Quality Assurance D R Rossmann South African National Road Agency Ltd

Typical Quality Assurance Flow Chart ModifierBase Bitumen Binder Blending Haulier Site Storage Sprayer Sprayer/Asphalt mixing plant

Information required from the Manufacturer at the start of contract Quality control measures for raw materials, including supplier’s certificates of analysis Manufacturers process control, including a blending method statement (type of polymer needs to be stated; recipe details need not be given) Storage and handling parameters/limits Sampling plan and testing frequencies, including sampling and test methods. Reporting of results against manufacturing specifications

Other information at start of contract Binder Manufacturer –Full set of test results showing mandatory properties of the modified binder –Certificate of compliance of base bitumen with SABS 307 On the Client’s request –Non-mandatory information at the discretion of client –Representative samples for mix design purposes Mandatory testing –Full range on first production batch –System of frequency testing according to manufacturer’s approved quality assurance programme and agreed with the client –Mandatory testing repeated if the base bitumen, crude diet or manufacturing process changes

Quality Control During Construction Quality control testing on every load supplied to site Test programme agreed between client and manufacturer (generally indicator tests) Torsional recovery test has potential as a process control test When assessing test results, the confidence limits (repeatability and reproducibility) should be taken into account The manufacturer should conduct the test in accordance with the agreed quality assurance plan before releasing the product

Testing Frequency of Hot Polymer Modified Binder TestManufacturerHaulier Site Storage Sprayer Softening Point Every batchEvery loadEvery dayEvery load Dynamic 165ºC Every batchEvery load Torsional 15ºC and 25ºC Every batch (if specified) Every load (if specified) 15ºC Every 5 th batchEvery 5 th load Elastic 15ºC Every 5 th batchEvery 5 th load Storage stability Every 5 th batchEvery 10 th load After RTFOT: Diff in Softening point Dynamic viscosity Every 10 th batch Every 10 th load Torsional recovery If specified

Testing Frequency of Polymer Modified Emulsions TestManufacturerHaulier Site Storage Sprayer Binder Content Every batch Sample only Every dayEvery load 50ºC Every batchEvery load Residue on Sieving Every batch Every load (if specified) Sedimentation Every 5 th batchEvery 5 th load Test on recovered binder: Softening Point 15ºC Elastic 15ºC Every 5 th batch Softening Point every day Softening Point every load Torsional 25ºC As specified Every day (if specified) Every load (if specified)

Testing Frequency for Bitumen-Rubber TestSpray Tanker Compression recovery (5 mins) Every 5 th load Compression recovery (1 hour) Every 5 th load Compression recovery (4 days) Every 10 th load Softening Point Every load Resilience Every load Flow Every load Dynamic 190ºCAt start and end of every load Bitumen-rubber normally blended on, or close to, site Final product normally blended in spray tanker (10 – 15 tonnes)

Reconstitution Generally not possible to reconstitute SBS modified binders that have lost their modified properties Old bitumen-rubber and SBR latex modified binders can be reconstituted –Blending of maximum 20% old modified product with new base bitumen and an appropriate percentage of modifier –Manufacturer’s guideline must be followed Reconstituted binders must still meet the requirements for the relevant modified binder class

Sampling and Testing Modified binders are multi-phase material and thermo-dynamically unsound Susceptible to problems not experienced with conventional binders Thermo-mechanical history has major influence on properties Relevant sampling and sample preparation must be strictly adhered to Correlation testing should be carried out between all stakeholder laboratories at the start of the contract

Sampling and Testing cont….. Report only requirements for certain tests –Force Ductility –Complex Shear Modulus (G* and sin δ) –Torsional 15 & 25 ºC Cannot expect suppliers to carry out “report only” testing in most cases Must be specified if required

Modified Vialit Adhesion Test (MB-7) Procedure for determining the adhesive and cohesive properties of modified binders to aggregates at 5ºC and 25ºC Procedure written for specification compliance May be modified to specific site conditions Degree of Retention (R) is calculated after impact Deviations from the specification test method should be reported

Torsional Recovery Test (MB-5) Determines the torsional recovery of polymer modified binders using a bolt and cup assembly Manual rotation of an aluminium blot embedded in a cup of modified binder Test conducted at 25ºC ± 3 ºC Rate of application of torque is critical to reliable results Spider assembly should not contact the rim of the cup

Rolling Thin Film Oven Test

Occupational Health and Safety Hot modified binders require extreme care when handling Sabita Manual 8 contains detailed information