Summary: | Crushed stone from the river sources in the District of Central Lampung
regency Padangratu, up to now has not been used optimally. The use of gravel
sand mining waste results are only used for road pavement layers or for
ornamental stone. Visual manifestation of this gravel has a characteristic that is
prospective for aggregate material, but have never done the research and testing
to find out about the properties and strength to concrete. Through this research is
expected to be a reference in the utilization of the aggregate in the manufacture of
no fines concrete brick so it can be more efficient, economical and legal
compliance. Apart from that expected to be a reference in respect of the nonstructural
development, especially in Central Lampung regency.
Scope of the study include the examination and testing of no fines gravel
and concrete. Gravel grain size fraction that is used is limited to 5-10 mm grain,
no fines concrete mixtures made with variations in the volume ratio of cement:
aggregate of 1:4, 1:6, 1:8, 1:10 and cement water factor of 0.40 . Each variation
was tested at 28 days. Cylindrical concrete specimens, diameter 150 mm, height
300 mm and 400 mm size concrete brick x 200 mm x 100 mm. Number of
specimens 24 and 20 cylinders of concrete bricks, which are used to determine the
effect of nature and the technical properties of concrete masonry no fines
concrete.
The results showed that the silica stones of Padangratu generally qualify
for use as concrete aggregate. Specific gravity, unit weight, hardness and wear
resistance aggregate shows characteristics of a normal aggregate. Specific
gravity, air voids, the compressive strength and modulus of elasticity of concrete
no fines has a specific characteristic. No fines concrete weight per m3 with a
volume ratio of cement: aggregate 1:4, 1:6, 1:8, 1:10 ranged from 1.83 to 2.12kgs/m3
(concrete cylinders) and 1.82 to 2, 09 kgs/ m3 (concrete brick), no fines
concrete air voids ranged from 8.64% -25.10% (concrete cylinders) and 8.08% -
26.31% (concrete blocks), no fines concrete compressive strength ranging
between 6.77 MPa - 21.77 MPa (concrete cylinders) and 4.49 MPa - 11.86
(concrete brick) MPa and elasticity modulus values ranged from 8334.20 MPa -
31 671 MPa.
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