道路工程材料Road Engineering Materials CH2

2.1.1 Based on source or method of manufacture
Natural aggregates
Natural sand is formed from weathering and decomposition of all types of rocks, the most abundant mineral constituent being quartz.
MC
Original
sample weight oven-dry oven-dry weight
weight
100
aggregate
≥4.75
沥青混合料的划分
粗集料指粒径大于2.36mm的碎石、破碎砾 石、筛选砾石及矿渣等。
细集料指小于于2.36mm的天然砂、人工砂 （机制砂）及石屑等。
矿粉mineral dust; mineral fines; filler指由 石灰岩或者岩浆岩等憎水性碱性石料经磨 细加工而得到的，在混合料中起填充作用 的，以碳酸钙为主要成分的矿物质粉末， 也称填料。
✓Oven dry (OD) ✓Air dry (AD) ✓Saturated surface dry (SSD)
✓Wet
Moisture content
➢Very important as it influences the w/c；
➢SSD state is most often used as a reference, although it is more difficult to obtain than OD state; ➢Absorption is very important;
堆积密度，指单位体积（包含物质颗粒固体及其
Based on density开口、闭口孔隙体积及颗粒间空隙体积）的物质 颗粒质量，分松散堆积密度和振实堆积密度。
Based on density
Lightweight
Fine aggregate
Coarse aggregate
Bulk density kg/m3 ≤1120
Pumice（轻石，浮石）
Tuff（凝灰岩）
凝灰岩
Shale 页岩
Slate 板 ash 粉煤灰
Normal-weight aggregate
Normal-weight aggregates are commonly used in the manufacture of normal-weight concrete, asphalt concrete, and road subbase. Crushed stone Gravel Ordinary sand
✓Most natural aggregates have an absorption capacity of 1 to 2 percent; ✓Effective absorption versus surface moisture.
Formula
moisture content weight of moisture 100 oven - dry weight
2.1.2 Based on size
Based on the maximum size of particles in a sample, aggregates are divided into two groups: Fine aggregate It refers to the aggregate whose diameter is less than 4.75mm. Coarse aggregate It refers to the aggregate larger than 4.75mm
2.1 Types of Aggregates
Crushed stone 碎石
Sand
砂
Gravel
砾石、卵石
Crushed stone
碎石
Crushed stone
碎石
Sand 砂
Gravel 砾石
Gravel 砾石
Other 40%
40%
27%
Concrete aggregates 27%
800
105
200 1650-1760
2400 1440-1600
2400 3040
2.2 Properties of Aggregates
Physical properties Specific Gravity and Bulk Density Moisture Content Porosity and Voids Gradation and Fineness modulus
9% 16%
Bituminous aggregates 9%
8% Fill 8%
Road base &unpaved roads 16%
Uses of crushed stone
Other 26%
26%
Concrete aggregates 17%
17%
15%
Chemical & metallurgical 15%
16% 26%
Bituminous aggregates 16%
Road base &unpaved roads 26%
Uses of sand and gravel
Types of Aggregates
Aggregates can be divided into several types
Based on source Based on method of manufacture Based on size Based on density
Based on size
cement concrete
Aggregates based on size
Fine aggregate
Materials sand
Particle size (mm)
0.075-4.75
Coarse aggregate
gravel
Crushed stone Manufactured
Lightweight aggregate
Natural Lightweight aggregate
Manufactured Lightweight aggregate
Materials
Pumice['pʌmis]浮石 Scoria['skɔ:riə]矿渣 Tuff凝灰岩 Blast-furnace slag Shale页岩 Slate板岩 Fly ash粉煤灰
Aggregate types and specific gravity
aggregate
Granite花岗岩 Gravel Limestone Perlite 珍珠岩 Pumice 浮石 Quartzite 石英岩 Scoria 矿渣 Expanded shale Sawdust锯屑 Expanded vermiculite 蛭石 Expanded perlite Sand Barite重晶石 Sandstone砂岩 Basalt 玄武岩 Magnetite磁铁矿 Hematite赤铁矿
2.1.3 Based on density
Based on specific gravity or density measured in bulk, aggregate is divided into three types: Lightweight aggregate Normal-weight aggregate Heavyweight aggregate
Road Engineering Materials 道路工程材料
College of Automobile and Traffic Engineering 汽车与交通学院
Ch2 Aggregates
2.1 Types of Aggregates 2.2 Properties of Aggregates 2.3 Mix design of aggregates
Specific gravity=
mass of material
volume of material density of water
2.2.2 Moisture content
Based on the moisture level, aggregates are divided into four states
2.69
Light weight, natural
0.75
Light weight, manufactured
1.00
Light weight, organic
0.50
Light weight, manufactured
0.20
Light weight, manufactured
0.75
Normal weight
Heavyweight aggregate
Heavyweight aggregate is used primarily in the manufacture of heavyweight concrete.
Materials Mineral Ore (limonite褐铁矿, hematite赤 铁矿, magnetite磁铁矿) Barite (BaSO4)重晶石
≤ 880
Normal-weight
1520-1680
Heavyweight
≥1680
Lightweight aggregate
➢Lightweight aggregates are used in the manufacture of lightweight concrete and light weight masonry blocks.
Mechanical properties Modulus of elasticity and Strength
Chemical properties
2.2.1 Specific Gravity
Specific Gravity——is defined as the ratio of the mass of a unit volume of a material - at a specific temperature – to the mass of the same volume of gas-free distilled water at that temperature.
Type
Average Specific Gravity
Normal weight, mineral
2.65
Normal weight
2.70
Normal weight, mineral
2.65
Light weight, natural
2.50
Light weight, natural
0.75
Normal weight, mineral
Manufactured aggregates
Manufactured sand is produced by crushing stone, gravel, or air-cooled blast-furnace slag, and is characterized by sharp and angular particles.
What is Aggregates?
Aggregates is a rocklike material of various sizes and shapes, used in the manufacture of Portland cement concrete, bituminous concrete, plaster, grout, filter beds, railroad ballast, base course, foundation fill, subgrade, and so on.
2.60
Heavy weight
4.50
Normal weight, mineral
2.55
Normal weight, mineral
2.85
Heavy weight
4.50
Heavy weight
5.00
Average bulk density (dry)
kg/m3 1600-1760 1600-1680 1520-1760