Rheology of Self-compacting concrete mortar phase

Luiz A Pereira de Oliveira, Miguel C. S. Nepomuceno and José C. M. Carvalho

C_MADE Centre of Materials and Building Technologies

University of Beira Interior, Covilhã, Portugal webpage: http://www.c-made.ubi.pt/

Twin International Conferences 2nd Civil Engineering & 5th Concrete Future

26-28 May 2013, Covilha, Portugal

5th International Conference on Concrete Future

26-28 May 2013, Covilhã, Portugal

1- Introduction SCC fresh properties required

Filling capacity Segregation resistance Passing ability

Slump-flow test (Yield stress)

L –box test

V-funnel test (Viscosity)

SCC = mortar + coarse aggregates (60%-70%) (30%-40%)

Mortar phase

Modelling the rheological

behaviour of SCC

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portland cement (CEM I 42.5R) specific gravity of 3.14 mineral additions: limestone powder specific gravity of 2.72, biomass ash specific gravity of 2.85, glass powder specific gravity of 2.53. modified polycarboxylic based superplasticizer density of 1.05 fine aggregate crushed granite specific gravity of 2.71

fineness modulus of 2.52.

Materials

2- Experimental Program

Mix proportions and powder materials

Ref. Mixtures CEM I 42,5R (C)

Biomass ash (BI)

Limestone powder

(FC)

Glass powder

(GL)

1 100C 1.00 --- --- ---

2 80C+20BI 0.80 0.20 --- ---

3 80C+20FC 0.80 --- 0.20 ---

4 60C+40FC 0.60 --- 0.40 ---

5 80C+20GL 0.80 --- --- 0.20

6 60C+40GL 0.60 --- --- 0.40

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Methods /Studies in concrete mortar

30

270 mm

60

240

mm

29

V-funnel test Spread test

Ø 70 mm

59

mm

Ø 100 mm

Dimensions of spread and v-funnel tests

1D

DmGm

2

0

t

10Rm


Mortars were produced combining each mixture of powder materials with a constant Vp/Vs =0.70

On average, for each combination of powder materials, three mortars were produced, varying the Vw/Vp and Sp/p% until required fresh properties were obtained.

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The experimental procedure is shown schematically

Mortar fresh properties

0,00

0,20

0,40

0,60

0,80

1,00

1,20

1,40

1,60

1,80

2,00

0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00 10,00

Gm

Rm

Increase of Sp/p% with constant value of Vw/Vp

Increase of Vw/Vp

Increase of Sp/p%

Sp/p% = constant

Vw/Vp = constant

Target assumed in this

research work

Mortar fresh properties

0,00

0,20

0,40

0,60

0,80

1,00

1,20

1,40

1,60

1,80

2,00

0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00 10,00

Gm

Rm

Increase of Vw/Vp with constant value of Sp/p%

Increase of Vw/Vp

Increase of Sp/p%

Sp/p% = constant

Vw/Vp = constant

Target assumed in this

research work



• Gm between 5.4 and 6.2 (Dm between 253 and 268 mm) • Rm between 1.14 and 1.32 s-1

(t between 7.58 e 8.77 s)

Rm and Gm when Vw/Vp increases with Sp/p% constant Rm and Gm when Sp/p% increases with Vw/Vp constant

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Results of fresh properties of mortars inside the admissible range for Gm and Rm

3- Experimental Results and Discussion

Mixtures Mortar proportions

(in weight) W/B ratio Vw/Vp Sp/P%

100C 1.00:1.23 0.278 0.90 1.70

80C+20BI 1.00:0.23:1.54 0.292 0.90 1.80

80C+20FC 1.00:0.22:1.54 0.262 0.80 1.45

60C+40FC 1.00:0.58:2.05 0.269 0.85 1.55

80C+20GL 1.00:0.24:1.54 0.305 0.92 1.60

60C+40GL 1.00:0.54:2.05 0.311 0.90 1.45

Vp/Vs = 0.70

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Torque versus velocity

3- Experimental Results and Discussion Concrete mortar rheological behaviour

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Breakdown detail of different mortars

3- Experimental Results and Discussion Concrete mortar rheological behaviour

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Yield stress Plastic viscosity Shear rate

Bingham model Herschel-Bulkley model

b model parameter indicating the degree of non Newtonian behaviour

b > 1 shear-thickening behaviour b < 1 shear-thinning behaviour

Modelling the concrete mortar rheological behaviour

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Mixtures Bingham Model R2 Herschel–Bulkley Model R2

100C T=-7.372 + 0.994 N 0,979 T=14.83 + 0.045N1.60 0,995

80C+20BI T=15.646+ 1,313N 0,929

80C+20FC T=-0.645 + 0.544N 0,910 T=3.42 + 0.273N1.13 0,994

60C+40FC T=-1.121 + 0.386N 0,993 T=0.80 + 0.205N1.12 0,995

80C+20GL T=-4.142 + 0.779N 0,986 T=6.72 + 0.140N1.33 0,994

60C+40GL T=0.310 + 0.061N 0,978 T=2.54 + 0.001N1.76 0,989

Models equations and correlations values R2

3- Experimental Results and Discussion Modelling the concrete mortar rheological behaviour

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Relative flow area as function of powder addition percentage

Relative flow velocity as function of powder addition percentage


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Relative yield stress as function of powder addition percentage

Relative plastic viscosity as function of powder addition percentage


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Relative flow area versus relative yield stress

Relative flow velocity versus relative plastic viscosity


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Conclusions

The influence of waste glass powder on rheological behaviour of self-compacting mortar phase was studied comparatively with the most common powder addition employed in SCC, the limestone powder.

The increase of glass powder reduces the hysteresis area denoting a reducing in the thixotropy of mixtures.

Indifferently of the powder type the relative flow area was affected by the percentage of powder addition in the mixtures.

The increase of powder addition was also responsible by the relative yield stress decreasing.

The relative flow velocity was reduced at high percentage of glass powder addition and this powder type was also responsible by the lowers relatives’ plastic viscosity.

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Documents

Rheology of Self-compacting concrete mortar phase