Low Carbon Construction
Reducing carbon emissions is a priority for all involved in construction: from product suppliers, manufacturers and merchants to designers, specifiers and contractors.
Portland Cement: the key component of mortars and concrete, releases significant amounts of CO2 during manufacture. Most agree we’re a long way from a world without mortar and concrete, but there’s a lot that can be done right now to substantially reduce energy and CO2 emissions when using cement-based products in construction.
Steintec have been developing energy lowering methodologies since launching low carbon bedding mortar and publishing "eco" guidance in 2006.
Our guidance has principally promoted the responsible and sparing use of our cement-based products as a way of minimising waste and reducing CO2 emissions.
Further to this, we’ve developed a strategy of five highly effective ‘carbon-reducing actions’ to be employed in combination to reduce CO2 emissions and waste.
CARBON REDUCING ACTION 1 Product Design and Development
In designing its ‘tuffbed 2-pack low carbon bedding mortar’ Steintec have achieved several significant carbon lowering benefits;
i) 80% of our tuffbed 2-pack low carbon bedding mortar is aggregate. By not drying this significant portion of the product we avoid significant energy use normally associated with drying the aggregates, which is typically done when producing pre-blended products: this saves 14kg of CO2 per tonne of mortar over more conventional products.
ii) The ‘Structure First’ principle of enhanced interlock of aggregate particles means the mortar achieves great performance whilst using significantly less cementitious binder: this saves an additional 128kg CO2 per tonne of mortar over more conventional products. see download 'Low Carbon Mortars’.
iii) By supplying the aggregate content separately it can be delivered in bulk to larger projects, significantly reducing the need for packaging.
CARBON REDUCING ACTION 2 ‘Just in Time’ Logistics for Source and Delivery
Steintec uses ‘Just-in-Time’ logistics, a demand-driven strategy where energy and time is expended on manufacturing and transporting products as directly as possible from source to site as the customer/market dictates. This has major carbon lowering benefits;
i) Use of raw materials is synchronised to manufacturing to keep transport to a minimum and avoid energy use in moving stockpiled materials around.
ii) Our manufacturing volumes are directly aligned with customer/market demand resulting in little or no surplus production.
iii) Delivery direct to site is encouraged in order to reduce the total ‘road miles’ covered by our finished products.
iiii) By supplying the undried aggregate content of tuffbed 2-pack low carbon bedding mortar separately to coincide with the delivery of binder we avoid the need for the double handling of materials associatated with pre-blended products.
CARBON REDUCING ACTION 3 ‘Innovation in Construction and Onsite Working Methods’
Steintec’s R&D programme has enabled us to develop innovation in 1. construction techniques and 2. On-site working methods.
- Construction techniques; that capitalise on the strength and high-performance characteristics of our products have helped us devise ways of eliminating the use of mass concrete in the base/foundation of some pavement designs. This approach, employing a bound surface over an unbound base or ‘bound over unbound’ is an effective way of reducing carbon emissions in pavement construction. There are, of course, projects where the elimination of mass concrete isn’t possible, due to particular project and site factors, but even in these scenarios it is still possible to achieve reductions in mass concrete used, through the carefully considered use of reinforcement.
- On-site working methods; our research also shows further CO2 and energy reductions are achievable using careful pre-planned site methods to include:
- strategic placement of materials throughout the site as close as possible to the point of use avoids double handling and reduces waste
- use of efficient portable forced action mixers, Steintec provide specialist tools and equipment including forced action mixers which improve working efficiency and quality of preparation
- use of specialist tools also encourage best practice on-site by preparing appropriately sized batches of fresh mortar to the lay worker on demand
In combination, these methods promote quality workmanship and realise measurable on-site reductions in waste and energy use.
Side note – The myth about silos.
Through our R&D we’ve also established that it is a common misconception that silos are efficient and economical. Quite the opposite! Silos require mains water and power supply and a fixed location on site for delivery vehicle access. Specialist vehicles are required that can't be used for other purposes while the empty silos themselves are large and heavy and require return haulage. Materials must be double handled on-site, requiring disruptive transportation of tubs of large batches of mixed material across the site. Mixed material settles/compacts in the tub during transportation and while waiting to be used. The material can become difficult to use risking performance issues in the finished pavement and slowing layworks. Unusable material becomes waste with all of the negative environmental issues of handling and disposal. The silo mixing trough requires constant cleaning causing further significant wastage of material. Silos can also be unreliable, requiring ongoing maintenance visits and causing disruption on site.
CARBON REDUCING ACTION 4 ‘Insistence on Good/Best Practice in Design and Specification’
Good design and correct specification are essential in delivering an attractive, durable and long-lived pavement. In support of this approach, Steintec makes its extensive technical knowledge and experience available to all professionals engaged in the design and construction of modular pavements.
With regard to poorly designed and constructed pavements the following cannot be overstated;
The premature failure of a pavement is the ultimate carbon crime. The demolition, disposal and subsequent replacement of a failed pavement with newly manufactured materials not only generates an excessive amount of CO2, but it is also entirely avoidable. Also, a pavement requiring high levels of maintenance to manage chronic flaws and defects resulting from poor design and construction is a ‘High Carbon Liability’.
Creating attractive pedestrian spaces is fundamental to encouraging people to leave their cars and enjoying our towns and cities on foot. High quality, well designed and constructed pavements lie at the heart of this approach with the potential to hugely reduce energy use and CO2 emissions. So, more than ever, it is incumbent on design professionals to deliver successful, attractive long-lived pavements. Getting is ‘more or less right’ is no longer good enough because the environmental costs are simply too high. Steintec’s products and technical support are dedicated to supporting designer and specifier and the imperative of ‘getting it right the first time.’
CARBON REDUCING ACTION 5 ‘Putting our Products into Context with BREEAM’
BREEAM is the Building Research Establishment’s Environmental Assessment Method. The BREEAM Green Guide to Specification allocates ratings (the degree of impact) to most building materials, products and systems used in construction, including pavement construction.
In the case of modular pavements the greatest environmental impact by far results from the choice of paving unit and base/foundation materials. Although bedding and jointing mortars are a critical component within these systems they also represent a relatively small proportion of the overall volume of material contained in a finished pavement. Therefore, in the BREEAM ‘Green Guide’ they are not allocated individual impact ratings.
Despite this, Steintec feels it important that the specifier is aware that at the heart of our products is our “structure first technology”, employing 30% less binder whilst delivering outstanding structural performance. This ensures our products achieve a responsible balance between product performance and environmental impact.
See download ‘BREEAM’ which contains more information on Modular Pavement materials and their environmental impact ratings in the BREEAM Green Guide.
See download ‘Green Credentials’, describing Steintec’s approach to product development and manufacture and how this contributes to reduced carbon emissions.