Highway Materials

# Highway Materials | Transportation Engineering - Civil Engineering (CE) PDF Download

### Group Index of Soils (G.I)

In order to classify the fine-grained soils within one group and for judging their suitability as subgrade material, an indexing system has been introduced in HRB classification which is termed as group index. Soils are thus assigned arbitrary numerical numbers known as group index (GI). Group index is function of percentage and is given by the equation G.I = 0.2a + 0.005ac + 0.01bd
Where,

Where, WL = Liquid limit, IP = Plasticity Index.
P = Percentage fines passing from 0.074 mm sieve.
0 ≤ G . I ≤ 20 Lower the group → best quality.

### Plate Bearing Test

(i)

Here,
k = Modulus of subgrade reaction
P = Pressure Corresponding to settlement of 0.125 cm.
(ii)

Where,
ks = Modulus of subgrade reaction for soaked condition.
Ps = Pressure required in the soaked condition to produce same deformation as deformation Produce by pressure ‘P’ in consolidated condition.
k = Modulus of subgrade reaction for the consolidated stage.
Δ = Deformation in ‘cm’.
a = Radius of rigid plate in ‘cm’.
k = P / Δ = E / 1.18a
E = Modulus of elasticity of soil subgrade in kg/cm2.
k.a = constant
a1 = Radius of smaller plate (other plate)

k1 = Modulus of subgrade reaction of other plate of radius ‘a1’ cm.

### Test for Road Aggregate

(i) Aggregate crushing test
Aggregate crushing value

Where, w1 = Weight of the test sample in ‘gm’
w2 = weight of the crushed material in ‘gm’ passed through 2.36 mm sieve.

(ii) Shape Tests

Where, Ga = specific gravity of aggregate
W = mass of mould containing aggregate
C = mass of mould containing water
(iii) Abrasion Test
(a) Los Angeles Abrasion Test

### Bituminous Material

1. Product of fractional distillation of Petroleum: Gasoline, Naptha, Kerosene, Lubricating oil and Residue – Petroleum Bitumen.
2. Cutback Bitumen: Reduced Viscosity Bitumen

N – Numeral [0, 1, 2, 3, 4, 5]
Show progressive thickening from 0 to 5
3. Specific Gravity:
Bituminous → 0.97 – 1.02
Tar → 1.1 – 1.5
1. Bituminous Mixes
(i) Determination of Specific Gravity

Where, Ga = Average specific gravity of blended aggregate mix.
w1, w2, w3, w4 are % by weight of aggregate 1, 2, 3 & 4 respectively. G1, G2, G3 & G4 are specific gravities of the aggregate 1, 2, 3 & 4 respectively.
(ii) Specific Gravity of Compacted Specimen
(a)

Where, Gt = Theoretical maximum specific gravity of the mix.
Wb = % by weight of bitumen.
Gb = Specific gravity of bitumen.
Ga = Average specific gravity of aggregates.
(b) Theoretical density γt, per-cent solids by volume

Where, G = Actual specific gravity of test specimen
Gt = Theoretical maximum specific gravity.
(c) Voids in the Mineral Aggregate (VMA)

Where, Vb = % of bitumen
Wa = Aggregate content percent by weight
Vv = % air voids in the specimen.

(d) % Voids Filled with Bitumen (VFB)
2. Marshall Method Bituminous Mix Design
Percentage Air Voids

Where, Gm = Bulk density or mass density of the specimen
Gt = Theoretical specific gravity of mixture

Where,
W1 = Percent by weight of coarse aggregate in total mix
W2 = Percent by weight of fine aggregate in total mix
W3 = Percent by weight of filler in total mix
W4 = Percent by weight of bitumen in total mix
G1 = Apparent specific gravity of coarse aggregate
G2 = Apparent specific gravity of fine aggregate
G3 = Apparent specific gravity of filter
G4 = Specific gravity of bitumen
Percent Voids in Mineral Aggregate (VMA)
VMA = Vv + Vb
Here, Vv = Volume of air voids, %
Vb = Volume of bitumen,

Per-cent Voids Filled with Bitumen (VFB)

HveeM Method of Bituminous mix Design Stabilimeter Value, (s)

Where, Pv = Vertical pressure at 28 kg/cm2 or at a total load of 2268 kg.
Ph = Horizontal pressure corresponding to Pv = 28 kg/cm2.
D2 = Displacement on specimen represented as number of turns of pump handle to raise Ph from 0.35 to 7 kg/cm2.

### Cohesiometer Value, (c)

Where, L = Weight of shots in cm.
w = Diameter of width of specimen in cm
H = Height of specimen in cm

### Stabilometer Resistance R-value

where, Pv = Vertical pressure applied (11.2 kg/cm2)
Ph = Horizontal pressure transmitted at Pv = 11.2 kg/cm2.
D2 = Displacement of stabilometer fluid necessary to increase the horizontal pressure from 0.35 to 7kg/cm2, measured in number of revolutions of the calibrated pump handle.

The document Highway Materials | Transportation Engineering - Civil Engineering (CE) is a part of the Civil Engineering (CE) Course Transportation Engineering.
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## Transportation Engineering

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## FAQs on Highway Materials - Transportation Engineering - Civil Engineering (CE)

 1. What are the different types of materials used in highway construction?
Ans. Highway construction materials can be classified into three main categories: aggregates, asphalt, and concrete. Aggregates include crushed stone, gravel, sand, and recycled materials. Asphalt is a mixture of bitumen and aggregates used for road pavement. Concrete is a composite material made of cement, aggregates, and water, often used for bridges and rigid pavements.
 2. What factors should be considered when selecting highway materials?
Ans. Several factors should be considered when selecting highway materials, including durability, cost-effectiveness, availability, sustainability, and performance under different weather conditions. Other factors include the expected traffic load, design life, maintenance requirements, and environmental impact. It is essential to choose materials that can withstand heavy traffic, resist deterioration, and provide a safe and smooth driving surface.
 3. How is the quality of highway materials evaluated?
Ans. The quality of highway materials is evaluated through various tests and inspections. For aggregates, tests such as sieve analysis, specific gravity, and abrasion resistance are conducted to assess their properties. Asphalt materials undergo tests like penetration, softening point, and viscosity to determine their suitability for road construction. Concrete is tested for compressive strength, workability, and durability. These tests help ensure that the materials meet the required standards and specifications.
 4. What are the challenges in using recycled materials for highway construction?
Ans. The use of recycled materials in highway construction offers environmental benefits, but it also poses some challenges. One challenge is the variability in the quality and characteristics of recycled materials, which may affect the performance and durability of the highway. Proper processing and quality control measures are necessary to ensure consistency and uniformity. Another challenge is the potential presence of contaminants in recycled materials, which can affect the performance and safety of the highway.
 5. How does climate affect the selection of highway materials?
Ans. Climate plays a significant role in the selection of highway materials. Different climates have varying temperature ranges, rainfall patterns, freeze-thaw cycles, and soil conditions. These factors can impact the performance and durability of the materials. For example, in regions with high temperatures, materials with good heat resistance and stability are preferred. In areas prone to heavy rainfall, materials with good drainage properties and resistance to water damage are necessary. The selection of materials should consider the specific climate conditions to ensure optimal performance and longevity of the highway.

## Transportation Engineering

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