What is the main advantage of the semi-mechanized process over hand-moulding?

It produces more uniform, denser, and stronger bricks due to better clay preparation in a pug mill and consistent moulding through a machine (Clause 5 & 6).

What type of soil is considered good for brick making according to this guide?

Silty clay or sandy clay with a plasticity index between 15 and 25, and low soluble salt content (<1%) is generally suitable (Clause 4.1).

What kind of kiln is typically used in this process?

The guide suggests continuous kilns like the Bull's Trench Kiln (BTK) or Hoffmann Kiln are suitable for the scale of semi-mechanized production (Clause 8.1).

How does this code relate to IS 1077 and IS 3495?

IS 11650 provides the 'how-to' for manufacturing bricks, while IS 1077 specifies the required final dimensions and quality of the bricks, and IS 3495 describes the methods to test if those quality requirements are met.

IS 11650

: 1991

Guide for the manufacture of standard burnt clay building bricks by semi-mechanized process

CurrentSpecializedGuidelinesMaterials Science · Clay and Stabilized Soil Products

Download PDF BIS Portal Google

This standard provides guidance on the manufacturing process of burnt clay building bricks using semi-mechanized methods. It covers all stages from site selection and raw material (clay) evaluation to clay preparation, moulding, drying, firing in kilns, and final handling. The guide aims to help manufacturers produce bricks that conform to the quality specifications laid out in IS 1077.

Guide for the manufacture of standard burnt clay building bricks by semi-mechanized process

Quick Reference Values

Recommended plasticity index for brick clay15 - 25

Recommended liquid limit for brick clay30 - 45 percent

Maximum allowable soluble salts in clay< 1 percent

Water required for pugging (tempering)12 - 18 % by weight of clay

Typical firing temperature range900 - 1100 °C

Maximum linear drying shrinkage7 - 10 %

Practical Notes

Ensure the clay is free from 'kankar' (calcareous nodules), as they can cause bricks to spall or burst upon wetting after firing.

The semi-mechanized process, particularly the use of a pug mill and extruder, yields bricks with higher density and uniformity compared to the hand-moulding process described in IS 2117.

Careful control of the firing schedule (temperature and atmosphere) in the kiln is critical to prevent defects like black cores, brittleness, or bloating.