This thesis has been developed inassociation with Strängbetong AB, Sweden. A few years backCementa AB introduced a new type of cement on the Swedish market: Byggcement,which is a Portland Limestone Cement. This type of cement is better for theenvironment and cheaper than Rapid Hardening Cement which is used today at SträngbetongAB. Strängbetong AB isvery interested in a change of cement in the factory and wants to know what ittakes to make a transition from Rapid Hardening Cement to Byggcement. This final projectaims at investigating how the workability and strength development are affectedby a transition from the existing cement to Byggcement and how we can change theproperties of the concrete by adding different types of superplasticizers.  Laboratory and factoryexperiments were made, to investigate the transition.

Examensarbetet redovisar försök utförda på betonggolv i syfte att studera betongens uttorkningsprocess. Testresultaten jämförs med beräkningar utförda i BI Dry och TorkaS. Betongen i testerna utsattes för fuktbelastning av olika grader och skeden. Detta skulle modellera att betong på byggen exponeras för väder och vind. Examensarbetet innehåller både litteraturstudier gällande betongensuttorkningsprocessen och tester. TorkaS 3.2, BI Dry 2.0 samt HumiGuards webbaserade beräkningsprogram användes för att beräkna uttorkningsprocessen och göra en analys av uppmätt data. / The thesis reports experiments performed on the dehydration process of moisture in concrete floor specimens. The aim is to study the RF-values in concrete exposed to humidity and for comparing actual measurements with calculation results from software. Investigation is made on the drying concrete affected by moisture at different levels and stages modelling for cases where concrete is usually exposed to weather conditions for fairly long periods before a controlled drying environment is achieved. The thesis was performed by using literature studies and tests. For each concrete slab specimen moisture controls were mounted sampling data which was implemented into the calculation program. TorkaS 3.2, BI Dry 2.0 and HumiGuard webbased calculation software was used for modelling the drying process and it is reported with graphs in the work.

Vid byggprojekt har det uppdagats fuktproblem i betongplattor där plastmattor har släppt från underlaget. Ett av problemen som beskyllts i media är förändringen från byggcement till bascement. Bascement är en cementsort som 14 % flygaska blandat med portlandklinker. Anledningen till att cementtillverkarna använder flygaska, som är en restprodukt från pulvereldade kolkraftverk, är att det ger minskade mängder portlandklinker som vid tillverkningen släpper ut stora mängder koldioxid. Cement är bindemedlet i betong och när flygaska används binds mindre mängd i vatten i betongens hydrationsprocess. För att undersöka vilken skillnad i uttorkning det finns i betong med bascement och byggcement gjöts två betongprover med samma betongrecept och VCT, men med respektive bascement och byggcement som bindemedel. Dessa betongprover förvarades i en uppvärmd lokal med låg relativ fuktighet. Fuktmätningarna utfördes enligt rådet för byggkompetens fuktmätningsmanual som är det gällande regelverket. Dessa resultat jämfördes med fuktprognoserna från TorkaS och BI Dry, som är de vanligaste fuktberäkningsprogrammen som används. Samtidigt intervjuades olika aktörer från byggbranschen för att undersöka hur de uppfattade problemet med uttorkning i betong. Fuktmätningarna visade ingen markant skillnad mellan betong med bascement och byggcement. Vid jämförelse med de prognosticerade värdena från fuktberäkningsprogrammen framkom att TorkaS värden var väldigt nära de uppmätta fuktvärdena, medans BI Dry:s värden låg långt under de uppmätta värdena. Vid intervjuerna framkom att byggbranschen har många frågor kring uttorkning i betong. Däremot finns svårigheter att avgöra vad som ligger till grund för problemen. Om det är bytet från byggcement till bascement eller om hanteringen av betongen i ett tidigt skede efter gjutningen som påverkar. Däremot om fuktfrågan tas upp i ett tidigt stadium i byggprocessen går det att bespara både tid och pengar. Byggbranschen behöver utbildas hur uttorkningens process ser ut för att öka förståelsen för problemet. / In construction projects, moisture problems have been discovered in concrete slabs where plastic mats have been released from the substrate. One of the problems reported in the media is the change from Portland cement to fly ash cement. Fly ash cement is a cement with 14% fly ash mixed with portland clinker. The reason that cement manufacturers use fly ash, which is a residual product from powder-fired coal power plants, is that it reduces the amount of portland clinkers that release large amounts of carbon dioxide during production. Cement is the concrete binder and when fly ashes are used, less amount of water is bound in the concrete's hydration process. To investigate the difference in dehydration found in concrete with fly ash cement and Portland cement, two concrete samples were obtained with the same concrete recipe and VCT numbers, but with different cement types. These concrete samples were stored in a heated local with low relative humidity. Moisture measurements were carried out according to the current regulations. These results were compared with the moisture predictions from TorkaS and BI Dry, which are the most commonly used moisture calculation programs. At the same time, various actors from the construction industry were interviewed to investigate how they perceived the problem of dehydration in concrete. The moisture measurements showed no significant difference between concrete with base cement and building cement. When compared with the forecasted values from the moisture calculation programs, it was found that the Dry values were very close to the measured moisture values, while BI Dry's values were well below the measured values. The interviews revealed that the construction industry has many questions about dehydration in concrete. On the other hand, there are difficulties in determining what is the basis for the problems. If there is a change from the portland cement to the fly ash cement, or the handling of the concrete at an early stage after the casting affects. However, if the moisture issue is taken up early in the construction process, it is possible to save both time and money. The construction industry needs to be educated how the process of desiccation works to increase understanding of the problem.

The following thesis is a comparison study which was performed in cooperation with Sika Sverige AB. The project was to examine concrete’s behaviour while being subjected to different accelerators which is used to speed up the hardening process in young concrete. Sika provided the materials and the instructions for the tests that were made. The tests used where almost like the tests being performed at Sika’s laboratories but with some adjustments to the testing equipment. According to the results of the tests a clear difference between the different accelerators were found. The conclusion that the efficiency of the different accelerators were affected on several variables such as cement type, hardening age and hardening temperature were drawn. Because of the corona outbreak (2020) the tests could not be performed in Sikas laboratories. The tests were therefore carried out at a temporary laboratory without any direct supervision and some professional equipment could not be obtained which resulted in replacements with creative solutions. These changes affected the individual test results with high certainty but should not interfere with the conclusions on account that all test samples were subjected to the same circumstances.