Conversion of industrial waste and by-products

Global Cement Magazine October 2006

Global Cement Magazine October 2006

In the early nineties Gary Hunt working as a technical manager in a multi disciplined precast works was given a project to look for alternative aggregate sources, during this project he began to notice some of his test materials had cementitous properties. This sparked an interest in alternative cement replacements, specifically for the precast sector of the construction industry where Gary was most experienced.

One of the key drivers was that there was and still is a major lack of understanding of what is needed by the precast industry from the cement and cement replacement suppliers such as Ground Granulated Blast Furnace Slag (GGBS) and Pulverised Fuel Ash (PFA).

Formed from over ten years of research I have now created a new company Celtic Cement Technology Ltd based in Wales UK. The first stakeholder partner (a small local company) has made a commitment to support this new technology by attempting to design and build a small scale production facility, the cost of this facility is expected to run into several million pounds. The facility is being designed using all the latest green technologies to ensure it is a truly sustainable production plant.

The technology I have researched and developed has endless possibilities. One of the most exciting would be for large consumers (or Groups of smaller companies) to use the technology to produce their own cement replacements. A production plant could produce several different recipes for different precast or ready-mix applications even tailor make a product for a large job and certainly vary things like setting time to suits the seasonal variations in temperature

Celtic Cement Technology changes the rules for the precast and ready-mix industries which instead of trying to make the best of cement substitutes supplied to them, companies can now specify and design the cementitous materials they need, and all this is created from industrial by-products not virgin materials.

This new technology was launched in the United States in January 2006 at The World of Concrete Exhibition held in Las Vegas. There has been a lot of interest been created which have resulted in the company already making several return trips to the states during this year.

The first introduction of this new technology in Europe was given at the 6th European Cement Conference where I was a guest speaker; this conference was held in London in March 2006.

Turn of the Century

What a difference a decade makes, the research project initially started in the early 1990’s, when it was realised that to remain competitive companies would have to find alternative materials for the construction industry. During that time the attitude was that you cannot put waste into concrete. Now in the 21st. century the question is how can we use waste or by-products as constituent materials in concrete?

Government drivers are starting to appear from the need to demonstrate the usage of recycled materials in new built projects and the need to cut carbon emissions. Remember 1t of Portland cement produces roughly 1t of CO2 emissions, 1t of our replacement uses a ton of waste material and produces virtually no emissions.

Acceptance Criteria

At present there are no official criteria to determine what by-products are acceptable for use in concrete. Therefore, as a company we are working with the Building Research Establishment (BRE) UK to obtain accreditation for the process and products for acceptance to the industry.

We have developed an analytical system to fully characterise the raw materials to establish the suitability of the individual or blend of materials for use as a cement substitute. This characterisation ensures us that the end product will pass all the relevant tests in accordance with the European standards for Portland cement.As a final check we use X-ray diffraction (XRD) to establish what compounds are forming with time.It is well known what compounds form in Portland cement with time, we also know the compounds that form with composite cements using GGBS and PFA. Therefore, we evaluate our raw materials or blends of materials to ensure that these compounds are not adversely affected by our materials.

Technical performance

We have produced cement substitutes that can out perform GGBS and PFA over the first seven days of strength development and at twenty eight days they fall between that of GGBS and PFA, these substitutes are flexible and can be altered to equal the performance of GGBS or PFA.

Industrial Partnerships

In addition to the companies first stakeholder we are currently seeking project partners to further develop the technology for a wide range of concrete applications.

The types of industries and companies we are targeting are manufacturers or producers of:
· Pavers
· Bricks
· Blocks
· Aerated concrete
· Dense precast concrete
· Prestress beam & block flooring
· Sea defence systems
· Ready mix concrete
· Cold lay road surfaces

In addition to theses manufacturers we are talking to cement companies, waste producers & recycling companies.

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Celtic Cement Technology Ltd.
The Research Centre
Unit 1, Former Stormydown Aerodrome
Stormydown , Bridgend, Wales, UK, CF33 4RS

Telephone: 01656 789970

Contact Gary Hunt

Recycle for Wales