UPGRADING STANDARDS OF RIDING QUALITY IN BITUMINOUS CONCRETE A CASE STUDY

Transcription

1 International Journal of Industrial Engineering& Technology (IJIET) ISSN Vol. 3, Issue 3, Aug 2013, TJPRC Pvt. Ltd. UPGRADING STANDARDS OF RIDING QUALITY IN BITUMINOUS CONCRETE A CASE STUDY BANT SINGH 1 & SRIJIT BISWAS FIE 2 1 Research Scholar, Manav Rachna International University, Chief Engineer, Haryana PWD (B&R), Presently Chief General Manager (Tech), National Highways Authority of India, Dwarka, New Delhi, India 2 Professor & Head, Department of Civil Engineering, Manav Rachna International University, Faridabad, India ABSTRACT The highways play a major role in the development of a country which is going at a very fast speed. The roads carry 85% passenger traffic and 70% of the freight traffic. With the availability of modern plants and equipment, the speed of construction of highways has further increased. Moreover, with the use of e-quality control system, the quality and quantity of the construction of a highway is assured. The present standards of riding quality have been fixed keeping in view the use of normal equipment and old system of construction. In this age of e-technology, the standards of riding quality needs to be relooked and upgraded so as to have a better riding quality of the road. This paper involves a case study which has been carried out to find out the solution of a real life problem faced by an engineer during the construction of a highway. In this paper, we present a methodology to upgrade the standards of riding quality of flexible pavements using e- quality control system. To understand the methodology, a field case study is also presented here. KEYWORDS: E-Control, GPS, Riding, Roughness, Tolerances INTRODUCTION General The economic development of the country largely depends on the road network and the quality of the roads. In India, there are 4.1 million km of roads out of which National Highways are 71,772 km, Expressways are 200 km, State Highways are 1,66,130 km, Major District Roads are 2,66,058 km and Rural Roads are 36,05,633 km. At present, out of 71,772 km of National Highways, only 23% of the road length is 4-lane or more than 4-lane, 54% of the road length is only 2-lane whereas the balance 23% are only single lane or intermediate lane. The present traffic growth in the country is about 7.5% whereas in the National Capital Region (NCR) of Delhi, it is about 11%. The fast traffic growth and Indian economy has increased the demand of road infrastructure. Historically, the budgetary resources from the Government have been the major source of financing for infrastructure projects such as road projects in India. But the development of the road network has failed to keep pace with the growth in the traffic. The reduction of the budgetary allocation towards road construction/upgradation on account of budgeting demands from other sources such as social and economical infrastructure etc. have resulted in deficiencies in the road network leading to capacity constraints, delay, congestion, fuel wastage and high vehicle operating cost. In view of these facts, as it was not possible to meet the road network requirement of upgradation of National Highways from public funds alone, the Govt. of India has taken a policy decision to develop the National Highways on Built, Operate and Transfer (BOT) basis with Public Private Partnership which aims at financing, designing, implementing and operating public sector facilities and services through partnerships between public agencies and private sector entities. Due to the active participation of the private entities in the upgradation of the highways, the quality of roads is improving

2 22 Bant Singh & Srijit Biswas Fie day by day. Due to availability and use of modern sophisticated instruments in the road construction, the quality of roads has improved a lot. Further, with the use of e-quality control system [1], the quality and quantity of the product is assured. The existing acceptance criteria of sample testing which is not matching with the speed of the construction also needs to be modified [2]. The use of electronic sensor paver gives the perfectness of the road surface as per desired levels. So, a better riding quality can be achieved with the use of these electronically controlled equipment. In the present age, everyone wants to travel on a safe road having excellent riding quality and hindrance free flow of traffic. The present standards of riding quality have been fixed keeping in view the normal use of machinery and old system of construction of highways. In case of highways where e-quality control system is used in which each and every activity of construction is electronically controlled, the old standards of riding quality and tolerance limits in Bituminous Concrete (BC) layer needs to be relooked and new better standards should be fixed so as to provide a better comfort to the road users. Tolerance Limits in Aggregates and Bitumen Content Road construction can be labour-intensive, mechanized or a combination of both depending on the importance of road and the availability of funds. With rapid industrialization and huge investment in road sector, the road building is becoming equipment oriented day by day. Computer, in-built in the plant, automatically controls the quality of the product. In BC, the contractor sets up the plant to get the percentages of the various ingredients in the actual mix as per job mix formula within the permissible limits of tolerance and the material is accepted within these limits. In the codal provisions/specifications, the tolerance limits have been given, so that the work can be accepted within those tolerance limits. The existing tolerance limits have been kept keeping in view the normal equipment and system of quality control which permits higher range of tolerance for acceptance. In this electronic age, the modern equipments are used which automatically control the various ingredients of product and check the quality of product. Now, with the use of e-quality control system where all the activities of a highway construction are electronically controlled and which assures the quality and quantity of the work, the tolerance limits prescribed in the codes needs to be re-looked and revised. The case study for the revised tolerance limits for Wet Mix Macadam (WMM) & Dense Bituminous Macadam (DBM) has been carried out by the author [3] whereas for BC is being presented here. Pavement Riding Quality The pavement riding quality not only determines the riding comfort but also has significant influence on the cost of vehicles operation, requirement of road maintenance and on the safety of movement with consequent effect on the road transport as a whole. Automatic Road Unevenness Recorder comprises of a Trailer of single wheel with a pneumatic tyre mounted on chassis over which are installed profile recording and integrating devices. The machine has panel board fitted with two electronic counters for counting the unevenness index value in cm and length in meter. The digital meter for unevenness index value is also fitted on the panel board with an arrangement for setting distance value from 50 mtr to 1000 mtrs. The operating speed of the machine is 30 to 40 km per hour and is towed by a vehicle. The vertical reciprocating motion of the axle is converted into unidirectional rotatory motion by the integrator unit; the accumulation of this unidirectional motion is recorded by operating sensor inserted in the circuit of electronic counter of accumulated unevenness. The average of the cumulative unevenness values of each wheel paths of each km was converted from the processor into unevenness index in mm per km.

3 Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study 23 The average Unevenness Index value of both the directions was represented as the unevenness of a particular kilometer. The bump integrator was calibrated before use. Requirements of Existing Specifications As per Ministry of Road Transport & Highways specifications [4], the Unevenness Index of the pavement shall not be more than 2000 mm per km when measured with Bump Integrator fitted in a vehicle or an equivalent device approved by the Engineer. As per IRC:SP [5] the road stretches with bituminous concrete surfacing has been categorized as- Good : Roughness < 2000 mm/km. Average : Roughness between 2000 mm/km and 3000 mm/km. Poor : Roughness > 3000 mm/km. METHODOLOGY Firstly, we selected a project to carry out the work in field. The modern equipment such as batch mix type hot mix plant with electronic sensor which automatically controls proportion of different fractions and bitumen, cone crusher (integrated stone crushing & screening plant), automatic wet mix plant with moisture content controller, paver finisher with electronic sensor, vibratory road roller, nuclear density meter automatic road unevenness recorder, total station & GPS etc. are used at site. All the relevant data collected at site at various stages is placed on web site.various physical tests are conducted to know the variations in different ingredients. Before going to our next session of case study, let us introduce briefly the e- quality control system.e-quality control is a system in which all the major activities at construction stage are electronically controlled through the modern equipment having computerized control [6] and the live data along with live photofigure s in real time is placed on the website in respect of the followings: E-Control on Receipt of Bitumen Generally the bitumen is received from the oil refineries. To control the pilferage of bitumen, the live photofigure s of the bitumen tankers taken during its weighing on automatic computerized weighing machine are placed in live time on the website with project ID indicating tanker & indent number, weight of loaded & empty tanker etc. E-Control on Mixing of Material at Plant Site The batch mix type hot mix plant with electronic sensor (which automatically controls the proportion of different fractions of aggregates and bitumen) is used. The proportions of various ingredients required for BC are set upon the computer of batch type hot mix plant. The live data with project ID indicating tipper no., type of material, temperature (of aggregates, bitumen & mixed material) and percentage of bitumen etc. is placed on the website. E-Control on Weighing Machine Site As soon as the tipper is filled with the mixed bituminous material, it is brought to the automatic weighing machine to carry out the weight. A camera & GPS instruments are also installed at the weighting machine site and the live data along with photofigure is placed on the website indicating tipper number, type of material, weight of loaded & empty tipper etc.

4 24 Bant Singh & Srijit Biswas Fie E-Control on Vehicles A Vehicle Tracking System along with various devices such as vehicle diagnostic sensors, fuel sensor & Global Positional System (GPS) etc. is attached with each tipper carrying out the material to check the route of the vehicle at all times, fuel consumption per km., kms traveled by the vehicle in a day, working hours of vehicles/day, halt hours of vehicles/day, idle hours of vehicles/day & speed of vehicles etc. [7] E-Control on Work Site On the start of the work with a particular tipper on the site, its photofigure during unloading in the hopper of the paver is taken and the live data along with location (RD) is placed on website indicating tipper number, weight of material, temperature of material, etc. The same exercise is repeated at the end point where material of this particular tipper finishes. Thus it controls the material used in a particular reach. E-Control on Testing of Samples Every Engineer is given a laptop enabled with GPS and Camera. While conducting the test, the live data is placed on website which includes the location where test is being conducted along with the photofigure of the person conducting the test. Thus, the system checks bogus entries of tests. A CASE STUDY To go ahead with the case study, a section of sanctioned project Construction of NH-4 (Belgaum-Dharwad from km.433 to km.515) is selected which is being executed in the State of Karnataka, India at an estimated cost of Rs crores on DBFO (Design, Built, Finance & Operation) pattern. The execution of work is being carried out by National Highways Authority of India according to technical specifications laid down by Ministry of Road Transport and Highways (MoRT&H), and IRC:SP-2000 [8]. During the case study, in first phase we carried out the study of tolerance limits of aggregates and in second phase on bitumen content in BC. Finally, the riding quality parameters were studied. Tolerance limits in Bituminous Concrete (BC) To study the variations at various stages of construction of bituminous concrete, the material of the same truck/tipper was tested at different stages of construction as under: Just after loading in the tipper. At the time when tipper reaches at work site. at site. AGGREGATES of construction: The data of 10 such tippers is placed below in Table-1 giving the gradation of various ingredients at various stages

5 %age passing through 13.2mm sieve Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study 25 Table 1: Gradation Data of BC at various Stages Sr. No Tipper No. RJ 06 G 3762 A 6610 RJ 06 G 4128 L 0913 L 0913 L 0913 L 0913 L 0913 L 0913 L 0913 Location Sieve Size in mm On loading On loading On loading On loading On loading On loading On loading On loading On loading On loading The above data is further presented in Figur 1 to 10 for %age passing through sieves 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm and 0.075mm (the Figure of 19mm is not shown as there is no variation) to check the variation of aggregates Figure 1: For 13.2mm Sieve Size (BC)

6 %age passing through 0.075mm sieve %age passing through 0.015mm sieve %age passing through 0.3mm sieve %age passing through 2.36mm sieve %age passing through 4.75mm sieve %age passing through 9.5mm sieve 26 Bant Singh & Srijit Biswas Fie Figure 2: For 9.5mm Sieve Size (BC) Figure 3: For 4.75 mm Sieve Size (BC) Figure 4: For 2.36 mm Sieve Size (BC) Figure 5: For 1.18 mm Sieve Size (BC) Figure 6: For mm Sieve Size (BC) Figure 7: For mm Sieve Size (BC)

7 %age passing through 0.075mm sieve %age passing through 0.075mm sieve Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study Figure 8: For mm Sieve Size (BC) Figure 9: For mm Sieve Size (BC) From the data presented in Figure 1 to 10, the variations in %ages of aggregates passing through various sieves during various stages of construction are presented below in Table No.2 along with the codal provisions and recommended tolerance limits: Table 2: Variations for Various Sizes of Aggregates in BC %Age Passing through Sieve S.NO Description As per tests Recommended As Per Code Conducted Tolerance Limits 1 Aggregate passing 19mm sieve 100% 100% 100% 2 Aggregate passing 13.2mm sieve % 87-93% 85-95% 3 Aggregate passing 9.5mm sieve 70-88% 74-83% 72-85% 4 Aggregate passing 4.75mm sieve 53-71% 54-60% 53-63% 5 Aggregate passing 2.36mm sieve 42-58% 43-48% 42-52% 6 Aggregate passing 1.18mm sieve 34-48% 35-40% 34-44% 7 Aggregate passing 0.6mm sieve 26-38% 27-31% 26-35% 8 Aggregate passing 0.3mm sieve 18-28% 19-23% 18-25% 9 Aggregate passing 0.15mm sieve 12-20% 13-16% 12-18% 10 Aggregate passing 0.075mm sieve 4-10% 5-8% 4-9% Bitumen Content The data collected in respect of bitumen content in BC for 10 tippers during various stages of construction is presented below in Table 3 Table 3: Comparison of Bitumen as per Data Set on System, Actual Tests at Plant Site & after Laying S. N. Description RJ06G3762 TN30A6 610 RJ06G 4128 TN30 L0913 TN30 L0913 TN30 L0913 TN30 L0913 TN30 L0913 TN30 L0913 TN30 L % of Bitumen set on system 5.40% 5.40% 5.40% 5.40% 5.40% 5.40% 5.40% 5.40% 5.40% 5.40% 2. % of Bitumen as per test at % of Bitumen plant site as per test 3 after laying (core extraction) 4 Difference of Sl. No.1 & 2 5 Difference of Sl. No.1 & % 5.38% 5.41% 5.43% 5.38% 5.42% 5.41% 5.40% 5.39% 5.37% 5.41% 5.39% 5.40% 5.41% 5.40% 5.41% 5.43% 5.42% 5.41% 5.39% (-) 0.01% (-) 0.02% (+) 0.01% (+) 0.02% (-) 0.02% (+) 0.02% (+) 0.01% (+) (-) (+) (+) (+) 0% 0% 0.01% 0.01% 0.01% 0.01% 0.03% 0% (-) 0.01% (-) 0.03% (+) (+) (-) 0.02% 0.01% 0.01%

8 % of Bitumen 28 Bant Singh & Srijit Biswas Fie The % age of bitumen set on system at plant site & bitumen found in BC material during actual testing at plant site & after laying has been shown in a Figure presentation Figure No.10 tipper-wise Tipper No. % of Bitumen set on system % of Bitumen as per test at plant site % of Bitumen as per test after laying (core extraction) Figure 10 From the above Figure No.10, it is clear that there is a variation in the bitumen contents in the samples in the range from (-) 0.03% to (+) 0.03%. Thus, the codal provisions for permissible tolerances of (+) 0.3% in bitumen contentseems to be on very much higher side and are recommended for revision as given in Table 4 S.No. Table 4: Tolerances for Bitumen Content in BC from Job Mix Formula Description Tolerances Permissible as Per Code Recommended 1. Binder content + 0.3% % Assessment of Riding Quality discussed below: Let us discuss the concept of assessment of riding quality. Before carrying out the test, some preliminaries are The installation and operation of the equipment has been checked which is in order and meets the requirements prescribed in its operational manual. The tyre pressure of wheel is maintained at 2.1 kg/cm 2 as per requirements. The instrument has been calibrated prior to its use for measurement as prescribed in its operational manual. The operators are familiar with the Bump Integrator & other equipment associated with its operation using its Test Model before commencing a Riding Quality Test. A speed of 31 to 33 km per hour has been maintained during the Test. The readings are taken for each carriageway independently. The equipment has run on two lanes in both the directions once and the average of two values taken as roughness index. Pavement unevenness/roughness of two lane carriageway has obtained from the average of the values of the two lane recorded. Now, we will carry out the riding quality test in two phases one for Left Carriage Way from km to and second Right Carriage Way from km to

9 Pavement roughness Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study 29 Study of Left Carriage Way (LCW) (from km to ) Equipment Used Vehicle Speed Vehicle Speed during Test : Bump Integrator (Automatic Road Unevenness Recorder), ARUR (STECO- 120) : 30 To 40 kmh (As per IRC:SP: ) : 31 to 33 KMPH Date of Testing : LCW of 6-Lane Highway : Lane-1 - Median side; Lane-2 - Central lane; Lane-3 - Shoulder side Sl. No. (km.) Carriage way Table 5: Uneven Index of Lane 1 LCW Length Observed in ARUR STECO-120 Bumps (in cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor From To (in m) (in km)trial-1 Trial-2 Avg. Lane LCW LCW LCW LCW LCW LCW LCW LCW LCW LCW (-wise unevenness index) Pavement Roughness Sl. No. (km.) Carriage way Figure 11: Lane 1-LCW Table 6: Uneven Index of Lane 2 LCW Length Observed in ARUR STECO- 120 Bumps (in Cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor From To (in m) (in km) Trial-1 Trial-2 Avg. Lane LCW LCW LCW LCW LCW LCW LCW LCW LCW LCW

10 Pavement roughness 30 Bant Singh & Srijit Biswas Fie Sl. No. (km.) Carriage Way Table 7: (Uneven Index of Lane 3 - LCW) Length Observed in ARUR STECO-120 Bumps (in Cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor From To (in m) (in km) Trial-1 Trial-2 Avg. Lane LCW LCW LCW LCW LCW LCW LCW LCW LCW LCW (-wise unevenness index) Pavement Roughness S. No. (km.) Figure 12: (Lane 3 - LCW) Table 8: Uneven Index of Lane 3 LCW Unevenness Index (mm/km) Permissible Limit 2000 (mm/km) Recommended Roughness Index (mm/km) Lane- Lane- Average Lane LCW RCW RP RP RP RP RP RP RP RP RP RP RP: Rigid Pavement Study of Right Carriage Way (RCW) (from km to ) Sl. No. (km.) Table 9: (Uneven Index of Lane 1 RCW) Carriag e Way Length Observed in ARUR STECO-120 Bumps (in cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor From To (in m) (in km) Trial-1 Trial-2 Avg. Lane RCW

11 Pavement roughness Pavement roughness Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study 31 Table 9: Contd., RCW RCW RCW RCW RCW RCW RCW RCW RCW (-wise unevenness index) Pavement Roughness Figure 13: Lane 1 RCW The test in km.440 has been carried out in the reach from km to and in km.441 from km to km only. Sl. No. (km.) Carriage Way Table 10: Uneven Index of Lane 2 RCW Length Observed in ARUR STECO-120 Bumps (in cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor From To (in m) (in km) Trial-1 Trial-2 Avg. Lane RCW RCW RCW RCW RCW RCW RCW RCW RCW RCW (-wise unevenness index) Pavement Roughness Figure 14: Lane 2 RCW

12 Pavement roughness 32 Bant Singh & Srijit Biswas Fie The test in km.440 has been carried out in the reach from km to and in km.441 from km to km only. Sl. No. Table 11: Uneven Index of Lane 3 RCW Length Observed in ARUR (km.) Carriag STECO-120 e way (in From To (in m) km) Bumps (in cm) Observed in ARUR STECO-120 Unevenness Index (mm/km) after Applying Calibration Factor (-wise unevenness index) Pavement Roughness Figure 15: Lane 3 RCW The test in km.440 has been carried out in the reach from km to and in km.441 from km to km only. S. No. (km.) Trial- Trial- Avg. Lane RCW RCW RCW RCW RCW RCW RCW RCW RCW RCW Lane- 1 Table 12: Test Reports Unevenness Index (mm/km) Lane- 2 Lane- 3 LCW Average RCW Permissible Limit 2000 (mm/km) Recommended Roughness Index (mm/km) RP RP RP RP RP RP RP RP RP RP RP: Rigid Pavement RESULTS & DISCUSSIONS The result of the case study shows that the variation in the aggregates passing through 13.2mm sieve is 87-93% only against the permissible limit of % as per codal provisions. Similar is the position of the percentage of aggregates passing through various other sieves as shown in Table No.2. It shows that with the use of e-quality control system in bituminous concrete layer, there is less variation in the %age of aggregates passing through the sieves during

13 Upgrading Standards of Riding Quality in Bituminous Concrete A Case Study 33 various stages of construction as compare to the permitted tolerance limits in the specifications. Thus, the lower tolerance limits are required than prescribed limits in the codes. Accordingly, the lower values of tolerance limits are recommended as given in Table No.2. The reduction in these tolerance limits will not only give a better quality of the product but also a longer life of the road. In case of permissible variation in the bitumen contents, the case study shows that the variation in the bitumen content in most of the cases is from (+) 0.01% to (-) 0.01%. However, considering all the cases taken during the case study as given in Table No.3, the variation is from (+) 0.03% to (-) 0.03% whereas the allowable variation as per codal provisions in bitumen content in case of bituminous concrete is (±) 0.3%. This permissible limit in the specifications seems to be on higher side and needs to be revised. Of course, in the case study the variation of bitumen content in BC comes only from (+) 0.03% to (-) 0.03%, yet the tolerance limit in case is recommended as (±) 0.05% as given in Table No.4. The results of the case study for unevenness index, as given in Table No.9 for Left Carriageway from km to km , shows the variation in unevenness index from 1145 to 1315 against the permissible requirement of 2000 mm/km. Similarly, the variation on Right Carriageway from km to km is from 1237 to 1328 mm/km as given in Table No.13. From these results of case study, it is clear that the use of e-quality control system has further resulted in improving the riding quality of the road. Thus, the permissible limit of unevenness index for riding quality of 2000 mm/km needs to be further reduced for a better riding quality. It is, therefore, recommended to introduce a new limit of unevenness index of less than 1500 mm/km in the specifications as given in para-1.4 for excellent riding quality. However, it is further recommended that wherever the unevenness index value is falling below 2000 mm/km, the frictional resistance needs to be restored due to safety reasons. CONCLUSIONS With the use of e-quality control system, the riding quality of the highways improves which gives a better comfort to the road users. The existing tolerance limits of aggregates and bitumen content in BC have been kept keeping in view the use of normal machinery in the construction of highways and seem to be on higher side. With the use of bay batch type hot mix plant, the various ingredients of the materials used in the bituminous concrete are totally controlled. So, in a system where all the activities are electronically controlled, lower tolerance limits then prescribed in the codal provisions are required for sizes of aggregates and bitumen content. The electronic censored paver controls the thicknesses of layers and maintains the perfect surface as per requirements which further improve the riding quality of the road. Thus, a new limit of unevenness index of 1500 mm/km is recommended for achieving an excellent riding quality on the highway subject to the condition that the frictional resistance on the highway is restored from safety point of view. REFERENCES 1. Bant Singh and Dr. Srijit Biswas; Modeling for Assured Quality Control in Flexible Pavements through e-control A Case Study; IJSER, ISSN , Volume 4, Issue 4, April (2013) 2. Bant Singh and Dr. Srijit Biswas; Modification of Acceptance Criteria of Sample Testing in Flexible Pavements; IJSER, ISSN , Volume 4, Issue 6, June (2013) 3. Bant Singh and Dr. Srijit Biswas; Effect of e-quality Control on Tolerance Limits in WMM & DBM in highway construction A Case Study; IJARET, ISSN , Volume 4, Issue 2, March-April (2013) 4. Ministry of Road Transport & Highways (Fourth Revision) 2001; Specifications for Roads & Bridge Works. 5. IRC:SP: ; Guidelines for Surface Evenness of Highway Pavements (First Revision). 6. Bant Singh, Dr. Srijit Biswas and Dr. Parveen Aggarwal; 2012, Use of updated machinery for Monitoring of

14 34 Bant Singh & Srijit Biswas Fie Quality & Quantity of a Pavement A case study on e-quality control ; IJIET, ISSN , Volume-4, Number-3 (2012), pp Bant Singh, Dr. Srijit Biswas and Dr. Parveen Aggarwal; Modeling of Economical & Efficient Use of Vehicles through e-control for Construction of a Highway; IJERT, ISSN , Volume 5, Number 3 (2012) 8. IRC:SP: ; Guidelines for Quality Systems for Road Construction.