Skip to main content

Wet Mix Macadam (WMM) technical specifications as per MORTH and Indian standard in Civil engineering

WET MIX MACADAM (WMM) sub – base /base:-

Wet mix macadam (WMM) act as a base course just below the bituminous layer (bitumen base course or surface course). 

The thickness of a single compacted Wet mix macadam(WMM) layer shall not be less than 75mm.when vibrating or other approved types of compacting equipment are used, the compacted depth of a single layer of the sub-base course may be up to 200mm.


How to calculate the loose thickness of WMM, compaction factor and quantity of WMM ? Kindly visit on below link 🔗

https://www.gyanofcivilengineering.com/2020/05/wet-mix-macadam-wmm-quantity-compaction.html







Physical requirements 


  • Material finer than 425 micron shall have plasticity index (PI) not exceeding 6.

To determine this combined portion, the flaky stone from a representative sample should first be separated out. Flakiness index is weight of flaky stone metal divided by weight of stone sample. Only the elongated particles are separated out from the remaining (non-flaky) stone metal. Elongation index is weight of elongated particles divided by total non flaky particles. The values of flakiness index and elongation index so found are added up.

If the water absorption value of the coarse aggregate is greater than 2%, the soundness test shall be carried out on the material delivered to site as per IS: 2386 (part-5)

Grading requirements:-
The aggregates shall conform to the grading given in table below-



The  final gradation approved within these limits shall be graded from coarse to fine and shall not vary from the low limit on one sieve to the high limit on the adjacent sieve or vice versa.

To get the information about surface finish and quality control work of WMM,  kindly click on below  link 🔗 

https://gyanofengineering.blogspot.com/2020/05/surface-finish-and-quality-control-of.html

CONSTRUCTION OPERATIONS:-

PREPARATION OF BASE:-

The surface of the sub-grade /sub-base/base to receive the WBM/WMM shall be prepared to the specified grade and camper and cleaned of dust, dirt and other extraneous material.

When WMM/WBM is to be laid on an existing metalled road, damaged area including depressions and potholes shall be repaired and made good with the suitable material.

If wet mix macadam (WMM)/ Water Bound Macadam (WBM) is to be laid directly over the sub- grade, without any other intervening pavements course, a 25 mm course of screening (Grading B)or coarse sand shall be spread on the prepared sub-grade.it is advisable to lay 100 mm  insulated layer of screening or coarse sand on the top of fine grained soil.

PREPARATION OF MIX:- 
Wet Mix Macadam(WMM) shall be prepared in an approved mixing plant of suitable capacity having provision for controlled addition of water and forced/ positive mixing arrangement like pugmill or pan type mixer of concrete batching plant. The plant shall have following features:
i) For feeding aggregates- three/ four bin feeders with variable speed motor
 ii) Vibrating screen for removal of oversize aggregates
iii) Conveyor Belt
iv) Controlled system for addition of water
v) Forced/positive mixing arrangement like pug-mill or pan type mixer
vi) Centralized control panel for sequential operation of various devices and precise process control
 vii) Safety devices

Optimum moisture for mixing shall be determined in accordance with IS:2720 (Part-8) after replacing the aggregate fraction retained on 22.4 mm sieve with material of 4.75 mm to 22.4 mm size. While adding water, due allowance should be made for evaporation losses. However, at the time of compaction, water in the wet mix should not vary from the optimum value by more than agreed limits. The mixed material should be uniformly wet and no segregation should be permitted.

SPREADING OF MIX:   Immediately after mixing, the aggregate shall be spread uniformly and evenly upon the prepared sub-grades/sub-base/base in required quantities. In no case shall be dumped in heaps directly on the areas where these are to be to laid nor shall their hauling over a partly completed stretch be permitted. The mix may be spread by a paver finisher.

 In exceptional cases where it is not possible for the paver to be utilized, Mechanical means like motor grader may be used with the approval of Engineer.

The Engineer may permit manual mixing and /or Laying of WMM where small quantity of WMM is to be executed.

COMPACTION:-After mix has been laid to the required thickness, grade and crossfall/camber the same shall be compacted to the full depth with roller. If the thickness of single compacted layer does not exceed 100 mm, a smooth roller of 80-100 KN weight may be used. For a compacted single layer up to 200 mm, the compaction shall be done with the help of vibratory roller of min. static weight of 80 to 100 KN. The speed of the roller shall not be exceed 5 KM/h.

To get the details about Rolling pattern, number of rolling passes to compact the bed of WMM and more about Rolling please click on below link 🔗 

https://www.gyanofcivilengineering.com/2019/02/standard-rolling-process-of-various.html





In portions having unidirectional cross fall/super elevation, rolling shall commence from the lower edges and progress gradually towards the upper edge. Thereafter, roller should parallel to the centre line of the road, uniformly overlapping each preceding track by at least one-third width until the entire surface has been rolled. Alternate trips of the roller shall be terminated in stops at least 1 met away from any preceding stop.
In portion in camber, rolling should begin at the edge with the roller running forward and backward until the edges have been firmly compacted. The roller shall then progress gradually towards the center parallel to the center line of the road uniformly overlapping each of the preceding track by at least one – third width until entire surface has been rolled.
Rolling should not be done when the sub-grade is soft or yielding or when it causes a wave- like motion in the sub-base/base course or sub- grade .
If irregularities develop during rolling which exceed 12 mm when tested with 3 m straight edge, the surface should be loosened and premixed material added or removed as required before rolling again so as to achieve a uniform surface conforming to the desired grade and crossfall.

Rolling shall be continued till the density achieved is at least 98 % of the max.dry density for the material as determined by the method outlined in IS: 2720 (part-8)

Setting and drying

After final compaction of WMM course, the road shall be allowed to dry for 24 hours.

Measurements for pavement
 WMM shall be measured as finished work in position in cubic metres.

Thank you
Mukesh Kumar
Gyan of engineering


Comments

  1. I am very happy to say that this is an interesting post. I learned new information from your article, you are doing a great job. Thanks for sharing this kind of blog. Parking Lot Paving

    ReplyDelete

Post a comment

Popular posts from this blog

Granular Sub base (GSB) specifications, GSB Grading, layer thickness, Water absorption, Physical requirements (like liquid limit, Plasticity index ,AIV), construction procedure or Rolling , measurement and treatment of GSB as per MORTH 5th revision and Indian standard in Civil engineering

Granular sub-base (GSB) SUB BASE (GSB)– The full form of GSB is granular sub base.it is being laid in road work because it plays two major roles 1- it works as  drainage layer 2- it provides a good sub base to laid base layer on it. How to calculate the quantity, compaction factor value and loose thickness of GSB? To know more information kindly visit on below link 🔗  www.gyanofcivilengineering.com/granular sub-base(GSB) Quantity. Material –     The material to be used for the work shall be natural sand, crushed   gravel, crushed stone, crushed slag, or combination thereof depending upon the grading required use of material like brick metal, kankar and crushed concrete shall be permitted in the lower sub base. The material shall be free from organic or other deleterious constituents. Grading III and IV shall be used in lower sub base. Grading V and VI shall be used as sub-base-cum-drainage layer. Where the sub-base is laid in two layers as upper sub-base and lowe

Full form of various terms used in civil engineering /highway engineering or road work

Full Form of various  terms used in civil engineering  (Highway and expressway)  List of various  acronyms or abbreviations used in civil engineering  TBM- Temporary Bench mark (टे᠎म्‌प्‌ररि बेंच मार्क) BM- Bench Mark ( बेंच मार्क ) / Bituminous Macadam ( बिटुमिनस मैकडम) MSL- Mean Sea Level (मीन सी लेवल) BS- Back sight( बैक साइट) FS - Fore sight  (फोर साइट) HI - Height of Instrument ( हाइट आंफ इन्‌स्‍ट्रमन्‍ट्‌) TS-  Total Station (टोटल स्टेशन) GPS- Global Positioning System (ग्लोबल पोजिशनिंग सिस्टम) ROW- Right of Way (राइट ऑफ वे) MTV- material Transport vehicle (मटेरियल ट्रांसपोर्ट वहीकल) NGL- Natural Ground Level (नेचुरल ग्राउन्‍ड्‌ लेवल ) OGL- Original Ground level (अˈरिजन्‌ल्‌ ग्राउन्‍ड्‌ लेवल ) C&G- Clearing and Grubbing ( क्लियरिंग और ग्रबिंग) EMB- Embankment SG- Subgrade (सबग्रेड) GSB- Granular sub-base WMM- Wet Mix Macadam ( वेट मिक्स मैकडैम) WBM- Water Bound Macadam (वाटर बाउंड मैकडैम) DBM- Dense Bituminous Macadam SDBM- Semi- Dense Bitumino

WMM(Wet Mix Macadam) quantity / Compaction Factor value for WMM / Loose thickness of WMM Layer

Wet Mix Macadam (WMM) quantity / Compaction Factor value for WMM / Loose thickness of WMM Layer  In this article we shall discuss three important points about wet Mix Macadam (WMM) 1- How can we calculate the required WMM  quantity?  2 -  What is value of compaction factor for WMM? 3- How much loose thickness should be taken to get proper compacted layer thickness ?  1- How can we calculate the required WMM quantity? Let us consider Length of WMM Bed(L) = 1 Km = 1000 Met. Breadth of WMM Bed(B)= 7 Met. Thickness of WMM Layer (T)  = 150 mm =0.150 Met. Max. Dry Density (MDD) =2.230 Gram/ Cubic Centimeter = 2230KG/ Cubic metre Note -  The value of MDD is calculated by conducting proctor density test as per IS 2720 (part -28) : 1983 (Reaffirmed - May 2015). Then Volume of WMM Layer = ( Length of WMM Bed X Width of WMM Bed X Thickness of WMM Layer) Volume of WMM Layer = L X B X T  Volume of WMM Layer   = 1000 X 7 X 0.150  Volume of WMM Layer    = 1050 C

Dense Bituminous Macadam (DBM) or Bituminous Concrete (BC) layer Quantity / Compaction Factor value / Loose thickness calculation

Dense Bituminous  Macadam (DBM) or   Bituminous Concrete (BC)  quantity / Compaction Factor value for DBM or BC / Loose thickness of DBM or BC Layer  In this article we shall discuss three important points about Dense Bituminous   Macadam (DBM) or Bituminous Concrete (BC) 1- How can we calculate the required DBM/BC quantity?  2 -  What is value of compaction factor for DBM/BC? 3- How much loose thickness should be taken to get proper compacted layer thickness ?  1- How can we calculate the required DBM/BC quantity? Let us consider Length of  DBM/BC layer (L) = 1 Km = 1000 Met. Breadth of DBM/BC Layer (B)= 5 Met. Thickness of DBM/BC Layer (T)  = 50 mm =0.050 Met. Max. Dry Density (MDD) =2.441 Gram/ Cubic Centimeter = 2441KG/ Cubic metre Note  -  The value of MDD is calculated by conducting suitable test . Then Volume of DBM/BC Layer = ( Length of DBM/BC layer X Width of DBM/BC layer  X Thickness of DBM/BC Layer) Volume of DBM/BC Layer = L X B X T Volume o

DBM (Dense Bituminous Macadam) specificatins,layer thickness, physical requirements, aggregate size, grades and its measurements

 DENSE BITUMINOUS MACADAM(DBM) DBM acts as a bituminous  base course and thickness of a single compacted  layer shall be 50 mm to 100 mm.  In this article we shall discuss about Technical specifications of DBM (Dense Bituminous Macadam), layer thickness, physical requirements, aggregate size, grades and its measurements A-Scope : The work shall consist of construction in a single layer of DBM on a previously prepared base or sub-base. The thickness of a single layer shall be 50 mm to 100 mm. B - Material : The choice of binder material shall be stipulated in the contract or by the engineer, where viscosity grades of bitumen are specified, they are referred to by a designation in accordance with IS: 73. Where modified bitumen is specified, it shall conform to the requirements of IRC:SP:53 and IS:15462. Selection criteria for viscosity grade bitumen based on highest and lowest daily mean temperatures at a particular site are ]given in table no -1. 1-Coarse Agg

Difference between nominal mix and design mix of concrete

Difference between nominal mix and design mix of concrete - Concrete is most extensively used mix to achieve desired properties of structure. There are two methods to prepare the concrete mix. 1-Nominal mix 2- Design mix Nominal mix - Nominal mix specifies the fix proportion of the cement , sand and aggregates. Ingredients of concrete are mixed on the basis of volume. It is a site level mixing of ingredients to prepare concrete mix. Such type of concrete mix is generally used in small quantity or where load is not high. There are many grade of nominal mix concrete like M-5, M-7.5, M-10, M-15 and M-20. In above grades of concrete mix  the letter 'M' refers to Mix where as the value like 5,7.5,10,15 etc indicates the compressive characteristic strength of concrete after 28 days in specified conditios. Unit of this compressive characteristic strength of concrete is  Newton /mm 2. The ratio of various grade of concrete is being given below - M-5 

Bituminous Concrete (BC) specifications viz. Layer thickness, Mix and material requirements, grading , laying trials, Rolling , Construction procedure, transport and joint specifications, surface finish and quality control,measurement and rate etc..as per MORTH and Indian Standard

Bituminous concrete(BC)- Bituminous concrete( BC) is used for wearing  course and profile corrective courses.BC is generally laid in single layer on a previously prepared bituminous bound  surface. The thickness of single layer of BC shall be 30mm,40mm and 50mm. 1 -MATERIAL A- Bitumen - The bitumen shall be viscosity graded paving bitumin complying with IS 73 or specified in contract aggrement. The type and grade of bitumen to be used would depend upon the climatic condition and the traffic. Selection criteria of viscosity graded (VG) paving bitumens based on climatic conditions B- Coarse Aggregate It consist of crushed rock,crushed gravel or other hard material retained on 2.36 mm sieve. It shall be clean ,hard,durable and of cubical shape,free from dust,and  soft organic and other deleterious substances. The aggregates  shall satisfy the physical requirements of table  no. -2 (Table no. 500-16 ,as per MORTH 5th revision) where crushed gravel is proposed 

Civil engineering interview questions in Roadway/Highway /Expressway department

  Welcome friends, We shall learn about the various questions which are frequently ask by an  interviewer In the field of infrastructure.  So let's get start....... EMBANKMENT/SUBGRADE/BORROW AREA •Liquid Limit  <50% •Plastic Limit  < 25% •Proctor Density(Min. Value) For Embankment =1.52 to 1.60 gram/cubic centimeter For Subgrade= 1.75 gram/ cubic centimeter Sub-grade top • Field Dry Density (FDD) For Embankment= min. 95% For Sub grade = min. 97% •Number of test For Embankment = 1set/3000 sq.meter(1set=10pits) For subgrade= 1set/2000 sq.meter (1 set=10 pits) GRANULAR SUB- BASE •Maximum thickness of single compacted layer = 200 mm • Minimum thickness of single compacted layer( only when GSB is laying in two layers) = 150 mm •Max. Allowable size of aggregate =75mm •Number of grading of GSB = 6 •Liquid limit  should not be  more than 25% ( test procedure as per IS 2720 (part 5)). •Plasticity index should  not be more than 6%

Process of laying of DBM/ BC( weather limitations, Rolling of laid material and cleaning of bed)

First of all i want to tell you that DBM act as bituminous base course while BC acts as wearing course. LAYING OF DBM(Dense Bituminous macadam) /BC(Bituminous concrete)  Laying of DBM/BC is done with the help of paver. There are following points which clearly indicates detailed process of laying. To know more about the bituminous concrete (BC) ,please click on below link......... https://gyanofcivilengineering.com/2020/05/bituminous-concrete-bc-specifications.html 1-Weather and seasonal limitations- Laying shall be suspended: A- In presence of standing water on the surface B-When rain is imminent, and during rain, fog, or dust storm C-When the base/binder course is damp D-When the air temperature on the surface on which it is to be laid is less than 10°C for mixes with conventional bitumen and is less than 15°C for mixes with modified bitumen E- When the wind speed at any temperature exceed the 40 km per hour at 2 m height. 2-Cleaning of surface- The