Length gauge is an digital instrument used to determine the elongation index of coarse aggregates. It can also be used to measure sample sizes of aggregates, sand and fillers.

Salient Features

• The instrument consists of a steel plate on which eight steel pins are vertically mounted with specified distance in between.
• It consists of a hard wood base with vertically mounted metal studs.

Working Principle of Length Gauge

• Particle is elongated when its length is more than 1.8 mm of the midsize of the sieve fraction.
• Aggregate, which has to be classified is parted into 7 sieve fractions from 63 to 6.3 mm and each part is examined separately.
• There are 6 labeled opening between pairs of metal pins. These pins measure particle from each of the 6 sieve cut below 50 mm.
• Elongation index is the mass of elongated particles failing to pass between pins as percent of the sample.

Applications

It is an instrument used to measure sample sizes of aggregates, sand and fillers. Some of the application area of length gauge are :

• Soil Analysis
• Cement & Concrete Industry
• Rock & Aggregate Testing
• Ceramic Industry
• Research & Development