Highway Materials

Softening point is the temperature at which bitumen becomes soft and starts flowing.

Soundness test is done to evaluate resistance against weathering of aggregate.
Crushing test is done to evaluate strength of aggregate.
Los angles abrasion test is to evaluate hardness of aggregate.
Stripping value test is to evaluate ratio of uncovered area observed to the total area of aggregate. The test is conducted to determine the effects of moisture upon the adhesion of binding material.

Los Angles abrasion test is carried out to examine the hardness i.e., abrasion resistance property of aggregate

Initial concavity in CBR test due to
Improper compaction.
Soft top layer
Inclined plunger

Bulk specific gravity =\frac{A}{B-C}
Apparent specific gravity =\frac{A}{A-C}
Where,
A= Mass of oven dry aggregate in air
B= Mass of Saturated surface dry aggregate in air
C= Mass of Saturated surface dry aggregate under water
\therefore Bulk specific gravity
=\frac{1000}{1025-625}=\frac{1000}{400}=2.5
Water absorption
=\frac{1025-1000}{1000} \times 100=2.5 \%

The graph between VFB and Bitumen content is,

Theoretical specific gravity,
\begin{aligned} G_{t} &=\frac{w_{1}+w_{2}+w_{3}+w_{4}}{\frac{w_{1}}{G_{1}}+\frac{W_{2}}{G_{2}}+\frac{W_{3}}{G_{3}}+\frac{W_{4}}{G_{b}}} \\ &=\frac{55+35.8+3.7+5.5}{\frac{55}{2.6}+\frac{35.8}{2.7}+\frac{3.7}{2.65}+\frac{5.5}{1.01}}+ \\ &=2.42 \end{aligned}
Effective specific gravity of aggregates (coarse + fine) is given by,
\begin{aligned} G^{\prime} &=\frac{(55 \times 2.6)+(35.8 \times 2.7)}{55+35.8} \\ &=2.639=2.64 \end{aligned}