THE EFFECT OF VARIATION OF LEVELS OF PAYAK NGORO SAND MUD IN JOMBANG DISTRICT ON COMPRESSIVE STRENGTH, SETTING TIME AND CONCRETE POROSITY

Concrete is formed from coarse aggregate, fine aggregate, cement and water with a
certain ratio that can affect the speed of hardening of concrete. Furthermore, the silt
content, cleanliness, and aggregate gradation affect the workability which includes
pouring, compaction, and curing methods, which ultimately affect the strength of
the concrete. The silt content in sand tends to inhibit hydration in concrete
(compounding cement with water). Payak sand is located in Ngoro District,
Jombang Regency. In this study to determine the effect of silt content in fine
aggregate (sand) on compressive strength, setting time and concrete porosity, five
variations of silt content were made in fine aggregate (sand), namely variations in
silt content of 3%, 5%, 10%, 15 %, 20%. The density and strength of concrete will
increase with the smallest variations in mud content. Determine the initial set time
and final set time of cement. Sand dug sand with a mud content of 3%, the results
of the examination carried out obtained the results of the initial setting time of
cement with a maximum decrease of 25 mm, which is 75 minutes and the final
setting time of cement with a decrease of 0 mm, which is 150 minutes. The less silt
content contained in the sand will further increase the compressive strength of the
concrete and reduce the porosity of the concrete. The concrete with the highest
compressive strength was 3% silt content concrete with a value of 22.66 MPa and
the smallest porosity with a value of 5.06%. Concrete that has a silt content of 5%
with a compressive strength value of 20.46 MPa and the highest porosity with a
value of 6.79%.