Different types of precast concrete products and their benefits

Beam and Block Floors: Beam and block is made of precast concrete and it is suitable for superior quality, cost-effective concrete floor construction.

Concrete beam and block floors are built up with prestressed concrete beams which provide support to standard concrete blocks stretching among ‘T’ beams. These come in different sizes to fit with several spans and loads. Individual concrete blocks are placed among the precast beams to build up an instant floor.

In prestressed concrete beams, beam spacing is modified to adapt probable loads.

Beam and Block Flooring

Manufacture: Long line prestressed production of concrete floor beams allows high performance beams to be formed economically.

ACP floor beams are wet cast from superior quality steel moulds with high strength engineering grade concrete, ensuring quality and performance.

Concrete Beams – Design: 150mm concrete beams are can be used for an extensive range of concrete floor construction like domestic house floors, flats, nursing homes and commercial developments.

225mm concrete beams can be used for floors depending on higher loads and larger unsupported extents.

Specification: ACP concrete floor beams are suitable for being applied with standard 440 x 215 x 100 concrete blocks in either 7.0N/mm2 or 3.5N/mm2 compressive strengths.

Closure blocks to adapt 530mm and 305mm concrete beam spacing to accelerate floor edge construction.

A dry grout system is applied to tie the beam and block floor jointly before setting up insulation and floor finishes.

A sand/cement screed is employed to the grouted beam and block system for a strong finished floor or base for ceramic floor finishes. Openings inside the floor for service ducts and pipes can be smoothly and inexpensively integrated in the scheme.

Specialist ceiling clips can be used to accelerate the ceiling installation process to the underside of the suspended concrete floor.

Benefits: Low cost concrete flooring is obtained with the ACP beam and block floor system.

It facilitates huge savings in both time and cost at ground floor level with regard to other flooring systems and also reduces groundworks. Beam and block flooring is also suitable for suspended flooring to consequent levels, even being effective to promote partition walling with double beam layouts.

The set up of beam and block floors is usually weather independent minimizing site delays and making sure that construction programme is retained.

The suspended beam and block floor system provides the scope to reduce excavations; of specific advantages where excavated material should be eliminated from site.

The high thermal mass inbuilt with precast concrete floor construction provides benefits for the finished buildings energy consumption. Precast concrete flooring also contains properties like exceptional noise reduction and fire resistance.

ACP precast floor beams are also suitable for the Tetris Thermal flooring system to attain even better insulation performance.

The concrete beam and block floor is ideal for underfloor heating systems with a high thermal mass.



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Published By
Rajib Dey
www.constructioncost.co
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Testing of Concrete masonry Blocks

Concrete masonry bricks are very useful in the rural areas as it is cheap, easily found and can form less strong buildings, the compressive strength of the bricks should be tested.

And in urban areas these kinds of buildings may present a combination of both office and houses or grocery stores and houses or offices and retail stores.

Concrete can be changed into formed masonry units like Hollow and Solid normal and light weight concrete blocks in right size to use for load and non-load bearing units for fencings or wallings. These concrete blocks are used more in the regions where soil bricks are costly, have less strength and not available all the time. As per the structural needs of masonry unit, the concrete mixes can be arranged using available ingredients or if not be suitable then with in the most economical distance.

Hollow concrete blocks are used for normal masonry when reinforced is used and it should not be leaner than 1 part cement of 8 parts room dry sand by volume. Compressive strength of concrete blocks or concrete masonry units is important to know the fitness of these in construction works for different reasons. Concrete masonry blocks are normally made of cement, amount and water which are usually comes in rectangular shape used in construction of masonry structure.

Patterns

20 full sized units shall be counted for length, wide and height and the center units shall be calculated for least thickness of face, shells and webs.

The minimal dimensions of concrete masonry block differ in three things such as:

• Length: 400/500/600mm
• Width: 200/100mm
• Height: 50, 75, 100, 150, 200 or 300mm.

Tests on Concrete Masonry Block Units

various tests are done on concrete masonry unit to check all the requirements, but among them three most applied tests are discussed in this article. The blocks of same mix shall be taken and classified to these following tests:

• Dimension measurement for all types of blocks

In this step all the blocks should be verified and calculated by the length, width and height with steel scale. After checking if the block found hollow, then the thickness of the web and face shell are calculated with caliper ruler, next a report need to be prepared included average length, width and height of block and with least face shell and web thickness using recorded dimensions.

• Density of the concrete masonry blocks (3 blocks)

At first the block has to be heated in the oven to 100°c, then the heated block need to be cooled in the room temperature. Next measure the dimensions of block to find out the volume and weight of it, the density of the block is calculated form a calculation and the standard density of 3 blocks will be the final block density. The formula is: mass/volume (kg/m3 )

• Compressive Strength tests

the average compressive strength of concrete masonry block is calculated by taking 8 blocks and all of them should be tested with in 3days after gathered in lab where the age of the blocks should be 28 days. The compressive strength is calculated in the Compressive

Strength Testing machine which has tow steel bearing blocks, one is in fixed position on which the masonry unit is kept and the other movable one can transfer the load to the masonry unit while applying. When the masonry unit’s bearing area is more than the steel blocks’ bearing area some different steel plates will be used. Those plates are organized on steel blocks in a way that the centre of masonry unit agreed with the center of thrust of blocks, bearing area units are completed with the Sulphur and granular materials coating. Then the unit in testing machine is placed and one-half of the expected highest loads are followed at a minimum rate while the rest is applied in not less than 2 minutes. Te load of masonry unit fails and the highest load is divided by basic sectional area of unit will give the compressive strength of block. By applying the same method, find out the rest 7 blocks’ compressive strength and then calculate the average strength of the 8 blocks which will be the final compressive strength of concrete masonry unit.

www.theconstructor.org

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Published By

Rajib Dey

www.constructioncost.co

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Definition of mortar and it’s different types

Mortar is a useful construction material combined with cement, lime, fine aggregates (sand, surkhi), water and various types of admixtures. It is utilized in masonry construction to bind the masonry or structural units as well as fill & seal the spaces among the stone, bricks and cement blocks applied in construction. It comes in the form of a paste and sets solid.

Often decorative colors are included for the architectural purpose. When the mortar in exact ratios of two or more components is available in premix mortar form, it is known as ready mix mortar.

The purpose of ready mix mortar is to unite building materials, to accomplish pointing work and plaster work, develop an flat and soft bedding layers, develop joints of pipe, conceal the open joints of brickwork and stone, accomplish structure maintenance work etc.

Given below, the details of various types of ready mix mortar accessible in the market on the basis of their functionality and mixture of binding material.

01. Ready mix cement mortar
02. Ready mix lime mortar
03. Ready mix surkhi mortar
04. Ready mix cement lime mortar

Ready mix Cement mortar is admixture of cement and sand, where cement functions as a binding material. The ratio of cement to sand fluctuates from 1:2 to 1:6 on the basis of their strength necessary for a specific work.

Ready mix Lime Mortar is premix of lime and sand, where lime functions as a binding material. The proportion of lime to sand ratio is maintained as 1:2(1 part of dry lime is combined with 2 part of dry sand).

Ready mix Surkhi Mortar is premix of lime, surkhi and water. Lime to surkhi ratio is kept 1:2 (1 part of dry lime is mix with 2 part of dry surkhi). It is type of lime mortar where sand is replaced by surkhi for saving and potency. Surkhi stands for finely burnt clay particles and normally formed with slightly under burnt bricks. Good surkhi should be rinsed properly and does not contain any admixture of foreign substances.

Ready mix Cement Lime Mortar is premix of Cement, lime and sand, where cement and lime function as binding materials. It is recognized as combination or gauge ready mix mortar. The formation of cement to lime mortar by volume is approximately 1:6 to 1:9. This type of mortar combination (i.e. lime and cement) is considered as tough, solid and cost-effective.

Ready mix mortar is obtainable in 5 kg (For Repairing), 25 kg and 50kg bags. Water should have been added on the construction site following specific work requirement.

Adding water in premix on the construction site should be done on the basis of IS Code or as suggested by an engineer in charge. In recent times, special mortar is utilized for the repair and maintenance purpose which contain properties like the free flow and high strength with regard to the normal mortar.

Based on their function, better shelf life and strength, several brands are found in the market with cost of Rs150to Rs700 per 50 kg bag of ready mix Mortar.

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What are the variations among Cement vs Mortar

The variation among cement and mortar is that cement refers to the binding agent, while mortar is a product formed with cement, sand and lime.

Both these materials have separate objectives like cement becomes usable with water and creates a bond with other elements to shape one solid object, while mortar is effective for retaining bricks or stone jointly, and cannot remain detached like concrete. Cement is a material that is applicable to form mortar grout and concrete etc.

Each mortar can be utilized in different ways, grout or concrete blended with cement, like grout can fill gaps among tiles, but if the joints in the blocks contain missing sections, mortar should be applied. Cement comes in different categories like portland, white or masonry cement. The objective of Portland cement is to develop an object for structural usages.

Mortar may comprise of either Portland cement with lime, or masonry cement, lime and sand, accumulates masonry units into structural systems. The compressive and bond strength as well as the absorption capacity is obtained by the mix ratio of cement and the other constituents.

There are bonding enhancers in mortar which are utilized for close the gapping among stone, brick or concrete blocks throughout building. It is also applied for repairing and renovating purposes. Mortar is used as a compact paste, and it turns out to be rigid after a short span to make a firm seal among stones or bricks so that air and moisture can’t get into the structure. Mortar can be easily fixed with joint reinforcements, etc, in the bricks.

It contributes to construct a building with strong structure and elegant look. There are various types of mortars like Portland mortar formed with Portland cement, sand and water. Another type is known lime mortar that facilitates the moisture to proceed freely, and pass away from the surface. Mortar has good longevity devoid of persistent repairs. Mortar is formed by mixing cement with lime and sand whereas cement is formed by mixing with sand.

In brief:

1. Cement stands for a binding agent to develop mortar, concrete and grout.
2. Mortar is formed by adding water, sand and lime to cement.

3. Mortar is generally utilized for closing the gaps among bricks and stones to resist moisture from leaking in.
4. Cement comes in various forms like Portland, masonry cement etc.
5. There are various categories and colors of mortar like terracotta or white etc.

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Benefits of concrete covers blocks in RCC work

This construction video tutorial will guide you to make concrete cover block or rebar spacer at a reasonable cost.

A rebar spacer belongs to a object that fastens the reinforcing steel or "rebar" in reinforced concrete structures since the rebar is amassed in place before the pouring of final concrete. The spacers are remained in place for the pour to set the reinforcing in place, and turn into a permanent part of the structure.

When RCC work is going on, implanting steel in concrete (called as cover) is a vital process for resisting rebar from decaying as well as arranging fire protection to the rebar. If the proposed cover is not arranged, the rebar will start to decay in due course of time and will lead to collapsing of the structure beforehand. So, cover blocks can extend the life of the structure considerably without incurring so much expenses.

The exact amount of cover is set by the application and the environment (e.g., is the RCC under water, etc.)

In India, following are considered as the standard size for the covers :

Slab : 20 mm
Beam : 25 mm
Column : 40 mm
Foundation : 50 mm

Concrete covers ensure the accurate position of steel, thus allowing in the practical application of the theoretical specifications of concrete construction. The cover of the steel concerning a specific construction component (for instance in a concrete slab or a beam) should be usually constant inside the element.

The application of covers can be beneficial to the areas where high earthquake activity along with corrosive environment (like proximity to salt water of sea) occurs.

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Concrete Blocks – Manufacturing Process & Benefits

(1) Raw materials utilized in Concrete Blocks :

The primary materials for developing the concrete blocks are aggregates, cement and water. Different types of aggregates are applied with changeable degree of success and they consist of crushed stones, gravel, volcanic cinders, foamed slag, furnace clinker, etc. In order to choose the aggregates, the factors like weight, texture or composition of the unit designed should be considered. The stability, texture and low-cost of the concrete block are subject to the grading of the aggregate cautiously. The cost will be reduced if locally accessible aggregate is used. The ordinary Portland cement is utilized for raw material. The required water should be the normal potable water.

(2) Concrete blocks manufacturing process:

The completely automatic plants are used to develop concrete blocks with superior strength. These automatic machines can made superior quality concrete blocks. But huge capital investment is required to set up & operate these machines. The transportation cost from the production area to the place of actual use will also be reduced for concrete blocks if the manually operated machines are installed at construction site itself.

The following manufacturing process is required for developing the concrete blocks :-

(i) Choice and ratios of ingredients: The primary factor for selecting the ingredients is the desirable strength of the block. If the coarse aggregate is mixed in perfect ratio, the strength of the quantity of cement applied will be superior.

(ii) Blending of ingredients: The aggregates, cement and water should be blended in a proper way. The mixing should be done through a mechanical mixer. While mixing manually, great care is necessary to check that the cement and aggregates are initially blended comprehensively in dry state and the water is then included slowly.

(iii) Positioning and vibration: The mixed concrete material is delivered into the mould box up to the top level and check carefully that the box is filled uniformly. The vibration of concrete is performed until it is set evenly in the mould box.

(iv) Curing: The block is drenched with water after around one day of casting and it should be sustained for at least 7 days and if possible up to 28 days. If the time for curing extends for a prolonged period, the block will be superior.

(3) Benefits of concrete blocks:The application of concrete blocks as a masonry unit is found on several construction sites due to the following benefits:

• It extends the carpet area of the building due to the small width of concrete block with regards to the brick masonry wall.

• It offers superior thermal insulation, improved fire resistance and strong absorption capacity.

• It can save major agricultural land which is applied for manufacturing bricks.

• The blocks are developed in an efficient manner so that the vertical joints can be taken back automatically and so the time spent for the careful supervision is minimized.

• The process for developing concrete block masonry is simpler, rapid and stronger as compared to the brick masonry.

• The shape and size of the concrete block is very accurate and it simplifies the work of a mason.

• As the numbers of joints are minimized, the time is saved for developing the mortar.

• The utility will be augmented by creating the reinforced concrete block (RCB) masonry units. The blocks are provided with two holes for arranging perfect reinforcing bars and the structure with RCB units could carefully withstand wind and earthquakes, if so designed. The conventional beams and columns are totally removed and the structure with RCB units will have a superior appearance.

Ref: www.theconstructioncivil.org

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Published By

Rajib Dey

www.constructioncost.co

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