Types of cement mortar and Tests on mortar | Mortar and pestle chicago
Types of Tests on cement mortar
Mortar and pestle chicago
Definition of mortar:
The cement Mortar is the presence of a mixture of binding material (Mortar and pestle chicago), fine aggregate, and water. When the water is added to the dry mixture of binding material and the insert material, binding material develops the property that binds not only the inert material but also the surrounding stones and bricks. If the mixed cement is the binding material, then the mortar is known as the cement mortar. The Other mortars that are commonly used are lime mortar and mud mortar. The inert material used is sand. In this chapter explain, first, an introduction is given to the insert material sand (fine aggregate), and then the proportioning, mixing, curing, properties, and uses of different type mortars are explained. At the end of this chapter, various tests conducted on mortars are presented.
- Cement mortar
- LIME MORTAR
- MUD MORTAR
- SPECIAL MORTAR
This type for preparing mortar, first, a mixture of cement and sand (fine aggregate) is made thoroughly mixing them in dry condition. Water is gradually added and mixed with shovels (scoop). The cement to sand preparation is recommended for various works. Mortar and pestle chicago
|S. No. Works Cement: Sand|
|1 Masonry works 1:6 to 1:8|
|2 Plastering masonry 1:3 to 1:4|
|3 Plastering concrete 1:3 4 Pointing 1:2 to1:3|
Cement gains strength gradually with hydration. Hence it’s necessary to see that mortar is wet till hydration has taken that place. This type of process to ensure sufficient moisture for hydration after laying that mortar/concrete is called curing (using gunny bags). Curing is ensured by spraying water. Curing normally starts 6–24 hours after the mortar is used. It was maybe noted that in the initial time period water requirement is more for hydration and gradually it is reduced. Curing is recommended for 28 days. Mortar and pestle chicago
The following points are the very important properties of cement mortar.
- When water is added into the dry mixture of cement and sand (fine aggregate), hydration of cement starts, and it was binding sand particles and the surrounding surfaces using masonry and concrete.
- It is mixed richer than the 1:3 ratio is prone to shrinkage.
- Well-proportioned mortar provides an impervious surface.
- The leaner mix is not capable of closing the voids in sand and hence the plastered surface is porous.
- The strength of the mortar depends upon the proportion of cement (PPC) and sand. Strengths obtained with the various proportion of cement and sand is shown in the Table are given below. Mortar and pestle chicago
|S. No. Cement: Sand Compressive Strength|
|1 1:3 10 N/mm2|
|2 1:4 7.5 N/mm2|
|3 1:5 5.0 N/mm2|
|4 1:6 3.0 N/mm2|
|5 1:8 0.7 N/mm2|
Mortar is used
- to bond masonry units like stone, bricks, cement blocks.
- to plaster slab and walls make them impervious.
- It was used to give neat finishing to walls and concrete works.
- for pointing masonry joints.
- for preparing building blocks.
- as a filler material in Ferro cement works.
- to fill joints and cracks in walls.
- as a filler material in stone masonry. Mortar and pestle chicago
Fat lime and hydraulic lines are used for making lime mortar. If the fat lime is used sand (fine aggregate) mixed is normally 2 times to 3 times its volume. If the hydraulic lime is used sand mixed is only 2 times the volume of lime (calculated). Lime is prepared by pounding, if the quantity required is small or by grinding, if the required quantity is more.
Pounding (Mortar and pestle chicago):
Pounding pits are formed on hard grounds. The size of the pit is usually 1.80 m long, 0.4 m wide and 0.5 m deep. It is provided with a lining of bricks or stones. Lime and sand dry mixed with the required proportion are placed in the pit. A small quantity of water is added at intervals. In each one of the intervals, the mix is pounded with wooden pounders, and the mortar is turned up & down. The process is continued till uniform color and desired consistency is achieved.
This is the better way of getting a good mix. The grinding (mixing) may be carried out in bulk driven grinding mill or in power to the driven grinding mill. a typical bullock drove grinding mill. It is consists of a circular trench of radius 3m to 4.5 m, 0.3 m wide, and 0.4 m depth. A wooden shaft pivoted at the center carries a stone wheel of width just 50 mm to 100 mm less than that of the trench. Bullocks drive this wheel in the trench for grinding mortar. The dry mix is placed in the trench. Water is added gradually (slowly), and bulk driven stone wheels grind into the mix. A worker turns the mix-up and down regularly. This method of preparing mortar needs 6 hours and can produce about 1.7 m3 of mortar.
a typical power to driven grinding (mixing) mill used for only preparing lime mortar. In this mill, inside Two rollers rotate in one pan of diameter 1.8m – 2.4 m. Either one pan or roller is rotated with the help of the oil engine or the electric power. During mixing the required quantity of water is added gradually.
Lime mortar is also having good grinding property. Fat lime mortar is used for plastering while hydraulic lime mortar is used for masonry construction. This type of mortar was considered very cheap in the olden days and it was commonly used in small towns for small works. However, the cumbersome process of preparation and ease in availability of cement in the market has almost replaced the use of lime mortar. Mortar and pestle chicago
Clay lumps are collected and are wetted with water and allowed to mature for 1 or 2 days. It is kneaded well until it attains the required consistency. Sometimes fibrous materials like gobbler are added to the mix. It prevents cracks in the plaster. If the plaster is to be used for outer walls, it is sprayed or painted with bitumen.
It is a cheap mortar. Its durability is less. It’s normally used for the construction work of temporary sheds and cheap houses (like government free gifted houses) in rural areas.
The following are some of the special mortars:
- Cement clay mortar
- Gauged mortar
- Decorative mortar.
Cement Clay Mortar: The Quality of clay mortar can be improved by adding cement to the mix of the clay mortar. The normal proportion of clay to cement is 1:1. It maintains the economy to some extent and there are sufficient improvements in the durability of mud-mortar.
Gauged Mortar: It’s the mortar obtained by adding cement (special cement) to lime mortar. The usual proportion of cement, lime, and sand are 1:1:6 and 1:2:9, 1:3:12. This mortar is to be used within half an hour (30min) after mixing the cement. Obviously, it is very cheaper than cement mortar and its quality is between that of cement mortar and lime mortar the gauged mortar is very special.
Decorative Mortar: These types of mortars are obtained by using colored cement. This mortar They are used to give a pleasant appearance to the outer walls.
TESTS ON MORTAR
The below following tests are conducted on the prepared mortars to finding their quality: Mortar and pestle chicago
- Crushing Test
- Tensile Strength Test
- Adhesive Test.
Crushing Test: This test is carried out on brickwork with the mortar. This brickwork is crushed in a compression testing machine and the load is noted down. Then the crushing strength (in n/mm2) is obtained as load divided by the specimen cross-sectional area.
Tensile Strength Test: The mortar prepared is placed in a mold of brick which has a central cross-sectional area of 38 mm × 38 mm. After curing the briquette [Fig. 2.3] is pulled under the grips of the tensile testing machine. The ultimate load noted. Then the tensile strength (in n/mm2) of mortar is load divided by the central cross-sectional area of the specimen.
Adhesive Test: Two bricks are joined with mortar to be tested as shown in The upper brick is suspended from an overhead support. A board is hung from the lower brick. After all, weights are added to the board un till the bricks are separate. The adhesive strength is the load divided by the area of contact.