Magnetite-Asphalt POT HOLE REPAIR Exploiting the thermal properties of Magnetite in hot pot patch repair

Partners Professor Denis Chamberlain, Consultant, Epicuro Ltd Dr Mujib Rahman, Senior Lecturer, Brunel University London Richard Hunt, Sales Manager, LKAB Minerals Ltd

PROJECT OBJECTIVES Prove pothole repairs can have similar life to surrounding pavement. (basis for 3-5 year warrantee rather than current 2 years) Create means of clearing 14 year backlog in pot hole repairs. (‘right first time’ thinking) Achieve substantial annual savings in pot hole repairs. (long life repairs and substantially reduced repair failures)

how POT HOLES FORM Water >> damage e.g. cracking, ravelling, rutting, potholes etc Research >> asphalt degradation Many new type of asphalt surfaces are failing prematurely Once pothole is formed, the deterioration process is very fast 4

Current REPAIR Practice Case Study Repair Observation 6th Aug 2017 Rainwater and loose stone brushed out of pot hole. Hot asphalt fill placed in excavation (105oC). Heater placed over fill for approx 5 mins. Fill compacted with roller Surface temperature measured (125oC) Edge sealer applied (gilsonite?) Return Visit 11th Sept 2018 13 months after repair. Stones lost on boundary Lost fill within repair area

ADDRESING FAILURES ISSUES IN Current REPAIR Practice (Using Granite-Asphalt Mixes) CURRENT PROCESS No scientific basis to heating process. No internal repair interface temperature control. High moisture content in pot hole. Weak perimeter pavement to pot-hole. Contaminated fill (mixed with existing). Restrained heating due to poor heating control. DYNAMIC HEATING PROCESS Variable high precision focused heating. Uses digital model of heating process. Based on thermal properties of materials. Increased interface bonding and rutting resistance. Prep’d hole & quality assured bagged fill. Minimalized heat energy consumption.

ADVANTANGES OF DYNAMIC HEATING METHOD Repair testing: accelerated life rutting 20,000 cycles of twin wheel loading simultaneously applied to assess the affect of pre-heating the pothole excavation. Rutting depth measured at 4 mm intervals along 96 mm repair interface (ref AASHTO T324-04)

ADVANTAGES OF DYNAMIC HEATING METHOD Repair testing: accelerated life rutting Improved rutting resistance through dynamic heating Non pre-heating Dynamic pre-heated Unintentional 60 cycles case: able to remove patch fill from excavation in case of non-pre-heated repair! 23% average reduction in rutting Interface bond strength increased >90% Epicuro Ltd 26th Sept 2018 Brunel University

THERMAL PROPERIES OF MAGNETITE-ASPHALT Substantially increased thermal conductivity 130oC Conductivity Values (k) Bitumen 0.17 Asphalt 0.75 Granite 1.30 Magnetite 6.00 Water 0.606 Thickness Values (s) Bitumen 1mm Stone 5mm Thermal Energy Conduction (W) Heat Conduction 0.450 Relative Increase in Thermal Energy Transmission (W) 0.400 0.350 0.300 q = dT A / ((s1 / k1) + (s2 / k2) + ... + (sn / kn)) 0.250 Substituting magnetite for stone aggregate results in 43% increase in thermal energy transfer at 103mm 0.200 0.150 depth (based on 1D stone/bitumen stack) 0.100 0.050 Area A 1 sqm dt 130oC-80oC 0.000 0.007 0.013 0.019 0.025 0.031 0.037 0.073 0.103 Depth (m) 80oC 5mm Stone/Magnetite 1mm Bitumen

EXPOITING properties OF Magnetite-ASPHALT (Compared with Granite-Asphalt) Substantially increased thermal conductivity. Faster and more effective heating of repair interface. Potential reduction in heat energy consumption High thermal energy for given temperature. Potential for reduced heat losses in transportation and use. Additional properties: interface bond, surface friction

Project plan: Next steps Develop Magnetite asphalt mixes for highways applications Quantify surface properties Produce & repair test pieces Establish longevity of Magnetite asphalt pothole repairs (compared to Granite repair) Determine additional advantages compared with current practices (cost, time etc) Identify commercial partners for magnetite asphalt Commercial product available to market Long term testing of product in situ 3 months 6 months 12 months

Project DELIVERABLES Magnetite Asphalt solution Increased repair life Reduced repair failures Huge cost savings Anticipated pavement life vs overall road life

THANK YOU. Any questions?