centre for cement and concrete strength retention of ar...

Centre for Cement and Concrete

Strength Retention of AR Glass Strength Retention of AR Glass Fibres in Alkali ExposureFibres in Alkali Exposure

Yanfei CheYanfei CheK. PilakoutasK. Pilakoutas

Centre for Cement and Concrete,Centre for Cement and Concrete,The University of SheffieldThe University of Sheffield

14th International GRC Congress14th International GRC CongressNov 2005, Hong KongNov 2005, Hong Kong

Centre for Cement and Concrete OutlineOutline

AimAimExperimental programmeExperimental programmeResultsResultsConclusionConclusion

Centre for Cement and Concrete AimAim

To examine the tensile strength retention of single To examine the tensile strength retention of single glass filaments and strands in different cement glass filaments and strands in different cement related alkali environmentrelated alkali environment

Centre for Cement and Concrete Experimental programmeExperimental programme

Weight lossWeight lossStrength retention Strength retention Single filament in saturated Single filament in saturated Ca(OH)Ca(OH)22 solutionsolutionStrands in saturated Strands in saturated Ca(OH)Ca(OH)22 solutionsolutionStrands in OPCStrands in OPC

sulfoaluminate cementsulfoaluminate cementChina rapid hardeningChina rapid hardeningChina low alkalinityChina low alkalinityUK productUK product

Centre for Cement and Concrete Weight lossWeight loss

80℃100%RH100hrs

Centre for Cement and Concrete Strength retentionStrength retention

Mounting specimens -- filaments

20135

20 20

Super glueGlass filament

adhesive tape

10

Single filament: Plain A4 paper

Strand: chrome paper (non-ageing)

cellophane paper (ageing)


Mounting specimens -- strands

30200

20 20

Super glueglass strand

resin

10

grip area

20

gauge length


SIC test specimens -- cements

OPC China Rapid Hardening

China Low Alkalinity

UK Sulfoaluminate


80℃100%RH

100hrs

rubber sealant tape

SIC test specimens


Hounsfield universal test machineHounsfield universal test machine

Crosshead speed:

For single filaments: 0.52mm/minFor strands: 1mm/min


GripsGrips

For single filaments For strands


Failure demoFailure demo


filament

0

0.05

0.1

0.15

0.2

0.25

0 0.1 0.2 0.3 0.4 0.5

Displacement(mm)

Load(N)

LoadLoad--displacement curvedisplacement curve

strand

05

101520253035

0 1 2 3 4

Displacement(mm)

Load(N)


Measurement of Cross-Sectional Area

Held at 80oC for 200 hours in saturated Ca(OH)2 solution

Filament separated from strand

Cam-Scan SEM


Measurement of Cross-Sectional Area

A=Wi

ρ

Centre for Cement and Concrete ResultsResults

Alkalinity of Ca(OH)2 and final weight loss

1.4112.3012.6312.6513.33

200 hours96 hours24 hours0 hour

Weight loss(%)

PH of Ca(OH)2


Alkalinity of different solution

11.5*10.5*13.2913.33PH

RapidHardening

Cement

Low AlkalinityCement

OPCSaturated Ca(OH)2solution

* Zhang L, Su M and Wang Y. Development of the use of sulfo-and ferroaluminate cements in China. Advances in Cement Research, Jan.1999, 1:15-21


Strength retention

58.1%52.4%56.4%36.5%82.7%30.3%Strength retention

UKRapidLowOPCCa(OH)2Ca(OH)2

StrandsSingle filaments

Variety

Centre for Cement and Concrete ConclusionConclusion

After the alkalinity exposure, fibre strands exhibit softer After the alkalinity exposure, fibre strands exhibit softer characteristics, it is believed that a substantial part of the wcharacteristics, it is believed that a substantial part of the weight eight loss is due to the damage to the sizing. loss is due to the damage to the sizing. AR glass fibre strands demonstrate 50% higher strength AR glass fibre strands demonstrate 50% higher strength retention in sulphoaluminate cements than in OPC retention in sulphoaluminate cements than in OPC fibre strands in saturated Ca(OH)2 showed much higher strength fibre strands in saturated Ca(OH)2 showed much higher strength retention than in OPC of similar alkalinity.retention than in OPC of similar alkalinity.

Centre for Cement and Concrete

Strands before and after Strands before and after alkali exposurealkali exposure

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