Types of aggregates on the basis of grain size & volume weight

Aggregates alias construction aggregates are made of materials like sand, gravel, crushed stone, slag and recycled concrete. The standard types of aggregates are granite aggregates, gravel aggregates, limestone aggregates, secondary aggregates and slag aggregates. The aggregates are obtainable in different sizes like 10 mm, 20 mm, 30 mm. It is mostly found in construction industry for erecting buildings, roads along with water filtration and sewage treatment processes.

Aggregates stand for the static materials which are blended in fixed ratios with a Binding Material to form concrete.

The aggregates can be applied as fillers or volume increasing components as well as liable for maintaining strength , solidity and longevity of the concrete.

Qualities of Aggregates

The most vital properties of aggregate are given below :-

1. It should be chemically inert that means they should not respond to cement or any other aggregate or admixture.
2. It should contain adequate rigidity to get rid of scratching and erosion in the hardened state.
3. It should contain enough toughness to tolerate impact and vibratory loads.
4. It should be sufficiently strong to withstand compressive and normal tensile loads in ordinary mixture.
5. There should be no impurities, inorganic or organic in nature, which may provide significant impact on its quality.
6. It should have the capability of developing an easily executable plastic mixture on amalgating with cement and water.

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Categorization of aggregate

Based on the grain size, origin and volume-weight, the aggregates are categorized as follows:

Types of aggregates on the basis of Grain Size

It is mostly recognized classification method, where there are two types of aggregates like fine and coarse.

(i) In the Fine Aggregates, the grain-size remains among 4.75 mm and  0.15 mm. Conversely, these go through from sieve having mesh size of 4.75 mm and are kept on a sieve of 0.15 mesh size.
Sand is considered as globally recognized natural Fine Aggregate.

(ii) Coarse Aggregates: These types of aggregates are kept on the sieve of mesh size 4.75 mm. Their upper size is normally around 7.5 mm. Gravels obtained from river bed are treated as the best coarse aggregates in the formation of Common Concrete.

Under these situations, if they are not accessible easily, appropriate rock types are crushed to the preferred particle sizes for forming coarse aggregates.

Types on the Basis of Density

Based on the weight per unit volume, there are three types of aggregates.

(i) Standard or Normal: These types of aggregates provide strength and weighting to the Concrete of around  2300 to 2500 kg/m3.

Gravels, Sand and Crushed stone are considered as Standard or Normal Aggregates.

(ii) High-Density Aggregates:  These types of Aggregates are utilized in standard proportions given in heavy weight concretes. Such concretes are mostly found as shields against X-rays and radiationsin atomic power plant.

Examples: Baryle – a natural mineral containing specific gravity of 4.3.

Concretes with such aggregate normally contain weight over 4000 kg/m3.

(iii) Light weight Aggregates. These comprise of natural and artificial materials with very low density in order that the consequential concrete has light weight, normally within a range of 350 to 750 kg/m3. They are particularly utilized in sound proofing and fire proofing constructions. They are also mostly suitable for developing light weight Pre-Cast concrete blocks.

For more details, go through the following construction article.
https://civilguides.com/aggregate-definition-aggregates-types/

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Published by
Rajib Dey
email : rajib_dey@aol.com
website : www.sketchup3dconstruction.com (construction related articles & news)

Basic guidelines for Brick Masonry Constructions

While going to develop brick masonry, the points given below should be taken into consideration :-

1. It is recommended to use standard quality bricks which contain consistent color. Besides, bricks should be burnt perfectly and contain perfect shape and size.

2. Prior to utilize the bricks in masonry, they should have been drenched in water for 2 hours to avoid water consumption from the mortar.



3. Bricks should be placed with the frog pointing upward.

4. The brick wall should be built up from the end or corner.

5. Brick courses should have been correctly horizontal.

6. A plumb-bob is used to verify the verticality of the wall on a regular basis.



7. Mortar should be applied on the basis of the specification.

8. Whenever work is finished brick masonry should be discarded with toothed end.

9. Refrain from utilizing brick bats.

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10. Walls should have been lifted up homogeneously. The variation among adjoining walls should not be over 1 m. In a day no wall should be lifted up by above 1.5 m.

11. To provide perfect key for plastering or pointing, the face joints should be lifted up to a depth of 12 to 20 mm, as soon as the mortar is green. If there is no plastering or pointing, face joints should be fixed flush and finished precisely.



12. Holdfasts for doors and windows should be set in brick masonry along with cement mortar or concrete while building up the wall independently.

13. Brick masonry should be cured frequently for 2 weeks.

14. Single scaffolding should have been utilized for the formation of brick work at higher levels.

Source : http://www.civilengineeringx.com

The process and benefits of concrete resurfacing

It is found that old concrete suffers from cracks, surface discoloration, or surface imperfections. In order to enhance the appearance of the concrete, old concrete should be removed and replaced properly. Here, lies the importance of concrete resurfacing.


Concrete resurfacing refers to a process with which tone or injured concrete floor or pavement surfaces are cleaned, repaired and coated with a new surface to make them usable again devoid of reconstructing the entire structure.

Various steps like cleaning, repairing the cracks, repairing the holes, coating the surface, coloring and sealing, curing are involved in concrete resurfacing.

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Benefits of Concrete Resurfacing

1. The concrete resurfacing is undertaken for the maintenance and durability of the surface. It facilitates resisting cracks for a prolonged period and reduces the chances for development of potholes (In the case of driveways).

2. The concrete contains a light color that helps in managing the temperature as well as delivering a convenient cooling effect throughout summer seasons.

3. Concrete resurfacing is now accomplished by staining with different types of color to apply artistic beauty to the surface.

4. Diverse color options exist in the concrete resurfacing option. It can provide a nice appearance for the home exterior.

5. The elimination of snow from the concrete surface becomes simple with regard to any other surface.


Drawbacks of Concrete Resurfacing
1. If the placement over surface is inappropriate along with the assessment of the present condition, the concrete resurfacing will not be successful. It may cause illustrating the cracks on the surface. To resolve this issue, eliminate the pavement fully and develop a new surface.

2. It is not cost-effective for bigger areas.

For more information, go through the following construction article
https://theconstructor.org/practical-guide/concrete-resurfacing-repair-concrete-floor-pavement-surfaces/20597/

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Posted By Rajib Dey
Website : www.sketchup3dconstruction.com
 Email : rajib_dey@aol.com

Types of mortar joints in masonry construction

The mortar joint provides a significant effect on water resistance as well as appearance. Based on their functionality (greater to lower) to withstand entrance of water, common joint types are categorized as follow :-

1. Concave Joint

Concave tooling of the mortar joint compresses the mortar perfectly contrary to the units. A thick, smooth surface is developed that clears water successfully. This type of joint is mostly suitable in withstanding rain penetration and so is suggested to be utilized in walls vulnerable to wind driven rain.



2. Weathered Joint

Though it is not as useful as the concave tooled joint, but it is recognized as a water resistant mortar joint because it is compacted to some extent and clears the rain.



3. Flush Joint

The trowelling of a flush joint develops a non-compressed joint that contains probable hairline crack where the mortar is moved away from the unit. Flush joints are not recognized as perfect rain resistant mortar joints and should only be applied on walls where supplementary finishes are provided.

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4. Raked Joint

The raked joint may or may not be compressed and it offers a ledge where rain water will set and probably penetrate the wall. So, it is not recognized as a rain resistant mortar joint and should not be applied on walls vulnerable to weather.

Note: As raked joints do not sustain well, the application of scored block (that needs the use of a raked joint) is not suggested for exposed walls.

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Types of maths found in civil engineering

Selection of maths is mainly dependent what section of Civil engineering you want to move your career to, and if you prefer to accomplish design/material selection, or more field type work that range from Constructability and Resident Engineer.

Most "Math" generally found is optimization algorithms and computer code in decision analysis. But several design engineers employ very complex maths in structural FEA, Watershed simulations, Material property selection and adjustments, etc.

Constructability Engineers generally deal with an order of magnitude or two less than design engineers in order that things like formwork, scaffolds, etc. can come up with the manufacturing or construction process.

As for instance, the design engineer might accomplish a comprehensive FEA on a structure, with calculus and software to produce stresses, strains, moments, at a rapid rate. It leads to a bearing pad for a standard size W-Flange column, and they require a 150mm square pedestal having 4 x 15mm anchor bolts at 120mm spacing centre to centre, centering on the pedestal.

But by some means they should be to be joined and cast in, or cored and grouted in place.

Here comes the importance of constructability. A grout can for an anchor bolt should have been 20mm round, i.e. 10mm of concrete exist among the can edge and the edge of the pedestal. This grout facilitates the schedule to be 3 days shorter, that leads to a small, but quantifiable savings to the owner. They'll tender an RFI to the design engineer, generally with supporting calculations or code references, requiring a sanction to modify construction, like forming the pedestal 175mm in each direction to obtain concrete cover requirements. As these calculations are essential for construction, the calculations are generally fast and complicated, so assumptions are created, and numbers are rounded. This math is normally algebraic at worst.