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Flyer 3 concrete for industrial floors
Flyer 3 concrete for industrial floors
Flyer 3 concrete for industrial floors
Flyer 3 concrete for industrial floors
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Flyer 3 concrete for industrial floors

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see also ; http://nl.linkedin.com/in/abvandenbos and www.vloerenadvies.eu en www.abt.eu

see also ; http://nl.linkedin.com/in/abvandenbos and www.vloerenadvies.eu en www.abt.eu

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  • 1. constructies civiele techniek bouwmanagement bouwkunde installaties Concrete for industrial floors Concrete for industrial floorsABT stands for jointless industrial floors without The upper limit of the consistency (stability) of the mixturelimitations. Reducing shrinkage is one of the most must be monitored by the mixer.important aspects under the principle of jointlessdesign. Research has been carried out for some timeto reduce shrinkage in concrete, and in the course ofthe years much experience has been gained inadapting concrete mixes for specific cases. Theconcrete mixture used for an industrial floor largelydetermines the ultimate quality of the floor.ABT therefore regards floor concrete as an integral partof the floor design. During execution the most importantproperties are checked by measuring specific parameters.ABT constantly strives to optimise the concrete mixture onthe basis of these findings.High requirements are made of the concrete mixture tobe used in monolithic industrial floors. This entails the figure: pouring concrete with a concrete pumpexamination of the limits of prevailing standards for floorconcrete. This text describes the most important principles Stabilitywith the ultimate formulation of a ‘standard’ mixture. The aggregate must have the right grading to ensure the stability of a concrete mixture. An unstable mixtureWhen determining the concrete composition the can result in bleeding or in extreme cases segregation.following aspects must be taken into account: When bleeding occurs this is particularly harmful to the• desired workability of the concrete during pouring quality of the top layer of the floor. A ‘too stable’ mixture• stability of the concrete mixture can, however, result in a reduction of workability while• shaping and bonding behaviour in the short term for the flow is still high. This also increases the likelihood of the finishing of the floor plastic shrinkage.• generation of heat as a result of hydration and consequent cooling Strength development• strength development in the long term for the load To be able to finish the floor in good time after pouring, bearing capacity of the floor whereby the top layer of the floor is smoothed and sealed,• shrinkage susceptibility of the concrete mixture; bonding must already take place in the concrete after just risk of cracking a few hours. This finishing process must be completed approximately 12 hours after pouring. Too fast bondingSpecific requirements that can be made of floor concrete means the floor cannot be finished. On the other handare: with slow strength development the top layer of the floor• liquid sealing will be insufficiently hard.• resistance to frost and road salt• high resistance to wear Hydration starts approximately 2 hours after pouring (depending on various factors) and continues for a longWorkability time. The 1st night after pouring hydration is fully underIn most cases consistency range F4 or F5 is desired for way and will then gradually slow. The course of hydrationworkability. The desired consistency class is often can be controlled by the adaptation of the cement typesindicated using a slump test. In consistency class 4 and and quantities. This is dependent on the mortar5 (generally the case for floor concrete), according to temperature and outside temperature, floor thickness andNEN-EN 206-1 the flow is normative for measurements. It other circumstances (open air or in a concrete hall).is of great importance to establish the requiredconsistency beforehand. A flow of 600 mm on arrival at After approximately 7 to 10 days the floor must be ablethe work is very likely not the same flow as at the end of to take loads to not impede the progress of the buildingthe pipe with a pipe length of 80 meters. Aspects such work. An average compression strength of 25 N/mm2 isas pipe length, mesh size and any gradients are decisive then desired. The ultimate strength after 90 days mustwhen determining the appropriate consistency. at least suffice with regard to strength class C28/35 for
  • 2. constructies civiele techniek bouwmanagement bouwkunde installatiesConcrete for industrial floorsthe load bearing capacity of the floor. A much greater Aggregate granulate gradationstrength is undesirable because then much higher Grading of 0-32 mm is used in most cases. With thinpercentages of reinforcement are required to limit the (overlay) floors with a thickness of 50 – 80 mm it maycrack width in a floor. be necessary to partly or wholly add 4-16 mm grit, being so-called spramex concrete. With very thin (overlay) floorsShrinkage susceptibility with a thickness of 30 – 50 mm, 2-8 mm grit granulateConcrete shrinks as a result of a chemical reaction, drying gradation can even be used, the so-called microconcrete.out and cooling. As a result of the shrinkage of concrete With a high dosage of steel fibres of over 30 kg/m3 a fineundesired splits and cracking can occur in a floor. grit part is added to the concrete practically as standard.Shrink-free concrete is not achievable within the The granulate gradation may be ‘optimised’ with apreconditions the concrete mixture must, however, be maximum of 20% 4-16 mm grit. The grading of theallowed to shrink as little as possible. Hence granulate aggregate must suffice with regard to the limits of thebedding is applied under the concrete to among other A-B line according to the VBT (regulations for concretethings reduce shrinkage. technology) for reasons of stability, low water requirements and workability.Liquid sealingIndustrial floors can be made ‘impermeable’. The termimpermeable means liquid on the top of the floor cannotpenetrate to the bottom of the floor. Then in any case thefollowing conditions must be satisfied:• minimum strength class C20/25• maximum penetration depth of the liquid amounts to 50 mm• the concrete density must be sufficient• floor working details must be attunedYou can find more information about this subject in CUR65 (design) and CUR 44 (verification). Figure: granulate gradationFrost and road salt resistance The granulate gradation may be ‘optimised’ with aThere is a major risk of the weathering of floors outdoors maximum of 20% 4-16 mm grit. The grading of thewhere road salt is spread. Making concrete extra dense aggregate must suffice with regard to the limits of the A-Band strong can create high resistance to the effects of line according to the VBT (regulations for concretewear. technology) for reasons of stability, low water requirements and workability.The concrete must have a water cement factor of 0.45 for The 70% sieve residue at 1 mm is favourable cost wise,reasons of technical standards. ABT deliberately departs but a strong ‘lounger’ with a flat section requires morefrom this because if the standard is strictly followed the water so there is more shrinkage. This problem can usuallycement content must be increased. Then, however, be remedied by also adding fine sand (0-2) besides coarseshrinkage and accordingly cracking also increase. CEM sand (0-4).III/B used as the basis for ABT concrete mixes has verygood resistance to the penetration of chlorides. Here ABT Fine partsalso counts fly ash from the perspective of durability for To obtain concrete that can be pumped, is workable andthe water binding factor, with a water cement factor sufficiently stable it must have sufficient fine parts smallerapproaching 0.45.The application of air bubbles works than 0.250 mm. For normal floor concrete this is at leastagainst monolithic finishing. Hence ABT usually uses the 140 litres, with steel fibre concrete it is at least 145 litres.basic mixture described in more detail. Spramex concrete requires 5 litres extra (total 150 l). Fine parts and microconcrete 10 litres extra (total 155 l).Mixture compositionThe principles mentioned must be seen as the scheduleof requirements for the concrete mixture composition.When determining a mixture the ingredients below canthen vary:• aggregate granulate gradation• fine part content• water dosage• cement content• cement type• binding agent• fillers• type and dosage of superplasticizer• steel fibre dosage Figure: the flow is also measured at the work site
  • 3. constructies civiele techniek bouwmanagement bouwkunde installaties Concrete for industrial floorsWater addition development and gives a high density to the concrete soOnly a part of the water present in concrete is required shrinkage susceptibility decreases. At low temperatures,for the hydration of the cement. The other part is required with the finishing of the floor, a part of the cement can befor working the concrete. Because the remaining water replaced by faster reacting Portland cement (CEM I). Oneimmediately causes more shrinkage and therefore more must exercise caution here with shrinkage in mind.cracking it must be limited to the extent possible. Henceonly the strictly required quantity of water is added to Binding agentthe mixture (the minimum water requirement of 165 l Materials are added to concrete that do not immediatelywith 4-32 mm grit). The increasing of the consistency is harden like cement but cause an increase in thefurther ensured by the superplasticizer. The values con- compression strength of the concrete. The best known iscrete mixing plants use for absorbed water differ greatly. the application of fly ash, but ground blast furnace slagAbsorbed water is water that at the start of bonding is not is often used in combination with Portland cement. Atinvolved in the hydration process. Despite it not having to higher temperatures, up to a maximum of a third partbe counted for reasons of technical standards, ABT is of of cement can be replaced by an alternative binder forthe opinion that in the long term it will evaporate from the reasons of technical standards. This also functions as anconcrete so will cause shrinkage. As a result, the choice of internal water binder, so drying shrinkage decreases andcement content and type and any binding agent level is the greater relaxation reduces cracking susceptibility. Silicadetermined. Fume is not used in floor concrete.Cement content FillersFor reasons of technical standards and for strength Fillers can be used to increase the content of fine parts. Asdevelopment, 280 kg cement can usually suffice. Because distinct from binding agents these do not or barelya large amount of water is not bonded here, this is not increase strength development so they cannot alsodesirable from the perspective of drying shrinkage and be used as a replacement for cement. The best knowncrack sensitivity. To bind this free water the total amount example of a filler is limestone powder. ABT preferablyof binder must be 360 kg. Depending on the working uses fly ash, however.conditions and environment class, the cement contentused will vary from 280 kg cement to 340 kg, combined Plasticizerwith 80 to 20 kg of fly ash from blast furnace slag Superplasticizer is applied to bring the workability ofrespectively. Then with a water content of 165 litres and concrete up to the necessary level. The dosage isa binding agent level of 360 kg (ABT calculates k=1 for fly determined by the concrete technologist. The startingash because the value is revised after 90 days) there is a point is that a minimum of water is used with thetheoretical water cement factor of 0.46. If, however, appropriate consistency being obtained by means ofabsorbed water is counted (usually 10 to 15 litres) the superplasticizer. The so-called 3rd generation of super-water cement factor amounts to approx. 0.50. The plasticizer is being increasingly used. In principle ABTcement/added binder proportion will depend on the advises against its use because many cases of damage areenvironment class, processing conditions and be known of which no clear cause is identifiable.determined in consultation with the parties.The advantage of this mixture is that adjustments canbe made depending on hydration heat. In specific cases(loading pit, impermeable) the mixture with 340 kgcement and 20 kg fly ash must be applied. Figure: air content measurement Steel fibres For construction steel fibre floors ABT uses steel fibres with end anchoring because the effectiveness of these fibres isFigure: concrete pouring summary the highest. The fibres are preferably mixed at the plant, but mixing on site is also an option. Steel fibre concrete isCement type preferably mechanically processed and transported on theThe basis used is blast furnace cement (CEM III/B 42,5 site using dumpers.LHHS). This cement initially has relatively slow strength
  • 4. constructies civiele techniek bouwmanagement bouwkunde installatiesConcrete for industrial floorsBasic mixture for floors on granulated debris SpecificationsBased on the aspects above, ABT uses the following low- The following text can be used as specifications for an ABTshrinkage floor concrete mixture as the basis: concrete mixture: Concrete C28/35 composition• granulate gradation 4-32 mm inside ABHA A-B lines according to ABT in accordance with the ‘Concrete for (possibly optimised with a 4-16 mm part) industrial floors’ flyer.• cement content default value 300 kg cement and 60 • environment class XC2 kg fly ash, depending on circumstances changes • fine aggregate: sand between 280 kg and 340 kg cement, supplemented • coarse aggregate: grit by 80 to 20 kg fly ash or ground blast furnace slag • filler: coal fly ash, quantity in consultation with the respectively, to be determined in consultation with ABT management• water content 165 litres of water • cement content: maximum 340 kg/m3• fine parts at least 140 litres • additive: superplasticizer, for approval by the manage-• superplasticizer 2nd generation ment. Quantity: approx. 1% of the cement volume.With the purchase of the concrete mixture ABT can advise The following information must be provided by theon the proportions of cement/fly ash and cement sorts supplier:to be used. Several days before pouring ABT receives a • composition of the mortarmixture calculation, on the basis of which any last • the consistency rangeadaptations can be made. • type and class of the cement • nature of the aggregatesTemperature • the brand of the cement with proof of originProcessing concrete in industrial floors is greatly • the cement contentdependent on temperature, because it is a relatively thin • the sieve analysis of the aggregatesplate with usually a very large surface exposed to the • the weight proportion of the aggregatesambient temperature. The following table can be used as • the largest granulea guide. • water cement factor • the slump • the additives Summary ABT strives to make matching the concrete mixture a partTable 1: mixture depending on mortar temperature of the design process for an industrial floor. The general quality of a floor is greatly improved by consulting on theExecution supervision concrete mixture and the properties, while makingDuring execution a mobile ‘laboratory’ can be used to adjustments as necessary when carrying out the work.control the weight by volume, the setting and flow, aircontent, water content and accordingly the water binding The concrete mixture is a part of ABT’s endeavours for thefactor. Samples can also be manufactured for testing the design of a ‘sustainable’ environment by reducing the usecompression strength, splitting tensile strength, bending of primary raw materials, and the reduction of greenhousetensile strength and shrinkage of the concrete. gas emissions with the use of residual products.Attendance of the start of pouring and the adaptationof the concrete mixture (if necessary) has the purpose ofhaving the actual work take place as closely as possible inline with the design principle.Figure: determining water content on the site Figure: rack warehouse in useVerdere informatie is te verkrijgen bijing. Ab van den Bos a.vd.bos@abt.euRaadgevend ingenieur civiele techniek www.vloerenadvies.nlABT bvArnhemsestraatweg 358 Velp Delftechpark 12 Delft Kammenstraat 18 Postbus 82 6800 AB Arnhem Postbus 458 2600 AL Delft 2000 Antwerpen www.abt.euT +31 (0)26 368 31 11 T +31 (0)15 270 36 11 T +32 (0)3 205 37 11 info@abt.euArtikelen mogen met bronvermelding worden overgenomen, na toestemming van ABT bv. © ABT bv 2012

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