infrared spectroscopy|Fourier transform infrared spectroscopy]] (FTIR) is commonly used for identifying [[Functional group|functional groups]] such as hydroxyl, carbonyl, and amide groups. In the context of algae concrete, FTIR is useful for confirming functional groups in algae biomass that may impact hydration and hydrophilic properties, such as carboxyl and hydroxyl groups, and in monitoring interactions of algal components with the cement phase. Additionally, FTIR can track hydration and reaction products that result from incorporation of organic algal components with inorganic cement. In the case of producing carbon-rich biochar from unprocessed algae, FTIR can be used to confirm the disappearance of characteristic peaks of hydroxyl and carboxyl groups. [[X-ray diffraction|X-ray diffraction (XRD)]] can be used to identify the [[crystal structure]] of the biocement compound produced from algae incorporation, and [[Energy-dispersive X-ray diffraction|Energy-dispersive X-ray diffraction (EDX)]] analysis can also be used to identify final product composition. Other methods of analysis of biocement include [[Scanning electron microscope|scanning electron microscopy (SEM)]] for visualization of nanostructure and [[Thermogravimetric analysis|thermogravimetric analysis (TGA)]] to study the extent of cement hydration, since water will be released upon heating which then correlates to a loss in mass of the sample.

Attempts have also been made to reduce wastage from traditional concrete fabrication methods by using [[Cement kiln|cement kiln dust]] and microalgae as base materials for biocement production. One group investigated the use of a [[photobioreactor]] setup to culture ''C. kessleri'' with fixed light intensity and flow rates of ambient air and CO₂{{Cite journal |last=Irfan |first=M.F. |last2=Hossain |first2=S.M.Z. |last3=Khalid |first3=H. |last4=Sadaf |first4=F. |last5=Al-Thawadi |first5=S. |last6=Alshater |first6=A. |last7=Hossain |first7=M.M. |last8=Razzak |first8=S.A. |date=2019-09 |title=Optimization of bio-cement production from cement kiln dust using microalgae |url=https://linkinghub.elsevier.com/retrieve/pii/S2215017X18302923 |journal=Biotechnology Reports |language=en |volume=23 |pages=e00356 |doi=10.1016/j.btre.2019.e00356 |pmc=6609786 |pmid=31312609}}. Cement kiln dust was then dissolved in deionized water and added to a smaller volume of the algae culture with acetic acid to maintain pH and stored under fluorescent Grolux bulbs. Precipitates were then collected every 24 hours after this and dried in an oven at 105C. While some parameters in this study were selected for further investigation and optimization, the general workflow for upcycling cement kiln dust into biocement with ''C. kessleri'' remains constant.

== Benefits over Traditional Concrete ==

Algae concrete provides a use case and method for addressing the expansion of algae which poses an environmental risk to [[marine ecosystems]]. [[Algal bloom|Algal blooms]] result from algae and other microorganisms expanding without control due to excess nitrogen and phosphorus, usually due to [[eutrophication]]. These blooms produce environmentally hazardous and toxic byproducts, deplete oxygen from the water, and can block sunlight from reaching lower levels of the water, severely harming aquatic ecosystems.

== Characterization ==

[[Fourier-transform infrared spectroscopy|Fourier transform infrared spectroscopy]] (FTIR) is commonly used for identifying [[Functional group|functional groups]] such as hydroxyl, carbonyl, and amide groups. In the context of algae concrete, FTIR is useful for confirming functional groups in algae biomass that may impact hydration and hydrophilic properties, such as carboxyl and hydroxyl groups, and in monitoring interactions of algal components with the cement phase. Additionally, FTIR can track hydration and reaction products that result from incorporation of organic algal components with inorganic cement. In the case of producing carbon-rich biochar from unprocessed algae, FTIR can be used to confirm the disappearance of characteristic peaks of hydroxyl and carboxyl groups. [[X-ray diffraction|X-ray diffraction (XRD)]] can be used to identify the [[crystal structure]] of the biocement compound produced from algae incorporation, and [[Energy-dispersive X-ray diffraction|Energy-dispersive X-ray diffraction (EDX)]] analysis can also be used to identify final product composition. Other methods of analysis of biocement include [[Scanning electron microscope|scanning electron microscopy (SEM)]] for visualization of nanostructure and [[Thermogravimetric analysis|thermogravimetric analysis (TGA)]] to study the extent of cement hydration, since water will be released upon heating which then correlates to a loss in mass of the sample.

== Environmental Impact [add CO2 sequestering here] ==

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Algae concrete provides a use case and method for addressing the expansion of algae which poses an environmental risk to [[marine ecosystems]]. [[Algal bloom|Algal blooms]] result from algae and other microorganisms expanding without control due to excess nitrogen and phosphorus{{Cite web |last=US Department of Commerce |first=National Oceanic and Atmospheric Administration |title=Harmful Algal Blooms (Red Tide) |url=https://oceanservice.noaa.gov/hazards/hab/ |access-date=2026-04-21 |website=oceanservice.noaa.gov |language=EN-US}}, usually due to [[eutrophication]]{{Cite web |last=US Department of Commerce |first=National Oceanic and Atmospheric Administration |title=What is eutrophication? |url=https://oceanservice.noaa.gov/facts/eutrophication.html |access-date=2026-04-21 |website=oceanservice.noaa.gov |language=EN-US}}. These blooms produce environmentally hazardous and toxic byproducts, deplete oxygen from the water, and can block sunlight from reaching lower levels of the water, severely harming aquatic ecosystems.