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Sustainability

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Advanced Low-carbon Buildings in Zero-Carbon Future

 

Modular Integrated Construction (MiC)

Module-integrated Construction (MiC) involves pre-fabricating elements offsite and transporting them to site for installation.

 

Self-compacting carbonation coating

Self-compacting carbonation coating is produced from the carbon dioxide-reactive materials: γ-dicalcium silicate.

 

Light foam concrete

Waste-based Carbonated Aerated Concrete (WCAC) is derived from industrial waste using carbonation technology as a substitute for autoclave technology.

 

IBA-derived concrete (Fully)

IBA-derived concrete is produced exclusively from municipal solid waste incineration residues.

 

Superhydrophobic carbonation coating

Superhydrophobic carbonation coating is made from CO2-induced calcium carbonate crystals, improving the durability of concrete.

 

Permeable concrete

High-strength permeable concrete is developed from waste glass with various environmental benefits: reduces waterlogging, and improves quality of air and groundwater.

 

Rapid-hardening block

Rapid-hardening block can achieve a compressive strength higher than 15 MPa after only 15 minutes of activation.

Novel Construction Process Towards Carbon Neutrality

 

Key Issues

• Productivity of the concrete casting industry is relatively low

• Labour costs have significantly increased due to population ageing and labour shortages

• Traditional precast concrete curing is time consuming and water/energy intensive

• Supply of traditional SCMs has regional limitations

• Use of formwork creates significant construction waste

 

Solutions  

1. CO2 activator

• Produces on-site calcium carbonate-based SCMs in concrete, reducing reliance on and use of traditional SCMs such as fly ash, GGBFS, and limestone

 • Uses CO2 mixing technology to accelerate concrete curing process, reducing production cycles and improving efficiency

 • Fresh concrete properties can be precisely controlled by simply controlling CO2 injection parameters, simplifying the existing concrete production process

 

2. CO2 printing 

• Develops a novel greenhouse gas CO2–based rheology modifier to achieve “set-on-demand”, enhancing printing efficiency and quality

• Establishes intelligent real-time quality control of CO2 printing systems that can adapt to different structural designs, enhancing construction flexibility and efficiency

 • Promotes reusable printing materials, reducing material waste, improving resource utilisation, and reducing environmental impact

 

 3. CO2 foaming agent

• Reduces concrete density, improve insulation, and lower energy consumption of buildings

 • Achieves internal carbonation curing and sharply improve strength development

 • Improves mechanical properties and thermal performance simultaneously

 • Reduces dependence on traditional resources, such as cement and fly ash, to enhance material sustainability

 

4. CO2 curing agent 

• Improves production efficiency

• Accelerates early strength and improve long-term durability of concrete

 • Develops eco-friendly construction materials and reduce environmental impact

Low-carbon Raw Materials Derived from Solid Wastes

 

Key Issues

  1. Concrete production is responsible for 9% of total greenhouse gas emissions

  2. Traditional CCUS & geological storage are facing Limited CO2 application, uncertain CO2 long-term storage

  3. The major disposal method for urban solid waste is through the process of landfilling (e. g C&D waste; glass waste; municipal incineration waste; metallurgical waste)

  4. Land-filling caused land occupation; methane emission; odor emission; surrounding water/land pollution

  5. Fact (HK/year)：

(a) Construction waste is 20.81 million tonnes  

(b) Glass waste is estimated at about 109500 tonnes

(c) Metallurgical waste is estimated at about 94900 tonnes

(d) MSW is estimated at about 4.15 million tonnes

 

 

Solutions

1. Eco-cement clinkers

  1. CO2-activated cement: Synthesized from solid wastes

  2. CE clinker: Low-carbon novel mineral phase

  3. GLC3: Glass + Calcined marine mud + OPC

 

Advantages

  • 1-day strength can reach 110 MPa subjected to CO2 curing.

  • low temperature of 1100 ℃ beneficial to reduce energy consumption

  • 70% of CO2 emission from cement making can be permanently sequestrated

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2. Functional aggregates

  1. High-strength aggregates: BOFS and IBA

  2. Lightweight and sound-absorbing Aggregates: alkali activation of IBA powder.

  3. Insulated aggregates: incorporate paraffin into the aggregate core and encapsulate it with a carbonation layer.

 

Advantages

  • Thermal conductivity of concrete is reduced by 60%

  • 1 t of aggregates can absorb 136.5 kg CO2.

  • Comparable strength can be achieved

 

3. High performance SCMs

  1. Convert C & D wastes into carbon sinks.

  2. Diversified high-value SCMs

  3. About 100 kg CO2/t C&D wastes were permanently sequestrated.

 

Advantages

  • Capture >200kg CO2/ tone recycled concrete fine.

  • 20-30% of cement can be replaced without scarifying strength development.

  • Improve early age strength and later age durability of concrete.

  • Convert waste concrete to multiple-scale products (nano to macro).

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