CLASSROOM AT SITE

Presented By:Sunil Srivastav (Sr. Manager)Date : 05.07.2011

We use material reconciliation to analyze and verifyingredients at the end of a production process. Itallows you to compare the material quantity thatactually flowed in with the planned quantity or thequantity of the material produced.

With respect to this topic, it is the process ofensuring that the standard and actual data agree aftertaking into consideration the data relating to thevariances.

“Reconcile = Getting two things to correspond/agree“

Material Reconciliation

Why? Reconciliation

To have a account of actual consumption ofMaterials.

Control of Wastage or Excess MaterialConsumption.

To know the measures to be taken to minimizewastage as we can know area where wastage ismore than norms to the extent possible andhence we can save cost on account of wastage.

Control of Wastage

What is Waste;Waste is defined as “any material by product ofhuman and industrial activity that has noresidual value”. However this is not true for theconstruction waste, since it has a residualvalue.

Construction Waste

Construction Waste;

Construction waste is defined as “the byproducts generated and removed fromconstruction, renovation and demolition atwork places or sites of building and civilengineering structures”.

Construction Waste

• Construction uses many materials extracted from deposit inthe earth’s crust. Some of these materials are directly usedat site, few after simple processing and others are prone tocomplex manufacturing processes.

• It is found that the construction industry is a large consumerof energy intensive manufactured materials such as iron,steel, copper, glass, synthetic materials, cement etc., But theconstruction industry produces considerable amount of solidwaste which is avoidable.

• Generally, it is noted that the wastage of materials in most of the construction sites are beyond acceptable limits.

• Natural waste• Direct waste• Indirect waste

Categories of Construction Waste

Natural Waste

• Natural Waste to a certain extent is inevitableon building Sites.

• Direct Waste, can be prevented and involves theactual loss.

Categories of Direct Waste

Category Description Example

Transit waste Transit waste occurs withbrittle materials duringtransportation and placingmaterials into the initialstorage.

BricksTiles

GlazingRoofing sheets

Cutting andconventional waste

Cutting waste occurs whenmaterials cut into various sizesand uneconomical shapes.

PlywoodFormwork

Tiles

Application waste

Application waste occurs withmost wet building materials.

PlasterPaint, Glue

Residue waste Residue waste occurs withmaterials normally delivered incontainers. Waste occurs whencompletely not used and whennot properly sealed.

PaintGlue

Table continued………………

Categories of Direct Waste

Category Description Example

Stockpile waste Occurs when most loosematerials are dispersed on thesite because of poor storage.

SandCause aggregate

Criminal waste Occurs due to theft andvandalism.

Tiles, Cement bagsSundry items

Waste caused by othertrades

Occurs due to succeedingtrades such as plumbing,electrical, etc.

Damages to wallsplaster etc.

Management waste

Occurs due to lack ofsupervision or incorrectdecisions of the management.

Throwing away excessmaterials

Waste due to wrong use

Occurs due to wrong selection Rejection of inferior

…….……… Table Continued

Indirect Waste

• Indirect waste is also known as cost waste.Indirect waste is distinguished from direct wasteby the fact that, materials are not lostphysically, but indirectly.

Categories of Indirect Waste

Category Description Example

Substitutionwaste

Occurs due to the substitutionof materials. Either contractoror client will loose. Whenconsidering the cost oftransport, delays to work andinconvenience of obtainingcorrect material, it is oftenmore cost effective to use anavailable, expensive materialthan to that cheaper materialto be used as specifications.But consequential cost mayarise if the specifications arenot met.

Use of high strengthconcrete instead ofweak mix.

Use of facing bricksinstead of commonbricks.

Productionwaste

Occurs when contractor doesnot receive any payments forthe works he has carried out.

Use of extra plasteringto rectify the unevensurfaces of the brickwalls

Table continued………………

Category Description Example

Operationalwaste

Occurs due to theunavailability of properquantities in the contractdocument and when thematerials are left in thebuilding.

Left form work

Negligencewaste

Occurs when more materialsare used than specified, due tothe use of unfit machineriesetc.

Use of extra concrete when over excavate.

Categories of Indirect Waste

…….………Table Continued

How to control wastage of construction

Material at site

Rising cost of construction materials now demands “No wastage” ofconstruction materials at work site. Following are few steps, whichmay help us in reducing wastages at site.

1. Consumption of Concrete: Concrete yield at batching plant need to be checked at interval of

15 days. Theoretical Quantity & actual Quantity of concrete in each pour

needs regular monitoring. There should be no difference in thesetwo quantities. Proper monitoring and analysis shall eliminate thedifference.

Calibration of batching plant at every fortnight. When concrete pumps are used, concrete left in concrete pipeline

should also be pumped in pouring place by pushing sponge ballat the end of each concrete. The quantity of concrete inside pipeshould be taken into account while finding out the volume ofconcrete required for completing the pour.

Delay in placing concrete after arrival of transit mixer at pouringpoint should be avoided. This delay may cause loss in slump andthen rejection of entire concrete inside the transit mixer.

Improper batching, delay in transporting concrete, no insulationof transit mixers in hot climate, incompatibility of superplasticizer (of fresh lot) etc. are few reasons causing loss ofworkability and rejection of concrete.

Avoiding any wastage of concrete after pour is completed. Concrete used for overflowing above cutoff level in piles or

D/walls should be well estimated. Assessed quantity required foroverflowing should be only be allowed to overflow to ensure freshconcrete at cutoff level.

Excess consumption of concrete / wastage of concrete is wastageof cement, sand, coarse aggregates, super-plasticizer plusmixing and transportation cost of concrete. This is very costlyand needs special attention.

Minimizing wastage of construction Material at site

2. Coarse Aggregate:• Checking acceptability/quality of aggregates before unloading at

concrete mixing plant. This is to avoid rejections further wastageof aggregate.

Well prepared base for stacking aggregates to avoid loweraggregates getting mixed with soil. In rainy season this wastagemay shoot up.

Avoid using flaky aggregates. Flaky aggregate demand morecement paste for cohesive mix and higher dosage of plasticizer forworkability. Cement & plasticizer consumption is high.

As far as possible number of handlings/ shifting of aggregatesfrom one place to other should be avoided. Reduce handlingwastage.

Conversion factor from weight to volume and volume to weightshould be checked periodically by determining DLBD ( Dry LooseBulk Density).

Minimizing wastage of construction Material at site

3. Fine Aggregate ( River Sand):• Checking acceptability/quality of aggregates before unloading at

concrete mixing plant. This is to avoid rejections further wastageof aggregate.

Well prepared base for stacking aggregates to avoid loweraggregates getting mixed with soil. In rainy season this wastagemay shoot up.

If screening of sand is required then procure screened sand toavoid wastage due to screening at site.

Try to replace maximum quantity of river sand with crushed sandwhen our own crushers are in operation. Partial replacement ofcrushed sand can improve strength and density of concrete ifproper combined grading is done during designing concretemixes. Higher percentage of river sand can be replaced withcrushed sand in Plain Cement Concrete or concrete where highslump retention is not required.

Minimizing wastage of construction Material at site

4. Cement: Avoid using flaky aggregates. More cement paste is required to

achieve strength and workability of concrete when flaky aggregates are used.

Storage of cement in dry place. Use cement on First in First out basis. Try to replace cement with Fly ash as far as possible. At least in

all PCC/ non- structural concrete fly ash can be used if clients do not accept our proposal of using fly ash in RCC for any reasons. However, approval for using fly ash in PCC should be acceptable to clients.

Minimizing wastage of construction Material at site

5. Admixture:For getting desired workability (Slump) and to retain workability till

concrete is poured super-plasticizers are added in concrete. Some timesto achieve and retain workability higher dosage than dosage estimatedduring designing mixes are required for maintaining the specified slump.The reasons of this additional requirement of super-plasticizer dosageshould be analyzed and as far as possible eliminated to avoid excessconsumption. The reason of excess consumption may be some of thoselisted below; New drum of admixture is not rolled on ground before using. This

rolling of drum on ground shall mix all solids settled at bottom. Admixture lot supplied is not same as tested in mix design. New lot is not compatible with cement due to some change in

formulation by manufacturer. Aggregates are flaky, Sand contains more silt. Change in proportions of ingredients of concrete. Rise in ambient temperature. Transit mixers are not insulated and concrete placed in hot drum of

transit mixer. After mixing concrete placing time is increased.

Minimizing wastage of construction Material at site

6. Reinforcement & Str. Steel: On opening a bar bending register the engineer can plan the

reduction of the wastage of cut-pieces to the minimum quantitysince he knows the desired size of the reinforcement required for hisstructure, hence he can order for similar size and or he can know theavailable cut pieces which can be used for making rings, chairs etc.Lastly the organization gets the benefit.

Diameter wise Reconciliation of stock on monthly basis.

Minimizing wastage of construction Material at site

Firstly, aim to reduce the amountof waste you create.

If waste is created, identify ways youcan reuse the materials.

Finally, if materials cannot be reusedthen collect them to recycle.

Only dispose of waste as a lastresort.

How? Reconciliation

Records to be maintain for Reconciliation on monthly basis

Variation Register ; to note various types of variations that occur at site withrespect to the Tender document like: Extra Item, Increase and / or decrease inquantity from original scope, Change in line and length, Change in specification etc.

Material Records,

Stock Records,

Material Issue Record,

Records for Approved Mix Designs

Record of Work Done ; (i.e. Record of Quantity of work as well material consumption

Material waste quantity = Consumption Qty - Theoretical Qty

(Consumption Qty- Theoretical Qty) X 100

Theoretical Qty.Material Wastage (%) =

How? Reconciliation

Three formats Table-A, Table-B, Table-C are used forestimating wastages / material reconciliation of aboveconstruction materials and Two formats for StructuralSteel and Reinforcement.

Reconciliation Formats

Table-A

Reconciliation Format

Table-B

Reconciliation Formats

Table-C Reconciliation Format

Wastage Statement

/ Reconciliation of

Reinforcement

Reconciliation Format – Wastage of Reinforcement Steel

Wastage Statement / Reconciliation of Structural Steel