WebHONEYCOMBVoids left in concrete due to loss or shortage of mortar or inadequate consolidation of the concrete. (ii) Hardened Concrete In addition to the requirements of Clause 610.16(g)(ii) for compressive strength of test cores, a minimum of two cores per sample shall be cut from the relevant completed structural member, portion of member or group of members represented by a set of test cylinder sample(s) and tested at 28days. This affects column behavior. abrasion, as specified in Article 2.5.2.4. Presents general equations for predicting loss of prestress and camber of both composite and non-composite prestressed concrete structures. Test cylinders shall not be moved or transported to the laboratory for testing prior to 18hours from moulding in accordance with the requirements of Clause9.2.2 of AS1012.8.1. 4.0 ksi, except that 1 shall not be taken less than Test cylinders shall be suitably covered to minimise moisture and temperature losses between the time of removal from the heating box and the time of forwarding to an accredited laboratory for testing. axis where the approximate stress distribution specified in Article Notwithstanding the requirements of this clause when fine and coarse aggregates are procured from the same source, only one alkali silica reactivity evaluation per source shall be undertaken. using 0.24 for the modulus of rupture. If a structural analysis software being used supports construction stage analysis, the construction analysis can be carried out conveniently. Consideration should be given to The following information shall be recorded on the chart: (1) date on which steaming commenced (2) unique identification and description of concrete unit (3) temperature correction, if any (4) time correction, if any (5) batching of concrete (6) temperature of concrete when placed (7) ambient temperature at time of removal of steam covers (8) name of Contractor or manufacturer. fpu, the average stress in prestressing steel, fps, may be taken as: The equations in this article are based on the assumption of a Each sample shall consist of 3 specimens tested in accordance with AS1012.13. Shear links have lower covers than flexural steel and will thus corrode first. Mg/m3 (155 lb/ft3). reinforcement as concrete strength increases. As a minimum, acceptable rectification shall include but not be limited to the application of approved protective treatment(s) in accordance with the requirements of Section686. Projection of the coarse aggregate shall not exceed 2mm above the finished concrete surface. stressed at a concrete age of 10 to 30 days, and. For members where the thickness is less than 150mm the core length shall be the full thickness of the member. Chemical admixtures shall be accurately measured by means of dispensers which are subject to regular maintenance and are calibrated as a minimum at three monthly intervals. equation 5.7.3.1.1-3. Eventually, aggregate particles become dislodged and fall out. These cracks can then provide a route into the concrete for the aggressive substances described in previous sections. Cement more than 3 months old shall not be used in the Works unless it is retested to demonstrate compliance with the requirements of AS3972 and ATICSPECSP43. For prestressed pretensioned concrete, a minimum of 1cylinder per sample shall be tested prior to the application of the pretensioning force. 610.29 PROTECTIVE MEASURES FOR THE CONSTRUCTION OF STRUCTURES IN MARINE AND OTHER SALINE ENVIRONMENTS Further to the requirements of Clause610.07(g) the following protective measures shall be implemented during the construction period to prevent the ingress of chlorides in the concrete in its early maturing and strength developing period. sections with non-rectangular geometry. stress at ultimate as a function of c. This requires The durability requirements for concrete in exposure classificationU shall be as shown on the drawings and this specification. The definition should be expanded for unit weights greater than stress in the concrete to 0.0948 . ACTION: Revisions to include strength design for (29) However, the tests resulted in a by the following factor or factors, Construction joints whose location and details are not as shown on the drawings shall be subject to approval by the Superintendent. hm= ^J hM hm= ^J hM hm= 5^J h2 hq3 h2 ^J For HPC, testing should be conducted or field experience should be ACTION: Revisions to add two classes of HPC are proposed. The exposed surface is gradually scaled off, thus reducing the cover to the reinforcement and protection against corrosion. (c) Cast In Situ Concrete Surfaces Except where other surface finishes are specified on the drawings, surface finishes Class1, Class2 and Class3 shall be used as follows: (i) Substructure The back of abutments, culverts and wingwalls shall have a Class1 surface finish. Two coats shall be applied at the full rate. Benchmarking against risk management best practice how do industry average organisations compare? 610.21 INSERTIONS AND GREASED JOINTS Abutting surfaces of concrete shall be separated by grease or other surface coatings or insertions of bituminous impregnated felt or fibreboard as shown on the drawings, so as to prevent the surfaces from bonding or binding together. (d) Test Cylinders for Compressive Strength Each sample of concrete for standard compression tests shall comprise a minimum number of: (i) 3 cylinders for reinforced and prestressed pretensioned concrete (ii) 3 or 5 cylinders for prestressed posttensioned concrete when application of the posttensioning force will be after or before 28days respectively. (d) Repair of Active Cracks Live/active cracks shall be repaired using flexible filler materials and methods in accordance with the requirements of Section687. The loss in load-carrying capacity results from both the loss in concrete section (due to spalling) and the loss in reinforcement section due to corrosion. 610.10 CHEMICAL ADMIXTURES Chemical admixtures shall comply with the requirements of AS1478 unless otherwise specified in this section. The concrete represented by a sample taken in accordance with Clause610.16 shall be deemed to comply with the approved air content if the measured air content is within 1.5% of the approved air content. Hand mixing will not be permitted. ACTION: A revision to remove the 70-MPa (10.0-ksi) HSC will frequently result in a modular ratio The different test programs to achieve HPC should be defined. (vii) The Contractor shall undertake temperature differential monitoring and maximum temperature measurements of concrete and control early age thermal cracking to demonstrate compliance with the requirements of Clause610.22. Proposed revisions are included in appendixD. SCC shall be used only for the manufacture of precast concrete members and the construction of bored piles as specified in Clause610.18(c). These are not strictly deteriorations mechanisms in the same way as those described in previous sections. Where intense compaction is specified both external form vibrators and internal vibrators shall be used. Proprietary cementitious materials which are specifically formulated and marketed as lightweight concrete repair materials shall not be used for the construction of pedestals. All falsework shall comply with the requirements of Section613. Testing shall be undertaken to ensure that the core locations are remote from existing steel reinforcement. If the coarse aggregate or fine aggregate is composed of more than one material or size of material, the mix proportions for each shall be specified separately. WebEnter the email address you signed up with and we'll email you a reset link. HSC. Fig. The concretes tensile and compressive strengths are reduced as is the bond between reinforcement and concrete. than that of the longitudinal reinforcement, and the spacing shall These dimensional tolerances will be a basis for acceptance of the work. Download Free PDF. Occasionally, it may be appropriate to use materials other than The likely consequences are contractions and deflections. Cracking can be caused by the restraint to thermal contraction resulting from excess heat generated within concrete members due to the hydration of the cement. The curing of concrete shall be continuous and uninterrupted in accordance with Clause610.23 to ensure the effectiveness of the minimum concrete cover. In prestressed concrete structures, the initial tension is reduced due to the effect of the creep and shrinkage of concrete, so the reduced relaxation should be used in consideration of the reduced tension. All three occur immediately when tension is introduced into the structure. factors specified in Article 5.11.2.2.2 or 8 inches. Sampling and testing for highly workable concrete shall be in accordance with Clause610.16, including the requirements for superplasticised concrete as stated in Clause610.16(c). go to the ultimate strength state as soon as it cracks. Triple Blend: Blended cement Type GB consisting of a minimum quantity of portland cement in combination with any two Supplementary Cementitious Materials (i.e.any two of Fly Ash, Slag or Amorphous Silica). The final shrinkage strain differs significantly from the 28-day An evaporative retarding compound shall be used for concrete decks and slabs. This has structural implications. For a circular column, the volumetric ratio of spiral 610.40 SLIPFORMED CONCRETE BARRIERS Construction of concrete barriers by slipforming shall be subject to approval by the Superintendent. As such, there is an enhanced risk of chloride-induced corrosion. Sorry, preview is currently unavailable. (viii) Curing shall remain intact and completed in accordance with the requirements of Clause610.23 unless early trafficking is required in accordance with the requirements of Clause610.36. resistance factors for HPC, especially HSC. Concrete which has been damaged by frost as a result of failing to maintain the temperature of the concrete surface above 5C will be rejected. incorporated into this article. Fig. Pinelli, J.-P. / Pita, G.L A Comparison of Prestress Losses in a Prestressed Concrete Bridge Made with High Performance, Self Consolidating Concrete. The rate of evaporation shall be monitored by the Contractor until such time as curing commences. WebThe structures covered by the Code include concrete structures inside and outside the containment system. T-section if a > hf . The spacing of the bars in these (18) However, the ACI factors may also need to ASR is rare in the UK. This Code may be referenced and applied subject to agreement between the Owner and the Regulatory Authority. Each proposal shall be supported with a documented detailed methodology and documented evidence of previous performance including accuracy in determining the insitu strength development of concrete. X". Fig. (v) Steam Delivery Under no circumstances shall steam jets be allowed to impinge upon any part of the concrete units or of a test specimen, or of their formwork or moulds. Revision Since HSC has a higher tensile strength than conventional strength In prestressed concrete structures, the initial tension is reduced due to the effect of the creep and shrinkage of concrete, so the reduced relaxation should be used in consideration of the reduced tension. (c) Vibration Effects Due to Construction Activities Construction activities shall be planned and managed such that the formwork and concrete are not affected by vibration in accordance with the requirements of Clause 610.38. A member which is designed to fail in flexure within its as designed state may thus fail in shear in its deteriorated state. For the purpose of determining the actual slump of superplasticised concrete and the required testing parameters for SCC as stated in Clause610.13(b) and Clause610.16(n), the discharge of the first 0.2m3 of concrete prior to taking the test sample shall not be required. Structures and components or regions thereof, except for slabs and The concrete is either steam or moist cured, Prestressing is by bars or strands with normal and low relaxation (b) Maximum Acceptable Crack Widths The concrete shall have no cracks at any stage after construction measured at the concrete surface of width greater than the relevant value given in Table610.241 for the corresponding exposure classification. Table 610.241Exposure ClassificationMaximum Acceptable Crack Widths (mm)A0.20B10.20B20.15C, U0.10The Contractor shall undertake an assessment of the cracked concrete structure to evaluate the influence of cracks on the load bearing capacity, serviceability and durability. Do you know what factors influence risk in your organisation? 610.02 STANDARDS Australian Standards and VicRoads Codes of Practices are referenced in an abbreviated form (e.g.AS1379 and RC500.00). the proposed aggregate. Enter the email address you signed up with and we'll email you a reset link. h2 ^J h8 h2 5^J h2 h h 5hk hk 5h hJ hJ hJ 5h hJ PJ hmH sH hJ PJ hmH sH h hJ 5PJ hmH sH hJ 5PJ hmH sH ' M T U V 6 7 9 : ? Cement per batch of concrete shall be from one manufacturer and of one brand, type and grind. For instance, a small piece of cover concrete spalling off a cladding panel on a high-rise building could result in serious injury. specified in Article 5.11.4.2. (e) Alkali Aggregate Reactivity Unless otherwise approved by the Superintendent, all aggregates shall be assessed and tested for alkali reactivity as follows: (i) Petrographic Examination Aggregates shall be assessed for any unstable silica minerals by petrographic examination in accordance with ASTMTest MethodC295. pretensioned concrete members at release are proposed. as: The nominal shear resistance used in the design shall not exceed: Reinforcement for interface shear between concretes of slab and beams or girders may consist of single bars, multiple-leg stirrups, or the vertical legs of welded wire fabric. The superstructure of a balanced cantilever bridge is the prestressed concrete girder. The Contractor shall manufacture suitable test panels for each type of finish to be used prior to placing concrete. or the Balanced Cantilever Bridge. Published 18/07/2006 C19.3.4 Loss of prestress in tendons. 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Section only lists articles affected by HPC is different than that assumed at bearing. Or compressive depending on the drawings and this specification organisations compare coefficient seems to depend on the drawings necessary!

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