Constructional- and material technical optimization of concrete - possible environmental benefits
(2021) VBKM01 20202Division of Structural Engineering
Department of Construction Sciences
- Abstract
- The greenhouse effect and the emission of greenhouse gases, namely carbon dioxide, is a global issue which today permeates alot of the societal consciousness and therefore also alot of the conducted research. The construction industry is not different in this regard. The construction sector in Sweden, for example, generates more than 12 million metric tonnes of carbon dioxide equivalents every year, this is around one fifth of all emissions in Sweden.
Concrete is the most common construction material in the world. Reasons for why concrete has taken this position in construction projects stem from, for example, its low cost, the global availability of raw materials and its durability. Despite all its positive characterstics concrete is,... (More) - The greenhouse effect and the emission of greenhouse gases, namely carbon dioxide, is a global issue which today permeates alot of the societal consciousness and therefore also alot of the conducted research. The construction industry is not different in this regard. The construction sector in Sweden, for example, generates more than 12 million metric tonnes of carbon dioxide equivalents every year, this is around one fifth of all emissions in Sweden.
Concrete is the most common construction material in the world. Reasons for why concrete has taken this position in construction projects stem from, for example, its low cost, the global availability of raw materials and its durability. Despite all its positive characterstics concrete is, and especially the manufacturing of cement, one of the largest producers of greenhouse gases originating from the construction sector. Currently it's reported that cement production amounts to between 3 and 8 \% of the global emissions of greenhouse gases. As urbanisation increases in third world countries, and with it the demand for cheap construction materials, studies have argued that the production of cement's share of global emissions can amount to as much as 30 \% by 2050. Something will have to be done to stop this development.
Many research projects are currently operating with the intent of analyzing what possibilities there are to mitigate emissions from cement production. This master's thesis focuses on two possibilities: material technical, namely the substitution of portland cement with additives, and structural technical where, during design, larger importance is given to the reduction of concrete use. Another way of investigating CO$_{2}$-emission, that the industry has shown intrest in, is Carbon Capture Storage (CCS). This means that the carbon dioxide which is released during the firing of limestone amid cement production is collected and stored (for example in pockets in the bedrock under the sea).
The material technical part is studied through casting and strength testing of concrete composed of different constituents. The types of concretes that were chosen were one reference recipe only containing portland cement as binder, one which represents todays additives; concrete where 20 \% of the cement has been substituted by blast furnace slag. In addition to this, two innovative types of concrete were chosen, which see limited use today. These were a concrete containing Calcium Sulfoaluminate (C\={S}A) cement and one containing cement composed of Limestone and Calcined Clay Cement (LCCC). The results showed that the properties of the two latter concretes, though different from one another, to a large degree displayed attributes that closely resembled that of the ordinary PC concrete and therefore also good opportunities for use.
During discussion with currently practicing consultants in design engineering it was brought up that concrete constructions are often oversized. This with regard to size and quality of concrete as a way to pass acoustics requirements as well as to reduce drying time of the concrete. The structural technical part therefore studies the floor part of a reference project which, though it will not be named due to confidentiality, is taken from the real world. In this project the floors were constructed as partially prefabricated concrete slabs with casting. Different design alternatives were suggested and their respective reduction of cement was analyzed. These suggestions consist of a partially prefabricated concrete slab with less in-situ casting, T-beams and, to a lesser extent, pre-tensioned hollowcore slab. The results of the analyses showed that large improvements can be made to minimize the environmental impact of this part of a residencial building project. These solutions are currently associated with increased cost of the projects, for example as a result of longer construction times.
It is concluded that there exist many possibilities regarding reduction of emission of greenhouse gases from the construction sector, but that it might be associated with increased cost. There are today very limited incentives to reduce the amount of cement used during construction. It might be advantageous for legislative bodies to examine the effect of, for example, excise duty on cement. (Less) - Popular Abstract (Swedish)
- Miljömässiga vinster genom konstruktions- & materialtekniska lösningar -betong
Byggindustrin står idag för 20 % av Sveriges inhemska utsläpp av växthusgaser. För konstruktörer och andra aktörer i branschen finns det idag få incitament att försöka minska användningen av cement, vars produktion är en av de största källorna till utsläpp från byggsektorn. Detta examensarbete undersöker några olika möjligheter att reducera utsläpp i samband med betonganvändning, dels genom att experimentera med materialets sammansättning och dels genom att optimera konstruktionslösningar.
Cementproduktion står redan idag för en avsevärd andel av jordens koldioxidutsläpp och en ökad tillväxt är väntad i takt med världens befolkningsökning. Om inte... (More) - Miljömässiga vinster genom konstruktions- & materialtekniska lösningar -betong
Byggindustrin står idag för 20 % av Sveriges inhemska utsläpp av växthusgaser. För konstruktörer och andra aktörer i branschen finns det idag få incitament att försöka minska användningen av cement, vars produktion är en av de största källorna till utsläpp från byggsektorn. Detta examensarbete undersöker några olika möjligheter att reducera utsläpp i samband med betonganvändning, dels genom att experimentera med materialets sammansättning och dels genom att optimera konstruktionslösningar.
Cementproduktion står redan idag för en avsevärd andel av jordens koldioxidutsläpp och en ökad tillväxt är väntad i takt med världens befolkningsökning. Om inte användningen av cement minskar globalt kan produktionen av detta material 2050 stå för 30 % av alla utsläpp av växthusgaser på jorden. Arbetet slår dock fast att det idag finns utrymme till väsentliga förbättringar ur miljösynpunkt, både genom förändrad konstruktiv utformning och förändrad sammansättning för den använda betongen. Alternativa konstruktiva utformningar, av i detta fall ett bjälklag, skulle kunna reducera cementanvändningen med så mycket som 80%! Detta både genom att minska mängden betong som användes och genom hur mycket vanligt cement som fanns i den använda betongen. Det som idag hindrar dessa lösningar från att användas är först och främst hur billigt betong är att producera. Man föredrar att använda stora mängder betong för att uppnå krav på, till exempel, akustik istället för att välja mer miljövänliga lösningar. Detta är ett tillvägagångsätt som sparar pengar på miljöns bekostnad! Vidare visar examensarbetets resultat att då det vanliga cementet byttes ut mot alternativa tillsatsmaterial producerades betong med egenskaper som till stor del liknar det som används av branschen idag. Detta ger tillsatsmaterialen mycket god möjlighet att kunna introduceras på en nationell och även internationell marknad. Resultaten också att två av de alternativa tillsatsmaterial som utvärderades påvisade både en högre tidig hållfasthet och en likvärdig (eller något högre) slutlig hållfasthet. Detta ger möjlighet till mycket intressanta lösningar då dessa betonger används.
Idag är åtgärder presenterade i detta examensarbete förknippade med förhöjda kostnader, vilket gör att de inte är särskilt attraktiva i en sektor som redan idag lider av höga kostnader. Situationen kommer troligtvis förändras i samband med framtida krav på klimatdeklaration och eventuella koldioxidskatter. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9042012
- author
- Tornerefelt, Hannes LU and Wong, Richard LU
- supervisor
- organization
- alternative title
- Konstruktions- & materialteknisk optimering av betong - möjliga miljövinster
- course
- VBKM01 20202
- year
- 2021
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- concrete, CO2-emissions, cement, environment, material, construction, betong, koldioxidutsläpp, miljö, konstruktion
- report number
- 21/5282
- other publication id
- LUTVDG/TVBK-0349/4969
- language
- Swedish
- id
- 9042012
- date added to LUP
- 2021-04-01 08:59:53
- date last changed
- 2021-04-01 08:59:53
@misc{9042012,
abstract = {{The greenhouse effect and the emission of greenhouse gases, namely carbon dioxide, is a global issue which today permeates alot of the societal consciousness and therefore also alot of the conducted research. The construction industry is not different in this regard. The construction sector in Sweden, for example, generates more than 12 million metric tonnes of carbon dioxide equivalents every year, this is around one fifth of all emissions in Sweden.
Concrete is the most common construction material in the world. Reasons for why concrete has taken this position in construction projects stem from, for example, its low cost, the global availability of raw materials and its durability. Despite all its positive characterstics concrete is, and especially the manufacturing of cement, one of the largest producers of greenhouse gases originating from the construction sector. Currently it's reported that cement production amounts to between 3 and 8 \% of the global emissions of greenhouse gases. As urbanisation increases in third world countries, and with it the demand for cheap construction materials, studies have argued that the production of cement's share of global emissions can amount to as much as 30 \% by 2050. Something will have to be done to stop this development.
Many research projects are currently operating with the intent of analyzing what possibilities there are to mitigate emissions from cement production. This master's thesis focuses on two possibilities: material technical, namely the substitution of portland cement with additives, and structural technical where, during design, larger importance is given to the reduction of concrete use. Another way of investigating CO$_{2}$-emission, that the industry has shown intrest in, is Carbon Capture Storage (CCS). This means that the carbon dioxide which is released during the firing of limestone amid cement production is collected and stored (for example in pockets in the bedrock under the sea).
The material technical part is studied through casting and strength testing of concrete composed of different constituents. The types of concretes that were chosen were one reference recipe only containing portland cement as binder, one which represents todays additives; concrete where 20 \% of the cement has been substituted by blast furnace slag. In addition to this, two innovative types of concrete were chosen, which see limited use today. These were a concrete containing Calcium Sulfoaluminate (C\={S}A) cement and one containing cement composed of Limestone and Calcined Clay Cement (LCCC). The results showed that the properties of the two latter concretes, though different from one another, to a large degree displayed attributes that closely resembled that of the ordinary PC concrete and therefore also good opportunities for use.
During discussion with currently practicing consultants in design engineering it was brought up that concrete constructions are often oversized. This with regard to size and quality of concrete as a way to pass acoustics requirements as well as to reduce drying time of the concrete. The structural technical part therefore studies the floor part of a reference project which, though it will not be named due to confidentiality, is taken from the real world. In this project the floors were constructed as partially prefabricated concrete slabs with casting. Different design alternatives were suggested and their respective reduction of cement was analyzed. These suggestions consist of a partially prefabricated concrete slab with less in-situ casting, T-beams and, to a lesser extent, pre-tensioned hollowcore slab. The results of the analyses showed that large improvements can be made to minimize the environmental impact of this part of a residencial building project. These solutions are currently associated with increased cost of the projects, for example as a result of longer construction times.
It is concluded that there exist many possibilities regarding reduction of emission of greenhouse gases from the construction sector, but that it might be associated with increased cost. There are today very limited incentives to reduce the amount of cement used during construction. It might be advantageous for legislative bodies to examine the effect of, for example, excise duty on cement.}},
author = {{Tornerefelt, Hannes and Wong, Richard}},
language = {{swe}},
note = {{Student Paper}},
title = {{Constructional- and material technical optimization of concrete - possible environmental benefits}},
year = {{2021}},
}