Pozzolanic Activity Assessment of LUSI (LUmpur SIdoarjo) Mud in Semi High Volume Pozzolanic Mortar

LUSI mud obtained from the mud volcano in Sidoarjo, Indonesia, is a viable
aluminosilicate material to be utilized as pozzolanic material. LUSI is an abbreviation of
the local name of the mud, i.e., Lumpur Sidoarjo, meaning Sidoarjo mud. This paper
reports the results of an investigation to assess the pozzolanic activity of LUSI mud,
especially in semi high volume pozzolanic mortar. In this case, the amount of mud
incorporated is between 30% to 40% of total cementitious material, by mass. The content
of SiO2 in the mud is about 30%, whilst the total content of SiO2, Fe2O3 and Al2O3 is more
than 70%. Particle size and degree of partial cement replacement by treated LUSI mud
affect the compressive strength, the strength activity index (SAI), the rate of pozzolanic
activity development, and the workability of mortar incorporating LUSI mud.
Manufacturing semi high volume LUSI mud mortar, up to at least 40% cement
replacement, is a possibility, especially with a smaller particle size of LUSI mud, less than
63 μm. The use of a larger percentage of cement replacement by LUSI mud does not show
any adverse effect on the water demand, as the flow of the fresh mortar increased with the
increase of percentage of LUSI mud usage.