The stress-strain relationships of UC tests of samples with remolding
water content of 200%, cement content of 15%, with
varying fly ash content are illustrated in Fig. 5. The maximum
stress, or strength, of material increased with increasing fly ash
content. The increase in strength with fly ash content is due to the attribution of pozzolanic reaction to enhance the strength of the mixtures. The pozzolanic reaction, which is the secondary reaction,
is to build up bonding between particles of the mixtures.
This demonstrated the preliminary possibility of using fly ash for
replacing cement in soil-cement column. However, more studies
on long-term strength should be investigated since low-strength
materials produced with fly ash can lose strength if exposed to
saturated conditions for a long period of time.