Effect Of Chemical Characteristics On Fly Ash On Compressive Strength Ofhigh-Volume Fly Ash Concrete (Hvfac)

The use of fly ash in concrete mixtures continues to be developed in the construction industry. In addition to
aiming to utilize waste from coal combustion at the steam power plant, its use can also reduce CO2 emissions caused by
cement production activities. An example of its use is in producing high-volume fly ash concrete (HVFAC) with the addition
of chemical admixture. Several studies have been carried out to determine the optimal mix design composition with the
results indicating that satisfactory compressive strength of HVFAC is strongly influenced by the type and chemical
characteristics of fly ash used. Therefore, this research aims to analyze the effect of chemical characteristics on fly ash on the
compressive strength of HVFAC at 3, 7, 14, 28, and 56 days using the experimental method. The specimens were made with
three variations, one of the normal concrete mixture using 100% Ordinary Portland Cement (OPC) as a control specimen,
while the other two are of the HVFAC mixture comprising blended cement (20% OPC + 80% fly ash) from different
sources. The comparison (M0), HVFAC-1 (M1) and HVFAC-2 (M2) mixtures used 100% OPC, OPC+fly ash A, and
OPC+fly ash B, respectively. The results showed that the compressive strength of all HVFACs at all ages was lower than
normal concrete with M2 having a higher compressive strength than M1 at 3, 7, and 14 days. However, at 28 and 56 days,
the reverse was the case, thereby indicating that fly ash's chemical characteristics affect concrete's compressive strength at its
Al2O3, SiO2, and CaO contents.