Advances in Building Materials

The arrangement of cross-laminates at the macroscale decreases the swelling anisotropy of the element and reduces the magnitude of dimensional changes.

...but, they do not decrease the magnitude of swelling/shrinkage of wood

The wood structure (cell walls) needs to be modified by:

• Thermal treatments
• Chemical modification

Wood modification via heat treatment

• temperature at least 160°C
• atmosphere without oxygen
• Parameters:
  • wood type; initial moisture
  • sample size and geometry
  • treatment temperature and duration
  • pressure, medium

Property changes:

• + reduced equilibrium moisture content
• + improved dimensional stability
• + improved duraibility
• + darker color
• - reduction in strength
• - increased brittleness

Modification of cell lumina

• Lumina filling usually with resins
• --> increase in density
• --> limited impact on wood properties
• can affect some mechanical properties (e.g. hardness)
• water adsorption can be slower, but no absolute change in the sorption behavior

Cell wall modification

• cell wall components are chemically affected
  --> chemical bonds are changed or modified
• water adsorption and thus durability and dimensional stability can be influenced
• functionalization of the OH groups (Acetylation)
• Cross-linking treatment (DMDHEU)
• Spruce - insertion of flavonoids into the cell wall

"Bulking" modification - cell wall and lumina

• generally changes the sorption behavior of the wood and the swelling and shrinkage can be reduced
• Disadvantage: the density of the wood is increased

Insertion of calcium carbonate in the wood structure

• lowers heat release rates and smoke production
• Process 1: decomposition of dimethyl carbonate (DMC)
• Process 2: mineralisation by alternating salt solutions

Polymerization of pyrrole in fir wood cross-sections

• Polymerization: process to form polymer chains or three-dimensional networks
• Pyrrole:  organic compound

Polymerization of aniline in pine veneers

• Aniline:  organic compound
• Pine veneers: a "paper thin" cut of wood that is attached to a panel of fiberboard or particleboard

Metalized wood (wood filled with tin-bismuth alloy)

Electric conductivity by laser-induced graphitization of wood

• graphitization: the process of heating amorphous carbon
  --> rearranging the atomic structure to achieve an ordered crystalline structure

Formation of superparamagnetic iron oxide particles

Directional water transport for autonomous fog collection

• Fog collection: harvesting water from fog

--> Janus wood membrane

• asymmetric wettability on two sides
  --> hydrophobic and hydrophilic side

Delignified wood

• Delignify:  the process of extracting lignin from plant sources
• Uses:
  • transparent wood (as optical lighting material)
  • thermal insulation
  • cooling purposes (scattering solar radiation)
  • enhancing piezoelectric properties

Densified wood

• obtained by delignification and hot-pressing
• good waterproof and excellent dimensional stability
• higher compressive strength

Moldable wood is a strong and flexible cellulose-based material. Moldable wood can be folded into different shapes without breaking or snapping. The patented synthesis is based on the deconstruction and softening of the wood's lignin, then re-swelling the material in a rapid "water-shock" process that produces a wrinkled cell wall structure. The result of this unique structure is a flexible wood material that can be molded or folded, with the final shape locked in by simple air-drying.

Early age

• Rheology

Intermediate age

• Early strength --> time to demolding
• Main heat released --> thermal stresses after demolding
• plastic shrinkage

Late age

• Final compressive strength
• Drying shrinkage
• Duariblity
• Creep

Carbonation depth refers to the average distance from the surface where CO2 reduces the alkalinity in concrete or mortar, leading to neutralization of the protection for reinforcing steel.

Limestone Calcined Clay Cement

Calcined clay and limestone are already commonly used as Supplementary Cementitious Materials (SCMs).

The major innovation in LC3 is to combine the use of abundantly available low-grade kaolinite clay with a further 15% of limestone, which together have a synergetic effect and reach a similar performance as OPC - CEM I.

C  -  CaO  (Calciumoxide)

S  -  SiO₂  (Siliciumdioxide)

A  -  Al₂O₃  (Aluminiumoxide)

F  -  Fe₂O₃  (Iron(III)-oxide)

C'  -  CO_{2  (Carbonoxide)}

S'  -  SO₃  (Sulfurtrioxide)

Portlandite (CH)

Calcium silicate hydrate (C-H-S)

Ettringite (AFt)

AFm

Mechanical properties

Physical properties

Interaction with the environment

Production properties

Economic properties

Sustainability

Recyclability

Function --> What does the component do?

Constraints --> What non-negotiable conditions must be met?
                         What negotiable but desirable conditions? ("hard" and "soft" constraints)

Objective --> What is to be maximized or minimized?

Free variables --> What parameters of the problem is the designer free to change?

"Filling holes in material-property space"

Constant time for double the amount.

\(P(t)=P_0 e^{kt}\)

\(P(t)\)  amount at time t

\(P_0\) initial amount

\(k\)  rate of growth

Shortening time for double the amount.

The utilization rate of natural resources does not exceed that of their regeneration.

The consumption rate of non-renewable resources does not exceed the rate of development of renewable substitutes.

The amount of pollution and waste does not exceed what the environment can absorb.

To preserve the environment:

• by measures to protect its quality
• by the restoration, accommodation, and maintenance of habitats essential to species
• as well as by sustainable management of the exploited animal and vegetable species

To improve social equity:

• to satisfy the needs of present and future human communities
• to improve life quality, for instance through access to quality housing

To improve economic efficiency

• to favor optimal management of human, natural, and financial resources
• in order to satisfy the needs of human communities, for instance by corporate and consumer responsibility

Environmental Performance Index

When human activities may lead to morally unacceptable harm that is scientifically plausible but uncertain, actions shall be taken to avoid or diminish that harm.

Morally unacceptable harm refers to harm to humans or the environment that is...

• ...threatening to human life or health, or
• ...serious and effectively irreversible, or
• ...inequitable to present or future generations, or
• ...imposed without adequate consideration of the human rights of those affected
• ...