Loading tests on composite concrete columns : A comparison between composite columns made of permanent 3DPC formwork filled with SCC and columns made of homogenous SCC

Sammanfattning: In order to achieve increased sustainability when casting concrete structures this thesis investigates the possibility of utilizing 3D-printing to construct formwork and digitalize construction. By digitizing construction less workers are needed and therefore less capital. The main aim of this thesis is to examine the load-carrying capacity of composite columns made of a permanent 3D-printed concrete formwork filled with SCC and comparing their strength with that of homogenous columns made of SCC. Another aim of this thesis is to examine the formwork pressure and lastly to examine the bond strength between the two concrete materials. The cylindrical columns were reinforced and cast in Tumba, Stockholm at ConcretePrint. Another rectangular temporary formwork was also constructed to measure the formwork pressure. The measured formwork pressure is compared to a calculated theoretical pressure. The load-carrying capacity was examined with the help of a hydraulic press at RISE in Borås. Bond strength was also tested at RISE in Borås by drilling out cores of the composite columns. Results prove that formwork pressure is not an issue for these types of columns. The results also show that the composite columns are stronger when wholly loaded over their cross section while they perform similarly when a concentrated centrally placed load is applied. When subjected to a concentrated centrally placed load it is thought that an eccentricity occurs and therefore lowers the load-carrying capacity in both the homogeneous and composite columns. Further, bond strength between the composite materials had such values that the bond is not thought to be a limiting factor either. While no conclusive conclusion can be drawn due to the limited number of columns, the results are promising and further research is recommended. Such research could for example be durability studies which will be treated in a special report by KTH and possibly a study regarding the economic benefit.