Comprehensive Study Guide: Construction Materials, Hemp Concrete, and BFUP

Recommended Fiber for Structural Reinforcement: For structural reinforcement purposes, metallic fibers (fibres métalliques) are the primary choice compared to organic fibers, nylon, or cellulose.
General Definition of BRF: The abbreviation BRF refers to bétons renforcés de fibres (fiber-reinforced concretes).
Fiber Slenderness Factor: The ideal slenderness factor for fibers, defined as the ratio between the length and the diameter of the fibers, is typically comprised between 50 and 100.
Implementation of BRF: During the pouring and placement of BRF, the concrete should not be vibrated using standard internal methods; if required, external vibration (vibration externe) is the preferred technique.

Classification of Natural Binders: Among various binders, NHL (Natural Hydraulic Lime) is classified as natural. Specifically, NHL 5 indicates a mechanical resistance at 28 days of $5\,MPa$ .
Definition of Natural Hydraulic Binders: A natural hydraulic binder is one that is issued from a single deposit and manufactured without the use of chemical additives or adjuvants.
Natural Cement Production: Natural rapid cement is obtained through a kiln firing process at temperatures ranging between $700\,^{\circ}C$ and $1200\,^{\circ}C$ .
Origin of Bio-sourced Materials: These materials are of natural origin (as opposed to synthetic, metallic, or plastic).
Biomass Components: Biomass materials include fibers, dust, and ashes. However, aggregates (agrégats) are typically not categorized as part of the biomass.

Composition: Hemp concrete consists of hemp shives (chènevotte/chènevis), binder powder, and water.
Hemp Aggregate Conformity Criteria: For hemp to be used as a natural aggregate, it must meet the following thresholds: - Loose bulk density (masse volumique foisonnée) of approximately $100\,kg/m^3$ . - Length between $1\,mm$ and $30\,mm$ .
Dust Content: French national recommendations specify a maximum dust content (passing through a $0.25\,mm$ sieve) of less than $2\%$ by mass.
Chemical Composition of Hemp: According to chemical data, the main component is cellulose at $46\%$ , followed by lignin ( $26\%$ ) and hemicellulose ( $21\%$ ).
Wood Components in Hemp: The layers of the hemp plant defined as "wood" include the primary xylem (xylème primaire) and the primary phloem (phloème primaire).
Typical Application: Hemp concrete is primarily utilized for its thermal and acoustic insulation properties rather than its mechanical strength.
Mechanical Characteristics: Known as agri-concrete, it is highly deformable with a usual compressive strength of $< 0.5\,MPa$ .

Energy Feasibility Study: New building project owners must conduct a feasibility study for energy supply, except in three specific conditions: - Buildings with a floor surface area less than $50\,m^2$ . - Individual or semi-detached houses already subject to the RT2012 thermal regulation requiring renewable energy. - Extensions of existing buildings.
BEPOS (Bâtiment à Énergie POSitive): Under thermal regulations like RT2020, BEPOS refers to a building where the energy production exceeds its consumption.
Eco-design Pillars: The goals of eco-design include the reduction of environmental impacts and the optimization of materials throughout the lifecycle.
CO2 and Carbon Storage: - Trees store $CO_2$ via the process of photosynthesis. - For every $1000\,kg$ of $CO_2$ absorbed, a forest releases approximately $700\,kg$ of $O_2$ . - One cubic meter ( $1\,m^3$ ) of wood can sequester $1851\,kg$ of $CO_2$ . - Concrete made of wood or hemp acts as a carbon sink through these biological processes.
Cement Emissions: The production of $1000\,kg$ of cement emits approximately $750\,kg$ of $CO_2$ .
Definition of the Lithosphere: It represents the layer containing sediments and rocks.

BFUP Definition: The abbreviation stands for Béton Fibré à Ultra-Hautes Performances (Ultra-High Performance Fiber-Reinforced Concrete).
Mechanical Resistance thresholds: - Standard BFUP compressive strength: $120\text{--}180\,MPa$ . - Ductal FM compressive strength: $200\,MPa$ . - Ductal FM tensile strength: $8\,MPa$ .
Microstructure and Porosity: - Unlike ordinary concrete (BO), BFUP exhibits no capillary porosity. - Typical water porosity of BFUP is between $1.5\%$ and $6\%$ .
Water/Binder Ratio: In BFUP, the water-to-binder ratio is approximately 2 times smaller than that of ordinary concrete, typically ranging from $0.15$ to $0.25$ .
Role of Fibers: - In compression tests, fibers primarily serve to increase the ductility of the material. - Short fibers act on the pre-peak domain of the stress-strain curve, while longer fibers influence the post-peak behavior.
Structural Reliability: There are 3 levels of calculation used to evaluate the reliability of a structural element.
Micro-cracking Threshold: Micro-fissures begin to develop when the load reaches $40\%$ of the characteristic compressive strength ( $f_c$ ).

Conductivity of Hemp Shives: The typical thermal conductivity ( $\lambda$ ) for chènevotte falls between $0.03$ and $0.05\,W\,m^{-1}\,K^{-1}$ .
Aerogel Properties: Aerogels have an extremely low density, consisting of $99.8\%$ air.
Humidity Effects: Both thermal conductivity ( $\lambda$ ) and mass heat capacity ( $C$ ) increase in proportion to the humidity present within a material.
Winter Temperature Fluctuations: A drop in temperature in winter leads to a diminution of both thermal conductivity ( $\lambda_T$ ) and mass heat capacity ( $C_T$ ).
Durability Risks: The "alkali-aggregate" reaction (alkali granulat) occurs primarily in the presence of water (l'eau).

Characteristics of Earth Concrete (Béton de Terre): - Density (p): $1500\text{--}2000\,kg\,m^{-3}$ . - Compressive strength: $2\text{--}8\,MPa$ .
History of Reinforced Concrete: The Alvord Lake Bridge, recognized as the first reinforced concrete bridge, was constructed in 1889.

Question: What is the major axis in granulometry?
Answer: It represents the largest dimension that can be measured on the particle.
Question: Which materials allow for $CO_2$ storage via photosynthesis?
Answer: Wood (Le bois) is the primary building material in the list (including steel, glass, and concrete) that performs this function natively.