Akademik Veri Yönetim Sistemi
Journal of Sustainable Construction Materials and Technologies, cilt.7, sa.2, 2022 (Hakemli Dergi)
Geopolymer concrete (GPC) is obtained by activating industrial wastes such as fly ash with
chemical liquids such as sodium hydroxide (NaOH) and sodium silicate (Na2
SiO3
). In order
to use environmentally friendly GPC obtained from industrial wastes instead of Portland
cement concrete (OPC), its behavior in structural elements is important and should be investigated in detail. Load-displacement characteristics, flexural and shear stiffnesses, and
crack development of samples were obtained by numerical analysis. The GPC beams to be
an alternative to OPC beams, their mechanical properties, and fracture modes must be at
least as much as OPC. As a result of the analyses, it was determined that the 110x20x15 cm
GPC beams with compression reinforcements of 2Φ8 and tension reinforcements of 2Φ8,
3Φ14, and 2Φ18, respectively, showed similar flexural, shear, and crack development with
OPC beams. Simulations of GPC beams were made up to the breaking point, contributing
to understanding its behavior. The ultimate load for both OPC and GPC beams in the FEM
model was 45 MPa, while in the experimental model, the OPCB was 55 MPa and the GPCB
was 60 MPa. While the first crack started at 1 mm in the OPCB-FEM model, the GPCB-FEM
model showed a more elastic behavior, and the first crack started after 3.5 mm displacement.
The load-displacement results for 2Φ8 compression and 3Φ14 tensile reinforced beams contain closer results in FEM and experimental. The ultimate load states are between 160 MPa
and 180 MPa, but the maximum strengths of OPCBs are slightly higher. After 7.5 mm, crack
formation continued to increase. Maximum strength in beams with 2Φ8 pressure and 2Φ18
reinforcement is in the range of 175–185 MPa. Although the values are very close to each
other, it seems that they did not exceed the strengths of the previous 3Φ14 reinforced beams.
On the other hand, it is seen that the plastic deformation of GPCBs starts from 7.5 mm,
while OPCBs start after 10 mm. Observing the load-displacement graphs and the mobility
of concrete and reinforcement, it can be said that the yield in the steel reinforcement and
the crack development in the beams are simultaneous, and the crack development in GPCs
starts a little earlier than the yield of the steel reinforcement.