Which of the following is the direct method of surface texture measurement of aggregates?
1
Tracing the irregularities by drawing a fine point over the surface and drawing a trace magnified by mechanical, optical, or electrical means.
2
The rock surface is held against rubber surface at a standard pressure and the resistance to the flow of air between the two surfaces is measured
3
Determining the weight of a fine powder required to fill up the interstices of the surface to a truly smooth surface.
4
Measurement of the degree of dispersion of light falling on the surface.
5
Question Not Attempted