SANS 10120-5 G-1982 Code of practice for use with standardized specifications for civil engineering construction and contract documents Part 5 Contract administration Section G Con.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

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3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. SABS 0120 : Part 5 Section G-1982 Concrete (structural) PART 5 : CONTRACT ADMINISTRATION SECTION G CONTENTS Clause Page Number START OF CONSTRUCTION . 1

4、General . 1 IMMEDIATELY AFTER THE HANDING OVER OF THE SITE 1 Action by Engineer 1 Essential data 1 Action by Contractor 1 Samples of aggregates . 1 Materials to be used . 1 Proposed mixes for strength concrete 1 Adjustment of concrete mixes 1 DURING CONSTRUCTION . 1 Administration 1 Expansive alkali

5、-aggregate reaction . 1 Water . 1 Plums . 1 Aggregates from beaches. etc 1 Admixtures 1 Fixing of reinforcement . 2 Slumps . 2 Mixing and mixers 2 Curing agents . 2 ejection of concrete . 2 Dealing with defects 2 Testing . 2 Epoxy grout . 3 . Measurement of reinforcement quantities 3 Construction Me

6、thods 3 Cement storage 3 Vibrators . 3 Assembly of formwork 3 . Reinforcement to be kept clean until embedded 3 Cover . 3 Treatment after removal of forms 3 Removal of formwork from cantilevers 4 Placing of concrete in water 4 Curing and striking periods 4 Material used for curing 4 Required average

7、 strength of special concrete . 4 Batching by volume 4 Method of determination of the bulking of fine aggregate 4 Delays in concreting 4 Placing . 4 Compaction 4 Preparation of surfaces for construction joints in concrete . 5 Unformed concrete surfaces 5 . Cold weather conditions 5 Hot weather condi

8、tions 5 . Watertight concrete for water-retaining structures 5 Plane surfaces . 6 Testing and frequency of sampling . 6 Grouting under bases with proprietary materials . 6 QUALITY CONTROL AND OTIIER CONSIDERATIONS 6 . Quality Control through Testing of Concrete Cubes 6 General . 6 Compressive streng

9、th test . 6 Conditions of testing 6 General Quality Control . 7 Disputes 7 Quantities of reinforcement . 7 Concrete floor tolerances . 7 Instructions to demolish 7 First Revision August 1982 This section of the code supersedes SABS 0120 : Part 5 : Section G-1982 Approved by the COUNCIL OF THE SOUTH

10、AFRICAN BUREAU OF STANDARDS SABS 0120 : Part 5 Section G-1982 Concrete (structural) SABS 1200 G : CONCRETE (STRUCTURAL) NOTE: The clause number(s) given at the beginning or after the heading of a clause is/are, unless otherwise stated, the number(s) of the relevant clause(s1 of SABS 1200 G. START OF

11、 CONSTRUCTION GENERAL. For the purposes of this part of the code contract administration starts with instructions to the contractor to commence work as set out in Subclause 4.1 of Section 0. IMMEDIATELY AFTER THE BANDING OVER OF TtIE SITE ACTION BY ENGINEER Essential Data. The engineer should supply

12、 the data set out in (a)-(d) below, as applicable, to the - contractor immediately after the award of the contract if they have not been provided in the tender drawinas or in the schedule: a) Fixing of reinforcenent (Subclause 5.1.2). If so required, reach agreement on details of welding procedure t

13、hat will be approved. - - b) Cover (Subclause 5.1.3). For each portion of the works, state which exposure conditions are applicable. C) egth concrete (Subclause 5.5.1.7). For each grade oi concrete and position on the works state whether concrete produced at a central concrete production facility ot

14、her than on the site of construct.on is permitted and, when a characteristic strength is specified, whether the test results obtained by such a production facility as part of its production control system are to be used as a basis for acceptance or rejection in terms of Subclause 7.3 of SABS 1200 G.

15、 d) Prescribed mix conce (Subclause 5.5.1.6). Advise, for each mix, 1) the water/cement ratio, or 2) the slump. ACTICN BY CONTRACTOR Samples 0: Aggregates. The contractor should supply samples of the aggregates that he proposes to use, obtain early approval for their use and, for strength concrete,

16、supply approved aggregates to the laboratory with detailed instructions as to the mixes to be designed. Materials to be Used (Subclauses 3.4.2, 3.5.1 and 3.5.2). If and as required, the contractor should reach agreement with the engineer in regard to the use of plums, admixtures, and air-entraining

17、agents. Proposed Mixes for StrengLh Concrete (Subclause 5.5.1.7). The contractor should submit details of the - proposed mixes for strength concrete to the engineer timeously for approval. Adjustment of Concrete Mixes (Subclause 5.5.1.7). The methods by which mixes will be adjusted as test - results

18、 become available should be agreed with the engineer before concreting starts. (See also Subclause 7.3 of SABS 1200 G.) DURING CONSTRUCTION ADMINISTRATION Expansive Alkali-Aggregate Reaction (Subclause 3.2 and 3.4). Where Malmesbury shale and similar coarse aggregates that are subject to expansive a

19、lkali-aggregate reaction are being used, monitor the alkalinity regularly. The recommendations given in Subclause 3.2.1 of Section G of Part 2 and Subclause 1.3.2 of Section G of Part 3 of the code are of particular importance, with regard to work in the Western Cape, for the prevention of failure o

20、f concrete due to reaction between Malmesbury shale coarse aggregate and cement. The cement specified will cost more than ordinary cement but the extra cost may be offset by the lower cost of local aggregate. Research to date indicates that the expansive reactivity of the Malmesbury aggregates in co

21、ncrete is considerably reduced when low-alkali cements are used. Until such time as more is known about this reaction, with specific reference to aggregate types arid suitable pozzolanic additives (see Subclause 3.5 of SABS 1200 G) to cement, it is suggested that the contractor should order sulphate

22、-resisting portland cement that complies with the applicable requirements of SABS 4711) and that, by virtue of the manufac- turing process, has a low alkalinity with the Na O-equivalent generally below 0,6 %. Although the alkalinity is not quite what is desired and can,20f course, not be guaranteed,

23、 the use of such a cement in conjunctiorl with Malmesbury aggregate is nevertheless regarded as the best action to take at this stage. To assess whether the sulphate-resisting cement is fulfilling its purpose, it is necessary to monitor alkalinity regularly, and to achieve this, certificates stating

24、 the alkalinity of the actual cement supplied should be obtained from the manufacturers. (It is understood that South Airican manufacturers have undertaken to supply such certificates on request.) Water (Subclause 3.3). Water supplied from a normal municipal source for drinking purposes need not be

25、tested. If the engineer or the contractor is doubtful of the quality of any water, he should arrange for it to be tested by an approved laboratory. Plums (Subclause 3.4.2). The contractor should obtain the engineers agreement to the use of plums and should submit samples for approval. Aggregates Bea

26、ches, etc. (Subclause 3.4). Although the presence of shell is comparatively unimportant in most concrete work, the interpretation of the results of the tests on fine aygregate containing shell, as discussed in Appendix C of SABS 1083), must be considered. Where aggregates of different chloride conte

27、nt are stockpiled on the same construction site, strict control over their use for different classes of concrete must be exercised. (See also Subclause 3.2.2.2 of Section G of Part 2 of the code.) Admixtures (Subclause 3.5) a) The use of chloride-containins admixtures should be prohibited. b) A larg

28、e number of products are available on the market, each of which is claimed to create particular effects. The engineer is advised to consult the nearest branch of the Portland Cement Institute for guidance if he is not thoroughly familiar with any particular product offered. C) Generally, air-entrain

29、ing agents should comply with the applicable requirements of ASTM 260) and water-reducing additives should comply with the applicable requirements of ASTM 494). - - - -. - - - - - - - - - - - - - - - 1) Portland cement (ordinary, rapid-hardening, and sulphate-resistiny). 2) Aggregates from natural s

30、ources. 3) Air-entraining admixtures for concrete. 4) Chemical admixtures for concrete. SABS 0120 : Part 5 Section G-1982 Concrete 3.1.6 (structural) Flxlnq of Renforcelnent (Subclause 5.1.2). The lntentlon of the third paragraph of Subclause 5.1.2 of SABS 1200 G 1s that, a) whether the engineer des

31、lgns and detalls supportlng steelwork or not, the contractor must, by arrangement wth the englneer, be glven the opportunity to vary both the design and detalls, and b) the supportlng steel actually used will be Included In the reinforcement schedule and paid for In terms of Subclause 8.1.2 of SAW 1

32、200 G. In discussing detalls wlth the contractor, the engineer should bear in mind that the contractor bears the responsibility for ensurlng thdt the rernforclng steel 1s so secured that t does not move while concrete 15 belng placed and vibrated, and that the steel recelves the sgeclfled coverlng o

33、f concrete. Slumps (Subclause 5.5.1.2). The contractor should specify the slump he requires as part of hls deslgn for strength concrete and he should mamtaln the slump to wlthln 33 X of that value. Mlxlng and Mlxers (Subclauses 5.5.3.1 (f) and (g) , and 4.3) . P Type or mlxer. The onus 1s on the con

34、tractor to establish to the satlsfactlon of the engmeer that any particular type of mlxer whlh the contractor claims has a shorter mlxlng perlod than that specifled, 1s capable of effrclent and conslatent mlxlng wlthn the shorter period clalmed and that the contractors slte control 1s good enough to

35、 ensure that iull benefit can be obtalned from the efflclency of the mlxer operating for the shorter perlod. U). Check measurements on the slump are the only practcal guide5) to the amount of water that should be added to replace water lost through evaporation when delay rn concreting occurs. Curlng

36、 Agents (Subclause 5.5.6). Curing agents if accepted should be membrane-formlng compounds (preferably of a whlte plgmented type) complying wlth the appllcable requirements of ASTM 309). Rejection of Concrete (Subclause 5.5.14). Patching of concrete surfaces after removal of the shutters may be toler

37、ated but no plastering or cement washing of these surfaces should be permitted by the engmeer. All holes left by the extraction of tles must be made good. The presence of areas of excessive honeycombing or other defects that are apparent on the fmished concrete surface, and that are considered sutfi

38、cent to lmpalr erther the structural strength or the appearance of the work, may be cause for rejection of the affected portlons of the structure. The employer requlres a structure that 1s sound and he 1s entitled to one that wlll not be a permanent eyesore. Because rt 1s a serlous matter, t 1s nece

39、ssary for the engineer to glve written instructions for relectlon of defective concretr., which 1s a reflection on the supervlslon of both the contractor and the engmeer. Such mstructrons are a cause of wasted tlme, disrupted work, and addltlonal expense and must, therefore, not be Issued merely as

40、a dlscxplinary measure. Where rejectloll 1s necessary, t 1s prudent to have adequate photographs taken of the offendlnq member and to record fully the reasons fur the mstruction to demolish and rebuild. Deallng wlth Defects (Subclauses 5.5.14 and 7.3.5). Where defects do not warrant the removal of d

41、efectlve concrete, the eng1nec.r mdy order one or more of the following procedures to be carried out: a) Where the structural strength mlght be affected, repalrs may be effected by the appllcatlon of elther pneumatically placed mortar or a mortar mdde of silwa sand dnd an approved epoxy formulatxon

42、mlxed and applled ln accordance wlth the manufacturers recommendations. In addltlon, neat cement grout may be mjected Lnto cracks or honeycombed areas through nlpples previously fixed in the concrete at appropriate ntervals. b) Where st 1s established that. the structural strength is not lmpalred, t

43、he defectlve materzal should be chlpped away untll solld coarse aggregate 1s exposed and a dense, unlform surface of concrete 1s obtalned. Feathered edges should be cut away to form surfaces perpendicular to the concrete face. Selzed shutter bolts should be cut back to about 35 mm, and the surface o

44、f the cavlty should be saturated wth water for at least 3 h, after whlch a thln layer of neat cement mortar should be applied to the surface. The cavlty should be fllPed wlth stlff mortar mixed In the same proportions of cement to sand as those used m the orlglnal concrete. The mortar should be thor

45、oughly tamped into place in layers. The use of up to 30 X of whlte cement m place of the normal cement may be requrred to ensure that the colour of the patch matches thdt of the orrginal concrete surface. An mterval of 30 mm should elapse betore a flnal surface tamplng 1s applled to the patch, after

46、 whlch the surface should be treated to resemble the surroundrng concrete as closely as possible. Board marks may be produced by pressing a sultable plece of tlmber flrmly agarrist the plastic concrete. The patch should be neat and workmanlike In appearance and after compleilon lt should be kept wet

47、 over a perlod of at least 3 d. Testing Laboratory testing (Subcliuse 7.2.3). The term “approved laboratory“ (see Subclause 2.3 of SABS 1200 G) is deemed to Include any laboratory equipped for concrete testing and established on the site rn terms of the reauirements of the uroiect. soecificatlon or

48、schedule. - Acceptance criteria (average of 3 or more sets of 3) (Subclause 7.3.2). In order to ensure compliance with the requirements of Subclauses 7.3.2 and 5.5.1.7 of SABS 1200 G a check on the average strength of all the sets of samples of any one grade of concrete should be made. If the averag

49、e strength is less than the applicable value given below, steps should be taken to adjust the mlx design. No. of sets wed average strength (of 3 test cubes) 4 specifled strength + 3 MPa 5 Specsfled strength + 4,5 MPa 6 Speclfled strength + 5.0 MPa 10 Specified strength + 6,O MPa 20 Specified strength + 7,O MPa 30 or more Speclfred strength + 8,O MPa Acceptance criterla (30 or more test results) (Subclause 7.3.3) a) Subclause 7.3.3 of SABS 1200 G is specially applicable to major works such as dams, concrete roads, and simllar projects for whlch the volumes of concrete