acc letter - by - 159 - cube test result

7/28/2019 ACC Letter - By - 159 - Cube Test Result

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? .&.,,.Swlt91&uL, ta l l &,&Im k ) l r L - A R I F ONTRACTING C O . (LLC)Eat Year - 1975 A L ARIF GROUP \ qv- - a"d

Ref: ACC//Site480/BY-159Date: 15/05/2013M/s. BEL-YOAHAH(Architectural Eng: Consultant)P.0Box :DubaiUnited Arab Emirates.Attention:Mr. Manoi-ResidentEndneerJob # 480Auci

ect: Cube test resultuDear Sir,Referring to the above project, subject, & your previous site instruction, & referring to technical review withconcrete supplier company (National Ready mix).

Find the attach here with the technical report, & corrective action required.


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/- ' / UI&i; ,en j'Jlfi 1,A! me~ u t i o n u l ~ e a d y m i ~oncrete CO.Date: 12 May 2013

Ref No. AA-2013/05/12To: MIS Al Arif Contracting Company

G+2 Private School Campus on Plot No. 424-4464 A1WarqaSubject: Site Cube Test Results Variation

Dear Sir,

Refer to our meeting at your office last 6thofMay regarding test results variation for site cubes, wewould like to inform you that after conducting site investigation and reviewed all data for the concretesupply to your site our comments are as follows:

1. Conducted Work:


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c) Site curing is not as per standard - Direct exposure to sunlight, contaminated andwithout temperature control mainly causes cube strength variation. (as shown inthe photos attached)

d) Testing - Variations due to sampling error and curing affects i ts compressivestrength results variation.


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Based on the above investigation and results, we would like to inform you that the concrete quality is okand variation is acceptable according to ACI 214.

Our recommendation to minimize this variation:1. Maintain cube moulds regularly by National Ready mixTeam2. Improve the curing facility at site By A1Arif Contracting.3. Give instruction o 3'('party lab to take more caution in handling& Testing.

This is for your information and for any clarification don't hesitate to contact us

' u' Attached:ACI 214Cube test results Analysis


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EVALUATION OF STRENGTHTEST RESULTS OF CONCRETE 21 4R-5

3.3.1 Mean x- The average strength tests result iscalculated usingEq. 3-1).

wherexi sthe i-th strength testresult, he average of at least twocylinder strength tests. Xz is the second strength test result in therecord, ZXi is the sum of all strength test results and n is thenumber of tests in the record.3.3.2 Standard deviation s-The standard deviation is themost generally recognized measure of dispersion of the indi-vidual test data from their average. An estimate of the popu-lation standard deviation


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MANUAL O F CONCRETE PRACTICETable 3.2-Standards of concrete control*

Overall variation

General Below2.8 2.8t03.4 3.4t04.1 4.1t04.8 Above4.8~Z8p" I I I Ibelow 400) (400 to500) ( 500 to 600) (600 to 700) (above 700)- .- - - - - -

Class ofoperationStandard deviation for different control standards, MPa (psi)Excellent 1 Very good 1 Good I Fair I Poor

- 1 I I I I

zlgEi Below 3.0 1 3.0 to 4.0 I 4.0 to 5.0 I 5 . 0 a 6 . O I Above6.0Classofoperation

trial Below2.O 2.0t03.0 3.0t04.0 4.0t05 .0 Above5.0L.bontOrylatches I I

Above2.4(above 350)Lainnatorytrialbatches~- - -~oef fici& tofva riatio n for diie &i t control standards, %Excellent 1 Very good 1 Good I Fair 1 Poor

-*f; i;34.5 MPa (5000psi).

W~thin-test ariation

Table 3.3-Standards of concrete control*

Below 1.4(below 200)

Overall variation

1.4to 1.7(200 to 250)

Class ofoperationCoefficient of variation for dii eren t control standards,%

Excellent 1 Very good 1 Good 1 Fair I PoorGeneralconstructiontesting

Laboratoryhal atches1.7t02.1(250 to 300) 2.1 to2.4(300 to 350)

Within-test variation

'f,' >34.5 MPa (5000 psi).

Below 7.0Below 3.5

ClassofoperationField con-trol testing~ ~ ~ ~ ~ " ,

SV l = 4 x 100X (3-6)where s l is the sample within-test standard deviation,zis theaverage within-test range of at least 10 tests, d2 is the factorfor computing within-test standard deviation from the aver-age range, V1 is the sample within-test coefficient of varia-tion, andX s the mean, or average, strength test result.

Coefficient of variation fm different control standards,%Excellent 1 Ve~ y ood 1 Good I Fair I Poor

of the sample standard deviation-is the sum of the sample(3-5) within-test and sample batch-to-batch variances

7.0 to 9.03.5 to 4.5

Below 3.0Below2.O

from which the batch-to-batch standard deviation can becomputed as

For example, if the overall sample standard deviation s frommultiple batches is 3.40 MPa (493 psi), and the estimated

9.0 to 11.04.5 to 5.5

3.0 to 4.02 .0to3.0

11.0 to 14.05.5 to 7.0

4.0 to 5.03 .0t04.0

Above 14.0Above 7.0

5.0 to 6.04.0to5.0

Above 6.0Above5.O


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acc letter - by - 159 - cube test result

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