The Project

Overview

As part of their ongoing commitment to drive down costs, reduce road occupation and become a carbon neutral organisation by 2030, Durham County Council’s Highways Department recently carried out a 13-day trial to explore the benefits of using a new type of sustainable road repair process known as Roadmender Elastomac.

Elastomac is a highly durable, sustainable eco-friendly road repair material made with 69% recycled aggregate, recycled bitumen and recycled polymers.

The trial took place across multiple different locations, road types and defect types including Ravelling, Fretting, Seam Joints, Pothole Repairs, Alligator Cracking, Patching, Wheel Rutting, and general Surface Deterioration to both asphalt and aged concrete roads.

Results

Over the course of the trial the team completed 942 m2 of repairs across 22 streets spanning various residential estates and link roads at an average daily output of 73 m2 per day.

During the trial, the team were given permission by the Council to extend the size of patches to cover any surrounding cracking outside the conventional markings and also given permission to carry out preventative repairs to other earlier stage shallower defects identified by the team while on site subject to their being pre-agreed with a supervisor over the phone.

Cost Benefit Analysis

A conventional 2-man team with a 3.5-ton truck carrying 1 ton of asphalt with no hot box can, on average carry out a maximum number of 16 temporary defect repairs a day totalling 8 m2. Grossed up into square metres, the all-in cost of 1 m2 of temporary repairs including fixed overheads is £127.50 per m2.

This is based on the following assumptions. Direct costs for the 2 men, truck, fuel, tools, asphalt and disposal of waste £620. Plus £150 for fixed overheads like head office rents, rates, utilities, admin, inspections and permitting, and £250 for a conventional subcontractor’s profit and risk. Based on these assumptions the total all in cost of a team for the day is £1,020, which, divided by 8 m2 works out to £127.50 per m2 of temp repairs.

If we assume that a temporary repair lasts on average 1 year, the annual cost of 1 m2 of such repairs is £127.50 per annum.

A 4-man Elastomac team is established by combining 2 conventional 2 man patching teams with 1 or 2 trailer mounted mastic mixers to heat and mix the Elastomac. While two conventional 2-man patching teams with 3.5 ton trucks can patch up to 16 m2 in a shift, the 4-man Elastomac team can patch up to 140 m2 in a shift depending on the size, number and proximity of the patches.

At an average daily output of 73 m2 per day during the trial, the Roadmender patching team cost £3,238 per day being £44.35 per m2. With an extra £438 per day for hotels, travel each week from Sheffield and short-term rental of equipment the actual cost for the trail was £50.70 per m2. If we assume the Elastomac repairs last at least 4 years, the annual cost per m2 for the Elastomac repairs at the trial rate of £50.70 per m2 worked out at £12.68 per annum. (£50.70/4=£12.68 annual cost/m2)

Over 4 years, temporary repairs will typically have to be revisited 4 times costing £510 per m2 over the period. (£127.50*4=£510/m2). This compares to just £50.70 per m2 for the Elastomac repairs. If we Multiply these savings by the 942 m2 of repairs carried out over the 13 days of the trial, compared to conventional temporary repairs, the trial delivered savings of £432,630, or 90%.

Material Movement and Waste

If a temporary repair team collects 1 ton of asphalt and installs 800kg per day to complete 8 m2 of repairs that’s 125 kg of material movement and waste per 1 m2 of repairs. To complete 942 m2 of repairs would require 117.8 tons of material movement and waste. Repeat this 4 times over 4 years and that number increases to 471 tons of material movement and waste.

The Elastomac team completed the 942 m2 of repairs using 24 tons of Elastomac, 2.72 tons of pre coated chips, and 2 tons of asphalt being a total of 28.72 tons of material used with no waste. Compared to conventional temporary repairs, this resulted in a reduction In material movement and waste across the network of 442 tons of asphalt over the next 4 years or a 93.85% reduction in material movement and waste.

As you might expect, in addition to the fact the Elastomac is also made with 69% recycled ingredients, this reduction in material movement and waste also has a massive impact on the carbon savings.

Carbon Savings (9 tons a day)

When adding up all the fossil fuels burnt and dividing them by daily outputs, the carbon footprint of conventional temporary repairs works out at 32 kg’s of C02e per m2. Over 4 years this works out at 32 kg per m2 per annum.

The carbon footprint of the Elastomac repairs is 4.33 kg of C02e per m2, but because they are expected to last at least 4 years, the annualised carbon footprint is 1.08 kg per m2.

Based on the 942 m2 of repairs completed during the trial, the trial generated 4,078 kg of C02e. The carbon footprint of conducting conventional temporary repairs to the same defects 4 times over 4 years would have been 120,576 kg of C02e. As such, the trial generated ~116,498 kg of C02e savings or a 96.4% reduction in Carbon Footprint.

SUMMARY

Savings on paper

Cost savings – 90%
Reduction in Material movement and waste – 93.8%
Carbon savings – 96.4%

While these savings sound amazing on paper, in reality, roughly 50% of the 942 m2 of repairs were preventative repairs administered to shallow surface defects that were in some cases 2 years prior to current intervention levels. While this improves customer satisfaction for local residents and eliminates the need for multiple repeat visits to the same areas over the next 4 years, it reduces the real world savings, as half the repairs could have been left for 2 years before they reached intervention levels.

Real world savings restated

Cost savings – 85% (£312,000, or £24,000 per day)
Reduction in material movement and waste – 91% (324 tons, or 25 tons per day)
Carbon savings – 95% (86 tons, or 6.64 tons per day)

Please see below for a selection of before and after photos from the trial