Chapter 2 Basic property of civil engineering material
• Material property is an important reason to select the
material;
• Category: Basic physical properties (Mass, density);
Basic mechanical properties;
Heat properties;
Durability.
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Chapter 2 Basic property of civil engineering material
Physical Properties
• Density
• Unit Weight / Specific weight
• Specific Gravity: dimensionless quantity that is defined as
the ratio of the density of a substance to the density of the
water at a specific temperature.
• Porosity
• Coefficient of Softening
• Permeability
• Hygroscopicity (吸水性)
• Fire Resistance
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Chapter 2 Basic property of civil engineering material
Mechanical Properties
• Strength: it is the ability of a material to resist the external forces without breaking;
• Elasticity
• Plasticity
• Ductility (延展性): It is the property of a material which enables it to be drawn
into thin wires under tensile force.
• Brittleness (脆性): A material is said to be brittle if it cannot undergo elastic or
plastic deformation but it breaks under the external force
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Chapter 2 Basic property of civil engineering material
Mechanical Properties
• Stiffness: it is the ability of a material to resist elastic deformation;
• Hardness: it is the ability of a material to resist scratching, wear and abrasion
• Toughness: it is the property of a material to resist fracture due to high impact
loads like hammer blow
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Chapter 2 Basic property of civil engineering material
2.1 Material composition
• It affects chemical stability and also determines physical
and mechanical properties of the material.
Chemical composition
Material Composition Mineral composition
Phase composition
Chapter 2 Basic property of civil engineering material
Production chain and preparation technique
• Influence factors: material composition、structure、working
conditions and ambient medium.
• Material composition、structure are internal reasons of the
material properties;
• Working conditions and ambient medium are determine if
the material could have good performance
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Chapter 2 Basic property of civil engineering material
2.1 Material composition
Material composition affects chemical stability and also
determines physical and mechanical properties of the material.
• Chemical composition： Variety and quantity of chemical
elements that make up a material.
• Usually, chemical composition is represented in a form of
oxide. For example, the chemical composition in the
Portland cement usually is CaO、SiO2
• Corrosion of steel (钢材锈蚀)、Cement corrosion (水泥腐蚀)
So，according to chemical composition, we can select material; or according
to requirement of engineering, adjust the chemical composition of material.
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Chapter 2 Basic property of civil engineering material
• Mineral composition: mineral type and quantity of the
material
Mineral: simple substances and chemical compound of a
certain chemical component、specific crystal structure and
physical and mechanical properties.
For example, Lime (CaO)、sand (SiO2) and water
lime mortar (石灰砂浆) (developed in the condition of hardened at room
temperature);
Limesand brick (灰砂砖) (developed in the condition of hardened at high
temperature and high humidity)
Note: For rock、cement, mineral composition is a key factor to
determine its quality.
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Chapter 2 Basic property of civil engineering material
Production chain and preparation technique
• Influence factors: material composition、structure、working
conditions and ambient medium.
• Material composition、structure are internal reasons of the
material properties;
• Working conditions and ambient medium are determine if
the material could have good performance
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Chapter 2 Basic property of civil engineering material
2.1 Material composition
Material composition affects chemical stability and also
determines physical and mechanical properties of the material.
• Chemical composition： Variety and quantity of chemical
elements that make up a material.
• Usually, chemical composition is represented in a form of
oxide. For example, the chemical composition in the
Portland cement usually is CaO、SiO2
• Corrosion of steel (钢材锈蚀)、Cement corrosion (水泥腐蚀)
So，according to chemical composition, we can select material; or according
to requirement of engineering, adjust the chemical composition of material.
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Chapter 2 Basic property of civil engineering material
• Mineral composition: mineral type and quantity of the
material
Mineral: simple substances and chemical compound of a
certain chemical component、specific crystal structure and
physical and mechanical properties.
For example, Lime (CaO)、sand (SiO2) and water
lime mortar (石灰砂浆) (developed in the condition of hardened at room
temperature);
Limesand brick (灰砂砖) (developed in the condition of hardened at high
temperature and high humidity)
Note: For rock、cement, mineral composition is a key factor to
determine its quality.
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Chapter 2 Basic property of civil engineering material
• When the mineral composition is the same but the proportion
is different, the performance of the material is still different.
• Four mineral composition in the Portland cement
C3S、C2S、C3A、C4AF，provided that the proportion of each
mineral composition is different, the performance of cement is also
Different.
Note: For rock、cement, mineral composition is the key factor
of properties.
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Chapter 2 Basic property of civil engineering material
• Phase composition: A number of material can be considered
as solid composite material of multiple phases.
Phase: the same physical and chemical uniform part in the
material;
Interface: the overlapping area between phases in the material
• Concrete: composite
material of the aggregate
phase (stone、sand) and
cement slurry matrix (basic
phase)
Sand: find aggregate
Stone: coarse aggregate
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Chapter 2 Basic property of civil engineering material
• Natural matter: Gas phase、Liquid phase、Solid phase
• Quality of material is closely related to its phase composition
and the property of the interface
• Concrete: composition and structure on the interface differs
those within the phase and interface is a weak zone,
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Chapter 2 Basic property of civil engineering material
Fig. 1: interface separating aggregate and cement mortar
(Microstructure of the concrete)
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Chapter 2 Basic property of civil engineering material
2.2 Structure of Material: internal organization of a material.
Key factor of the material.
1. Macroscopic structure 宏观结构: naked eyes or
Magnifier. ~ mm tissue. Size > 10-3 m;
2. Submicroscopic structure 亚微观结构: micron structure
observed using optical microscope. Size: 10-3 m ~ 10-6 m;
3. Microcosmic structure 微观结构: the structure observed using
electron microscope or x-ray diffraction. Atom or macular
structure. Size: 10-6 m ~ 10-10 m.
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Chapter 2 Basic property of civil engineering material
2.2.1 Macroscopic structure determines performance of materials
Selection of material:
e.g. Solid concrete (密实混凝土): beam、board、column;
light concrete (轻骨料混凝土): : filler、heat insulation
Macroscopic structure determines the utility of the material
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Chapter 2 Basic property of civil engineering material
• Macroscopic porosity character
1) Particle structure (散粒结构)：the material is composed of
single grain
Dense grains (密实颗粒): sand、rock etc. (high strength &
suitable for aggregate of load-bearing concrete)；
Light porous grains (轻质多孔颗粒): ceramsite 陶粒、perlite etc.
(porous structure & suitable for heat insulating material)
Porosity is a key factor of influencing
the property !
Fig. 2: ceramsite
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Chapter 2 Basic property of civil engineering material
2) Aggregation structure (聚集结构): developed by grain material +
binding material
Including: cement concrete 水泥混凝土、mortar 砂浆、
asphalt concrete 沥青混凝土、
architectural ceramics 建筑陶瓷 、sintered brick (烧结砖)
Note: Aggregation structure has phase composition.
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Chapter 2 Basic property of civil engineering material
3) Porous structure 多孔结构: including a number of coarse or
miscroscopic (10-3 ~ 1 mm) uniformly distributed or enclosed or
connected porosity
Examples： aerated concrete、cellular concrete、
expanded plastic、plastering、clay tile
Porous structure material: properties depend on porosity and
characteristic of the void.
Note: low strength of the material lower, weak anti-permeability, good
water-absorbing quality, good heat insulation;
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Chapter 2 Basic property of civil engineering material
Polyethylene foam board
Aerated concrete brick
Clay brick
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Chapter 2 Basic property of civil engineering material
4) Compact structure material (致密结构): Internal and external
appearance is compact
Example: steel、glass、plastic
Note: High strength of the material, good anti-permeability, weak
water-absorbing quality, bad heat insulation, good wear-resisting
property.
5) Fiber structure material 纤维结构材料: internal tissue of the material
directivity, compact in the portrait direction、loose in the crosswise
direction. There exists a large number of small openings.
Example: wood、fiberglass、asbestos
Note: Strength of the material and heat conductivity anisotropy
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Chapter 2 Basic property of civil engineering material
6) Stratified structure material (层状结构材料): The material is
laminated and cementing material is used to get laminated
material together.
Example: Wood plywood 木胶合板、 plasticfaced plywood 塑料
贴面板、 gypsum plaster board 纸面石膏板
Note: common structure of the board material. The material shows
plane isotropy. The strength、hardness、 heat insulation or
decorative properties are significantly enhanced.
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Chapter 2 Basic property of civil engineering material
2.2.2 Submicroscopic structure : crystalline grain 晶粒 & crystal
boundary 晶界, porosity 孔隙 and microfracture 微裂缝
determines physical、mechanical and durability of the material.
Research of microstructure is an effective approach to improve
Material and develop novel material.
1). Non-metallic material (rock、cement、ceramic)
Using microscope, one could identify
a) Variety of the crystalline phase, shape, particle size and its
distribution;
b) Concentration of glass phase and its distribution;
c) Pores、microfracture and defects。
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Chapter 2 Basic property of civil engineering material
Concrete: base phase、aggregate、interface
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Chapter 2 Basic property of civil engineering material
2) Metallic material: ferrite 铁素体、pearlite珠光体、cementite 渗
碳体. Distribution and concentration.
Smaller size of crystalline grain within the metallic material、more
unified distribution、 more unified distribution of the stress，high
strength、 worse brittleness and higher wear resistance.
3) Organic material: wood
wood fiber 木纤维、duct 导管、pith ray 髓线、resin duct 树脂道
Exhibiting: annual ring 年轮、wood grain 木纹 etc. and physical and
mechanical anisotropy.
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Chapter 2 Basic property of civil engineering material
2.2.3 Microstructure: arrangement of the material at the level of
atoms、ion、molecular
Microstructure determines mechanical properties of the material:
strength、hardness、elastoplasticity、melting point、heat
conductivity、electric conduction etc.
The degree of order of the arrangement:
crystals
Solid Matter
amorphous body
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Chapter 2 Basic property of civil engineering material
Crystal material: solid of periodic rearrangement in the three-
dimensional space
Parallelogram Structure 格子构造: as metals cool from the molten
phase, the atoms are arranged into a definite structures
dependent on the size of the atom and the valence electrons.
Certain characteristic are apparent in the three-dimensional
array of points formed by the intersection of the parallel lines
shown below
(a) Linear lattice 直线点阵
(b) plane lattice 平面点阵
(c) Space lattice 空间点阵
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Chapter 2 Basic property of civil engineering material
Lattice structure: solid of periodic rearrangement in the three-
dimensional space
Fig. : Lattice structure and lattice parameters
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Chapter 2 Basic property of civil engineering material
7 Crystal system and 14 kinds of lattice structures
Fig.: Seven Crystal system
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Chapter 2 Basic property of civil engineering material
Fig.: lattice constant
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Chapter 2 Basic property of civil engineering material
7 Crystal system and 14 kinds of lattice structures
Fig.: 14 Bravais lattices
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Chapter 2 Basic property of civil engineering material
• Unit cell 晶胞: points in the lattice structure are substituted by
ion、atom or molecular.
What is the difference between lattice
and Unit cell?
• Unit cell is tiny small, e.g. 1 mm3
rock crystal contains 1018 ~ 1019
unit cells
• A crystal material can be thought as
developed by a number of unit cells repeatedly arrangement
without gap in 3D space
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Chapter 2 Basic property of civil engineering material
Lattice structure: solid of periodic rearrangement in the three-
dimensional space
Fig. : Lattice structure and lattice parameters
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Chapter 2 Basic property of civil engineering material
7 Crystal system and 14 kinds of lattice structures
Fig.: Seven Crystal system
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Chapter 2 Basic property of civil engineering material
Fig.: lattice constant
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Chapter 2 Basic property of civil engineering material
7 Crystal system and 14 kinds of lattice structures
Fig.: 14 Bravais lattices
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Chapter 2 Basic property of civil engineering material
• Unit cell 晶胞: points in the lattice structure are substituted by
ion、atom or molecular.
What is the difference between lattice
and Unit cell?
• Unit cell is tiny small, e.g. 1 mm3
rock crystal contains 1018 ~ 1019
unit cells
• A crystal material can be thought as
developed by a number of unit cells repeatedly arrangement
without gap in 3D space
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Chapter 2 Basic property of civil engineering material
Characteristic of crystal 晶体的特性:
• homogeneity and anisotropy (质点周期性重复排列，但不同方向
的排列不同；各向异性。)
• Minimum internal energy and maximum chemistry stability：
质点按能量最小原则排列。
• Constant melting point：energy required to destroy the
bonding energy of atoms is the same. 破坏质点间的结合能所
需的能量相同。
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