Concrete blocks are a major part of most building constructions it has a primary role in building materials as partition walls.  Concrete blocks are usually referred to as a concrete masonry unit (CMU).  There are many types of CMU in the construction practice.

Weight classifications of blocks are divided into Light Weight (less than 105 lb./cu. ft. oven dry weight of concrete), Medium Weight (105 to less than 125 lb./cu ft.), and Normal Weight (125 lb./cu. ft. or more).  Using lighter weight blocks can be used in partition walls because of its lower weight which reduces the overall weight of the building.

Depending upon the structure, shape, size and manufacturing processes concrete blocks are mainly classified into 2 types and they are

(a) Solid concrete blocks

(b) Hollow concrete Blocks.

The aim of this study was to develop a solid lighter weight interlocking concrete masonry block with reduced cost and adequate strength for possible use in non-load bearing (partition) wall applications.  The objectives were to:

1. To develop mix proportion that will have adequate strength with reduced weight and reduced cost as compared to conventional mix being used for the conventional blocks in the market.

2. To develop lighter weight, lower cost solid (6"x8"x12") concrete masonry block with adequate strength for potential use in the partition (non-load bearing) walls of the buildings.

3. Ascertain the weight and cost effect of the use of the light weight block for a G+5 Residential Building with 04 units/floor, with each unit of 720 sft.

4.  To select geometry of solid light weight interlocking concrete masonry block.

A zero-cement trial mix with adequate strength, lower unit weight and reduced cost was developed using fly ash and lime as binder and pumice as light weight coarse aggregate.  The use of CMU using this mix in the infilled walls of RC frame for a G+5 Residential Building with 04 units/floor, with each unit of 720 sft showed substantial reduction in weight and cost of the infilled walls and thus the weight of Building.  One type of interlocking block was selected for the CMU which would provide mortar less construction of walls.