Flexural capacity of vertical and diagonal joints in self compacting concrete to old concrete

Casting concrete at different times is often unavoidable due to insufficient casting time. Some conditions require further casting connections on concrete. Casting connections between new concrete blocks and old concrete will affect the strength of the concrete. The strength of the connection needs to be assessed so that the capacity of the concrete due to the connection can be known. This study was conducted to determine the characteristics of fresh concrete, compressive strength, and flexural capacity of new self-compacting concrete (SCC) connections to old concrete using diagonal and vertical connection models. The maximum aggregate grain size is 20 mm, fas 0.35 using superplasticizer type F Sika Viscocrete 1003. The test object in the form of a concrete cylinder was tested for compression at the ages of 3, 7, 14, 21, and 28 days. Concrete blocks with a length of 750 mm, a width of 150 mm, and a height of 150 mm with a maximum aggregate size of 20 mm, with vertical and diagonal connections that were tested for flexural strength after 28 days to determine the flexural capacity. The results of the slump flow test are greater than 60 cm, and the L-box test shows that the h2/h1 ratio is more than 0.8. The results of the fresh concrete test show that the concrete is SCC concrete. The results of the SCC concrete compressive strength test at the age of 28 days are 46.87 MPa. The percentage of concrete compressive strength at the ages of 3, 7, 14, and 21 days is 70.69%, 85.60%, 94.75%, 93.74%. SCC concrete produces fresh concrete that has a thin characteristic, can solidify by itself without compaction, and has high compressive strength. The flexural capacity of SCC concrete without joints is 6.38 MPa. The flexural capacity with vertical joints without adhesive is 2.77 MPa (43.46%), while with diagonal joints without adhesive is 4.73 MPa (74.14%). Using diagonal joints produces a higher flexural capacity than using vertical joints.