zobacz nasze inne realizacje »

Goods concrete in building of high objects

In last decade many office buildings about high standard were built in Warsaw. among new office buildings are among other things the high buildings about steel with reinforced concrete core , e.g. the Warsaw the Trade of Tower ( the called the sky-scraper popularly Daewoo, about height 184 m) and the high buildings about whole of the reinforced concrete construction, as the object of Varsovian Financial Centre ( the WCF).

Budynek WCF about 34 above - grounds storeys together with from entresols and 2 underground storeys, about total height 144 m (without aerial) so far, gave to use in 1999,is the highest in country the building of reinforced concrete construction (fot. 1). It be builds still and plans the building of many sky-scrapers; near the end 2001 during of building or preparation to build in Warsaw was at least seven buildings about height above 100 metres. The scale of high building approaches so to European scale which has reached for 200 m (Vienna) to 260 m ( the Frankfurt over Men). During erect of freight concrete high buildings are doing the following elements of construction:

  • foundation: it the most often it is the reinforced concrete plate about thickness from 0,8 to 2,5 m, in places wher is deeper the thickness of plate can be to 5,0 m
  • the wall of underground part and communication cores ( the lift, stairs)
  • poles and ceilings
  • others,e.g. the plate of landing field strip for helikopters

To realization of listed elements the most often applied classes of concrete:

  • foundamental plates: class B25 to B35
  • wall: class B25 to B40
  • poles: class B35 to B55
  • ceilings: class B25 to B40.


Location in centre the squares of buildings applying solutions extorts city technological taking into account the considerable time of transportation of mixture from factory of concrete.

Foundamental plates

The concreting the foundamental plates under high buildings, with cubic volume one section even to 2500 m3, it does not inflict hard the organization, because for few years works in region many modern, very effective factories of goods concrete. An important question is design composition of concrete mixture, to paid out the quantity of warmth during hardening the concrete did not lead to after the getting up in massive concrete too high temperature. Deformation causes of difference of temperatures can causes scratches in concrete. building all larger buildings conducts oneself systematic the measurements of temperature of concrete since moment of end concreting till moment, when the temperature begins to fall, what usually requires the measurements by about 7 days.

In projecting it usually places the requirements to the maximum temperature of concrete did not cross 60 ° C, and the difference between the the highest and the lowest temperature in given moment was not larger than 20 ° C. Requirements can be fulfilled during using of cement CEM II 32,5 or better CEM III 32,5. in clean the portlands cements is CEM And 32,5 the almost sure, that the maximum temperature of concrete in foundamental plate about thickness 1,5 m will cross 60 ° C, however in thickness 2,0 m can cross 70 ° C. Hypotetical the composition of concrete mixture to make a foundamental plate about thickness 2,2 m of building of Telecommunication the Polish SA (fot. 2) was passed in board

The board 1. Composition and propriety of mixture concrete B35 to realization the foundamental plates about thickness 2,20 m

The components

Dosage of identifier / the m3 of

Propriety of concrete mixture

Cement CEM III And 32,5

370

Consistency: fall cone 14-17 cm

Mineral sand 0-2 mm

575

Gravel 2-8 mm Sobolewo

360

Gravel 8-16 mm the Sobolewo

500

Thickness of mixture: 2385 identifier / m3

Gravel 16-32 mm the Sobolewo

400

Admixture Lubet - C

2,2

Index w / c: 0,485

Water

178

Manufacturer of mixture was PPB Budokrusz firm from Grodzisk Mazowiecki. Excavation under underground part be executed in crevice jostled with ceilings walls. Concreting of foundamental plate required the use of pipelines, therefore provided in prescription consistency was relatively liquid in fall cone 14-17cm. Maximaum registered temperature in four concrete blocks carried out 58,9, 55,6, 55,5 and 55,3 ° C in temerature of air 19-22 ° C.Endurance on grip samples taken on building place had carried out after 28 days since 44,8 to 51,5 MPa on average, however after 90 days about 58 MPa. Concrete mixture designed to build in in foundamental plate should be to characterize not smaller ...than 8hours. delay the beginning and end of bond. This makes possible an arrangement the next layer of concrete mixture without fear that arranged layer earlier will begin bonding. It was possible to get such delay using an admixture the Lubet - C, which is the complex, plasifingly, dealy the bond and it improves considerably on waterproofness of concrete. Dosage this admixture in case of massive concretes should carry out 0,6-1,0 % the mass of cement. Be desirable, to awaited class of concrete define after 60 or 90 days, what makes possible decrease content of cement and lowering temperature during hardening concrete. It is should be remember that concrete in foundamental plate more considerably quickly achieves projected endurance than concrete in kept in laboratory conditions samples, which results with different temperatures maturation.

Wall And ceilings

The building of walls and ceilings of buildings proceeds in quick pace, even in winter; usually after concreting finished evening of already next day the morning disboarding is possible . The qucik work with boarding resulting with them high price turn requires the concrete to characterize quick it grows of endurance. It should be apply the cements CEM I 32,5 R or CEM I 42,5 R. In one of high buildings the concrete mixture according to passed lower the prescription (deliver of concrete Hydrobudowa -1 Concrete - mixing works – Laboratorium from Warsaw).

The board 2. the composition and properties of mixture concrete B 35, K -5, W8, F 100

The components

Dosage of identifier / the m3 of

Propriety of concrete mixture

Cement CEM III And 32,5

385

Consistency: fall cone 14-17 cm

Mineral sand 0-2 mm

600

Gravel 2-8 mm

400

Gravel 2-16 mm the

810

Thickness of mixture: 2380 identifier / m3

Admixture Lubet - C

2,0

Index w / c: 0,479

Water

183

The results of investigation on grip the samples introduced on pic.1 charakterized the small range of endurance . In temperatures of environment above 10 °C an admixture Lubet -C using with cement CEM I 32,5 R makes possible disboarding of wall next day.In periods of lower temperatures it is recomended to use a superplasticiser Skorbet or an admixture winter Zimobet 334.

Poles

Poles in high buildings very often are project of concretes B45 and B50 class. To make an economic mixtures may apply concrete CEMI 32,5 R, good quality mineral sand, gravel 2-8 and 8-16 mm and superplasticiser Skorbet. Dosage of Skorbet in quantity 2-2,5 % makes possible mass on obtainment concrete mixture about coefficient w/ c lower than 0,45 in very liquidity consistency and fall cone 18-22 cm. During the building of build on Królewska Street poles were made of concrete B50, and manufakturer of concrete was firm PPB Budokrusz (tabl. 3). Passed on pic. 2

The averages results of researched of endurance of concrete in samples of five mounths period(October -February) it showed large homogeneity of concrete, especially it pays the attention on the changeability of endurance cement 32,5 (admitted standard) and changeability weather conditions. Basis of observation of many buildings sites to affirm that the assurance of solid quality of concrete requires on site of building production of concrete mixture without no corrections of consistency should. Pouring some more admixtures fluxing on building to mixing machine can and should have place in emergency situations. Treatment as rule such correction on quality concrete affecting often negatively . Inaccurate mixing an admixture in mixing machine is the cause of heterogeneous consistency, different endurance of concrete and soaking up of water ,differents times of bond, heterogeneous appearance of surface of concrete after disform.

The board 3. the compositions and properties of mixture concrete B50 on of high poles building

The components

Dosage of identifier / the m3 of

Propriety of concrete mixture

Cement CEM III And 32,5

450

Consistency: fall cone 18-23 cm

Mineral sand 0-2 mm

480

Gravel 2-8 mm

490

Gravel 2-16 mm the

800

Thickness of mixture: 2423 identifier / m3

Siliceous dust Laziska

25

Admixture Skorbet

11,5

Index w / c: 0,368

Water

167

Passing concrete mixture be holds the most often using of pumps station . Pumping of concrete mixture on distance above 100 m, in this often over 50 m and more, is easier with plasticifingly concrete admixtures about consitency to 14-17 cm. Concrete mixtures with superplasticiser should have consistency about fall cone 18-22 cm because during it pumping it is getting density . Using of stationary pumps and closed sped pipelines requires very exact their cleaning after every concreting.

In last years were got the considerable practical experiences in range projecting as well as the mass production of goods concretes, destined to realization of high buildings. The stable production of concretes of classes to B70 with use inexpensive, the national materials does not create problems. It the special, applied in atypical elements of high buildings, concretes were projected carefully , carrying out indispensable experimental researches.E.g. to realization of plate of landing field strip for helikopters on roof of building the TP .SA used the special concrete B40 about high froostproofness and durability,used with addition of fibres glass proof on working the alkalies. Because the high buildings are responsible and very exhibitily objects in city, building of them is connect with high quality, what maens larger than usually the stores of safety in projecting and the production of goods concrete.

doctor hab. inż. Michał A. Clinicki

Institute of Basic Problems

Technique of PAN in Warsaw

ma inż. Kazimierz Ładyżyński

Hydrobudowa -1

Copyright © 2004 - 2011 Lubanta S.A.

wykonanie - SoftwareStudio Sp. z o.o.