Introduction of Quality Control & Quality Assurance in Highway project(Sampling of Materials for Lab testing)

R.A. Singh,B. Tech (Hons), Seuj Ban Path, Fatasil Ambari, Ghy-25Former Chief Engineer P.W.D. (Roads), AssamChartered Engineer & Consultant, Ph. 94355-52579

Quality assurance is basically defined as those planned and systematic exercises executed to ensure that the product meets the specification. The quality assurances cover up all the aspects of road development, design, construction, maintenance and Rehabilitation. It forms the crux of the whole process of a successful road development system. In a broader sense quality assurance is an organised action which objective with respect to highway engineering, is to ensure that the product, the pavement, is of envisaged level of serviceability and it would fulfill the expectation of road user for the entire period, it is designed for. In other words the quality assurance is a form of quality inspection or quality audit whereas in quality control, the quality of future product is regulated and it involves a number of activities in order to build up and regulate the product and performed by executing agencies at execution stage. [It may be further stated that ascertaining of quality of materials and carrying out exercise to obtain the quality product while laying is a quality control and whether test conducted while executing the work, is verifying, correct or not, is quality assurance].1) Elements of Quality Assurances System The need for the quality assurance system is the desire to have appropriate returns to the investment made in the term of appropriate design, specification construction practices and quality control during construction. In case of road pavement quality assurance system may be said to have the following. a) Proper assessment of requirement of the road pavement.b) Choice of quality material and design.c) Development of appropriate Technical Specification and acceptance criteria.d) Choice of construction method / equipment plant.

e) Field supervision and quality control.f) Assessment of quality of finish pavement.g) Periodic inspection and maintenance measures.2) Assessing Requirement of a Road project.Proper assessment of road project within the frame works of fund available is to be made which would include, design criteria, design life, minimum acceptable service life & riding for the service period.3) Choice of Quality Material & Design.The selection of material to be incorporated in the pavement is based on its cost, and its suitability to meet the design parameters. Development of Specification and acceptance criteria.The different category of roads, have its own specification and standard, Even then quality assurances group has to examine whether any addition to it is needed or not, in the condition the project is going to be executed for. Choice of construction method.The selection of right type of equipments is the key to obtaining the desired product.Inspection of Quality control.Quality control is a exercise involving inspection & testing of materials, production process, ascertaining variation from predetermined standard, acceptance or rejection of work.Assessing Quality of Finished pavement.An exercise need to be conducted to examine whether desired quality of end product has actually bee achieved.

4) Periodic inspection and maintenance measure:-Periodic inspection is to be caused on walking along the road in stretches, and not traveling in vehicle.Quality assurances commences at the very beginning of planning the project.

Preparation of DPR- Fixation of P.B.M. tied with G.T.S. and checking the design of Geometric standard. The DPR is to be checked so as to ensure that provision made in the DPR would meet up the requirement in the project, Moreover it reflects the ground realities too.

ii) Bridges:- It is to be seen whether H, DATA have been correctly collected or not, Prior to collection of DATA one permanent B.M. is to be fixed at safe location tied with G.T.S. and subsequent data should be based on this, Moreover corresponding railway bridges H. DATA need to be collected and compare with it.After finalization of span arrangement, the location of Bore holes along with R.L. of termination of Boring is to be finalized and thereof SSI work is to be awarded to.

iii) Contract:- Prior to issue of notice inviting tender, the specification being incorporated in is to be thoroughly checked in order to ensure the accomplishment of intended purpose of the project. The choice of equipment to be deployed for execution of different component is to be finalized at N.I.T. Level itself.

5) Inspection and quality control:- Checking of profile of the road to be constructed is to be done with respect to designed profile. The setting of Horizontal curves is to be checked at site along with toe line..

Materials:- Sources of different materials as mentioned in DPR are to be identified and quality of materials against each source is to be ascertained to.

Soil for building embankment:- Tests to be conducted, are sieve analysis, Atterberg limits (LL, PL) Dry density & C.B.R. and these tests are to be also conducted for G.S.B. construction.

ii) Stone Aggregate:- W.B.M:- Impact, Flakiness test, water absorption, specific gravity, Gradation & soundness test if needed.

iii) P.C. & Seal Coat:- Grading, Impact, Flakiness test, water absorption specific gravity, stripping value, Bulk Density.iv) Bituminous materials:- Straight run bitumen- penetration, softening point, ductility, specific gravity, viscosity.v) Emulsion- Emulsion test as per IS 8887-2004.Design:- Design of GSB, such as gradation and degree of compaction is to be finalized & similarly mix design of bituminous mixes is to be finalized prior to execution.6. Bridges:- The centre line X-X & Y-Y direction is to be fixed in the line of G.A.D. and B.M. is to be verified. Source of coarse as well as fine aggregate is to be located and properties of the same are to be ascertained. Thereafter mix design for control concrete is to be finalized. After that weigh batcher, slump cone, etc are to be brought to the site, If subsequent change in source of material, grade and make of cement becomes unavoidable, fresh design of mix is to be done.Quality Policy:- The overall quality intensions and direction to be issued to the organization, as would be expressed by top management.Quality Management:- The quality is the body management that determines and implements the quality policy. The basic parameters of quality management are:- i) The arrangement of desired quality, requires the commitment and participations of all members of the organization whereas the responsibility for quality managements belongs to top management.ii) Quality managements includes strategic planning, allocation of recourses, quality planning operation and evaluation of the product.7. Requirements set out in the project should reflect need of road users.i) For effectiveness, the quality assurances usually requires a continuing evaluation of factors that affect the adequacy of the design or specification as well as verification and audit of production, installation and inspection operation. One senior executive expresses thus In fact our attitude towards quality is perfunctory.

We senior are responsible for poor quality of the product. In the beginning we insist for adherence to quality but later on tell the same worker to produce the targeted out turn even ignoring the quality.ii) The Other short-coming in quality assurance is the impression crated in quality control staff is that for any lapse in quality control and subsequent processing of data to assurance quality, the staff on duty would be accountable, This factor often compels them to manufacturer the data which satisfy the norms. But it puts question mark to integrity of the data. Clear picture immerges only when certain portion fails prematurely, otherwise it speaks of bright performances. Frequency of Test and Acceptance criteria for earthwork, sub grade, granular sub-base, base course & wearing course.

TestTest MethodFrequencyAcceptance criteria1)Earthworki. Placement moisture content.ii) Degree of compaction.iii) CBR on Sub-grade on remolded sample.2)Granular sub-base/base/ wearing course.i) Sieve analysis. ii) Plasticity index.iii) Placement moisture.iv) Degree of compaction. v) CBR3)W.B.M. Coursei) Impact value.ii) Grading.iii) Flakiness.iv) PI of binding materials.v) PI of materials passing 425 mic. Sieve. 4)Wet Mix Macadam.i) Impact value.ii) Grading.iii) Flakiness index.iv) PI of materials passing 425 mic. Sieve. v) Density of compacted layer.IS-2720-Part 2IS-2720-Part 20IS-2720-Part 16

IS-2386 Part 1IS-2720 Part 5IS-2720 Part 2IS-2720 Part 28IS-2720 Part 16

IS:2386 (Part 4)IS:2386 (Part 1)IS:2386 (Part 1)IS:2720 (Part 5)IS:2270 (Part 5)

IS:2386 (Part 4)IS:2386 (Part 1)IS:2386 (Part 1)IS:2720 (Part 5)

IS:2720 (Part20)1 in 300 sqm. for each layer. 1 in 1000 sqm. for each layer.As required.

1 in 200 m3, minimum of 2 test per day1 in 200 m3, minimum of 2 test per day1 in 250 m2, minimum of 1 test per day1 in 500 m2, minimum of 1 test per day1 in 1000 m3

1 in 200 m31 in 100 m31 in 200 m31 in 25 m31 in 100 m3

1 in 200 m31 in 100 m31 in 200 m31 in 100 m31 in 500 m2For fine grain soil+2% of OMC. For course grain soil 1.5% of OMCIn lower level 95% and in top 97% of part-8.

As required.As required.+ 1.5%100% of PDAs required.

As per required.As per required.As per required.As per required.As per required.

As per required.As per required.As per required.As per required.

As per required.

Bituminous construction (Prime coat & Tack coat)Laying of test track:After ascertaining the quality & properties of building materials, spreading of one layer of different components of embankment/ pavement for stretch 30 m in length & 3.75 m in width and it should be compacted at parameter determined in the laboratory with the help of compacted equipment proposed to be utilized, In this operation, the loose thickness to be spread, nos of passes of road rollers to obtain the desired degree of compaction at O.M.C. that is achieved in the field either adding of water or drying by acriation as the case may be similarly factors for compaction of G.S.B. and base are to be determined. Table 5Frequency of Test for Bituminous Macadam

5)i) Quality of binder

ii) Temperature of binder for cut back when used.iii) Rate of spread of binder.IS:8887 viscosity, sieve test, storage stability, particle charge residue and test on it.As per design.1 test per lot

Regularly

1 test for 500 m2 not less than 2 test per day. As per required.

As per required.

As per required.

Sl NoTestTest MethodFrequency 1

2345

6

789Quality of binder

Temperature of binderAggregate impact valueFlakiness indexStripping of aggregate

Water absorption

Grading of aggregateBinder contentThicknessPenetration, Softening Point & Ductility Tests for Paving Bituminous (IS:73)Penetration, Softening Point and Elastic Recovery Tests for Modified Bitumen (IRC : SP 53) Appendix 10.6 of RRM IS: 2386 (Part 4)IS: 2386 (Part 1)IS: 6241 - 1971

IS: 2386 (Part 3)

IS: 2386 (Part 1)Appendix 10.8 of RRM-One test per lot

Regularly 1 test per 250 cum/source 1 test per 250 cum/source1 set per 3 representative specimens per source1 set of 3 representative specimens per source 1 test per 100 cum per day 2 tests per day per plant Regularly

Table 6Frequency of Test for Built- up Spray Grout/Modified Penetration Macadam Frequency of test for DBM, S.D.B.C. & B.C. refer Table 900-4 item 6, mastic asphalt item No. 7

Sl No.TestTest MethodFrequency 1

2345

67

8910Quality of binder

Temperature of binderAggregate impact valueFlakiness indexStripping of aggregate

Aggregate gradingWater absorption

Soundness of aggregate Rate of spread of binder.Rate of spread of aggregates Penetration, Softening Point & Ductility Tests for Paving Bituminous (IS:73)Penetration, Softening Point and Elastic Recovery Tests for Modified Bitumen (IRC : SP 53) Appendix 10.6 of RRM IS: 2386 (Part 4)IS: 2386 (Part 1)IS: 6241 - 1971 IS: 2386 (Part 1)IS: 2386 (Part 3)

IS:2386 (Part 5)Appendix 10.7 of RRM Appendix 10.10 of RRM One test per lot

Regularly 1 test per 250 cum/source 1 test per 250 cum/source1 set per 3 representative specimens per source1 test per 100 cum of aggregate 1 set per 3 representative specimens per source1 test per source 1 test per 1000 sqm or per day1 test per 1000 sqm or per day

Quantity of Sample Soil

Minimum weights for sampling for Aggregate

Quantity of sample required for Determination of water content Quantity of soil required for grain size analysis Size of particle more than 90 P.C. passing

425 I.S. Sieve 2 mm I.S. Sieve4.75 mm I.S. Sieve 9.50 mm I.S. Sieve 19 mm I.S. Sieve 37.5 mm I.S. SieveMinimum Quantity of soil specimen to be taken for test massing (gm)

25502003005001000Maximum size of material present in substantial Quantitymm7537.51913.29.56.74.75Mass to be taken for testKg

60256.53.51.50.750.40

Max size present in substantial proportionsmm

63504025201612.510.06.3Minimum weight of sample dispatched for testingKg100100505025251263

Sample to be sent to lab, asphalt 5 kgCoarse aggregate 20 kg each Fine aggregate 20 kgFiller 8 kg Nominal maximum size of particles passing Sieve minimum wt of field sampleKg2.36 mm54.75 mm59.5 mm512.5 mm1019 mm1525 mm2537.5 mm3050.0 mm4063 mm4575 mm6090 mm 65

Collection of samples for Bituminous work.Collection by consultant or Depth for preparation of D.P.R.i) Selection of quarries based on its qualitative and quantitive aspect and a few testing of sample will serve the purpose, the test to be corrected are impact & water absorption etc. ii) Collection by contractors for installation of crushing plants and evaluation of its quality. Contractors should select the quarries that produces relatively higher strength, less water absorption and less stripping values, as impact values of material manufactured by crushing plants are generally less than sample manually prepared- After selection of the quarry crusher plant is installed suitably. The contractor has to adjust crushing after conducting F.I. test so that produce is not Flaky one.iii) Prior to crushing it is better to determine the sizes of different components and start manufacturing the same. It is done as preliminary design testing. iv) Collection for design of mixes:- Material has to be stacked size wise at mixing plant site, representative sample is to be taken from different stacks of respective size. Mix up and take required quantity as per size after quartering the collected sample.b) Source Acceptance testing:- Source acceptance testing is often performed after the award of the contract and has indicated the proposed source of all material and asphalt. The main objective is to determine the most economical blend of materials that will satisfy both gradation and mix design requirement of the specification. Source acceptance test serve to assure the owner and contractor that the proposed source of material will yield the paving mixture that meets specification and further will permit the contractor to proceed with stock piling of the required material at Job sites.c) Job mix control testing:- Job mix control testing is executed at the start of plant production and in conjunction with the calibration of mixing plant for J.M.F. This is one of the key points of design control for the paving construction since the Job mix formula establish the actual gradation and asphalt content to be obtained in the mixing plant.