Reinforcement of Concrete Slabs

The determination of a formwork framework ought to be made based on the chosen floor framework that satisfies the basic stacking conditions. Floor slabs in concrete structures are classified into two essential sorts, in view of the heap appropriation applied on the Reinforced Concrete slab:

Two-way slab, in which the rectangularity proportion (slab length/width) is somewhere in the range of 1 and 2, and the slab load is moved to the supporting pillars in two directions.Two-way development incorporates flat plate, flat slab, waffle slab, and two-way slabs bolstered by drop shafts.

Single direction slab, in which the rectangularity proportion (slab length/width) is more than 2, and the slab load is moved to the supporting bars a single way. Single direction development as a rule remembers strong slabs for shafts or dividers, single direction joist (ribbed) slabs upheld on bars or bearing dividers.

Two-Way Flat Plate: Such slabs might be cantilevered at the outside of the structure to allow the utilization of outside balconies.The supporting segments for flat plates are normally similarly dispersed to encourage the plan and development of such slabs.

This framework is prudent for ranges of up to 23 ft (7.0 m) with mellow reinforcing.Flat plates can be built in least time since they use the easiest conceivable formwork. Level plates have been utilized effectively in multi storey inn, lodging, medical clinic, and high rises.

Two-Way Flat Slab: A flat slab basic framework comprises a steady thickness of Reinforced Concrete slab with drop boards at the sections areas. Note that the framework is normally appropriate for square or about square boards.

In prior years, section capitals were utilized alongside drop boards, but since of the higher formwork cost, segment capitals are less preferred in the present development practice. Level slabs are utilized to oppose heavier burdens and longer ranges than flat plates. Generally, the framework is generally appropriate for square or about square boards.


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Different types of BBS shape codes for steel

Sami Ullah, the renowned civil engineer, presents this useful video tutorial in civil engineering youtube channel. In this video, the detail process is given for finding out the quantity of steel as well as shape codes for the steel bars.

Shape codes are considered as the basis of a proper bar bending schedule.

While going to estimate the reinforcement detailing for various members concerning a building, small bent ups and other angle detailing should be considered in the calculation to produce valid and cost-effective bar bending schedule.

It will significantly reduce the cost and wastage of reinforcement.

In beams & slabs there exist various bent ups, cuttings, and development lengths. Each and every bend and angle presented in the member is the outcome of design calculation. Therefore, these should be carefully enforced in practice.

For small projects, it is unnecessary to compute these details, just include a few more inches and work out the Bar Bending Schedule.



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How to Control Reinforcement Activities On-site

It is imperative to control reinforcement activities in a building construction site. Otherwise the building may get damaged due to any shift in loads, or may simply break down at the slightest seismic activity.

First of all, you need to hire one or more qualified engineers to oversee different parts of the construction process. Aslo, you need to assign as many assistants as necessary to them.

A. Planning Phase: You need to study the documents concerning the project carefully as to divine the exact requirements. You also have to make sure the planning goes according to technical specifications. Then locate the provisions regarding mode of measurement in item fee agreement.

Check the objects payable which includes reinforcement, and whether or not laps, spacers and chairs are payable or inclusive. Arrange the required applicable codes,requirements and different related documents at the website for reference and study.

Study the tender drawings without fail. Calculate quantity as in keeping with the preliminary drawings, Dia clever and grade sensible. Mastermind the necessary pertinent codes, standards and other related archives at site for reference and study.

Study the delicate drawings without fail.Calculate amount according to the starter drawings, Dia savvy and grade insightful. Set up the monthly shrewd obtainment plan according to the development plan. Get ready to obtain a calendar of authoritative alongside support plan.

Plan for spread squares and joins (whenever required) ahead of time to get the required quality of spread squares thrown at site. Get Dia shrewd and grade savvy amounts from creator for singular amount contract if drawings were not accessible at starting phases of undertaking for arranging acquisition.

Permit a stock of 45 days while arranging obtainment or relying on the accessibility. Indent just 90% of amounts of absolute necessity till you have every endorsed attracting to keep away from varieties because of configuration/drawing corrections.

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About Precast Concrete Piles - the Pros and Cons

The most common type of them, a precast concrete pile is a deep foundation used to transfer loads from a upper, soft layer of soil to a hardar, capable lower layer. They can be rectangular, square, round or polygonal in shape. Extra reinforcements are provided in the concrete so as to provide support for the forces received before the instalent.

The precast concrete piles are constructed in a casting yard. Then they are transported to the required location and installed as necessary. They are constructed by pouring the concrete in a conventional reinforcement cage. This has several steel bars in horizontal and vertical positions, held together by individual or spiral ties.

Types of Precast Concrete Piles - There are two main categories into which we can divide:

1. Driven Precast Concrete Piles: It is precast in a construction yard and then hammered into the soft ground at the target location. At most they can go up to 40 feet deep.

2. Bored Precast Concrete Piles: After they are made in the construction yard, they are transferred to the target location. The location already has boreholes for the piles; they are just lowered into these holes. Any space remaining between the bore hole and the pile is grouted.

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How to work out cutting length for column circular stirrups

This construction video is recorded to provide you some useful tips for estimating the cutting length of the circular column stirrups.

Here the radius of the column is taken as 400 mm.

Dia of stirrup is taken as 8 mm

Concrete Cover is taken as 40 mm

Stirrups are also known as Links or Rings or Transverse Reinforcement. Stirrups are applied in Beams and Columns. The stirrups remain vertical in a beam and horizontal in a column.

Benefits of column stirrups :
To settle and withstand the longitudinal (main) steel bars in columns to bulging below the vertical forces (compression force) particularly in the middle of the column prior to get to the concrete.

Increase the quantities (diameter or by spacing) of stirrups at both ends of the column with the intension of combating the horizontal forces which produce horizontal shear forces on both ends of the column.

Go through the following video, to get the detailed process.

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How to avoid Honeycombing in RCC Structures

Definition of a honeycombing: Honeycombing refers to a structural fault in a RCC Structure. Honeycombed surface is the areas of the concrete surface where the coarse aggregate are eminently observable.

If precaution is not taken for honeycombed surface, the RCC structure fails to achieve optimal performance according to its design (structurally weak). Besides, it also lets damaging agents like contaminated water and air entering through the produced voids which can impact the strength of structure considerably.

Causes for Honeycombing: Honeycombing in RCC Structure is happened because of the following reasons -

1. Concrete mix is not homogenous.
2. The applicability of concrete is inadequate and not matched with its placement need.
3. Inadequate compaction to concrete.
4. Concrete flow is not dispersed to all corner due to steel congestion.

5. Concrete is set afore time prior to placing.
6. High free fall of concrete, at the time of pouring
7. Form work is not waterproof or inflexible.
8. Incorrect detailing and/or fixing of steel

How Honeycombing in Concrete can be avoided?

Check concrete production/cohesiveness from time to time to organize all concrete batches.

Tip: If it is possible to create ?ball? from the fresh concrete, a cohesive concrete mix is produced.

Concrete workability should tally with the placement need. As for example, a lightly reinforced column should contain 75mm slump, a heavily reinforced column may require 150mm slump.

Make sure that the compaction of placed concrete is perfect, vibrators should have been detached as big air bubbles stops to come out (over vibration can lead to bleeding). Various sizes (25mm, 40mm, and 60mm) of vibrator needle should have been utilized according to RCC sections.

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Steel Quality Field Test

It is essential for the constructors to have good quality material for their building project. Compromises in the quality of construction material can cause severe results leading to serious repercussions. One of the most important materials of a building is the steel reinforcements used in concrete columns, beams, and other structures.

The quality of steel received on site determines the strength of the structure with steel reinforcements inside it; so it is imperative that you check the steel quality right on the project site to ensure that your building will be made out of materials capable of handling the load.

Observations on Steel on Site:

1. Cleanliness: The reinforcements that you receive in the field must be clean ones. Dust, rust, earth, mild scales, paint, oil, grease or any similar coating clinging to the bars is detrimental to the bonding between reinforcement and concrete. Also, these contaminants can cause corrosion in the structure. For this reason, you must make sure that the steel bars and other reinforcements you receive are clean. Point to note: a little rusting on the bars is considered to be helpful in forming better bonds with the concrete. But excessive rusting and/or scaling is absolutely harmful for the building.

2. Manufacturer Marking: The bars should have their steel grade, manufacturer name/logo, brand name, diameter etc should be embossed on themselves. Do check if you have received everything of the same type as you expected.

3. Bending the Bars: When satisfied with the above, proceed to the Bend Test to examine the actual capabilities of the steel you have received on site, under realistic strain.

a. Bend Test: This test should be carried out as per the specifications in IS 1599 and you should use mandrels of size specified in IS 1786. The rebar sample should be bent in 180 degrees, results recorded, and then proceed to bending it 180 degrees.

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Standards of Reinforcements Detailing in Slabs and Beams

Reinforcement Detailing in Slabs and Beams performs a vital role in a construction process to provide durability and strength to the structure. It also helps out in the cost optimization for the project. A structure’s cover to reinforcement, length of the reinforcement, it’s curtailment, number and diameter should all be clearly defined by the detailing of the reinforcement of the concrete beams and slabs.

Consider a generic concrete slab or beam, supported via simple means. This structure would experience the maximum bending moment at the center of the span. The shear force will come at a distance of d/2 from the face of the support (where d = effective depth of the slab or the beam).

This indicates clearly that the bending reinforcement is required at the center of the span, where the bending moment occurs, not at the support. Whereas the support should be reinforced to withhold the shearing forces.

Therefore, it would not be necessary to cover the full length of the structure in tension reinforcement. In fact, as much as 50% of the reinforcement can be curtailed at suitable locations. They can also be repurposed as shear reinforcements by bending them upwords.

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What is Self-Compacting Concrete and How is it used

Self-compacting Concrete, or Self-Consolidating Concrete, generally called SCC, is a fresh concrete that runs under its own weight and does not want external oscillation to undergo compaction. Constructors use SCC in the building structures where it is troublesome to use vibrators for the consolidation of concrete.

Why is Compaction Needed?

After the liquid or paste concrete is poured in place and should be left to set, it should undergo the compaction process before it starts to harden. Compaction or Consolidation significantly enhances the final strength of concrete and improves bonding with reinforcement. It also increases the abrasion resistance and overall sturdiness of the concrete. Moreover, this process decreases the permeability of concrete and helps to minimize its shrinkage and creep characteristics.

What is SCC?

The SCC or Self-compacting concrete is a form of concrete that can flow under its weight, and that does not need to go through a separate compaction process to fill and flow through heavy reinforcement areas.

SCC has more or less equivalent cement binders and water ratios as the standard concrete mix. However, the variations in the mix cause the SCC to produce a higher strength without vibrating the concrete by forming better bonds between the hardened paste and the aggregates and reinforcements. You can pour SCC into structures more than five meters tall because due to its characteristics the aggregates will not get segregated. The self-compacting concrete can also be poured faster than the regular mix.

What are the Materials in SCC Mix?

To give the concrete paste diverse properties, somewhat different materials ratios are used in the SCC mix. These are as follows.

Cement: Grade 43 cement is used in self-compacting concrete, which must meet the physical properties according to IS:8112 code. The following table will give a better understanding of the cement used in SCC

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Some useful tips to design a T-beam with the use of limit state method

This construction video briefly describes how to create the design of t-beam with the use of limit state method.

A T-beam (or tee beam) is applied in construction extensively. It is a structural element developed with reinforced concrete, wood or metal. It contains a t-shaped cross section that is formed by a stem and a flange of reinforced concrete or rolled metal.

The top of the t-shaped cross section acts as a flange or compression member in withstanding compressive stresses. The web (vertical section) of the beam underneath the compression flange contributes to withstand shear stress and offer better separation for the coupled forces of bending.

A T-beam has the capacity to tolerate large loads by providing resistance in the beam or by internal reinforcements. It operates similar to singly reinforced beam.

In order to enhance the structural strength of a T-beam, just utilize an inverted T-beam together with a floor slab or bridge deck linking the tops of the beams. If it is accomplished perfectly, the slab performs as the compression flange.

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Guidelines for rebar detailing of RCC structures

Reinforcement Detailing or Rebar detailing is a detailed construction engineering process normally accomplished by the Rebar fabricators, structural engineering consultants or the contractors for generating ‘shop/placing’ drawings or shop drawings and bar bending schedule of steel reinforcement for construction. Architect/Engineers(A/E) produce ‘Design Drawings’ with the purpose of adding strengths with rebar size, spacing, location, and lap of steel.

Rebar Detailing is also known as Rebar scheduling, RC Detailing and Bar Bending schedule predation, RC Drafting, etc in different countries.

Objective of Rebar Detailing - The rebar detailing is done for the following purposes :

a) To produce an error-free Bar bending schedule, when fabricated should be accommodated in the concrete formwork devoid of any issue. The similar Bar Bending Schedule should be utilized for accounting and invoicing.

b) To develop a detailed Rebar placing drawing (known as Rebar Shop drawings). This Rebar placing drawing assists an Ironworker to place rebar perfectly in the site efficiently.

c) To allow the structural engineer to verify and approve when the structural design intent is precisely transformed into the Rebar Placing drawings and Bar bending schedules.

d) To perform a Rebar wastage analytics and minimize probable scrap existing in the Drawing level.

Standard Hooks: The term “standard hook” is defined as follow -

1. 180o bend together with an extension of minimum 4 bar diameters, but not below 65 mm at the free end of the bar.
2. 90o bend together with an extension of minimum 12 bar diameters at the free end of the bar.
3. For stirrup and tie anchorage.

For 16 mm φ bar and smaller, a 90o bend along with an extension of minimum 6 bar diameters at the free end of the bar,

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Effect of segregation and bleeding on quality of concrete

Segregation in concrete: Segregation means the detachment of ingredients in concrete. In concrete, the following types of segregations mainly occur:-

1. Detachment of coarse aggregate from the concrete mixture,
2. Detachment of cement pastes from the concrete throughout its plastic phase.
3. Detachment of water from the concrete mix (Bleeding in concrete)

Concrete is formed by mixing cement, fine and coarse aggregates. In a standard quality concrete, is all the ingredients are grouped properly to develop a uniform mixture. Segregation in concrete is primarily occurred due to variations in specific gravities of the ingredients.

Specific gravity of Cement remains among 3.1-3.6g/cc, and for aggregate it remains among 2.6-2.7g/cc. Because of this variation, the aggregate is detached from the matrix and segregation in concrete occurred.

There are various other factors to create segregation in concrete :-

1. Moving concrete mixes for long distances.
2. Weak mix ratio, where adequate matrix does not exist to unite the aggregates.
3. When concrete falls from over 1m.
4. Vibrating concrete for a prolonged period.

Guidelines to reduce segregation in concrete:-

Segregation is managed properly with exact mix ratio.

Handling, placing, transporting, compacting and finishing of concrete in perfect manner.

With the addition of air entraining agents, admixtures and pozzolanic materials in the mix, the segregation is controlled to some extent.

Bleeding in concrete: Bleeding is a type of segregation in which existing water in the concrete mix is forced upwards owning to the settlement of cement and aggregate. Since specific gravity of water is low, the water may proceed upwards. Bleeding normally occurs in the wet mix of concrete.

Due to greater amount of water cement ratio, the bleeding is found in concrete. If the water-cement ratio is higher, the concrete becomes weak and as a result excessive bleeding happens.

The bleeding in concrete is not a cause of great concern when the rate of evaporation of water is identical to the rate of bleeding. Normal bleeding improves the workability of concrete.

When the concrete becomes completely plastic, bleeding is not injurious. However, concrete still remains in the plastic stage and it is subsidized and compacted in due course.

How bleeding impacts the stability of concrete :-

1. Since water is pushed upwards in bleeding, sometimes with this water, specific amount of cement proceeds together with water to the concrete surface. If the top surface is worked up with the trowel, the aggregate comes downward and cement paste is developed at the top surface and it is known as ‘Laitance in concrete.’ As Laitance is developed, the wearing strength of structure is reduced and the longevity of structure is hampered.
2. While directing to the top from bottom, water produces continuous channels. Because of these channels, concrete turns out to be porous and facilitates water to move, that develops water voids in the matrix and decreases the bond among aggregate and the cement paste.
3. If water is accumulated at the top surface of concrete, the surface finishing is deferred.
4. Concrete becomes porous and its consistency is affected.
5. Excessive bleeding results in rupturing the bond among the reinforcement and concrete.

Remedies to control the bleeding :-

1. Bleeding in concrete is managed with the inclusion of minimum water content in the concrete mix.
2. Allowing the application of air en-training admixtures in the mix.
3. By providing more cement in the mix.

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Some useful guidelines for RCC slab design

In this exclusive civil engineering tutorial, you will get some useful guidelines for designing any RCC slab.

A) Effective span of slab – It should be least of the two

1) L = clear span + d (effective depth)
2) L = Center to center spacing among the support

B) Depth of slab: The depth of slab is influenced by bending moment and deflection criterion. The trail depth is achieved with the following :-

Effective depth d = Span/((L/d) Basic x modification factor)

To get modification factor, the percentage of steel for slab is taken from 0.2 to 0.5.

The effective depth d of two slabs is also taken as cl.24.1,IS 456 on the condition that short span is 3.5m and loading class is <3.5KN/m2.

Categories of supports: Fe-250 – L/35, Fe-415 – L/28

Continuous support: Fe-250 – L/40, Fe-415 – L/32

The following thumb rules are commonly applied :-

One way slab d = (L/22) to (L/28). Two way simply supported slab d = (L/20) to (L/30). Two way restrained slab d = (L/30) to (L/32)

Load On Slab: The load on slab contains dead load, floor finish and live load. The loads are measured according to unit area (load/m2).

Dead Load = D x 25 kN/m2 (Here D denotes thickness of slab in m). Floor finish (taken as) = 1 to 2 kN/m2. Live load (taken as) = 3 to 5 kN/m2 (based on the occupancy of the building)

Nominal Cover
For mild exposure – 20 mm
For moderate exposure – 30 mm

When the diameter of bar does not go beyond 12 mm or cover is decreased by 5 mm. For main reinforcement up to 12 mm diameter bar and for mild exposure, the nominal cover is 15 mm.

Least reinforcement: The reinforcement in either direction in slab should not remain under :-

0.15% of the total cross sectional area for Fe-250 steel. 0.12% of the total cross sectional area for Fe-415 & Fe-500 steel

Distance of bar: The maximum distance of bars should not surpass. Main steel – 3d or 300 mm which is lower. Distribution steel – 5d or 450 mm whichever is lesser

Here, d denotes the effective depth of slab. The least clear spacing of bars should not be under 75 mm (desirably 100 mm). Highest diameter of bar. The highest diameter of bar should not go over D/8, here D denotes the total thickness of slab.

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Details about structural and non structural defects in buildings

Concrete has diversified nature. It casts in place by including or excluding reinforcement. It is also precast or pre-stressed to attain necessary strength. For this purpose, there should be adequate knowledge on the behavior and constituents based on which the concrete is produced.

There should not be any type of laxity in any of its phase like placement, design & maintenance as these can create deterioration and resist concrete to accomplish its proposed functions. Given below, some vital factors which can weaken the quality of concrete:

1. Accidental loading
2. Chemical reaction like sulfate attack, alkali carbonate reactions, alkali silica reactions etc
3. Erosion of steel reinforcement
4. Inferior construction detailing

5. Erosion
6. Freezing and Thawing
7. Shrinkage
8. Settlement
9. Fire and weathering

Flaws in Building Design: Due to deficient structural design, the concrete is uncovered to flexural and shearing stresses and as a result spalling and cracking of concrete are developed. Any sudden modification in cross section of any member can result in raising the stress concentration in that member that leads to cracking of concrete.

Deflection is considered as one of the significant part in structural design. If there exist any issue in its consideration throughout design, that can produce cracking of concrete. Insufficient arrangement of drainage and expansion joints throughout the design also leads to deterioration and spalling of concrete.

Flaws During Construction: Flaws throughout building construction vary from inappropriate mixing, placing and curing of concrete. Detachment of shoring & formwork can also produces cracks in concrete.

When extra water is provided in concrete to enhance the workability of concrete, the water cement ratio is raised significantly and it can reduce the strength of concrete. Inappropriate alignment of formwork produces corrosion in concrete.

Structural Defects in Building Construction - The following structural defects are found in buildings:

1. Cracks in foundation (substructure)
2. Cracks in floors and slabs (superstructure)
3. Cracks in Walls (superstructure)

These above defects are occurred due to the following factors:

1. Inappropriate soil analysis
2. Inappropriate site selection
3. Application of defective materials
4. Inferior work

These structural issues can be resolved with perfect design and planning.

Non Structural Defects in Building Construction - The following non structural defects are common in buildings:

1. Defects in brick work
2. Dampness in old structures
3. Defects in plaster works

So, it is found that minimum design and construction defects lead to minor cracking or spalling which can weaken the concrete and result in collapsing of the structure. To get rid of these issues, proper care and attention should be taken in designing, detailing and construction of concrete structure.

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Impact of course aggregate on mix design of concrete

Coarse aggregate is considered as one of the vital elements of concrete and captures the major volume in the mix as well as impacts the concrete mix design significantly. Its different characteristics like strength, maximum size, shape, and water absorption affect water demand, the quantity of cement and fine aggregate in concrete mixture.

It is found that high maximum coarse aggregate size can reduce water demand in the mixture as such aggregate contains lower surface area with regards to small coarse aggregate size.

While considering shape, rounded type aggregate offers reasonable mix design for normal strength concrete.

For high strength concrete, angular coarse aggregate is essential. The scope of segregation is reduced when coarser aggregate is graded perfectly for concrete mix design.

While considering strength, greater aggregate strength generates higher concrete strength.

1. Maximum Aggregate Size: The maximum size of coarse aggregate is another vital factor that checks water demand to attain definite workability. It also determines the quantity of fine aggregate content required for developing cohesive mix.

For a specified weight, if the maximum size of aggregate is increased, the surface area of coarse aggregates is reduced and conversely. When the maximum size of coarse aggregate is decreased, the surface area of coarse aggregate is raised. If the surface area is large, the water demand will be increased to coat the particles and produce workability.

For smaller maximum size of coarse aggregate, larger fine aggregate content is required to coat particles and retain cohesiveness of concrete mix. Therefore, for similar workability, 40mm down aggregate contains lower water/cement ratio, thus strength is raised with regards to 20mm down aggregate. Due to its lower water demand, higher maximum size of coarse aggregate can reduce the cement consumption.

Maximum size of aggregate is confined with clear cover and minimum distance among the reinforcement bars. Maximum size of coarse aggregate is lower than clear cover or minimum distance among the reinforcement bars. As a result, the aggregates can get through the reinforcement in congested areas, to form dense and uniform concrete.

2. Grading of Coarse Aggregate: Grading means the establishment of the particle-size distribution for aggregate. It influences the amount of cement and water requirements, workability, pumpability, and stability of concrete. The grading of coarse aggregate is crucial to acquire cohesive and dense concrete. The voids due to larger coarse aggregate particles are filled with smaller coarse aggregate particles.

If the grading of coarse aggregate is perfect, the scope of segregation is reduced, specifically for higher workability and the compatibility of concrete in enhanced. The coarse aggregate grading limits are provided in ASTM C33/ C33M and IS 383 – 1970 – table 2, Clause 4.1 and 4.2 for single size aggregate as well as graded aggregate.

3. Shape of Coarse Aggregate: The shape of coarse aggregates range from round, angular, or irregular. Rounded aggregates contain lowest water demand because of lower surface area, and also contain lowest mortar paste requirement.

These properties facilitate to produce rounded aggregate to give in the most reasonable mixes for concrete grades up to M35. However, for concrete grades of M40 and above the scope of bond failure would slant the balance in support of angular aggregate containing larger surface area.

Flaky and elongated coarse aggregate particles raise the water demand as well as the susceptibility of segregation. The flexural strength of concrete is minimized due to flakiness and elongation. Specifications provided by Ministry of Surface Transport confine the combined flakiness and elongation to 30% by weight of coarse aggregates.

4. Strength of Coarse Aggregate: Material strength of coarse aggregate is determined by crushing strength of rock, aggregate crushing value, aggregate impact value, aggregate abrasion value. The IS limits for above tests range from Aggregate Crushing value, Aggregate Impact value, and Aggregate abrasion value.

5. Aggregate Absorption: The purpose of aggregate absorption is to employ a correction factor for aggregates in dry condition and find out water demand for concrete in saturated surface dry condition. Aggregate can consume water up to 2 % by weight when remains in bone dry state. But occasionally, the aggregate absorption remains as high as 5%.

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How to make concrete formwork system safe in the job site

If the safety plans for formwork system remain perfect, construction project will be completed according to approved construction practice and without unnecessary hazards like failure of formwork and consequent delay in construction and possible loss of life. Normally, safety will be commenced in the planning and management of a project.

The safety of workers and the public is mainly dependent on the construction work supervision, equipment deployment practices, and construction method used.

Formwork designers, project planners, and managers should abide by the requirements of relevant standards like OSHA regulation with the purpose of providing good safety planning.

1. Supervision and Inspection: Supervision work should be perfect throughout placing formwork, concrete pouring, and stripping of formworks for maintaining safety in the use of forms.

A supervisor has to take the responsibility for the construction of formwork based on the design and deploying a secure erection method to get rid of overloading of members.

Rectifications of the false work, forms, or erection method in construction site should be performed as per suggestions of the form designer. The application of unusual loads should be controlled when the formwork system is not designed for such loads.

2. Platforms and Access for Workers: There should be proper working platform for the works to be accomplished at elevated positions. Long ladder to the tops of false work should be rest or passing platform. In specific structures like bridges, special scaffolds should be utilized or any other appropriate equipment for the detachment of decks and piers forms.

There should be proper safety signs and barriers to restrict the entry of the unauthorized individuals to the working area throughout erection and striping formwork system. Platforms and access means for worker should be adhered to suitable codes like OSHA requirements.

3. Monitoring Concreting Practices: Controlling concrete pouring plays an important role in formulating the proper safety plan. The sequence and rate of concrete placement should take limitations into account which are provided in the formwork drawings.

At the time of placing concrete, unbalanced form loading should not occur. As for example, in beam and slab construction, initially fill the beams and then work outward uniformly on both sides while setting the slab. The durability of the formwork system is increased in a column-and-slab structure by concreting the columns minimum one day before placing the slab.

Hardened concrete in the columns contributes to extra lateral stiffness to the formwork structure all through the concreting of the slab. Repeatedly, Reinforced concrete column is built up and then erection of floor system is started.

4. Advancement of Soil Bearing and Bracing: Normally, the condition of soil is unidentified while designing the forms and scaffoldings; assumed bearing capacity is applied. Therefore, the contractor should verify whether the bearing strength of the soil at construction site is higher or smaller as compared to the one accepted during design phase. If soil bearing strength is dubious, then it’s stability can be improved by tamping or making a cover with layer of crushed stone. Formworks should be designed to resist gradual collapse caused by localized failures.

5. Shoring and Reshoring: Setting of out of plumb shores, bent jacks, and defective timber should not be done else these supporting elements would support only a small area of design loads. Throughout Concreting, forms should be checked repeatedly to detect problems and instantly rectify them.

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Some important checklists for RCC slab and beams

The following checklists are extensively utilized for RCC slab and Beams.

1. Examine the bottom line, level & width of beam properly.
2. Examine the side line, level & plumb of beam properly.
3. Beam to beam measurements should be examined according to architectural drawings.
4. Individual level & diagonal of each slab bay should be examined properly.

5. The thickness level of slab should be marked with nails on the peripheral beam’s exterior sides.
6. Examine the thickness of slab and depths of beam properly.
7. Support props for slab & beam bottoms should arrange in line & plumb. Bamboo bracing should be accomplished at around 4′ ht from floor level. Support props for double staging terraces should be examined cautiously.
8. Line of external /peripheral beam’s sides should be examined & cross supported to get rid of buldging out of sides.
9. Junctions of columns & beam should be verified to make them water resistant.
10. De-shuttering oil should be provided to beam/slab shuttering.

11. Formwork of stair case should be examined for dimensions of tread and riser, level of treads, plumb of risers.
12. Reinforcement should be examined for beams and slab as per R.C.C drawing
13. Ensure to provide exact cover for bottom /sides of beams.
14. Proper cover should be provided for slab.
15. Electrical points, electrical piping (conduits)/fan hooks should be examined as per drawing.
16. Reduction of column according to drawing should be performed if any.
17. There should be exact numbers of chairs should be arranged for slab.
18. Dowels (if any) should be arranged for elevational feaures / future expansion.
19. Parapet (Pardi) bars should be provided for balconies/staircase etc.

20. Ring (stirrups) should be arranged at the free end of each column reinforcement.
21. Distances among plates /planks should be filled. Taping should be performed at ply joints for the protection of ply shuttering.
22. Before starting pouring work, consent of the architect and R.C.C Consultant should be obtained.
23. Prior to start concreting work, verify the accessibility of necessary labour strength, mixer, lift, vibrators, masons, weigh batcher, diesel/petrol and plastic sheets etc before start of concreting.
24. Hidden beams /inverted beams/cantilever beams should be examined properly.
25. Based on the approved drawings, verify the sunk.
26. Packing underneath support props should not be provided. As an alternative, single wooden plank should be inserted as packing.
27. For large slabs, exact location of concrete joints should be determined beforehand as per approval of RCC consultant.
28. Accessibility of raw material for concrete /RMC per grade of concrete, water , electricity should be examined beforehand prior to start concreting work.

29. Initially, concreting should be performed for the beams & then slabs.
30. Compaction of concrete should be accomplished with vibrators & tamping rods.
31. The top level of the slab should be completed with mason & there should be restrictions to walk on the fresh finished concrete.
32. Carpenter should be provided under the slab shuttering throughout concreting to keep the form work tight.
33. For protection against rains, large plastic sheets should be used to wrap finished concrete.
34. Cast 6 cube moulds for testing.
35. Curing of slab should be accomplished with ponding method by making ponds in cement & sand mortar (1:10) of size around 5′ X 5′. Curing of beams and slabs should be performed for 7 to 10 days or as suggested by the consultant.
36. Deshuttering of the exterior sides of the beam should be accomplished after 24 hours . Deshuttering of the inner sides of beam should be accomplished after 48 hours . Deshuttering of the beam bottoms should be accomplished after 14 days for beam lengths up to 3 M or as per suggestions of the consultant. Deshuttering of the slab should be performed after 7 days for slabs up to 3 M span or as directed by the consultant.
37. Finishing of honeycomb should be accomplished cautiously in front of engineer the next day.
38. Hacking of the beam sides, beam bottoms, slab bottoms should be accomplished within 1 or 2 days from deshuttering.
39. Date of casting and the number of slab should be painted on the front side beam.

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Published By
Rajib Dey
www.constructioncost.co
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