GLA44-055 Brand and Rae Final Report.fb9e4d6d

8/3/2019 GLA44-055 Brand and Rae Final Report.fb9e4d6d

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R&D

Final

Report:Glass

Creating markets for recycled resources

Full Scale Operational Trials Involvingthe use of Recycled Glass in theManufacture of Concrete Blocks

Project code: GLA44-055

Date of commencement of research: May 2005Finish date: December 2005

Writ ten by: Gary Bell

Brand & Rae LimitedRussell M ill, Springfield, Cupar, Fife, KY15 5QX.

Tel: 01334 652828 , Fax: 01334 655967 ,www.brandandrae.co.uk

Published by:

The Waste & Resources Action Programme

The Old Academy, 21 Horse Fair, Banbury, Oxon OX16 0AH

Tel: 01295 819900 Fax: 01295 819911 www.wrap.org.uk

WRAP Business Helpline: Freephone: 0808 100 2040

Date (published) March 2006

ISBN: 1-84405-257-5038GLA
http://www.wrap.org.uk/http://www.wrap.org.uk/


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Full Scale Operational Trials Involving the use of Recycled Glass in the Manufacture of Concrete Blocks 1

Contents

Page

1 Summary ......................................................................................................................................2

2 Research Objectives.....................................................................................................................3

3 Methodology................................................................................................................................4

3.1 Bonnyrigg Trials ..................................................................................................................4

3.2 Russell Mill Trials................................................................................................................5

3.3 Market Acceptance ..............................................................................................................7

4 Results..........................................................................................................................................8

4.1 Bonnyrigg Trials of Standard Dense blocks ........................................................................8

4.2 Russell Mill Trials of Albatherm Lightweight blocks and Albatherm Dense Standard

blocks ..............................................................................................................................................8

5 Conclusions................................................................................................................................11

6 Appendix....................................................................................................................................12


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1 Summary

This project seeks to determine into which products and at what level it would be most advantageous to use crushedrecycled glass in concrete blocks. The tests were carried out at our two site locations: Bonnyrigg, a mobile block makingplant situated to the South east of Edinburgh; and Russell Mil, a static block making plant in Springfield, Cupar, Fife. Thisallows a comparison of mobile and static block making methods. Approximately 75,000 blocks of four types wereproduced: Eden Dense, Albatherm Dense, Albatherm Lightweights and Dense Paint Grade. These were subsequentlytested in our own laboratory and in a NAMAS accredited laboratory.

Tests were carried out at Bonnyrigg on the mobile plant during June and July 2005 on Eden Dense Blocks. These trialshave shown that the maximum level of acceptable aggregate replacement with crushed recycled glass is 40%. Once thelevel exceeded 40% of recycled crushed glass then the blocks began to slump, i.e. the amount of moisture in the mixcould not be absorbed by the aggregates and cement which meant that the block was not able to retain its shape.

Tests commenced at Russell Mill on the static plant in August and were completed in November 2005. These have

shown that the amount of crushed recycled glass which can be used is greatly increased without the problems ofslumping taking place. This is due to the orientation in which the blocks are laid, on the static plant they are laid on thelong end, whilst on the mobile plant they are laid on the short end which means a much greater weight is to be broughtto bear on the block as it sets. 80% of crushed recycled glass has been used as a direct replacement for naturalaggregates in these trials without any detrimental effect on the performance or handling of the block. However, thecolour did significantly change, giving a greener tinge as the percentage of glass increased.


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2 Research Objectives

To determine if recycled crushed glass can be used as a replacement for primary aggregates in themanufacture of concrete blocks;

To determine if there is any difference in the quality of a concrete block produced using recycled crushed glasson a mobile or static plant;

To determine the optimum amount of crushed recycled glass that can be used as a direct replacement forprimary aggregates in a range of concrete blocks;

To demonstrate that a concrete block made with crushed recycled glass as one of its component parts does notaffect its performance when compared with a conventional concrete block;

To produce a series of commercially viable concrete blocks using crushed recycled glass as a replacement for aproportion of the primary aggregate;

To gain market acceptance of concrete blocks produced using crushed recycled glass.


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3 Methodology

3.1 Bonnyrigg Trials

At our Bonnyrigg site the blocks were produced on mobile block making equipment (pictures of the site shown below).

The concrete plant uses a 4 bin aggregate delivery system, feeding via a weighing conveyor to the pan mixer, at whichpoint the cement and water are added. The glass, sand, fine aggregate and coarse aggregate are loaded into the bins bya wheeled loading shovel, the mix design is then fed into the plant computer control system and the aggregates areweighed onto the conveyor as required by the mix design.

Once the block mix has been combined in the pan mixer it is gravity fed into a holding hopper, a forklift fitted with ahopper then loads the mix and carries it to the Finlay F44SGA block making machine. This is an Egg Layer machine andoperates by vibrating the concrete mix into a mould; the mix is then tamped down to ensure correct density. The mouldis then lifted off the blocks and the machine moves forward leaving 44 blocks on the floor behind it. It is then ready to

commence the production cycle once more.

The blocks are allowed to cure for 24hrs and are then banded in batches of 44, picked up and taken to the storagearea, where they are left in place for a minimum of 2 weeks before they are ready for sale.

Illustration 1 Crushed glass ready for use Illustration 2 Glass being loaded into concrete plant bins



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Illustration 4 - Glass and aggregate mixed in bins Illustration 5 & 6 - Blocks being manufactured

A series of trials were carried out with the crushed recycled glass replacing the fine and coarse aggregate, thepercentage replacement being expressed as a total by weight of the total materials used in the block. In the 10 and 20%mixes the glass replaced only the fine aggregate. It is only as the total amount of glass used increases that an elementof the coarse aggregate is taken out.

The glass was prepared by Viridor/MacGlass, by crushing, washing and screening to a 6mm to dust size. It has beenshown that if the glass is allowed to become any larger then health and safety and handling issues with the blockbecome more prevalent as the glass tends to break into slivers that can be sharp.

The standard mix proportions for the blocks produced at Bonnyrigg are:

Coarse Aggregate 800kgDust 800kgSand 300kgCement 145kgWater 140kg

3.2 Russell Mill Trials



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At Russell Mill the blocks are produced on a static plant in the following manner. The aggregates are fed into a groundhopper by the wheeled loading shovel and into the 4 bin aggregate delivery system via a radial conveyor. Theaggregates are then fed into a weigh hopper, controlled by the plant computer and according to the mix design, andthen by an elevating conveyor to the pan mixer, at which point the cement and water are added.

Once the block mix has been combined in the pan mixer it is fed via a short conveyor into the static block plant receivinghopper and is vibrated into the block mould. Batches of 11 are made directly onto wooden or plastic pallets, which arethen transported to the curing rooms by forklift truck. The blocks remain in the curing room on the pallets for 24 hrs andare then moved by forklift truck to the cubing machine where they are sorted into packs of 44, strapped and taken intothe storage area where they remain for a minimum of 2 weeks before they are ready for sale.


Illustration 7 - The concrete plant at Russell Mill Illustration 8 - Blocks being manufactured at Russell Mill

A series of trials were carried out with the crushed recycled glass replacing the fine and coarse aggregate, thepercentage replacement being expressed as a total by weight of the total materials used in the block. In the 10 and 20%mixes the glass replaced only the fine aggregate. It is only as the total amount of glass used increases that an elementof the coarse aggregate is taken out.

Once again the glass was prepared by Viridor/Macglass as per the specification for Bonnyrigg, although the trials weredelayed due to the glass being too large for use in the paint grade blocks. B&R screened the glass supplied by

Viridor/Macglass to a 6mm-dust size, using its own screening plant at Russell Mill.

In these trials a series of higher quality blocks were made:

Lightweight these blocks are a lightweight alternative to standard dense blocks and are designed to be no more than14kg in weight but have all the other properties of a dense block. As such a minimum amount of lightweight materialmust be used in the mix in order that the desired weight can be achieved.

Paintgrade these blocks have a higher quality of finish, i.e. a closer surface texture, to allow them to be paintedwithout the application of a render finish, as would be required with a standard dense block.

Masonry Grade these blocks have a quality of finish to allow their use externally without any further treatment and areoften coloured by the addition of a pigment.


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3.3 Mark et Acceptance

To gain market acceptance of the glass blocks an open day for customers has been organised for 30th May 2006 atBonnyrigg. It is intended to invite all interested customers, specifiers and local authority personnel in order that they canbe made aware of the new product. In the meantimemix designs and results will be forwarded to British Standards in

an attempt to change the relevant standard (BS60731

) to allow for the incorporation of glass as a replacementaggregate in concrete blocks. Details of the trial results will also be posted on the Brand & Rae website to allowcustomers access to the block specification. In addition B&R will be presenting at the Glass Action event in Sheffield on21st 2006 March, to which members of the Concrete Block Association will be invited.

1

BS6073 : Part 1 : 1981 : Appendix B (relating to strength testing)


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4 Results

4.1 Bonnyrigg Trials of Standard Dense blocks

The trials at the mobile plant at Bonnyrigg were completed on 28th July 2005. Internal results have indicated that amaximum of 40% crushed recycled glass can be included in the concrete block. Above this level the block exhibitedsigns of slumping as previously described. The external test results have shown that the block does have an optimumpercentage of crushed recycled glass at which the strength is at a maximum and the drying shrinkage is at a minimum;that percentage of replacement glass is 30% by weight. The strength drops off quickly once this level has beenexceeded, as shown in the summary of results in the appendix. This may be due to a limited amount of slumping, whichdoes not affect the shape but causes a differential in density from top to bottom of the block, resulting in failure at alower load. The Drying Shrinkage shows a minimum level at 30% replacement glass and starts to increase once againwhen that level is exceeded; again this may be caused by a differential in density. Lower levels of drying shrinkage aredesirable as the block is less prone to crack when it dries out and is less likely to suffer any adverse affects caused byexposure to the elements.

MacGlass/Viridor have a limited amount of suitable glass available to B&R and have indicated that this is likely to be17,000 tonnes per annum. B&R intend to manufacture a 30% glass replacement block and market it as a new product toits range, this should permit around 2 million of the blocks per annum to be manufactured.

4.2 Russell Mill Trials of Albatherm Lightw eight blocks and AlbathermDense Standard blocks

Trial results from the static Russell Mill plant can be summarised as follows:

Albatherm Lightweight blocks:

Operational Handled and behaved as would a conventional lightweight block and averaged 13.8kg in weightPerformance Achieved 8N/mm2 strength in 28 days so will conform to the relevant standard

Aesthetics There were no colour or texture variations

Trials of the 20% replacement in the lightweight blocks at Russell Mill took place and the blocks have handled andbehaved as would a conventional lightweight block. The internal 28 day test results have shown crushing strengths toaverage 8.0 N/mm2 (Newton per square mm), which shows that the blocks will therefore meet British StandardBS60731. All British Standard blocks have to meet a minimum crushing strength, which involves crushing a block todetermine at what strength it fails. This is important when designing failure loads and load bearing capabilities of thestructures in which the block will be used. Three standard strengths are used in the British Standard, 3.5 N/mm2, 7.0N/mm2 and 10.5 N/mm2; the strength is increased/decreased by adding/removing cement from the mix. The targetstrength for the lightweight block trials was 7.0 N/mm2, so by achieving 8.0 N/mm2 the blocks have surpassed theBritish Standard requirement. This opens up the opportunity to reduce the cement in the production trials to get nearer

the 7.0 N/mm2 target and thus save money in the process, although this will have to be determined over a longer periodof time and in all weather conditions.

Albatherm Standard Dense Blocks Albacrete Paint Grade and M asonry Grade block trials:

Operational Handled and behaved as would a conventional block although at higher levels of replacementglass the edges of the blocks became sharper

Performance Achieved better 28 day strength to conventional block

Aesthetics There was a variation in colour with increasing levels of glass sand

Trials of the Standard Dense, paint grade and masonry grade blocks at Russell Mill, have shown that much higher levelsof replacement glass can be achieved on a static plant as compared with the mobile equipment at Bonnyrigg. As


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previously discussed, this is thought to be due to the different orientation in which the blocks are manufactured; theyare laid on their long dimension as opposed to being laid on the short dimension in a mobile plant. This results in theblocks being less prone to slumping and as they are moved away from the manufacturing area then the vibration of thenext batch being made does not have an affect on the block. Strengths continued to increase as the levels ofreplacement glass increased, this may well be due to the finer particles of glass displaying a pozzolanic effect and ofcourse less slumping. However, with the increased glass content the likelihood of an alkali-silica reaction (ASR)increases. As such we need to await the outcomes of the accelerated ASR testing being carried out by Napier University,before these blocks can be marketed. These results are anticipated in late spring.

The external test results showed that the strengths did indeed exceed those of the control blocks and that the dryingshrinkage results were also better than those of the control blocks. This would indicate that the blocks containing theglass were a stronger more competent block than the standard blocks produced. There was no clear demonstration ofwhat would produce the best block as was the case at Bonnyrigg, the strength of the block increased with the increasingamount of glass. However the best drying shrinkage result was achieved at 45% glass replacement, after that the dryingshrinkage began to increase once more, although at 50, 60 and 70% glass replacement the results achieved were stillbetter than those of the standard blocks.

The improved drying shrinkage results could well be as a result of the glass not absorbing water as a standardaggregate does, which would have the added advantage of making the block less susceptible to frost and adverseweather conditions.

Full Scale Operational Trials Involving the use of Recycled Glass in the Manufacture of Concrete Blocks 9Illustration 9 - Sample blocks in the laboratory


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Test Panels

Test panels have been built and rendered for each block type produced. The purpose of this is to determine if there isany reaction between the mortar/render and the block and to ensure that the adhesion of the render is not affected bythe presence of glass in the block. This is obviously critical to the end use of the block. The cut outs from the panelswere sent to Bureau Veritas for testing in accordance with British Standard BS1881: 2072. The results indicate that thebond between the render and the block is sound. Therefore, there should be no problem in rendering this type of block.

Illustration 10 - Test Panels before and after rendering


BS1881 : 207 : 1992 (relating to adhesion of render)


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5 Conclusions

There is little doubt from the results that recycled crushed glass can be used as a replacement for natural aggregate in aconcrete block without affecting its performance, indeed in many cases the performance is enhanced. The dryingshrinkage results are most encouraging as they seem to suggest that the blocks are more compact and less likely toabsorb water which results in the block being less susceptible to frost and other adverse weather conditions.

The only concern is the possibility of an alkali-silica reaction (ASR) at the higher glass contents. Even this can bedesigned out of the block by adding some furnace ash to the mix at as little as 10%. The furnace ash acts in very muchthe same way as does Pulverised Furnace Ash (PFA), where research at Dundee University has shown that adding PFA toconcrete mixes including crushed recycled glass results in no ASR.

At Russell Mill B&R have yet to find an economic, reliable source of supply of crushed recycled glass. The distance fromMacGlass/Viridor makes the use of glass from that source uneconomic as compared with natural aggregates, and theydo not have sufficient glass for both Bonnyrigg and Russell Mill. B&R are committed to the use of crushed recycled glassas an aggregate replacement and have entered into negotiations with a local recycling company in an effort to secure a

supply of suitable glass sand. The potential at Russell Mill is far greater than that of Bonnyrigg, as much as 35,000tonnes of glass could be used at as little as 45% replacement for natural aggregate.

It is felt by B&R that the glass needs to be collected and recycled locally in order for it to be economic as well asenvironmentally beneficial; the more road miles the glass has to travel, both in collection and reprocessing, and indelivery to end use, the less the extent of the beneficial environmental impact.


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6 Appendix

Summary of External Block Analysis

Thermal Conductivity *

W/mK

DateTested

ReportNos.

Block Type

Identification,

Percentage

Glass

MeanDensity,

Kg/m 3

MeanCompressive

Strength,

N/mm 2

MeanDrying

Shrinkage,

%age Protected

Exposed

Bulk DryDensityKg/m 3

6-9/8/05 M23931,M23931/1

BR-E/D,0% Control

1950 10.1 0.060 0.99 1.09 1930

6-9/8/05/

M23912,M23912/1

BR-E/D,20%

1940 10.4 0.060 0.99 1.09 1930

6-9/8/05 M23913,M23913/1

BR-E/D,30%

1920 12.6 0.045 0.99 1.09 1960

3/11/05 M24711,M24711/1

BR-E/D,35%

1800 7.5 0.050 0.87 0.96 1800

3/11/05 M24710,M24710/1

SP-A/C- STD20%

1780 11.6 0.045 0.87 0.96 1780

3/11/05 M24729M24729/1

SP-A/C- STD30%

1920 12.0 0.065 0.99 1.09 1930

3/11/05 M24730,M24730/1

SP-A/T- STD20%

1440 10.4 0.080 0.51 0.57 1440

20-21/12/05

IHT

M21107/AIHT

Control440 STD 7N

1520 8.8 N/A N/A N/A N/A

* An empirically (experimentally) based formula, based on density has been used to calculate thermalconductivities.


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Summary of External Block Analysis

Thermal Conductivity *

W/mK DateTested

ReportNos.

Block Type

Identification,

Percentage

Glass

MeanDensity,

Kg/m 3

MeanCompressive

Strength,

N/mm2

MeanDrying

Shrinkage,

%ageProtected

Exposed

Bulk DryDensityKg/m 3

M25198M25198/1

AC/PG, 0% 1800 10.7 0.100 0.87 0.96 1800

M25222M25222/1

AC/PG, 25% 1830 10.8 0.090 0.91 0.99 1830

M25223,M25223/1

AC/PG, 45% 1840 11.7 0.080 0.92 1.01 1840

M25298M25298/1

AC/STD, 0% 1800 11.1 0.115 0.87 0.96 1800

25-Novto

03-Dec

M25297,M25297/1

AC/STD,50%

1860 12.8 0.095 0.94 1.04 1860

* An empirically (experimentally) based formula, based on density has been used to calculatethermal conductivities.

Abbreviations:

N = Newton.K = Degrees KelvinKg = Kilogram = Lambdam = Metremm = MillimetreW = WattsKg/m3 = Kilograms per metre cubed.N/mm2 = Newtons per millimeter squared.

W/mK = Watts per metre per Kelvin.

A/C = Albacrete. A/T = Albatherm.BR = Bonnyrigg.E/D = Eden Dense.IHT = In House Test.SP = Springfield.STD = Standard.

GLA44-055 Brand and Rae Final Report.fb9e4d6d

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