3.2. Water absorption
Fig. 3 presents water absorption results. From the results, MC-
5% absorbed the least water content, above and below which more
water was absorbed. In fact, the more the latex content above this
limit the higher the water absorbed.
Since NC contains voids as depicted in its structure by the morphology
in Fig. 2a, it follows that latex content below 5% is insufficient
to provide the most effective water rejection qualities. Even
though, MC-2.5% indicated a marked improvement over NC, this
content failed to yield optimum result. Similarly, modifications beyond
5% depicted poor water exclusion properties perhaps due to
excess latex over that which is sufficient for the most effective
voids filling. Indeed, excess latex beyond that which is necessary
to fill capillary pores may prevent proper compaction of aggregates
by appearing at interface boundaries. Thus, as the latex coalesces,
which is normally accompanied by volume reduction, more voids
may arise over that witnessed in MC-2.5% and MC-5%.