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Guidelines on Wet Mix Plant Published by: indian Roads ConGRess Kama Koti Marg, Sector-6, R.K. Puram, New Delhi-110 022 noveMbeR, 2017 Price : ` 400/- (Plus Packing & Postage) IRC:126-2017 First Published : November, 2017 Reprinted : September, 2019 (All Rights Reserved. No part of this publication shall be reproduced, translated or transmitted in any form or by any means without the permission of the Indian Roads Congress) Printed by I G Printers Pvt Ltd, New Delhi-110020 600 Copies IRC:126-2017 Contents s. no. description Page no. Personnel of the General Specifications and Standards Committee (i) 1. Introduction 1 2. Scope 2 3. Purpose 2 4. Advantages of Wet Mix Plant 2 5. Major Assemblies of Wet Mix Plant 3 6. Power Requirement 10 7. Pug Mill Performance 10 8. Plant Maintenance 11 9. Plant Safety 14 Appendix-I: Emission and Noise Limits for a Diesel Genset used in Wet Mix Plant 17 Appendix-II: Recommended Frequency of Calibration and Permissible Tolerance 18 in Accuracy for a Wet Mix Plant Appendix-III: Air Pollution Control Measures in a Wet Mix Plant 19 Appendix-IV: List of Do’s and Dont’s for a Wet Mix Plant 20 Appendix-V: Sample Calculation for Output Analysis of a Wet Mix Plant 21 Appendix-VI: Plant Calibration 22 Appendix-VII: Typical Layout of a Wet Mix Plant 26 References 26 list of Figures s. no. description Page no. Fig. 1 Gathering Conveyor 4 Fig. 2 oversize Removal screen 4 Fig. 3 Charging Conveyor 5 Fig. 4 Pug Mill 6 Fig. 5 typical Paddle arms in a Pug Mill 6 Fig. 6 Filler Fines Feeding system 7 Fig. 7 Gob Hopper 7 Fig. 8 storage silo 8 Fig. 9 Control Panel 9 Fig. 10 typical Calibration Chart for a 4-bin Fixed drive WMM Plant 23 Fig. 11 typical Calibration Chart for a 4-bin variable drive WMM Plant 24 Fig. 12 typical layout of a 200 tPH Wet Mix Plant with Filler silo 26 Fig. 13 typical layout of a Wet Mix Plant with integrated Gob Hopper 26 arrangement list of tables s. no. description Page no. table 1 average Power Requirement for a Wet Mix Plant 10 table 2 Requirement of Paddle tips for various Plant output Capacities 11 table 3 emission limits for diesel Gensets up to 800KW 17 table 4 Recommended Frequency of Calibration and Permissible tolerance 18 for a Wet Mix Plant IRC:126-2017 PERSONNEL OF THE GENERAL SPECIFICATIONS AND STANDARDS COMMITTEE (GSS) (As on 24th June, 2017) 1 Kumar, Manoj Director General (RD) & Special Secretary to the Govt of India, Ministry (Convenor) of Road Transport & Highways, New Delhi 2 Singh, B.N. Additional Director General, Ministry of Road Transport & Highways, (Co-Convenor) New Delhi 3 Verma, Dr. S.K. Chief Engineer SR&T(R), Ministry of Road Transport & Highways, (Member Secretary) New Delhi Members 4 Basu, Kaushik Chief Engineer, Ministry of Road Transport & Highways 5 Bhardwaj, R.S. Senior Principal Scientist, Central Road Research Institute, New Delhi 6 Chacko, Dr. K.M. Director, Shriram Institute of Industral Research, Delhi 7 Eligar, J.H. Superintending Engineer, Ministry of Road Transport & Highways 8 Gupta, D.P. DG(RD) & AS (Retd), Ministry of Road Transport & Highways, New Delhi 9 Jain, Prof (Dr) S.S. Professor, IIT Roorkee 10 Jhamb, S.B. Addl. Director General(Retd.), Central Public Works Department, New Delhi 11 Joshi, L.K. Secretary(Retd.), Ministry of Road Transport & Highways, New Delhi 12 Lal, Bhure Chairman, Environment Pollution (Prevention & Control) Authority, Delhi 13 Mathur, Dr. Ajay Director General, The Energy & Resource Institute, New Delhi 14 Narain, Sunita Director General, Centre for Science & Environment, New Delhi 15 Goel, O.P. Director General(Retd), Central Public Works Department, New Delhi 16 Pandey, I.K. Chief Engineer, Ministry of Road Transport & Highways, New Delhi 17 Parrikar,G.M. Naik Superintending Engineer, PWD Goa 18 Pateriya, Dr. I.K. Director (Technical), National Rural Road Development Agency, New Delhi 19 Puri, S.K. DG(RD) & SS (Retd), Ministry of Road Transport & Highways, New Delhi 20 Rajoria, K.B. Engineer-in-Chief(Retd.), Delhi PWD, New Delhi 21 Raju, Dr.G.V.S. Engineer-in-Chief(Retd.), R& B Deptt., Hyderabad 22 Rajvanshi, Ms. Asha Head, EIA Wild Life Institute, Dehradun 23 The Director Engineering Staff College of Engineering, Hyderabad (Reddy, D.N.) 24 The CEO & PD National Automotive Testing and R&D Infrastructure Project, New Delhi (Sahay,Vishvajit) i IRC:126-2017 25 Sarangi, D Chief General Manager, National Highways Authority of India 26 Sharma, D. C. Principal Scientist, Central Road Research Institute, New Delhi 27 Sharma, M. P. Chief Engineer, Ministry of Road Transport & Highways, New Delhi 28 Sharma, R. S. Managing Director, M/s STP Ltd New Delhi 29 Sharma, V. K. Chief General Manager (LA), National Highways Authority of India, New Delhi 30 Sinha, A.V. DG (RD) & SS (Retd.), Ministry of Road Transport & Highways, New Delhi 31 Sinha, B.N. Chief Engineer (Retd.), Central Public Works Department, New Delhi 32 Tawade, D.O. Member(Technical), National Highways Authority of India, New Delhi 33 The Director Society of Indian Automobile Manufacturers, New Delhi General, (Mathur, Vishnu) 34 The Director Automotive Research Association of India, Pune (Urdhwareshe, Mrs. Rashmi) 35 Vasantha, Dr. C. Superintending Engineer, PWD Hyderabad 36 Verma, S.K. Advisor, Engineering Staff College of India, Hyderabad 37 Verma, Maj V.C. Director, M/s Oriental Structures Engineers Pvt. Ltd., New Delhi 38 Vyas, Neha Senior Environment Specialist, World Bank, New Delhi Corresponding Members 1 Momin, C.W. Chief Engineer, PWD Meghalaya 2 Parsekar, U P Principal Chief Engineer, PWD Goa 3 Sachdev,V.K. Chief Engineer (Retd), Ministry of Road Transport & Highways, New Delhi 4 Temjen, R. Temsu Addl. Chief Engineer, PWD Nagaland 5 Vanlaltluanga, R. Engineer-in-Chief, PWD Mizoram (cid:40)(cid:91)(cid:16)(cid:50)(cid:73)(cid:191)(cid:70)(cid:76)(cid:82)(cid:3)(cid:48)(cid:72)(cid:80)(cid:69)(cid:72)(cid:85)(cid:86) 1. President, IRC (Pradhan, N.K.) Engineer-in-Chief cum Secretary to the Govt. of Odisha, Bhubneshwar 2. Director General (Kumar, Manoj) Ministry of Road Transport and Highways, New Delhi (RD) & Spl. Secretary to the Govt. of India 3. Secretary General (Nirmal, S.K.) Indian Roads Congress, New Delhi ii IRC:126-2017 Guidelines on Wet Mix Plant 1. intRoduCtion Use of Wet Mix Macadam (WMM) over the conventional Water Bound Macadam (WBM) as a pavement layer has proved to be quite effective in the sense that it ensures superior gradation of aggregates, faster rate of construction, higher standard of compaction that can be achieved, lower consumption of water and stricter standards of quality achievable. Specifications for Wet Mix Macadam are given in IRC:109-2015. This document “Guidelines on Wet Mix Plant” caters to the mechanisation aspect of preparation of Wet Mix Macadam in a central mixing plant so that the laid down requirements of end result specifications in respect of sizes and grading of aggregates, optimum moisture content, proper mixing etc. are achieved. The initial draft document “Guidelines on Wet Mix Plant” was prepared by Shri Anand Patel. Necessary inputs obtained from the Representatives of Industry and Shri Ananyabrata Maulikwere incorporated in the document. The Mechanization and Instrumentation Committee (G-4) deliberated on the draft document in a series of meetings and finally approved the draft document in its meeting held on 12th June, 2017. The document was approved by the General Standards and Specifications Committee in its meeting held on 24th June 2017 and thereafter by IRC Council in its 212th meeting held at Udaipur (Rajasthan) on 14th to 15th July, 2017. The Composition of Mechanization and Instrumentation Committee (G-4) is as given below: Basu, Kaushik -------- Convenor Verma, Maj. V.C. -------- Co-Convenor Sharma, K.C. -------- Member Secretary Members Bajaj, Sanjay Kumar, Swartantra Bhattacharya, Shantanu Kumar, V.G.S. Dalela, Saurabh Maulik, Ananyabrata Das, Prof. (Dr.) L.K. Nayak, Niranjan Kumar Gandhi, K.K. Parameswaran, Dr. (Mrs.) L. Garg, Dr. Rajeev Kumar Patel, Anand Ghate, Akshima T. Patwardhan, S.V. Kamath, Jai Kumar Raj, Hans Krishnamurthy, K.V. Raju, Prof. (Dr.) K. Solomon Krishnan, Dimitrov Sachdev, V.K. Kumar, Jitendra Verghese, B. Corresponding Members Basu, S.B. Ravisankar, Dr. K. Bhattacharya, C.C. Singh, Prof. (Dr.) K.P. Ghoshal, Amitabha 1 IRC:126-2017 Ex-Officio Member President, IRC DG(RD) & SS, MORTH (Pradhan, N.K.) (Kumar, Manoj) Secretary General, IRC (Nirmal, S.K.) 2. sCoPe This document covers advantages and major assemblies of a Wet Mix Plant, typical average power requirement of various parts of the plant, pug mill performance, plant maintenance and safety. This document is intended for use by highway engineers, field personnel within road construction agencies and contractors entrusted with the task of road construction and maintenance. Emission and noise limits for a diesel genset used in a Wet Mix Plant have been provided in appendix-i. Sample calculation for output analysis of a Wet Mix Plant has also been included in appendix-v 3. PuRPose Wet Mix Macadam (WMM) is a base or sub base pavement layer below the bituminous layer, wherein clean, crushed, graded aggregates and granular materials, like graded course sand are mixed with water and other additives like lime, cement etc. in desired proportion in a mixing plant and rolled to a dense mass on a prepared surface. A central mixing plant used for producing the wet mix macadam is called a wet mix plant. It has provision for: ● Controlled feeding of aggregates of different sizes in the required proportion. ● Addition of specified quantity of water. ● Addition of specified quantity of other ingredients like lime or cement. ● Forced/positive mixing of all the ingredients to produce a consistent homogeneous mix. A wet mix plant can be used with slight modification and other optional devices for: ● Production of cold bituminous mix – addition of emulsion ● Certain type of soil stabilisation – addition of cement or lime ● Blending of material for GSB 4. advantaGes oF Wet Mix Plant Use of a central mixing plant provides the following advantages: ● Higher production ● Proper quality control ● Lower unit production cost 2 IRC:126-2017 ● Proper blending and proportioning of aggregates for uniform gradation ● Uniform control of additives ● Uniform and homogeneous mixing ● No segregation 5. MajoR asseMblies oF Wet Mix Plant A Wet Mix Macadam Plant shall consist of the following assemblies/sub assemblies: ● Aggregate Feeder ● Gathering Conveyor ● Oversize Removal Screen ● Charging Conveyor ● Pug Mill Unit ● Water Tank and Metering Unit ● Filler Fines Feeding System ● Gob Hopper ● Storage Silo (optional) ● Control Cabin (housing the control panel) 5.1 aggregate Feeder Efficient wet mix plant operation starts with the cold aggregate feeder. The functions of the feeder system are to provide an even flow of accurately metered aggregates (meeting the gradation requirements) and provide surge storage capacity between the feeders and aggregate stockpiles. Surge capacity, as determined by bin size, keeps a ‘material head’ over the feeders for constant metering and determines how frequently the front end loader must cycle between the stockpiles and the cold aggregate feeder. The feeder system consists of four or more bins, with separators between them, to avoid inter mixing of aggregates being loaded in different bins. Bins are welded modular units made with mild steel, duly reinforced and stiffened and mounted on a rigid frame of such dimensions that there is no distortion of the bins under fully loaded conditions. Bin walls and bin gates are so designed as to prevent sagging and ensure smooth flow of aggregates to feeders. Only graded aggregates are to be fed to the feeder system. Otherwise, grizzly screens are to be put over the bins. Each bin should have provision for the adjustment of total and proportional feed and should be capable of being locked in any setting. Bin gates should have a graded scale to control the gate opening. Variable speed drive provided below each bin to control speed of auxiliary conveyor belt also helps in controlling aggregate flow. Therefore, aggregate flow may be regulated by adjustment of either or both gate opening and conveyor belt speed. The capacity of the bins should be sufficient to run the plant for minimum 10 minutes. The bin containing fines is provided with a bin vibrator to avoid sticking of fines with the bin wall. 3