Technology Design

7/28/2019 Technology Design

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Technology design

Concrete works:

-establish the concrete mix proportions according to NE 012-1999

1 .Concrete mix

The concrete composition will be established in two situations:

A) Normal mix , without additional agents;B) Concrete mix with additives for additives for delaying the setting for the concrete.

A) Normal mix , without additional agents:

Concrete mix parameters:

-the concrete type is: C20/25/P8/G100-T3-1 32.5(R)/31mm-II

-the concrete workability is T3 with a cone settlement of 7020 mm (annex 1.4 , table1.4.3, table 1.4.3, line 2 foundations of reinforced concrete , columns , beams, structural walls);

-the cement type, according to table 1.2.1, is I 32.5 or II/A 32.5, depending on:

a. service and exposure conditions;

b. erection condition and the used technologies;

c. the concrete class.It chosen the cement with the class II/A 32.5 R

-the maximum grain size is according to point 3.7, from annex 1.4: max1/4(1/3D, incase of slabs, D-the minimum thickness of the structural element);

max1/31 50 mm, hp=15 cm;

maxd -5mm=50-5=45 mm, d=50, the minimum distance between bars;

max1,325=32,5 mm, c=25 mm, thickness of the concrete cover , max,aggregate =31 mm

The concrete class used is C20/25 for the superstructure: beams, girders, columns andslabs.

Standard mix for one cubic meter:

C20/25-T3-II/A32,5R-31


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1. Evaluation of the water quantity is according to the concrete class and the concreteworkability (annex 1.4, table 1.4.2).

A=1851/m 3, for aggregate =31 mm

2. Evaluate of the water-cement ratio depends on the concrete class an the concreteworkability (annex 1.4, table 1.4.2)

3. Evaluation of the cement quantity (table 5.5)

C= 3

From table 1.4.5: C min =290 kg/m 3 C=336 kg/m 3

4. Evaluation of dry quantity of aggregates

1 m 3 = 1000 dm 3 =

a = 20 dm 3/m3 betons = 2 %

c=3kg/dmc

aggregate =2,7 kg/dmc

Gag = ag (1000 - A -a )

Gag = 2,7 (1000 - - 185 -20 )=1844kg/m3

5. Grading the aggregates

The area of granularity recommended according to the concrete workability and thecement quantity (300-400 kg/mc) is: II(annex 1.4, table 1.4.5). The limits for the granularity areaII, for aggregates with dimensions between 0-31 mm are(annex 1.4, table 1.4.8):


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Area Limit Passing throught the sieves

0,2 1 3 7 16 31

II max 7 30 40 60 80 100min 2 21 31 51 71 95

average 4,5 25,5 35,5 55,5 75,5 97,5

rounded 4 25 35 55 75 100

N0 3 =

N3 7 =

P7 16 =

P16 31 =

1844kg/m 3

Laboratory mix for one cubic meter:For the laboratory work mix 185 l/m 3 water is used, in order to obtain T3 workability.

From the tests resulted bef = bcomputed . The standard mix becomes the laboratory mixA=183 l/m 3; A/C=0,55 ; C=336kg/m 3; Gag=1844 kg/m 3, N0-3=635 kg/m 3, N3-7=369 kg/m 3,P7-16=369 kg/m 3, P16-31=461 kg/m 3.

b= 336+185+1844=2365 kg/m 3

Working mix for one cubic meter:

The natural moisture of the aggregate is considered. The quantity of aggregates iscorrected taking into account their humidity:

-fine aggregates 0-7 mm: Us=2%;

-coarse aggregates 7-71 mm: Ug=1%.

This humidity represents a quantity of water that has to be subtracted from the quantity of water. The aggregates moisture is evaluated with the formulas:


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= = 13 l/m3

= = 7 l/m3

= = 4 l/m3

=

=

7 l/m3

29 l/m3

1873 kg/m3

The water quantity introduced for one cubic meter is:

W=W - =185-29=156 l/mc

b= W+C+Gag=156+336+1871=2363

Working mix for a composition:

All the above computation has been made for one cubic meter of concrete. In reality,there are mixers with different capacities. For a mixer of g=550dm 3, the result becomes:

r- reduction coefficient by mixing and compaction, r=0,7

= = 54,6 l/m 3

= = 118l/m 3

G ag=130+132+130+163=655kg/mix


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TS1.Technological sheet for the concrete mix

Component Concrete type C16/20-T3-II/A32,5R-31Standard Working

1 m 550 dm

Water 185 156 54,6A/C 0,55 0,55 0,55Cement 336 336 118

Aggregate N0-3 645 658 230 N3-7 369 376 132P7-16 369 373 130

P16-31 461 466 163Gag 1844 1873 655Pb 2365 2365 -

B. Concrete mix with additives for delaying the setting of concrete

The additives have the following purpose:

- decrease the water content from the mix;- increase the concrete workability;-increase the time for the setting of the concrete;-increase the compression resistance of the concrete;-increase the durability of the concrete.

Preliminary mix for a cubic meter of concrete:

C16/20-T3-II/A32,5R-31/REPLAST

1. Evaluation of the water quantity- is reduced with 10%A=185 -18=1671 l/mc

2. Evaluation of the water-cement ratio

3. Evaluation of the cement quantityC= 3

4. Evaluation of dry quantity of aggregates

1 m 3 = 1000 dm 3 =

a = 20 dm 3/m3 betons = 2 %


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