Reusing Construction and Demolition Waste to Prepare Alkali-Activated Cement

Area of Science:

• Materials Science
• Civil Engineering
• Sustainable Construction

Background:

• Construction and demolition waste (C&DW) presents significant landfill challenges and disposal costs.
• Current C&DW reuse is limited to low-value applications like filler or aggregate.
• There is a need for advanced methods to valorize C&DW and promote sustainable building materials.

Purpose of the Study:

• To investigate the feasibility of manufacturing alkali-activated cement using C&DW.
• To enhance the sustainability and recovery of construction and demolition waste.
• To develop a novel binder alternative to Portland cement.

Main Methods:

• Characterization of C&DW from Valencia, Spain (physical, chemical, XRF, XRD).
• Preparation of alkali-activated binders using C&DW and blast furnace slag (BFS) with sodium hydroxide and sodium silicate.
• Characterization of pastes (thermogravimetry, SEM) and determination of mortar compressive strength.

Main Results:

• C&DW primarily composed of concrete, mortar, and ceramics, with CaO, SiO2, and Al2O3 as main chemical components.
• Alkali-activated blends of 50% C&DW and 50% BFS achieved a compressive strength of up to 58 MPa.
• Successful development of sustainable binders without Portland cement.

Conclusions:

• Alkali activation of C&DW-BFS mixtures provides a sustainable route for binder production.
• This method effectively valorizes construction and demolition waste, reducing environmental impact.
• The developed binders offer a promising eco-friendly alternative in the construction industry.