LBS Asphalt

INTRODUCTION TO LBS (LABOUR INTENSIVE ASPHALT)

LBS Asphalt (labour based road repair and surfacing)  is a cold asphalt formulated mixture of inert fillers, bitumen extenders and binder enhancers designed to be blended with selected aggregates and water based bituminous emulsion in the manufacture of asphalt for general road surfacing and repair. LBS is designed as a labour intensive alternative to traditional machine laid asphalt that maximises labour input whilst still complying with the technical specifications for asphalt design.


LBS Asphalt Applications

  • Rural and residential roads
  • Road maintenance and repair
  • Labour intensive road construction
  • Poverty relief programmes

Advantages of LBS Alphalt

  • Self-priming
  • No heating required
  • Mix design conforms to South African TRH8
  • Exceeds design criteria for E4 classification of roads (TRH8)
  • Easy application – no specialised equipment necessary
  • Ideally suited to labour based construction
  • Minimal disruption to traffic
  • Cost effective – 80% of the final mix is sourced locally thereby reducing transport costs significantly

Environmental Impact of using LBS Asphalt

LBS is environmentally friendly, it has no long-term adverse impact on the environment and is safe to handle. It is non-toxic and non-hazardous.

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Labour Intensive Construction

LABOUR INTENSIVE CONSTRUCTION

LBS is a formulated mixture of inert fillers, bitumen extenders and binder enhancers designed to be blended with selected aggregates and water based bituminous emulsion in the manufacture of asphalt for general road surfacing and repair. The final LBS asphalt mix is designed to conform to TRH 8 specifications for ‘fine continuously graded asphalt’. Being a process carried out at ambient temperatures utilising bitumen emulsion, LBS Asphalt is especially suited to labour-based surfacing operations.


Material Requirements
Aggregate: The LBS asphalt mixture utilizes a combination of 9.5mm, 6.7mm roadstone and crusher sand.

Aggregate Grading

 

Sieve Size(mm) Nominal size of stone percentage passing sieve)
9.5mm 6.7mm Crusher Sand
13.2 100
9.5 85 -100 100
6.7 0 – 30 85 – 100
4.75 0 – 5 0 – 30 90 -100
2.36 0 – 5
0.15 0 – 20
0.075 0 – 10

Bitumen

An anionic stable grade bituminous emulsion containing a 60% nett bitumen content is used as the binder. The emulsion should conform to SABS 309 specification.

Physical and chemical properties:

  • Appearance – brown
  • Viscosity at 50°C, Saybolt Furol seconds, max.
  • Binder content, % (m/m)
  • Residue on sieving, g/100 ml
  • Sedimentation after 60 complete rotations
  • Coagulation value, % (m/m)
  • Dolerite chippings
  • Portland cement
Min
60

Max
620.25
Nil-
2

Mix Design Procedure
Typical LBS composition – 25 mm seal (30 mm loose placed uncompacted material)

Material Mix (%) Mass (kg)
LBS filler 20 200
Crusher sand 50 500
6.7, 9.5mm roadstone 21 210
Bitumen emulsion 9 90
Total: 100 1,000

NOTE: The water content is not included in the above calculations and will need to be adjusted as required dependent on site conditions.


Application Procedure

Site Preparation

  • The road surface should be firm, well compacted and swept free of loose material.
  • A prime or tack coat can be applied if specified or required.

Suggested Plant and Equipment Requirements for up to 350 – 500m²/Day Output

(excluding spares in case of breakages and all relevant safety signs and devices)

4 × wheel barrows8 × shovels6 × containers (25 l)1 × broom2 × hammer (plus 6” nails and fish line)2 × thickness guides(30 mm angle iron × 30 m long) 3 × metal rakes3 × watering cans1 × 4 m level1 × pedestrian roller (or hand tampers if required)1 × 500 -1000 L water tank1 × drum stand1 × drum tap

Suggested labour requirements for LBS Asphalt

Task Workers Activity
Supervision
Materials Supply &Mix
Thickness guides & Setting out
Spread and levelling of final mix
CompactionTraffic Control
Materials Stockpile
Materials Supply
Bitumen Emulsion Supply
Sweeping and watering
Final Level
Compaction Water
2
10
2
4
2
Check quality and maintain production rate
Mix the measured aggregate LBS Filler and Bitumen Emulsion
Setting out of the road and the thickness guides
Place and roughly level LBS Asphalt
Compact the asphalt road surface + WaterMaintain safe traffic flows
Supply correct quantities of LBS filler and aggregates
Move materials to work area
Supply correct quantities of bitumen emulsion
Clean road surface, and apply water and brush surface
Adjust final level of the LBS Asphalt
Water the levelled LBS and the compactor drums
TOTAL 20

NOTE: The above is an indication only as workers tasks will vary during the day to best meet the output needs of the team * Additional labourers can be used to increase productivity

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Application Procedure

Site Preparation

  • The road surface should be firm, well compacted and swept free of loose material.
  • A prime or tack coat can be applied if specified or required.

LBS product preparation

  • Adjust the size of the buckets to hold the correct volumes of crusher sand, roadstone & bitumen emulsion for the LBS mix.
  • Place the bags of LBS filler at regular intervals along the length of the surface to be sealed.
  • Place the required quantity of crusher sand and roadstone next to each bag of LBS filler.
  • Mix the crusher sand, roadstone and LBS filler thoroughly.
  • Add the required quantity of bitumen emulsion to each stockpile and mix thoroughly.
  • If the prepared mix is not to be placed immediately, cover with the empty bag and/or water lightly.

Note: Should it be required to improve workability of the mix, add water until the required consistency is achieved.

LBS Product application

  • Place thickness guides (30 mm loose placed material for a nominal 25 mm compacted seal).
  • Lightly water the base sweeping off any free standing water (no prime is required).
  • Spread the prepared LBS mix and level to the required thickness.
  • Lightly apply water to the surface of the levelled LBS mix if necessary
  • Compact the area by roller with 2 – 4 passes without vibration.
  • Compact the area by roller with 2 to 3 passes using vibration (water the drums to assist with sticking of material).
  • If required lightly water the compacted area again and roll again with 2 to 4 passes without vibration.
  • Once the surface becomes saturated with brown liquid sufficient water and compaction has been applied.

NOTE: If a greater labour input is required, the road surface can be compacted by hand using hand tampers, although if this is done, greater attention should be paid to the quality of the compaction and the densities achieved.


Traffic control

LBS can be opened to traffic within a few hours however speed should be reduced for the first 24 hours, full strength will only be achieved once all the water used has evaporated.

Labour Based Premix Production

LABOUR BASED PREMIX PRODUCTION 25kg

LBS is a formulated mixture of inert fillers, bitumen extenders and binder enhancers designed to be blended with selected aggregates and water based bituminous emulsion in the manufacture of asphalt for general road surfacing and repair. The final LBS asphalt mix is designed to conform to TRH 8 specifications for ‘fine continuously graded asphalt’. Being a process carried out at ambient temperatures utilising bitumen emulsion, LBS Asphalt is especially suited to labour-based production and surfacing operations.


Material Requirements
Aggregate: The LBS asphalt mixture utilizes a combination of 9.5mm, 6.7mm roadstone and crusher sand.

Aggregate Grading

Sieve Size(mm) Nominal size of stone percentage passing sieve)
9.5mm 6.7mm Crusher Sand
13.2 100
9.5 85 -100 100
6.7 0 – 30 85 – 100
4.75 0 – 5 0 – 30 90 -100
2.36 0 – 5
0.15 0 – 20
0.075 0 – 10

Bitumen

An anionic stable grade bituminous emulsion containing a 60% nett bitumen content is used as the binder. The emulsion should conform to SABS 309 specification.

Physical and chemical properties:

  • Appearance – brown
  • Viscosity at 50°C, Saybolt Furol seconds, max.
  • Binder content, % (m/m)
  • Residue on sieving, g/100 ml
  • Sedimentation after 60 complete rotations
  • Coagulation value, % (m/m)
  • Dolerite chippings
  • Portland cement
Min
60


Max
62
0.25
Nil-
2

Plastic Bags

 

470 x 690mm x 180 micron plastic bags are used to package the 25kg LBS premix.


 

Mix Design Procedure

Typical LBS composition – 25 mm seal (30 mm loose placed uncompacted material)

Material Mix (%) Mass (kg)
LBS filler 20 200
Crusher sand 50 500
6.7, 9.5mm roadstone 21 210
Bitumen emulsion 9 90
Total: 100 1,000

NOTE: The water content is not included in the above calculations and will need to be adjusted as required dependent on aggregate.


 

Suggested Equipment Requirements for 1,000 x 25kg Per Day Production

(excluding spares in case of breakages and all relevant safety signs and devices)

6 × wheel barrows28 × flat spades12 × containers (25 ℓ – supplied by RMS)2 × drum decanter stand2 ×measuring scales (0.1kg accuracy) 2 × metal rakes6 × watering cans6 × brooms1 × drum tap2 × impulse heat sealers

Note: The selected site will require the availability of water and single phase electricity


Suggested Labour Requirements for 1,000 x 25kg Per Day Production

Task Workers Activity
SupervisionAdministrationMaterials Supply & Mix
BaggingSealing of bagsStockpiling
1124
424
Check quality and maintain production rateKeep record of materials, production and requirementsCollection premix components from stockpiles, mixing of asphalt and transport of final mix for baggingBagging and weighing the final premixSealing of the bagged asphalt mixCollecting and stockpiling the sealed LBS asphalt premix
TOTAL 20

Note: The above is an indication only as workers tasks will vary during the day to best meet the output needs of the team. Additional labourers can be used to increase productivity

 


LBS Asphalt Preparation

  • Adjust the size of the buckets to hold the correct volumes of crusher sand, roadstone & bitumen emulsion for the LBS mix.
  • Place the required quantity of crusher sand and roadstone.
  • Place the bags of LBS filler with the aggregate pile.
  • Mix the crusher sand, roadstone and LBS filler thoroughly.
  • Add the required quantity of bitumen emulsion to each stockpile and mix thoroughly.
  • Should it be required to improve workability of the mix, add water until the required consistency is achieved.
  • Transport the completed mix to the stockpile for bagging

LBS Asphalt Bagging

  • Place approximately 25kg of LBS Asphalt into the plastic bag
  • Place the filled bag onto the scale and adjust the weight to 25kg
  • Seal the bag with the impuls heat sealer
  • Stockpile the sealed 25kg bag for collection
Pothole Repair Procedure

POTHOLE REPAIR PROCEDURE

LBS Asphalt is a formulated mixture of inert fillers, bitumen extenders and binder enhancers designed to be blended with selected aggregates and water based bituminous emulsion in the manufacture of asphalt for general road surfacing and repair. The final LBS Asphalt mix is designed (dependant on the final layer thickness required) to conform to TRH 8 specifications for ‘fine or medium continuously graded asphalt’.


LBS Asphalt Mix Preparation

  • Mix the required quantity of LBS filler, crusher sand and roadstone.
  • Add the required quantity of bituminous emulsion and mix thoroughly.NOTE: If it is necessary to improve the workability of the mix, add water until the required consistency is achieved.

Approximate LBS ASPHALT MIX Coverage Guide

Final thickness (mm) Loose depth (mm) LBS mix (kg/m²) Yield per mt/m²
30252015 35302520 55403527 18252937

Dependent on the smoothness of the road base surface, 25 kg of final asphalt mix can yield 1 m² at 20 mm thickness. Where uneven or coarse bases are encountered, additional LBS Asphalt should be allowed for.


Application

pothole-imageSite Preparation

  • The pothole should be squared off using a pick and spade or mechanical cutter.
  • Ensure the base surface area of the pothole is firm, well compacted and free of loose material.
  • For potholes deeper than 30 mm, fill with crusher run (or equivalent) to within 30 mm of the road surface and compact using a hand tamper or suitable mechanical compactor.
  • If desired, the crusher run or fill can be stabilised with cement.

LBS Product application

  • Slightly dampen the surface and edges of the pothole with water or alternatively a prime or tack coat can be applied if specified or required.
  • Place the prepared LBS Asphalt mix into the pothole allowing a 20 mm overlap to the edges of the pothole and a thickness of not less than 5 mm above the surface of the surrounding road.
  • Level the LBS Asphalt evenly to ensure a smooth finish with good riding characteristics.
  • Lightly apply water to the surface of the levelled LBS Asphalt mix.
  • Compact the area using a hand tamper or with a suitable pedestrian roller (water the tamper/roller drums to assist with sticking of material).
  • Once the surface is saturated with brown liquid, sufficient water and compaction has been applied.

 

LBS Asphalt Feasibility Study PDF upon request – Contact Us