Definition
Uses reactions between reactive siliceous and aluminous materials and calcium-bearing systems to form binding products; both ancient natural volcanic ash and some modern activated clays can participate in this mechanism.
Ancient approach
Roman engineering combined lime with volcanic ash to obtain a binder system capable of hardening underwater, and used it in concrete.
Modern extensions
Modern calcined clays can provide reactive silica and alumina components. Formulations such as LC3 also exploit their synergistic reactions with limestone. This entry describes a shared material mechanism; it does not assert an unverified, continuous line of transmission from antiquity to modern products.
Principles and impact
Problems solved
- Improved the ability of simple air-hardening lime systems to harden in damp or underwater environments.
Principles
- Reactive siliceous and aluminous components react with lime or calcium-bearing components formed by cement hydration.
- Natural volcanic ash and modern calcined clay are different raw materials, but can have related reactivity.
Improvements
Not recorded
Significance
- Connects ancient lime binder systems with modern approaches using supplementary cementitious materials.
History and applications
People
Not recorded
Organizations
Not recorded
Events
Not recorded
Applications
Lime–pozzolan binders、Blended cements containing reactive mineral additions
Limitations
- Reactivity varies with the raw material's mineral composition, activation and fineness.
- Not all powdered volcanic rock or unactivated clay can be treated as an effective binder material.
Upstream and downstream relations
Upstream
Sources: Preservation Brief 15: Preservation of Historic ConcreteTypes of Cement
Sources: Lime plaster cover of the dead 12,000 years agoPreservation Brief 15: Preservation of Historic Concrete
Downstream
Sources: Preservation Brief 15: Preservation of Historic Concrete