József Kovács
Krisztián Hajnal
Beton wysokiej trwałości z cementu
hutniczego CEM III/B 32,5N  LH/HSR/NA
w budowie oczyszczalni ścieków
HIGH PERFORMANCE CONCRETES FOR SEWAGE TREATMENT
PLANTS, MADE WITH SULPHATE RESISTANT BLAST FURNACE
SLAG CEMENT
Streszczenie
Oczyszczalnie ścieków na Węgrzech nie odpowiadają swoją wielkością zaleceniom Unii
Europejskiej, tak więc w roku 2004 rozpoczęto rozbudowę i modernizację obiektów już
istniejÄ…cych oraz zaprezentowano nowe inwestycje.
Specyfikacje dla betonów pod ww. inwestycje zostały opracowane przez projektantów
zgodnie z obowiÄ…zujÄ…cymi normami oraz wymaganiami krajowymi obowiÄ…zujÄ…cymi na
Węgrzech. Za dobór składników oraz typ cementu odpowiedzialni zostali technolodzy
betonu. Poza wymaganiami wytrzymałościowymi szczególną uwagę zwrócono na dużą
wodoszczelność i odporność na korozję chemiczną betonu, pracującego w różnych klasach
ekspozycji zgodnie z normÄ… MSZ EN 206-1:2002.
Do budowy opisywanych obiektów zastosowano cement hutniczy CEM III/B 32,5
N-LH/HSR/NA. W niniejszym artykułu przedstawiono realizację inwestycji ze szcze-
gólnym uwzględnieniem trwałości konstrukcji betonu, a opisane doświadczenia posłużą
w realizacji największej oczyszczalni ścieków budowanej w Budapeszcie, na Węgrzech
zużyto 186 000 m3 betonu.
Abstract
The capacity of Hungarian sewage treatment plants do not comply with the requirements
of the European Union therefore, in 2004 the risingincrease of the capacity of the existing
plants and building investments of new sewage treatment plants has begun. The concre-
József Kovács  Duna-Dráva Cement Kft.; Vác, Hungary
Krisztián Hajnal  Duna-Dráva Cement Kft.; Vác, Hungary
tes requirements for this investments were determined by the designers according to the
established technical regulation. The determination of the composition and the suitable
cement type was put under the care of concrete tehnologists.
From the aspect of the concreting and the planning of the the concrete s composition,
besides the high strength requirements, the good impermeablity and corrosion resistance
according to the MSZ EN 206-1 : 2002 standard with the application of a sulphate resistant
blast furnace slag cement CEM III/B 32,5N  LH/HSR/NA is also a point of professional
interest. This article describes the way how we could resolve this problem considering,
that we need these experiences before the beginning of the biggest investment (sewage
treatment plant Budapest, 186 000 m3).
Beton wysokiej trwałości z cementu hutniczego ...
1. Structural design of sewage tratment plants
(BQ
cs, Szeged)
BQ
cs: the enlarging of the sewage treatment plant was realised with the building of 2 reac-
tors 1512 m3 cubic space, caurational 132 m3, anaerob 520 m3, 990 onoxic, 2 pieces 750 m3
clarifier, 920 m3 cubic space balancing tanks engineering structures. This structures were
built with 40 cm thick impermeable chunkwall bedplates, 30-40 cm thick impermeable
walls and 15-20 cm thick impermeable floors (ceilings).
Photo 1. Sewage tratment plants in various construction phases
The main buildings are the primary setting basin with a dimension of 1500 m3, the
18920 m3 sedimentation basin, the 26 300 m3 biological basin and two individual pieces
of 4000 m3 rotting towers. The 18 m in diameter, 22 m high towers have 30 cm thick walls
braced with 90 pcs after-spanning staples. The impermeability of the structural connec-
tions was guaranteed by the internal walls with one-ply, by the outer walls with twofold
BAUHAUS Bautec BT 2025 expanded bands. Connection of the rotting towers BAUHAUS
Kontaflex Activ bentonid sheated joint plates was applied at the wallplate and bedplate.
The after-treatment of the bedplates happened with water flooding. The after-treatment
of the other structures was guaranteed with a SIKA Antisol sheating.
Photo 2. Szeged sewage treatment plants in various construction phases
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József Kovács, Krisztián Hajnal
2. Concrete-technological respects
The concrete in the engineering structures was placed with concrete pump. The structural
distributions and the layered working-in of the vertical structures resulted a working-in
with different rapidity. The guarantee of the impermeability of the structures was possible
only with planned interspaces.
Photo 3. Planned interspaces
This required also from the concrete transporter a redoubled effort for organisation of
labour. In case of an operating trouble a reserve concrete plant and a reserve concrete pump
had to be guaranteed. The building technology of the rotting towers with sliding formwork
required a continuous, uninterrupted work in three shifts with its all logistic relations.
Photo 4. Szeged rotting tower in various construction phases
3. Planning of the concrete structure answering
the requirements
The prescribed technical requirements for the concrete were as follows:
 prescribed characteristic strength of cylindrical specimen 30 N/mm2,
 minimal cement content 350 kg/m3,
4
Beton wysokiej trwałości z cementu hutniczego ...
 maximal water/cement ratio 0,45,
 consistency S3 (100-150 mm),
 application of sulphate resistant cement,
 water and gas permeable concrete,
 crack-free concrete,
 long lasting fresh-concrete with and expanded working-in possibility resulting from
the demanding execution of the permeable engineering structures.
On the basis of the conciliation with the constructors and the cement makers the
quality marks of the cement are as follows:
BQ
cs C30/37-XC4-XV3(H)-24-F3 MSZ EN 206 -1: 2002,
Szeged C25/30-XA2-XV2(H)-32-F3 MSZ EN 206 -1: 2002.
Basing on the above requirements the concrete composition has been designed with
the CEM III/B 32,5N-LH/HSR/NA (Duna-Dráva Cement Kft., Vác) sulphate resistant
blast furnace slag cement, because of its below qualities:
 sulphate resistance,
 low heat evolution,
 moderate hardening, significant after-hardening.
BQ
cs
To reach the convenient average strength, in case the relative high cement charging allowed
just a little amount of water in the concrete, the 0,42 w/c ratio was assumed.
Table 1. Composition characteristic
CEM III/B 32,5N  LH/ 380 kg/m3 Density of fresh concrete 2410 kg/m3
HSR/NA DDC Vác
Water 158 Modulus of fineness 6,67
Sand 0-4 823 kg/m3 Planning air 9 liter
Gravel 8-16 580 kg/m3 Fineness content 440 kg/m3
Gravel 16-24 468 kg/m3 Paste content 280 liter
Muraplast FK6230 2,3 kg/m3 Aggregates fineness 3,2 %
MC-bauchemie
size of sieve [mm]
Fig. 5. Granulometric composition of aggregates
5
passed [%]
József Kovács, Krisztián Hajnal
Szeged
The rotting towers were built using a sliding formwork. With this technology, the con-
creting, the iron mounting and the other ancillary works create a periodic and cyclical
building process. Therefore the individual 30-40 cm high concrete layers has to be built on
each other when the layers still can be mixed and their homogenity is guaranteed. During
the time among the working-in of the individual layers, every other building activity has
to be resolved in the way that the building stroke can be kept with the lifting frequency
of the shutter. Thus for the building technology with sliding formwork the concrete had
to carry out the following demands besides the previous requirements :
 till 3 hours the fresh-concrete must be workable,
 after 8 hours it has to be hardened and dismantlable.
The creation of the artifical air pores tranformes the capillary pores in the concrete
(their pore dimension and distribution of pore dimension changes) so the structure of
the concrete becomes more homogene and free from damaging capillaries. Despite that
its body thickness is smaller. The rearrangement and reduction of the capillary air pores
make the concrete more body closing in.
Table 2. Composition characteristic
CEM III/B 32,5N  LH/HSR/ 320 kg/m3 Density of fresh concrete 2360 kg/m3
NA DDC Vác
Water 158 Modulus of fineness 6,66
Sand 0-4 648 kg/m3 Air pole content 2-3 %
Gravel 4-8 333 kg/m3 Fineness content 410 kg/m3
Gravel 8-16 389 kg/m3 Paste content 266 liter
Gravel 16-32 482 kg/m3 Aggregate fineness 4,9 %
Dynamon Easy 31 Mapei 1,6 kg/m3 w/c ratio 0,5
Mapetard + Mapeplast PT 2 0,96 kg/m3
Mapei
size of sieve [mm]
Figure 6. Granulometric composition of aggregates
6
passed [%]
Beton wysokiej trwałości z cementu hutniczego ...
The concrete which is applied for the permeable concrete buildings must reach the
required properties with little cement and total water amount. Total small amount of
water reduces the shrinking, the reduction of the cement volume with a cement, which
has a small heat of hydratation, decreases the development of heat and with this reduces
the maximum concrete temperature. Choosing the hardness class must respect for 56 days
the after-setting volume of the concrete in order to be able to decelerate the development
of the hardness and avoid the evolution of the extreme hardness. In case of applying
0,5 w/c ratio the conctrete reaches the convenient average strength after 28 days and it
does not become too strong and brittle after 56 days either.
For determination of the composition of the concrete needed for sliding form techno-
logy, we could set out from the former particularized combination (Table 2), namely the
requirements for the concrete were the same. The extra demands towards the fresh-concrete
that is workable till 3 hours and hardens and becomes dismantleable after 8 hours, could
only be veryfied by testing. First we omitted the bond-retarding additive and reduced the
w/c factor for 0,48; for keeping the total water amount of 158 l we increased the cement
feeding for 335 kg. The surplus pulp, which was originated from the modification hel-
ped the lifting of the jalousie. For keeping the consistency we had to increase the fluxing
additive charging for 0,7 %.
4. Implementation
The building process of the concrete-structures had begun in December 2004 and fi-
nished in July 2006, so the production and the construction had to be resolved among
great temperatural extremities. We have chosen the applied cement with moderate heat
evolution primarily to the productivity of the concrete-structure, which combined with
the low winter-temperature resulted with a very slow solidification rate. Together with
the concrete structural specification we had to give to the implementer a technological
instruction for the winter season. The concrete plant produced a mixture with restricted
tempreture in order to guarantee the beginning of the hardening and the setting of the
concrete mixture. We made a condition for the dismantle and the winterizing to reach the
critical hardness value of the concrete structure. We have recommended the closing of the
working-in surfaces with vapour barrier cover as after-treatment by low temperature.
Photo 7. BQ
cs, Szeged in various construction phases
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József Kovács, Krisztián Hajnal
5. Quality control results
BQ
cs
The 37 N/mm2 cube strength is eqiuvalent with the prescribed 30 N/mm2 cylinder
strength under wet storage from beginning to the end. During the preliminary trials we
had qualified the test pieces under the up to the present usual mixed storage, so they
ought to product a 40 N/mm2 value treshold. The 48-50 N/mm2 average strengths and
the 8 mm value of the influx of water of the test pieces we examined during the manu-
factoring qualified the concrete as convenient. During the investigations on the spot we
could realise that the sructures were free from cracking. We could realise during ocular
inspection the excellent suitability for smooth, the closed and massiv surfaces and on the
fresh throuth-leadings the characteristic bluish-green colour of the high blast furnace slag
content attainable by the cement with high milling fineness.
Szeged
Table 3. Examination of fresh and hardened concretes
Average compressive
Produ- Char- Consistency Influx of
strength
cer Additive ging [cm] water
[N/mm2]
[%] 0-90-120 [mm]
Cem.m. minute vz4 7 day 7 day 28 day 56 day
Dynamon EASY 31 0,5 49-44-41
MAPEI 22 18,1 35,5 41,9
Mapetard & PT 2 0,3
6. The hydratation process of the cement with blast
furnace slag content
Generally, we can set down the fact that with the rising of the complementary additive
substances in the cement (66 % granulated blast furnace slag) the properties of the concrete
change for their advantage:
 low permeability, high capability of resistance against the chemical aggressiveness.
As result of the hydratation of the slag granulates and the wandering of the Ca, Si
and Al among the concrete and slag granulates results in an Al rich CHS gel, the calcium
silicate  calcium aluminate hydrate gel. The microstructure of the cement stone is more
prosperous. The volume of the gel pores (-30 mm) is higher, the volume of the capillary
pores is lower.
The damaging effect of the sulfate swelling is influenced by the next elements:
 the C3A content,
 sulphate concentration of the soil water,
 Ca(OH)2 content,
 the permeability of the concrete.
The usual protection against the sulphate swelling is the reduction of the C3A content.
The C3A content in the concrete with sulphate resistant blast furnace slag cement with
8
Beton wysokiej trwałości z cementu hutniczego ...
66 % granulated blast furnace slag content is smaller than 3 %. The sulphate resistant
blast furnace slag cement besides the fulfilment of the chemical requirement reduces the
permeability of the concrete, making more difficult the influx of sulphate, increasin the
physical protection against the sulphate corrosion.
Figure 8. Sulphate resistant test with MSZ 4737-1:2004
In case of relative high cement content and big mass concretes the low heat develop-
ment is important. Content smaller setting heat develops by the hydratation of a cement
with 66 % blast furnace slag rather than by the hydratation of a pure portland cement.
The temperature increase caused by the hydratation of the concrete is lower, also the
temperature accumulation peak is later observable.
Figure 9. Temperature increasing of the cement pastes as a function of the time
7. Summary
From concrete technological aspect we resolved a special job. The expected properties of
the concrete and the conditions of the concretizing represented extremities. With CEM
III/B 32,5N  LH/HSR/NA cement we have the possibility to build excellent hydrotech-
nical structures, otherwise to keep the properties of the fresh concrete we should put all
9
József Kovács, Krisztián Hajnal
our weapons into action. The misson which we had succesfully realized veryfies that
the concretes made from specially developped cement are suitable in wide technological
territories.
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