Saturday, 25 February 2017

Quality control of Ready Mix Concrete plant.


As per Indian Standard code of practice (IS 4926) Ready Mixed Concrete (RMC) is defined as the concrete delivered in plastic condition and requiring no further treatment before being placed in position in which it is to set and harden. Instead of being batched and mixed on site, concrete is delivered for placing from central batching plant. First RMC was patented in Germany in 1903, but the transportation system it had not done properly introduced to achieve proper workability of concrete. The first delivery of RMC was made in Baltimore in 1913, and the transit mixer was born in 1926. In 1931 erected a plant at Bedfont, west of London and launched a company named as Ready Mixed Concrete Ltd.

What is need of RMC plant?

The consumer wanted his concrete delivered to the job in a ready-to-place condition. Volume batching is completely replaced by the weight batching and presently computerized weigh batchers are used in most of the batching plants. Aggregates are stored in properly installed bins and cement and flyash are stored in silos. Conveyors are used to transport the aggregates. Cement and flyash is pumped into the central mixer with pneumatic pumps. Electronic moisture meters, digital admixture dispensers are used in fully automatic batching plants. So due to such practices in RMC plant the workable concrete can produce which may be more durable, because of that there is a need of RMC plant.

Wednesday, 15 June 2016

Types of Stairs

The stairs may be built with wood, concrete masonry or with cast iron. Wooden stairs are not safe, because of the danger of fire. However they are used in buildings to access to small areas in the upper floors.

 Cast iron or steel stairs in the spiral forms were used commonly to reduce stair case area. In many residential buildings masonry stairs are also used. Reinforced concrete stairs are very commonly used in all types of buildings.


Applying mortar on the surfaces of walls, columns, ceiling etc. to get smooth finish is termed as plastering.

Mortar used for plastering may be lime mortar, cement mortar or lime-cement mortar.

Lime mortar used lime to sand ratio of 1 : 3 or 1 : 4.

Cement mortar of 1 : 4 or 1 : 6 mix is very commonly used for plastering, richer mix being used for outer walls.


It is a light weight concrete produced by introducing large voids in the concrete or mortar. Its density varies from 3 kN/m3 to 8 kN/m3. It is also known as aerated, foamed concrete.

Properties of cellular concrete
1. It has low weight.

2. It has good fire resistance.

Compaction factor test.

This is another test to  identify the workability of concrete. This test is conducted in the laboratory.

The test equipment consists of two hoppers and a cylinder fixed to a stand, the dimensions and the distances between the three vessels being standardized. Vessel A and B are having hinged bottoms whereas cylinder C is having fixed bottom.

What is uses of timber?

1. For heavy construction works like columns, trusses, piles.

2. For light construction works like doors, windows, flooring and roofing.

3. For other permanent works like for railway sleepers, fencing poles, electric poles and gates.

4. For temporary works in construction like scaffolding, centering, shoring and strutting, packing of materials.

What is CEMENT & its Chemical properties

Cement is a commonly used binding material in the construction. The cement is obtained by burning a mixture of calcarious and argillaceous material at a very high temperature and then grinding the clinker so produced to a fine powder.

It was first produced by a mason Joseph  Aspdin in England in 1924. He named it as portland cement.

#Chemical properties of ordinary portland cement.

What are the common building stones?

(i) Basalt and trap

(ii) Granite

(iii) Sand stone

(iv) Slate

(v) Quartzite.

(vi) Marble

Uses of Stones.

(i) Stone masonry is used for the construction of foundations, walls, columns and arches.

(ii) Stones are used for flooring.

(iii) Stone slabs are used as damp proof courses, lintels and even as roofing materials.

What are the Properties of Stones?

(i) Structure

(ii) Texture

(iii) Density

(iv) Appearance

What is stone ?

Stone is a ‘naturally available building material’ which has been used from the early age of civilization. It is available in the form of rocks, which is cut to required size and shape and used as building block. It has been used to construct small residential buildings to large palaces and temples all over the world.

A. Type of Stones

• Geological   • Physical    • Chemical

Monday, 6 June 2016

What is membrane curing?

Sometimes, concrete works are carried out in places where there is acute shorting of water. the lavish application of water for water curing is not possible for reason of economy.

It has been pointed out earlier that curing does not mean only application of water, it means also creation of condition for promotion of uninterrupted and progressive hydration.

Membrane curing is a good method of maintaining a satisfactory state of wetness in the body of concrete to promote satisfactory state of wetness in the body of concrete to promote condition hydration when original water/cement ratio used is not less that 0.5. to achieve best result, membrane is applied after one or two days of actual wet curing.

Since no replenishing of water is done after the membrane has been applied it should be ensure that the membrane is of good quality and it is applied effectively. two or three coats may be requires for effective sealing of the surface to prevent the evaporation of the water.

when water proofing paper or polyethylene paper are used care must be taken to see that these are not punctured anywhere and also whether adequate lapping is given at the junction and this is effectively sealed.

Water curing

This is by far the best method of curing as it satisfies all the requirements of curing, namely, promotion of hydration, elimination of shrinkage and absorption of the heat of hydration. it is desirable that a certain extent of water curing is done before the concrete is covered with membranes. water curing can be done in following ways:-

1. Immersion

2. Ponding

3. Spraying

4. Wet covering

the precast concrete items are normally immersed in curing tanks for a certain duration. pavement slabs, roof slabs etc. are covered under water by making small  ponds. vertical retaining wall or plastered surfaces or concrete column etc. are cured by spraying water. In some cases, wet covering such as wet gunny bags, hessian cloth, jute matting, straw etc. are wrapped to vertical surface for keeping the concrete wet. for horizontal surfaces saw dust, earth or sand are used as wet covering to keep the concrete in wet condition for longer time so that the concrete is not unduly dried to prevent hydration.

what are the partial properties of workability ?

Mixability, Transportability, Mouldability and Compactibility are the partial properties of workability.

a)  Mixability:-

It is the ability of the mix to produce a homogeneous green concrete from the constituent materials of the batch, under the action of the mixing forces

b) Transportability:-

Transportability is the capacity of the concrete mix to keep the homogeneous concrete mix to keep the homogeneous concrete mix from segregating during a limited time period of transportation of concrete.

c) Mouldability:-

It is the ability of the fresh concrete mix to fill completely the forms or moulds without losing continuity or homogeneity under the available techniques of placing the concrete at a site.

d) Compactibility:-

Compactibility is the ability of concrete mix to be compacted into a dense, compact concrete, with minimum voids, under the existing means of compaction at the site.

What is Workability of concrete ?

The ease with which the concrete can be mixed up with minimum quantity of water, transported, placed and compacted without segregation and bleeding is called workability.

Workability is defined as the property of concrete which determines the amount of useful internal work necessary to produce full compaction. workability concrete is one which exhibits very little internal friction between particle and particle.

The factor helping concrete to have more lubricating effect to reduce internal friction are as follows:-

a. water content

b. mix proportion

c. size of aggregate

d. surface texture

d. shape of aggregate

f. grading of aggregate

g. use of admixture.

Saturday, 2 January 2016

Types of constructions

1 load bearing structure

2 framed structure

1) load bearing structure:- 

 1. in load bearing structures the entire load of the superstructure is transmitted through the walls to the soil below the ground. 

2. these walls are supported on continuous foundation that resist on hard strata. thickness of such walls is too large.

3. if the number of storey is increased the thickness of the wall increases.

4. this type of construction reduces the carpet area

5. this type of construction cannot be used for multi-storeyed building.

2.) framed structure

1. framed structure consists of a series of frame made up of beams and columns.

2. walls are constructed within the frames which are known as a partition walls

3. thus the load of floor roofs and partition walls are supported by beams which in turn transmit the load to the column.

4. column transmit the load to the foundation, which rests on a hard soil below the ground

5. framed structure are suitable for medium and multi storeyed building.

Basic function of building.

1. it should be sufficiently strong to withstand the effects of the atmosphere and environment.

2. it should be durable and stable to take up the anticipated loads coming on it including the self weight live load and earthquake load.

3. it should be well ventilated and free from dampness.

4. it should be resist penetration of moisture

5. it should be provide maximum living and working comfort

6. it should be dimensionally stable

7. grouping of rooms should be so planned as to ensure circulation and optimum utilization of space and maximum efficiency fire hazards.

8. the building should be safe against fire hazards

9. the building should be safe against theft and burglary the external wals should be made so strong to resist any such attempt.

10. the building should be sound insulating so as to reduce sound passing through it.


For good planning and designing of building, the site of the building is the most important aspect. the fallowing general guidelines should be kept in mind while selecting a site for a building.

1 . SITE plot must be of clear title along with clear ownership rights of the land.

2. the building site should be located on a fully developed or fat developing locality.

3. for happy living the neighborhood should be of equal status in society.

4. the shape of the plot shall not be irregular

5. as far as possible rectangular plot should be selected because maximum area of plot can be used for construction.

6. the site should be have general facilities such as a sewer line,  water line, power construction, street lights, and garbage disposal.

7. the site should be well connected by road by pass and service lines.

8. the site should be elevated land so as to have easy surface drainage  of rain water

9. the ground water table level at the site should be not too high not too low.

10.the soil condition of plot should be such that economical foundation should be possible, good compact soil, hard strata, rock or sand is desirable at minimum depth.

11. the site should have good view of landscape such as hills, gardens, rivers, lake, seashore as to promote healthy and peaceful living.

12. the site should away from kilns, quarries, congested and noisy localities and such other places.