1 Alexander Andersson Fredrik Ljungberg Byggingenjörsprogrammet Högskolan i Halmstad ...

85 Pages·2012·3.11 MB·Swedish

by  Fredrik Ljungberg [frelju09]

Byggingenjörsprogrammet VT 2012
Högskolan i Halmstad
Sektion för Ekonomi och Teknik
Examensarbete 15hp

1
Alexander Andersson

Fredrik Ljungberg

Abstract
The maturation of concrete is strongly affected by surrounding temperature and wind conditions.
During the summer, when the temperature is around 20 °C, there are normally no complications
when stripping form but when the outdoor temperature is around 0 °C there is a risk of collapse and
other complications. The general rule is that the compressive strength of the concrete has to reach 5
MPa before form stripping is allowed to be performed. Some tools, for example the computer
program Hett11, are available to help you create a predicted, theoretical, picture of how the
concrete’s compressive strength develops under certain conditions but the material parameters that
are used by the program are out of date.
The purpose of this thesis is to update the old material parameters in Hett11 and to create a
document of recommendation that consists of different measures that has to be done to be able to
strip a form after 18 hours.
This thesis is composed of both theoretical and practical parts which are comprised of:
 Litterature studies
 Laborations
 Field studies
 Data collection of comlpleted laborations and field studies
 Evaluation of material parameters
 Verification of material parameters
 Simulations in Hett11
The thesis was conducted in collaboration with Betongindustri AB.

Förord
Det här examensarbetet har utförts i samarbete med Betongindustri AB och genomfördes under
våren 2012 som en avslutande del av vår byggingenjörsutbildning på Högskolan i Halmstad.
Under arbetets gång har ett antal personer bistått med hjälp i alla dess former.
Vi vill först och främst tacka Jonas Carlswärd på Betongindustri som varit till vår hjälp med hans
värdefulla kunskap och bidragande av material och litteratur. Det är även Jonas som har tagit fram
idén till detta examensarbete.
Vi vill även tacka Jan-Erik Jonasson, professor på Luleå tekniska universitet, för utvärderingen av våra
laborationsresultat. Utan hans hjälp hade det varit svårt att fullfölja examensarbetet.
Vidare vill vi tacka vår handledare Bengt Hjort för värdefull hanledning.
Slutligen vill vi passa på att tacka följande personer:
Fredrik Bengtsson, Betongindustri AB
Steve Gustavsson, Betongindustri AB
Daniel Bäckström, JM AB

___________________________ ___________________________
Alexander Andersson Fredrik Ljungberg

Innehållsförteckning
Abstract .....................................................................................................................................................
Förord ........................................................................................................................................................
Sammanfattning ........................................................................................................................................
1.0 Inledning ............................................................................................................................................ 1
1.1 Bakgrund ....................................................................................................................................... 1
1.2 Syfte ............................................................................................................................................... 1
1.3 Omfattning - genomförande ......................................................................................................... 3
1.4 Begränsningar ................................................................................................................................ 3
Beteckningar ............................................................................................................................................ 5
2.0 Mognadsutveckling i ung betong ...................................................................................................... 7
2.1 Modeller ........................................................................................................................................ 7
2.1.1 Hållfasthetsutveckling ............................................................................................................ 7
2.1.2 Ekvivalent mognadsålder ....................................................................................................... 8
2.1.3 Hydratationsvärme ................................................................................................................. 8
2.2 Manuell beräkning av mognadsålder .......................................................................................... 11
2.3 Mätning av hållfasthet................................................................................................................. 12
2.3.1 Comameter ........................................................................................................................... 12
2.3.2 Utdragsprov (LOK-test) ......................................................................................................... 12
2.3.3 Brytprov (BO-test) ................................................................................................................ 13
2.3.4 Objekthållfasthet .................................................................................................................. 13
2.3.5 Utborrning av provkropp ...................................................................................................... 13
3.0 Tillsatsmedel .................................................................................................................................... 15
3.1 Accelererande tillsatsmedel ........................................................................................................ 15
Mekanismen bakom acceleratorer ............................................................................................... 15
3.2 Flyttillsatsmedel .......................................................................................................................... 17
4.0 Vintergjutning .................................................................................................................................. 18
4.1 Interna åtgärder .......................................................................................................................... 18
4.1.1 Högre betongklass och snabbhärdande cement .................................................................. 18
4.1.2 Förhöjd betongtemperatur .................................................................................................. 18
4.1.3 Accelererande tillsatsmedel ................................................................................................. 18
4.2 Externa åtgärder .......................................................................................................................... 18
4.2.1 Isolerade formar ................................................................................................................... 18
4.2.2 Uppvärmning av bjälklag och väggar .................................................................................... 19
4.2.3 Täckning av färdiggjuten konstruktion ................................................................................. 19
4.3 Risker och skador ......................................................................................................................... 19
5.0 Utförande av laborationsförsök ...................................................................................................... 20
5.1 Betongrecept ............................................................................................................................... 20
5.2 Gjutningsprocessen ..................................................................................................................... 20
5.2.1 Val av recept ......................................................................................................................... 20
5.2.2 Förberedelser ....................................................................................................................... 21
5.2.3 Vägning av material .............................................................................................................. 21
5.2.4 Gjutning ................................................................................................................................ 22
5.2.5 Lagring .................................................................................................................................. 23
5.2.6 Mätutrustning....................................................................................................................... 23
5.2.7 Efterarbete ........................................................................................................................... 23
5.3 Provtagning ................................................................................................................................. 23
5.3.1 Hållfasthet ............................................................................................................................ 24
5.3.2 Datainsamling av temperaturförlopp ................................................................................... 24
5.3.3 Semi-adiabatisk mätning ...................................................................................................... 24
6.0 Resultat av laborationsförsöken...................................................................................................... 26
6.1 Redovisning av Försök 1- C25/30 Bygg ........................................................................................ 27
6.2 Redovisning av Försök 2- C25/30 SH ........................................................................................... 28
6.3 Redovisning av Försök 3- C25/30 Bygg ........................................................................................ 29
6.4 Redovisning av Försök 4- C32/40 Bygg ........................................................................................ 30
6.5 Redovisning av Försök 5- C32/40 SH ........................................................................................... 31
6.6 Redovisning av Försök 6- C25/30 Bygg+ Acc ............................................................................... 32
6.7 Redovisning av Försök 7- C32/40 Bygg+ Acc ............................................................................... 33
6.8 Iakttagelser vid granskning av laborationsresultat ..................................................................... 34
6.9 Utvärdering av materialparametrar ............................................................................................ 35
7.0 Fältstudier ........................................................................................................................................ 36
7.1 Utförande .................................................................................................................................... 36
7.2 Resultat ........................................................................................................................................ 38
7.3 Iakttagelser vid fältstudier........................................................................................................... 40
8.0 Verifiering ........................................................................................................................................ 41
8.1 Verifiering av teoretiska och verkliga resultat ............................................................................ 44
8.2 Iakttagelser av verifiering ............................................................................................................ 48
9.0 Resultat - Rekommendationsdokument ......................................................................................... 49
10.0 Slutsats och erfarenheter .............................................................................................................. 50
Referenslista .......................................................................................................................................... 52
Litteratur............................................................................................................................................ 52
Standarder ......................................................................................................................................... 52
Illustrationer ...................................................................................................................................... 52
Internet .............................................................................................................................................. 53
Personer ............................................................................................................................................ 53
Bilaga 1 – Betongrecept ............................................................................................................................
Bilaga 2 – Tillsatsmedel .............................................................................................................................
Bilaga 3 – Hållfasthetsutveckling ...............................................................................................................
Bilaga 4 – Utvärdering av betongparametrar ............................................................................................
Utvärdering av försök 2 C25/30 SH .......................................................................................................
Utvärdering av försök 3 C25/30 Bygg ....................................................................................................
Utvärdering av försök 4 C32/40 Bygg ....................................................................................................
Utvärdering av försök 5 C32/40 SH .......................................................................................................
Utvärdering av försök 6 C25/30 3% acc. ...............................................................................................
Utvärdering av försök 7 C32/40 3% acc. ...............................................................................................
Redovisning av betongparametrar ........................................................................................................
Bilaga 5 – Underlag till verifiering - Teoretiska resultat ............................................................................
Bilaga 6 – Rekommendationsmatris ..........................................................................................................