Masonry - Construction Materials and Testing

MATERIALS AND TESTING

1. MASONRY

2. Masonry consists of building structures by laying individual masonry units (brick, concrete block, stone, etc ). Normally the masonry units are laid with cement mortar, which binds them together to create a structure. Similar to concrete, masonry tends to be high in compressive strength but low in tension strength. Crack control tends to be a major concern in masonry structures and normally is addressed by Design Professionals on the Plan

3. Concrete Masonry Units One of the most common masonry units is the concrete block. It consists of hardened cement and may be completely solid or contain single or multiple hollows. made from conventional cement mixes and various types of aggregate. These include sand, gravel, crushed stone, air-cooled slag, coal cinders, expanded shale or clay, expanded slag, volcanic cinders (pozzolan), pumice, and “scotia” (refuse obtained from metal ore reduction and smelting). The term “concrete block” was formerly limited to only hollow masonry units made with such aggregates as sand, gravel, and crushed stone. Today, the term covers all types of concrete block-both hollow and solid—made with any kind of aggregate. Concrete blocks are also available with applied glazed surfaces, various pierced designs, and a wide variety of surface textures. The cement-aggregate ratio in concrete blocks is 1:6. Aggregate used is of 60% fine aggregate and 40% coarse aggregate. Their Minimum strength is about 3N/mm2. ASTM C-90-91 specifies the compressive strength requirements of concrete masonry units Most common siszes of concrete blocks are: 8 inches x 16 inches x (4” , 5” and 6”)

4. Types of Concrete Masonry Units Solid concrete blocks heavy in weight and manufactured from dense aggregate very strong and provides good stability to the structures. for large work of masonry like for load bearing walls these solid blocks are preferable. available in large sizes compared to bricks.

5. Types of Concrete Masonry Units Concrete Hollow Blocks (CHB) contains void area greater than 25% of gross area. Solid area of hollow bricks should be more than 50%. The hollow part may be divided into several components based on our requirement. They are manufactured from lightweight aggregates. They are light weight blocks and easy to install.

6. Types of Concrete Masonry Units Concrete Hollow Blocks (CHB)

7. Types of Concrete Masonry Units Concrete Hollow Blocks (CHB)

8. Types of Concrete Masonry Units Concrete Hollow Blocks (CHB)

9. Types of Concrete Masonry Units Concrete Hollow Blocks (CHB)

10. Advantages of Concrete Blocks Width of wall can be reduced compared to brick walls. It provides better heat and sound insulation and fire resistance properties. Construction will be much faster. Number of joints in the masonry are reduced and the mortar can be saved. Manual: https://www.youtube.com/watch?v=fdG0zyXpuYs&t=371s With Machine: https://www.youtube.com/watch?v=rhF0740mbx8 Manufacturing of Concrete Blocks

11. Field Testing of Concrete Hollow Blocks https://www.youtube.com/shorts/gcbLfjmZAqI  Randomly select one block from the total no. of blocks of the particular batch. Lift the block at about 4 to 4.5 feet which is nearer to your chest level and drop it on the hard ground surface.  Vertical drop: The length of the block should be kept in a vertical position before dropping it on the ground. The concrete block should be intact in shape without any damage after crushing over the ground surface. If the sample block breaks into pieces or develops a crack then it is better to reject such concrete blocks. Horizontal drop: You have to hold the concrete block with the length of the block in the horizontal position as shown in fig. 2. From the same chest height, you again drop the block on the hard surface. If the block breaks into no. of pieces, then such blocks can be considered as low-quality blocks.

12. Laboratory Testing of CHB ASTM C140, 2013 Edition, March 15, 2013 - Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units https://www.youtube.com/watch?v=nt_OCdAaA5k Minimum strength is about 3N/mm2