Cementing a green solution

While contractors, water companies and local authorities are addressing maintenance problems, the environmental implications of their activities are becoming just as important. We look at how the latest cement technology can help.

It makes you wonder why, exactly, when a company has an extremely successful
product, well-established in a market sector, that it decides to direct significant research and development resource into the quest for an alternative material to carry out the same job. Doesn't make sense, does it?
Well, on the face of it, it doesn't. But, just like basic economic theory, it is all a matter of supply and demand. When demand begins to change, as it always does, the best companies and organisations change with it. The most resourceful - those that are physically closest to their particular market or who invest in ongoing market and product research - often change before the market knows it. One of the most potent issues of our time is that of the environment. Never before has the subject been so high on the agenda and it has evolved into a major driving force for the commercial world - this includes the highways sector of the construction industry, and the water industry.
Here, risk and asset management are becoming increasingly entwined to such an extent that whilst local authorities, water companies and contractors are strategically addressing maintenance problems, the environmental implications of their activities are becoming equally important.
In order to carry out conventional maintenance work, they are becoming less and less able to accept products that are now classified as harmful. The problem applies in respect of both operative handling and packaging waste. So, demand is changing and products must adapt also. One such firm is Tamworth-based Instarmac Group, which has been building a product portfolio to assist local authorities, water companies and contractors to meet their road maintenance and environmental responsibilities.
Instarmac has just developed and la new high strength, rapid setting cement-based mortar, which will form part of its Ultracrete range. Importantly, the new material is wholly environmentally safe, as well as being able to meet the very tough highway specifications.
The new Ultracrete Envirobed HA104 is based upon the very latest chemical developments in cement technology. The material is the forerunner of the next generation of environmentally-friendly alternatives to resinous-based materials for the bedding of ductile ironwork conforming to the DTI Design Manual for Roads and Bridges Mortars for bedding ironwork to BS EN 124.
Current estimates indicate that more than £250M is spent annually on the ironwork aspect of manhole reinstatement in the UK, yet it is likely that within 12 months of repair, upwards of 50% of the jobs will have failed again.
Vehicle volumes have increased by more than 135% in the past 30 years, larger lorries and payloads have been permitted since 1994 and much of the carriageway ironwork is located directly within vehicle wheel tracks.
Secondly; sub-standard reinstatement products, poor workmanship and premature road re-opening has adversely affected performance.

Permit schemes
Plans such as Section 74 New Roads and Streetworks Act (NRSWA) and new
legislation to allow local authorities to charge for prolonged Streetworks, have been introduced to assist. Other initiatives, such as the Traffic Management Act, permit schemes to gain approval to carry out works. Fixed penalty notices for some NRSWA and Highways Act offences help as do NRSWA fines and highways works being subject to the same regimes as utilities. So, why is the development of Envirobed HA104 a breakthrough?
The introduction of Instarmac's Envirobed HA104 is set to completely change the means by which, and the materials with which, future ironwork covers and frames will be installed.
Envirobed does not have any of the inherent environmental disadvantages of polyester resin-based materials, which previously were the only products able to conform to the specification.
It is also believed to be the only cement-based bedding material available that can develop the required compressive and tensile strengths within the specified three hour limit, thereby ensuring roads are not closed for lengthy periods and labour costs are kept to a minimum.
It is common for cement-based mortars to exhibit high compressive strengths, but they generally perform poorly when it comes to tensile strengths.
The material's tensile strength is about twice as high as that expected from other fast setting cementitious mortars.
In order to satisfy the guaranteed performance demanded by the Highways Agency specification, mortars must be non-shrink, able to achieve a compressive strength of 30N/mm2 after three hours. Envirobed HA104 achieves compressive strengths of between 30N/mm2 to 50N/mm2 in the same time frame, a tensile strength of 5N/mm2 after three hours and has a minimum workable life of 15 minutes. From a health and safety viewpoint, the polymer-modified cement-based mortar is much less hazardous than the traditional polyester resin-based materials, and there are no problems with regard to the disposal of the used packaging. Polyester resin contains styrene, now classified as harmful, and is also flammable.

Safety benefits
Ian Deneven, NRSWA manager for Wakefield-based specialist contractor Peter Duffy Drains-aid, comments: "We have been trialling Envirobed HA104 at Yorkshire Water in Sheffield since April of this year with great success. Peter Duffy Drains-aid works very closely with 13 local authorities and the company's excellent working relationship facilitates the trialling of new products to determine the benefits for ourselves, our partners and their highways.
"Safety is a big issue and as well as our operatives enjoying the added safety benefits provided by the cement-based mortar, we found Envirobed HA104 very easy to use and work with.
"We used it to bed two D400 H cover frames in a type-2 road, which is heavily congested and have been monitoring the installation since to see how it fairs against existing materials we use from Instarmac.
"The results so far are very encouraging and we are looking forward to the new material going live."

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