Some important points for civil site engineer

 Civil engineer accomplishes several tasks at construction site. Given below, some points, tips and tricks essential for a civil engineer for doing rapid calculations and providing instant solutions to construction site problems.

Given below, some general points which civil site engineers should focus on to simplify the construction work whereas retaining the quality of construction.

Lapping should not be provided for the bars with diameters in excess of 36 mm.

Highest spacing for chair should be 1.00 m (or) 1 No per 1m2.
For dowels rod, lowest 12 mm diameter should be applied.

For Chairs, bars with minimum diameter of 12 mm should be utilized.
Longitudinal reinforcement should remain not below 0.8% and in excess of 6% of gross C/S.
Least bars for square column is 4 No’s and 6 No’s for circular column.
Main bars in the slabs should not be under 8 mm (HYSD) or 10 mm (Plain bars) and the distributors should not be under 8 mm and not in excess of 1/8 of slab thickness.

Least thickness of slab should be 125 mm.
Dimension tolerance for cubes should be + 2 mm.
Free fall of concrete is permissible maximum to 1.50m.
Lap slices should not be applied for bar greater than 36 mm.
Water absorption of bricks should not be in excess of 15 %.
PH value of the water should not be under 6.

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Published By
Rajib Dey
www.constructioncost.co
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Stirrups in a Concrete Beam

 As engineers, we plan fortified concrete members and frequently we are approached to watch the steel reinforcement in field before the concrete is set. We must ensure the concrete establishments, beams, segments, and so forth are fabricated the manner in which they were structured. During our perceptions we regularly find that steel beam stirrups, utilized in fortified concrete plan, are not introduced accurately and it isn't in every case clear to the installer why they are significant.

Truly, beam stirrups had been utilized sparingly in private development. In any case, as of late concrete beam sizes have gotten shallower and ranges have expanded. We would say, this has been the aftereffect of structural plan and building tenant prerequisites. The expanded expense of establishment components, for example, bored docks, has additionally been a factor. Expanding concrete beam ranges, to lessen the requirement for extra wharfs, has brought about the requirement for the utilization of steel stirrups.

Usage of Stirrups

Concrete beams shift inside and out. The more profound the beam, the more shear limit. At the point when the profundity isn't satisfactory, steel stirrups must be added to expand the shear limit of the beam. These stirrups are normally one bit of steel that is twisted into a rectangular shape. Regularly little distance across steel is utilized, for example, #3 and #4 rebar. The stirrup normally folds over the base and top bars of the beams.

A planner ought to determine the size, dispersing and area along the length of the beam where the stirrups are required. We like to indicate the stirrup measurements in our areas, with the goal that the stirrup can be made before establishment. Stirrups will be required at zones of high shear, for example, bearing focuses and beneath huge point loads.

The installer ought to be mindful so as to manufacture the stirrup from one bit of steel and sufficiently cover each end (contact the Structural Engineer or allude to the ACI code for varieties). Again and again, the stirrup isn't pre-manufactured and the installer attempts make the stirrup in the field, after the flat bars are as of now set up.

This is normally self-evident, in light of the fact that the stirrup is built from two pieces with insufficient lap join. It is a lot simpler and effective to introduce a stirrup simultaneously the even reinforcement is being introduced. Continuously contact the Structural Engineer with any inquiries concerning size, shape, separating and establishment of stirrups preceding assessment. This will help forestall a minute ago changes, while the concrete truck is pausing.

Stirrups are closed circle bars tied at normal stretches in beam reinforcement to hold the bars in position. Sidelong ties are utilized to hold the situation of the reinforcement in a segment without upsetting the concrete space.

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Published By
Rajib Dey
www.constructioncost.co
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Importance of mortar in brickwork construction

In brickwork construction, different types of mortars like M1, M2 etc. are applied. Normally, lime mortar and cement mortar are frequently utilized for brickwork. The characteristics, strength and applications of these mortars are discussed below :-

Consideration should given on the following factors for Mortar in Brickwork Construction :-

1. The strength of brickwork is not affected by the grade of the mortar used, i.e. several mortar mixes of diverse grades like M1 and M2 contain dissimilar strengths, but the strength of brickwork is not compromised. As for instance, mortars of mix ratios 1:6 and 1:4 provide equivalent strength of brickwork with the similar type of bricks, while they contain different strengths. It signifies that the strength of brickwork is based on the strength of bricks.

2. If the mortar mix ratio of 1:3 is applied for cement to sand or (cement + lime) to sand ratio, a solid mortar is produced with less voids.

3. Benefits of Lime Mortar – As the strength of lime mortar is under cement mortar, inclusion of lime in mortar brings the following benefits:

• Shrinkage in mortar is fewer, thus less susceptible to cracks because of shrinkage.
• The workability and plasticity of the mortar mix is enhanced with lime.
• Lime contains superior water retention strength and does not vaporize rapidly. Besides, dry bricks can’t absorb water from the lime mortar.
• Lime raises the volume of mortar and fills the voids so that it becomes water resistant against rain infiltration.
• Lime mortar can bond with bricks efficiently.
• Cement-lime mortar is more flexible and can adjust the normal movements of brick masonry without causing cracking. So, normally, cement lime mortar less susceptible to cracking as compared to cement mortar.

4. Lime mortar attains strength gradually and contains lower ultimate strength as compared to cement mortar. Besides, lime mortar with hydraulic lime can get superior and early strength. Lime mortar with fat lime does not consolidate at all in wet locations. While applying fat lime, some pozzolanic materials like burnt clay should be utilized instead of sand to enhance the strength of mortar.

5. Cement-lime mortar of leaner mixes from ratio 1:4 to 1:8 becomes rough specifically when the sand is coarse and not graded. Consequently, plasticizers should be utilized for better workability and plasticity of the mortar.

6. The strength of cement mortar is impacted by the following factors for the same ratio of cement and sand:

a. Grading of sand
b. Fineness and coarseness of sand
c. Angularity and roundness of the sand particles

7. If fineness of sand is raised, the workability of the cement-mortar mix is also increased. On the other hand, the surface area of the sand is also increased for which requirement for cement and water quantity for the same strength is also increased.

The strength will be reduced when the cement quantity is not raised. To attain the required workability, adequate water is necessary. This condition raises the water-cement ratio and as a result the strength is decreased.

8. Curing plays an important role to attain the maximum strength as well as maximum coating of the obtainable cement around sand particles.

9. Mortar beyond a mix ratio of 1:3 should not be applied in brickwork masonry construction due to high shrinkage and no considerable increase in strength of masonry, although the strength of mortar itself raises.

10. Overly thick joints decrease the strength of the brickwork.

11. Inclusion of pozzolana enhances the strength of the mortar as well as resistance capacity against chemical attacks.

Read more

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Published By
Rajib Dey
www.constructioncost.co
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