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, W_L = Liquid limit, I_P = 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,
k_s = Modulus of subgrade reaction for soaked condition.
P_s = 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.

California Bearing Ratio (CBR) Test

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, G_a = 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, G_t = Theoretical maximum specific gravity of the mix.
   W_b = % by weight of bitumen.
   G_b = Specific gravity of bitumen.
   G_a = Average specific gravity of aggregates.
   (b) Theoretical density γ_t, per-cent solids by volume
   
   Where, G = Actual specific gravity of test specimen
   G_t = Theoretical maximum specific gravity.
   (c) Voids in the Mineral Aggregate (VMA)
   
   Where, V_b = % of bitumen
   W_a = Aggregate content percent by weight
   V_v = % air voids in the specimen.
   
   (d) % Voids Filled with Bitumen (VFB)
2. Marshall Method Bituminous Mix Design
   Percentage Air Voids
   
   Where, G_m = Bulk density or mass density of the specimen
   G_t = 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 = V_v + V_b
   Here, V_v = Volume of air voids, %
   V_b = Volume of bitumen,
   
   Per-cent Voids Filled with Bitumen (VFB)
   
   

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

Where, P_v = Vertical pressure at 28 kg/cm² or at a total load of 2268 kg.
P_h = Horizontal pressure corresponding to Pv = 28 kg/cm².
D₂ = Displacement on specimen represented as number of turns of pump handle to raise P_h 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, P_v = Vertical pressure applied (11.2 kg/cm²)
P_h = 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.