GENERATION AGGREGATES - RWE02 GENERATION AGGREGATES QUALITY PROTOCOL FOR THE PRODUCTION AND USE OF PFA RWE Power International and RWE npower’s coal fired power stations supply ash

RWE Power International

GENERATION AGGREGATES Providing readily available, cost effective secondary aggregates

1: Aberthaw – supply of FBA and dry and conditioned PFA

3: Tilbury – Supply of stockpiled PFA

2: The Generation Aggregates sales desk and RWE npower head office, Swindon

GENERATION AGGREGATES

Our secondary aggregate PFA can replace primary aggregates, helping to meet environmental targets.

1 2 3

PROVIDING READILY AVAILABLE, COST EFFECTIVE SECONDARY AGGREGATES 01

Pulverised Fuel Ash, or PFA as it is more commonly known, is a by-product of coal-fired power stations. Along with Furnace Bottom Ash (FBA), which is also produced by burning coal to generate power, PFA is recognised as a safe and versatile construction material.

The properties of PFA make it an ideal, cost-effective

alternative to primary aggregates across a range

of applications, including:

– grouting: filling voids created by old mines or

redundant quarries and improving the bearing

capacity of soils

– engineering fill: for use as a load-bearing fill when

building embankments and road sub-bases, as well

as soil stabilisation

– landscaping: used in large-scale earthworks or the

reclamation of derelict land

– building materials: in the manufacture of building

materials, including concrete, concrete blocks,

cement, tiles and bricks.

With the environmental impacts of obtaining primary

raw materials becoming less and less acceptable, PFA

helps to reduce the demand for virgin aggregates and

assists businesses in meeting their recycling targets and

reducing their carbon footprint.

About us

RWE Power International coordinates the sales and

distribution of ash from RWE npower’s coal-fired power

stations in Southern England and South Wales, ensuring

that PFA is readily available to our customers. As part

of the RWE group, we can call upon the capabilities and

resources of one of Europe’s largest utility companies.

With the expertise that comes from over 80 years

of producing and utilising PFA in the UK, we have

an outstanding knowledge of the material and its

use in different industrial applications.

Technical support

With our engineers and scientists specialising in ash and

environmental issues, RWE Power International is able to

offer an exceptional level of technical advice, supporting

the sale and use of power station ash products.

We can offer extensive knowledge covering the

geotechnical, physical and chemical analysis of PFA.

Our technical support includes:

– monitoring ash quality in accordance with the Quality

Protocol (please refer to the following page) to ensure

its suitability

– advising on the standards relevant to the use of ash

across different applications

– providing product certificates for all our ash products

– providing technical data to enable you to assess the

suitability of ash in your particular application

– advising on best practice for use in your application.

Our quality system is accredited to ISO 9001. For more

information, or if you would like an ash sample to trial for

your particular application, please contact us.

ABOUT PULVERISED FUEL ASH

02 GENERATION AGGREGATES

QUALITY PROTOCOL FOR THE PRODUCTION AND USE OF PFA

RWE Power International and RWE npower’s coal fired power stations supply ash products in line with the WRAP Quality Protocol specifically for bound and grouting applications.

Quality Protocol compliant PFA is produced to meet

the requirements of a relevant product standard or

client specification for a given application and is

therefore regarded as a product and not as a waste.

Benefits

The Quality Protocol will bring the following benefits:

– makes it easier for you to use PFA in projects or processes

without the need for waste management controls

– provides you with the confidence that the ash

product you receive conforms either to a known

relevant product standard or your own specification

and is suitable for a given application

– provides suppliers, customers and regulators with the

assurance that ash products are produced and used

in a manner that protects and brings overall benefits

to the environment.

We provide product certification to accompany all

our commercial supply documentation.

We are always interested in developing new uses

for PFA and are happy to work together on the

creation of client specifications where standards are

yet to be developed.

Our responsibility

We are committed to acting responsibly, so advise

you to use all of our products in accordance with best

practice and in a manner that does not cause harm

to the environment or human health. Please contact

us for more information on best practice.

RWE Power International now supplies ash based

products in accordance with the Quality Protocol

for the following applications:

PFA based products – Bound and grout applications

We manufacture lightweight aggregate filler products

according to BS EN13055 parts 1 and 2 suitable for

use in the following applications:

– hydraulically bound mixtures, for example, to form

pavement layers by stabilisation with lime or cement

– bitumen bound mixtures, for example, to form road

base layers and surfacing

– concrete and other bound building products, for

example, as a lightweight filler aggregate in blocks

– grout, for example, geotechnical grouting of caverns

or redundant mine workings.

PFA based products – Unbound applications

We manufacture a lightweight aggregate filler product

according to BS EN 13055-2 and in accordance with

the Specification for Highway Works (SHW) 600 series

for the following applications:

– engineering fill and landscaping, for example,

embankment construction or raising of levels.


MAKING YOUR PROJECTS GREENER

Government and industry is working collectively through the “Green Construction Board” (GCB) to drive forward actions set out in the Low Carbon Construction Action Plan. The target is to achieve an 80% reduction in greenhouse gas emissions in the built environment vs 1990 levels by 2050.

See how Generation Aggregates and

our ash products can make your project

more sustainable and help ensure that

the construction sector secures

continued growth whilst using green

goods and services:

ACT ON WASTESelling ash products from coal-fired

electricity ensures beneficial utilisation

of large quantities, avoiding landfill.

PFA can also be used to stabilise poor

or contaminated soils on your projects,

eliminating the need for costly disposal.

ACT ON WATERPFA absorbs water and is therefore not

easily saturated, so where it is used as

engineering fill, it allows construction work

to continue in bad weather, keeping your

projects on track.

ACT ON CARBONPFA is lower in density than other virgin

aggregates and soils so requires less

vehicle movements (approx. 25%) to

transport the same amount of material. The

replacement of Portland cement with PFA

also reduces the greenhouse gas signature

of concrete by lowering emissions of CO2.

ACT ON MATERIALSOur ash products are certified to the

UK Quality Ash Associations (UKQAA)

Responsible Sourcing Certification scheme.

Ash products as opposed to virgin

aggregates can be used across a range

of construction and building applications.

They offer a low cost alternative with low

environmental impact whilst maintaining

performance and improving the resource

efficiency of your projects.

ACT ON BIODIVERSITYPFA can be covered by or blended in with

topsoil to support a full range of

biodiversity and boron tolerant vegetation.

Where landscaped and left uncovered, PFA

gradually becomes colonized by plant and

animal species. This gives rise to biodiverse

habitats, particularly plants that thrive in

the alkaline conditions of PFA such as

Orchids and Marsh Helleborine. These in

turn attract many insects including

butterflies and bees, and birds such as

Skylarks and Sand Martins.

PFA is typically used as an engineering fill material behind bridge abutments and in the building of embankments and bypasses or as part of any major civil engineering project where an extensive amount of imported fill is required.

The superior benefits of PFA as a fill material come

from its lower density when compared to soils.

PFA has a density of 1.5Mg/m3 compared to around

2Mg/m3 for soils. These benefits include:

Reduced settlement in poor underlying soils. There is

also minimal long-term measurable settlement within

the fill material after placement and full compaction.

It is lightweight leading to savings in materials and

haulage costs. For example, there is approximately

a 25% reduction in lorry movements.

Increased stability as its self-supporting properties

provide stable conditions for shallow trenches and

other excavations.

Other significant benefits include immediate and

increasing strength. For example, field tests on

existing embankments have demonstrated the

positive strength gain and long term stability of PFA.

In addition, PFA will absorb water and therefore is not

easily saturated, allowing construction work

to continue in bad weather conditions.

To suit specific project requirements, RWE Power

International can supply two types of PFA for use

as engineering fill:

Conditioned ash taken directly from silos to which

water has been added. This assists with the delivery

and subsequent compaction on site.

Stockpiled ash previously conditioned ash which has

been placed temporarily on a stockpile before delivery

to site.

We have supplied PFA for use in many successful

engineering fill projects, including the widening of the

M25 motorway, see opposite.

PFA FOR ENGINEERING FILL



RWE Power International supplied over 88,000 tonnes of PFA to the M25 widening project in Essex for various construction applications, proving what a successful and versatile construction material it is.

CASE STUDY 1PFA PROVIDES A SUSTAINABLE SOLUTION TO THE M25 WIDENING SCHEME

The M25 widening project (Junctions 27 to 30) is

currently being carried out by Skanska Balfour Beatty

Joint Venture for Connect Plus, working on behalf

of the Highways Agency, as part of the Design, Build,

Finance and Operation contract for the M25.

This is one of a number of major improvement

schemes on the M25, which was originally completed

in 1986 with the use of over one million tonnes of PFA.

RWE Power International secured a contract in 2009 to

supply conditioned PFA for the project. Material was

supplied from RWE npower’s Tilbury Power Station in

Essex for the first phase of works between Junctions

27 and 28. Approximately 88,000 tonnes of

conditioned PFA was used as a general fill to

widen the existing motorway embankments and

as fill behind some of the retaining wall solutions.

At its peak, up to 3,250 tonnes of PFA were being

delivered per day, with RWE Power International

coordinating up to 175 daily lorry deliveries.

PFA being used as fill to widen the existing M25 embankments PFA being compacted on site

PFA FOR GROUTING

Grouting is the injection, under pressure, of suspensions for structural purposes. This is often undertaken to improve the geotechnical properties of soils and rocks and allow for the future development of the land.

Cheaper and easier to use than sand cement grouts,

PFA grouts normally consist of PFA, Portland cement

and water. They bring the environmental benefit

of a reduced need for primary aggregates and high

cement contents, meaning cost savings for customers,

improved durability and reduced CO2 emissions.

The self-hardening properties of PFA also allow for

the production of low strength grouts containing

only PFA and water.

PFA grouts can:

– reduce the permeability of the ground

– increase the shearing resistance and subsequent

strength and durability of the ground

– fill inaccessible voids.

The benefits of PFA grouts include:

Reduced bleeding

A low rate of bleeding (typically less than 1%)

that improves the stability of grout suspensions.

Increased yield

Compared to cement, using PFA produces higher

volumes per unit weight. Typically it takes 0.7 to

1.0 tonnes of PFA to produce a cubic metre of grout,

compared to 1.6 tonnes of a primary aggregate

such as sand to produce the same. The need for

less materials and transportation reduces costs.

Ease of use

Grouts containing PFA are more easily pumped

and require less water than those without. It is also

possible to delay the setting of PFA mixtures for

up to four hours, so they remain pliable for longer.

These improved flow properties mean PFA grouts

can be pumped longer distances and through small

diameter pipe work.

Using PFA in cementitious grouts results in a more

durable composition. PFA can replace the use

of sand as a filter, improving flow properties and

penetration (without limiting the size of cracks

or fissures to be injected).

Increased strength

The slower rate of strength development but longer

term final strength of PFA/cement grouts can offer

economic benefits.

Increased resistance to chemical attack

PFA improves the sulphate resistance of grouts,

leading to reduced volume requirements and

less disruption.


grouting projects, including a ground stabilisation

project in South Wales, see opposite.



RWE Power International provided PFA from RWE’s Aberthaw Power Station for a grouting project to facilitate the construction of a new 7km bypass close to Pontypridd, South Wales.

CASE STUDY 2PFA PROVIDES COST AND USABILITY ADVANTAGES OVER PRIMARY AGGREGATES IN GROUND STABILISATION FOR THE CONSTRUCTION OF A BYPASS

Ground stabilisation specialist, Forkers Ltd, was

employed by the main project contractor, to

undertake shallow mineworkings treatment at

four points along the route. These locations were

considered to pose a threat to the future stability

of the road if left untreated and in fact, prior to

grouting, the area was deemed unsuitable for

development and construction, due to the unstable

nature of the ground.

Therefore, ground stabilisation in the area was

essential and this phase of the project commenced

in September 2008. During this period, probe drilling

was used to locate mineshafts and subsequently,

Forkers drilled 1,920 holes into 59,530 metres

of mine workings, injecting almost 7,000 tonnes

of PFA grout.

To complete this work, up to eight rotary percussive

water flush drilling rigs were used at up to three

areas concurrently, to ensure the earthworks and

road construction programme could proceed at the

required rate.

PFA rather than sand grout was selected in this case,

due to the compressive strength achieved when

mixed with cement. The mix also conformed to the

flow and bleed characteristics specified for the job,

whereas the use of sand would have required the

use of more water and increased costs and logistical

difficulties. Furthermore, the flow properties of the

PFA grout allowed it to be pumped further,

which made site logistics easier to manage for the

project contractor.

From an environmental perspective, the use of PFA

rather than sand reduced the need for ongoing

quarrying, whilst the density of sand is considerably

greater than PFA, which would have required more

material to produce the same volume of grout; the

lower density and cost per tonne of PFA considerably

reduced the cost of the grout mix in comparison

with sand.

The ground stabilisation phase of the project

was completed, on time and within budget, in

January 2009.

PFA is ideal for reclaiming areas of land by providing

subsoil fill.

With the growing importance of planning consent

conditions requiring landscape treatment, PFA can

be the answer to a range of land related problems.

The benefits of PFA in landscaping include:

– it is of known properties and consistency

– it is sterile and free from weeds

– it can be used as a soil forming material.

PFA can be used under topsoil, blended with topsoil

or with treatment it can support vegetation itself.

It is usual to cover PFA with topsoil to allow growth

of plants. However, if there is insufficient good quality

topsoil then PFA can be blended into the available

material to provide adequate cover.

If PFA is not covered it will weather over time and

plants will naturally colonise the surface. This starts

with mosses and, in time, grasses and will ultimately

result in trees such as willow, birch and alder.

However, it is usual to establish growth soon after

placing the PFA to eliminate erosion and dust

blow. This can be done by ripping the surface and

hydroseeding the area. Rye grasses and clovers can

be established on PFA relatively easily, provided

there is sufficient nutrient applied.

It is important when planning to grow plants

on unweathered PFA to select those that are

tolerant to boron, an essential plant nutrient,

and saline conditions.


landscaping projects, including the creation

of the Twenty Ten golf course for the Ryder Cup

at Celtic Manor, see opposite.

PFA FOR LANDSCAPING

As well as having many uses in industry and civil engineering projects, PFA can also be used for landscaping.



RWE Power International supplied over 150,000 tonnes of PFA from Aberthaw Power Station, to help Celtic Manor Resort prepare for the 2010 Ryder Cup.

CASE STUDY 3PFA REDUCES CO2 EMISSIONS AND ENVIRONMENTAL IMPACT IN THE CREATION OF A GOLF COURSE

In order to host one of the world’s most popular

sporting events, a number of significant improvements

were required at Celtic Manor. These included the

construction of a new club house, an extensive

television compound and practice ground, plus

improvements to the championship golf course to

enable it to meet the needs of the world’s top golfers,

media and thousands of expected visitors.

PFA was used to raise up parts of the course that will

eventually form the television compound, driving

range and practice area. This initial phase of

development, involving 100,000 tonnes of PFA, was

so successful that an additional 50,000 tonnes of PFA

was requested to complete the work.

James Norvill at GD Environmental, the contractors

responsible for the improvements at Celtic Manor,

said: “This has been a great project to be involved

in and it has been extremely successful. Ash is the

perfect product for the job, both from an

environmental and construction perspective.”

PFA being compacted to raise levels at the Celtic Manor resort The completed works

PFA IN BUILDING MATERIALS

PFA can be utilised in the manufacture of a wide range of building materials, including cement, concrete and ceramic products such as tiles and bricks and also in aerated and non-aerated blocks.

Concrete

PFA can be used in ready-mixed concrete, concrete

blocks and other concrete products, primarily as

a replacement for cement.

The use of PFA in concrete improves long-term

strength, durability and finish, whilst reducing

thermal cracking, segregation, bleeding and

permeability. The replacement of Portland cement

with PFA reduces the greenhouse gas signature

of concrete by lowering the emission of CO2.

Cement

The UK cement industry consumes nearly 20 million

tonnes of raw materials annually. However, not all of

these ingredients need to be primary raw materials.

PFA can be used in the production of cement

as a replacement for raw materials like clay or

shale. It can also be used to supplement cement

clinker, producing more cement per tonne of

quarried material.

Ceramic products

The properties of PFA make it an excellent raw

material replacement in the manufacture of ceramic

based products, such as bricks.

Aside from reducing the need to use primary

raw materials, utilising PFA can improve the finish

of ceramic products, as well as reducing drying

shrinkage and providing additional strength.

Aerated blocks

PFA can be used as an alternative for ground sand

in the manufacture of Autoclaved Aerated Concrete

Blocks (sometimes known as Aircrete or AAC Blocks).

The use of PFA in aerated block manufacture results

in an increased durability and high insulation values,

making the blocks suitable for the construction of

building foundations.

RWE Power International supplies PFA to some of

the UK’s largest manufacturers of building materials

including H+H UK Limited.


RWE Power International offers a full service to customers from supply of aggregate to technical expertise, after sales advice and guidance through the process.


322/10/13

RWE Power International

Generation Aggregates Electron Windmill Hill Business Park Whitehill Way Swindon Wiltshire SN5 6PB

T +44(0)800 731 2865 F +44(0)1793 892421 E [email protected] I www.generationaggregates.com

Registered office: RWE Npower plc Windmill Hill Business Park Whitehill Way Swindon Wiltshire SN5 6PB

Registered in England and Wales no. 3892782

Documents

GENERATION AGGREGATES - RWE02 GENERATION AGGREGATES QUALITY PROTOCOL FOR THE PRODUCTION AND USE OF PFA RWE Power International and RWE npower’s coal fired power stations supply ash