AGGREGATES GENERAL REQUIREMENTS

 

1.       Except as may be modified hereunder the aggregate (fine or coarse) for all types of concrete shall comply with BS 882 “CONCRETE AGGREGATES FROM NATURAL SOURCES” & shall also comply with Dubai municipality administrative order no. 143/91.

2.       The aggregates used in the permanent works shall be naturally occurring or crushed materials obtained only from approved sources.

3.       Before any material from a particular source is used, representative samples of fine & coarse aggregates shall be obtained & necessary tests & analyses shall be carried out to show that the samples comply with the specification. During the progress of the works, the grading & chemical characteristics may be checked at frequent intervals.

4.       Before using the material in the works all the tests result shall be approved by the engineer. Part of each sample will be required for concrete trial mixes & part shall be retained for comparison with subsequent deliveries.

5.       Sampling for testing & analysis shall be carried out, where applicable, in accordance with BS 812 Part 102.

6.       The maximum size of the aggregate shall not be larger than 1/5 of the narrowest dimension between sides of the member for which the concrete is to be used & not larger than 3/4 of the maximum clear distance between reinforcing bars.

7.       Fine aggregate shall be natural or crushed sand & beach sand shall not be permitted for use in concrete mixes.

8.       Coarse aggregate shall be crushed aggregate obtained from a quarry approved by the engineer.

9.       Unless otherwise authorized by the engineer, coarse aggregate shall be delivered to site in separate sizes according to the maximum specified aggregate size for each grade of concrete.

10.   Aggregate shall meet the requirements of table I.

11.   The frequency of testing of aggregates shall be in accordance with table ii or as directed by the engineer.

12.   Aggregates shall contain no harmful material that will adversely affect the strength & durability of the concrete or attack steel reinforcement. Aggregates shall not be composed of or contain any materials likely to cause staining or otherwise to disfigure finished concrete surfaces.

13.   The aggregate source shall not contain material that is potentially reactive to alkalis. Potential analysis of aggregates in accordance of ASTM C 294 & C 295 to identify the mineral constituents. Only the aggregate which is not susceptible to alkali aggregate reaction hall be used. These tests made by the Contractor.

14.   Fine aggregates shall be natural sand, manufactured crushed rock, sand, or combination of both. Manufactured crushed rock sand does not include crushed rock fines which are by-products of course aggregate production. A combination of natural sand & manufactured crushed rock sand will only be permitted where the two materials are separately batched & where each separate material, with the exception of grading ,complies with the requirements of this specification.

 

 

LIMITS FOR PHYSICAL, CHEMICAL &MECHANICAL

PROPERTIES OF AGGREGATES FOR CONCRETE

table i

 

 

KIND OF REQUIREMENT

TEST

 METHOD

PERMISSIBLE LIMITS

 

BS 812

ASTM

FINES

COARSE

 

BS 812

ASTM

FINE

COARSE

 

GRADING

 

PARE 103

 

STD

STD

 

MATERIALS FINER THAN 0.075 MM NAT-URAL , UNCRUSHED / CRUSHED

CRUSHED ROCK

 

PART 103

 

 

 

 

MAX. 3 %

MAX. 7 %

 

MAX. 1 %

MAX. 1 %

 

CLAY LUMPS & FRIABLE PARTICLES

 

 

C 142

MAX. 1 %

MAX. 1 %

 

LIGHT WEIGHT PIECES

 

 

C 123

MAX. 0.5 %

MAX. 0.5%

 

ORGANIC IMPURITIES, TEST 8 OF BS1377

 

 

 

MAX. 0.05%

 

 

WATER ABSORPTION

 

 

 

C 128 /

C 127

MAX. 2.3 %

MAX. 2 %

 

SPECIFIC GRAVITY ( APPARENT )

 

 

 

C 128 /

C 127

MIN. 2.6

MIN. 2.6

 

SHELL CONTENT IN AGGREGATES

COARSER THAN 10 MM

BETWEEN 5 MM & 10 MM

BETWEEN 2.36 MM & 5 MM

FINER THAN 2.36 MM

 

PART 106

 

 

 

 

MAX. 10 %

NOTE 1

 

MAX. 5 %

MAX. 15 %

 

 

 

NOTE 1: THERE IS NO REQUIREMENT OF SHELL CONTENT IN SANDS PASSING 02.36 MM SIZE SIEVE

 

 LIMITS CONT..................................

LIMITS FOR PHYSICAL, CHEMICAL & MECHANICAL PROPERTIES OF AGGREGATES FOR CONCRETE

(TABLE I CONTINUE)

 

 

KIND OF REQUIREMENT

TEST

 METHOD

PERMISSIBLE LIMITS

 

BS 812

ASTM

FINES

COARSE

 

BS 812

ASTM

FINE

COARSE

 

PARTICLE SHAPE

FLAKINESS INDEX

ELONGATION INDEX

 

PART 105.1

105.2

 

 

MAX. 25 %

MAX. 25 %

 

ACID SOLUBLE CHLORIDES , CL

FOR REINFORCED CONCRETES MADE WITH SRPC CEMENTS

OPC & MSRPC CEMENTS

 

FOR MASS CONCRETE MADE WITH

SRPC CEMENT

OPC & MSRPC CEMENTS

 

FOR PRESTRESSED CONCRETE &

STEAM CURED STRUCTURAL  CONCRETE

 

PART 117,

APPEN. C

 

 

 

MAX 0.03 %

MAX 0.05 %

 

 

MAX 0.03 %

MAX0.05 %

 

 

MAX 0.01 %

 

 

MAX 0.01 %

MAX 0.02%

 

 

MAX.0.02 %

MAX. 0.04 %

 

 

MAX. 0.01 %

 

 

ACID SOLUBLE SULPHATES, SO3

 

PART 118

 

MAX. 0.3 %

MAX. 0.3 %

 

SOUNDNESS , MgSO4 ( 5 CYCLES )

 

 

C 88

MAX. 12 %

MAX. 12 %

 

MECHANICAL STRENGTH

10 % FINE VALUE

OR  IMPACT VALUE

 

LOS ANGELES ABRASION

 

PART 111

PART 112

 

 

 

 

C 131/

C535

 

 

MIN. 100KN

MAX. 30 %

 

MAX. 30 %

 

DRYING SHRINKAGE

 

PART 120

 

 

MAX 0.05 %

 

POTENTIAL REACTIVITY , NOTE 2

OF AGGREG., CHEMICAL METHOD

OF CEMENT-AGGREG. COMBINATION

 

 

 

C 289

C 227

 

INNOCUOUS

6 MONTH EXPANSION 0.10 % MAX

 

INNOCUOUS

6 MONTH EXPANSION 0.10% MAX

 

 

 

NOTE 2 : AGGREGATES MAY INITIALLY BE STRESSED FOR ITS REACTIVITY IN ACCORDANCE WITH ASTM C 289 & IF POTENTIAL REACTIVITY IS INDICATED, THEN MORTAR BAR TESTS IN ACCORDANCE WITH ASTM C 227 SHALL BE CARRIED OUT

 

 

 

FREQUENCY OF ROUTINE TESTS ON AGGREGATES

table ii

 

 

KIND OF REQUIREMENT

TEST METHOD

TEST FREQUENCY RATE

1.     GRADING

 

BS 812 PART 103

EACH TWO WEEKS OR PER 100 M3 WHICHEVER IS MORE FREQUENT

2.     MATERIAL FINER THAN 0.075 MM

BS 812 PART 103

- DO -

CLAY LUMPS & FRIABLE PARTICLES

ASTM C 142

- DO -

ORGANIC IMPURITIES

 

 

BS 1377 TEST 8

EACH MONTH OR PER 200 M3 WHICHEVER IS MORE FREQUENT

WATER ABSORPTION

 

ASTM C 128 / C 127

- DO -

SPECIFIC GRAVITY

 

ASTM C 128 / C 127

- DO -

SHELL CONTENT

 

 

BS 812 PART 106

EACH TWO MONTHS OR PER 100 M3 WHICH EVER IS MORE FREQUENT

PARTICLE SHAPE

 

BS 812 PART 105.1,105.2

- DO -

ACID SOLUBLE CHLORIDES , CL

 

QUALITATIVE -

 

QUANTITATIVE -

 

 

BS PART 117 APPENDIX  A / B

BS 812 PART 117 APPENDIX C

 

 

ON EACH DELIVERY TO SITE

 

EACH WEEK IF RESULT IS MORE THAN 75 % OF THE LIMIT & EACH MONTH IF RESULT IS LESS THAN 75 % OF THE LIMIT

 

ACID SOLUBLE  SULPHATE , SO4

 

 

 

 

BS 812 PART 118

EACH TWO WEEKS IF RESULT IS MORE THAN 75% OF THE LIMIT & EACH TWO MONTHS IF RESULT IS LESS THAN 75 % OF THE LIMIT

SOUNDNESS MgSO4 ( 5 CYCLES )

 

ASTM C88

EACH TWO MONTHS

MECHANICAL STRENGTH

 

% FINES OR IMPACT VALUE

 

LOS ANGLES ABRASION

 

 

 

BS 812 PARTS 111,112

 

ASTM C 131 / C535

 

 

EACH THREE MONTHS

               

              - DO -

MOISTURE VARIATION IN SAND

 

BY MOISTURE METER

TWICE DAILY

NOTE : DRYING SHRINKAGE & POTENTIAL REACTIVITY OF AGGREGATES SHALL BE DETERMINED INITIALLY AT THE START OF THE PROJECT OR WHENEVER THERE IS A CHANGE IN THE SOURCE OF SUPPLY

 

FINE AGGREGATES

1.       The gradation of fine aggregate shall be in accordance with BS 882 latest edition excluding grading designation F.

2.       Each batch of aggregate delivered to site shall be kept separate from previous batches & shall be stored for at least 3 working days before use to allow inspection & tests to be carried out.

3.       Fine aggregate shall be clean sharp natural & / or crushed sand & shall be within BS 882 zones c & m only.

4.       Aggregate shall be mechanically washed to remove salts & other impurities in order to meet the requirement specified. ( contractor)

COARSE AGGREGATE FOR CONCRETE.

 

1.       Coarse aggregate shall be prepared as single sized aggregate & blended to produce normal size grading. The combined grading shall be within the appropriate grading limits given in BS 882.

2.       Aggregates that are deleteriously reactive with the alkalis in the cement in an amount sufficient to cause excessive expansion of concrete shall not be used.

3.       Aggregate shall be mechanically washed to remove salts & other impurities in order to meet the requirement specified. ( contractor)

 

COMBINED AGGREGATE.

1.       Approved coarse aggregate & fine aggregate in each batch shall be combined in proportions as specified in BS 882 & as approved by the engineer. However, in no case shall materials passing the 0.075 mm, sieve exceed  3% by wt. of the combined aggregate.

2.       The combined aggregate gradation used in the work shall be as specified except when otherwise approved or directed by the Engineer. Changes from gradation to another shall not be made during progress of the work unless approved by the Engineer.

 

MATERIALS FOR STONE PITCHING

 

1.       Stone for pitching shall be hard, sound, durable, stones as approved by the Engineer. Samples of the stone to be used shall be submitted to & approved by the engineer before any stone is placed.

2.       The requirements for the properties of the stone shall comply with the following values in TABLE I.

TEST

STANDARD

LIMIT

Los Angeles Abrasion

ASTM C-535

45%  Max.

Specific gravity ( apparent )

ASTM C 127

2.5 Min.

Absorption

astm c 127

03% max.

 

3.       The size & shape of the stones shall be such to allow for proper placement. The width of the stone shall not be less than one & one half ( 1-1/2 ) times their respective thickness & lengths of not less than two ( 2 ) times their respective widths. The minimum width shall be 100 mm. 

CONSTRUCTION REQUIREMENTS.

1.       The stones shall be arranged in such a way that the largest stones are at the bottom of the slope of the sub grade or base which is firm & well compacted. The stones shall be placed on a mortar bed.

 

GABIONS.

 

DESCRIPTION

 

Gabion shall consist of furnishing & placing wire mesh boxes rectangular in shape ( galvanized steel fabricated in double twisted woven hexagonal shape with wire diameter of 2.7 mm for mesh size of 8*10cm for boxes & of 2.2 mm of 6*8 cm for mattresses ),filled with clean & uniform rocks larger than the mesh openings in accordance of the following specifications.

 

MATERIAL

 

1.      The rock shall be greater than 150 mm in size

2.      The rocks shall consist of clean solid rock non-friable & resistant to weathering & frost action meeting the following requirements:-

 

TEST

STANDARD

LIMIT

Bulk Specific gravity

ASTM C 128/C127

2.6 Min.

Absorption

astm c 128/C127

02 % Max.

Soundness by MgSo4

ASTM C 88

12 % Max.

 

METHODS OF SOFT AREA TREATMENT

 

Alternative methods of soft area treatment which may be directed by the Engineer:-

1.       Non friable Boulders of sizes between 150 - 300 mm shall be end dumped over the soft area & rolled until the area is stabilized to the satisfaction of the Engineer. Further stones of 10 - 70 mm size shall be rolled into the area until all the areas are leveled & well blinded.

2.       Crushed rock material free from dirt, organic matter, shale & any other deleterious material. The acceptance criteria when graded according to BS812 Part 103 shall be as follows:

 

sieve size

% PASSING

         150  MM

100

100

80 - 100

37.5

-

25

20 - 50

19

-

9.5

0 - 15