UK Quality Ash Association....the power behind PFA

Transcription

1 UK Quaity Ash Association...the power behind PFA

2 The UK Quaity Ash Association Introduction The UK Quaity Ash Association (UKQAA) is a trade association representing the producers and users of PFA (puverised fue ash), aso known as fy ash in some appications and many countries and FBA (furnace bottom ash). We promote the use of PFA and FBA to the benefit of the environment by reducing primary materia consumption, and encourage its use as a vaued resource with significant technica benefits. Sponsorship of research The association sponsors a broad range of research projects reating to the environment, soi stabiisation, sufate, choride, carbonation and chemica resistance of fy ash concretes. This creates documentation to hep specifiers adopt European Standards and provides guidance for seecting measures to enhance durabiity. We are aways activey ooking at ways to target specific areas and yet to broaden our research profie to subjects which are new and possiby radica. European and British standard committees The UKQAA heps to expand the utiisation of PFA and FBA through representation on numerous European and British Standards committees. Presentations at your premises We provide information to a and offer presentations at your preferred ocation and time on the uses of coa ash aong with the potentia advantages and environmenta benefits. Various appications PFA and FBA can be used in a variety of appications incuding: concrete / concrete bocks / bricks grouting (fiing redundant mine workings etc) as a fi materia ightweight aggregate road construction / maintenance soi stabiisation

3 PFA the benefits and advantages Puverised Fue Ash (PFA) and Furnace Bottom Ash (FBA) are by-products from coa fired power station eectricity generation. This vaued resource is a safe and versatie construction materia with a history of use spanning amost 60 years. Types of ash Dry PFA - suppied into readymixed and precast concrete products, bock manufacture, grouts, etc Cassified ash - dry PFA, processed to remove the coarser partices - it is used as a concrete addition and suppied in tankers Conditioned ash - PFA that is mixed with an appropriate percentage of water - it is used for bock manufacture, grout, oad bearing fi and andscaping - suppied in tipping vehices Some of the various appications and benefits Fy Ash as an addition in concrete 1 PFA is a pozzoana. This means it reacts with ime to form siicate hydrates - these hydrates give concrete its enhanced strength and durabiity. Suppied to EN450-1 Gives increased concrete strength and durabiity Cassified fy ash reduces the water content of concrete - reducing permeabiity Improves sufate resistance and reduces the risk of ASR Reduces the heat of hydration compared to Portand Cement Lightweight concrete permits smaer bases to be used in construction due to reduced oad Produces highy workabe concrete that easiy fows around reinforcement, such as in sef compacting concrete 1 For further detais see Technica Datasheets 1.0 and 1.1

4 PFA as a structura fi: Used as a oad bearing fi 2, in road sub bases and andscaping: Lightweight - reduces the oad on weak ground Sef hardening - offers considerabe advantages over natura cay/granuar materia Low permeabiity - sheds rain water naturay, which reduces eaching Can be mixed with ime to give increased strength due to pozzoanic reaction PFA for grouting When mixed with cement and/or ime, PFA grout 3 is used for fiing fissures, voids and cavities such as, redundant mine workings and pipe work systems e.g. sewers. It is aso used in gunite appications and for fiing behind tunne inings. PFA grouts have many advantages over traditiona sand/cement grouts: Economica Reduced water/soids ratio Increasing strength, extended setting time, ow shrinkage and reduced permeabiity with time Improved pumpabiity A high resistance to chemica attack PFA and FBA as ightweight aggregates PFA dampened with water is passed across a dish peetiser. The peets are heated to fuse the partices. This aggregate 4 known as Lytag is used in structura concrete. FBA ightweight aggregate is used in ightweight concrete bock manufacture. Benefits of ightweight aggregate and aerated concrete bocks Produces a cost effective and insuating buiding materia Reduces the environmenta impact of bock production, with the possibiity of obtaining environmenta credits. An aerated concrete bock contains over 80% PFA Lightweight bocks are easier to hande and cheaper to transport Fy Ash in soi stabiisation Fy ash can be used in soi stabiisation to hep prevent sufate heave in cay. 2 For further detais see Technica Datasheet 2 3 For further detais see Technica Datasheet 3 4 For further detais see Technica Datasheet 4

5 Cenospheres Cenospheres are unique free fowing powders composed of hard sheed, hoow, minute spheres. The main appication is that of inert fier. Cenospheres can be used in paint, varnish, pastics, amost anywhere traditiona fiers can be used. As a resut of their fexibiity they are used in many high technoogy and traditiona industries e.g. Aerospace, hovercraft, carpet backing, window gaze putty, concrete repair materias, horticutura use and off shore oi and gas production. Environmenta considerations Coa fired power station ash has a ong history of use in and recamation, heping to encourage new growth of trees, grass and fowers in areas that woud remain barren and toxic. The ist of appications incudes restoring farm and and woodand habitats. With carefu management no probems shoud be found. To our knowedge there is no recorded case of an environmenta probem being caused by coa fy ash products in the UK. For further information see "Ashes to Assets?" 5. The use of coa ash is resource efficient and minimises the use of primary aggregates thus saving them for more appropriate speciaised uses. This aso diverts materia from andfi and resuts in concrete with substantiay ower CO2 emissions.it is the strength enhancing properties of coa fy ash that reduces the overa energy needed in the manufacture of concrete and so provides benefits when whoe ife costing techniques are empoyed. Back in October 2010 the Quaity Protoco for PFA was pubished in coaboration with WRAP and the Environment Agency. 5 Ashes to Assets? Wooey GR, Simpson DT, Quick W & Graham J, PowerGen UK pc. In genera usage the term fy ash is used for puverized coa ash but it can aso cover ash from burning other materias. Such fy ash may have significanty differing properties and may not offer the same advantages as ash from burning puverized coa. Information provided in this document is intended for those who wi evauate its significance and take responsibiity for its use and appication. UKQAA wi accept no iabiity (incuding that for negigence) for any oss resuting from the advice or information contained in this document. It is up to the user to ensure they obtain the atest version of this document as the UKQAA revises and updates its pubications. Advice shoud be taken from a competent person before taking or refraining from any action as a resut of the comments in this guide which is ony intended as a brief introduction to the subject. V3 February

6 UK Quaity Ash Association Mape House Kingswood Business Park Hoyhead Road Abrighton Woverhampton West Midands WV7 3AU UK Te: +44(0) emai: