Concrete is a construction material used in almost all buildings. This study aims
to determine the flexural strength of concrete using Serayu sand and Mount
Sindoro sand. The sample used was in the form of a block with a size of 15 cm x
15 cm x 60 cm with a total of 6 samples, 3 samples for Serayu sand and 3 for
Mount Sindoro sand. The test sample was tested when the concrete was 7 days old
without conversion. The results of the study for Serayu river sand with a slump
value of 3.74% obtained results of 2.8122 Mpa. The results for the Mount Sindoro
sand study with a slump value of 2.88% obtained results of 3.27 Mpa. With this
research, it is known that mountain Sindoro sand is more flexible than Serayu
Banjarnegara sand.