Study on the weathering resistance of fly ash-lime compacts

The relationship between the inner quality factors (such as the amount of effective calcium oxide and the pore structure) of steam-cured fly ash-lime compacts (clinker-free) and the environment factors (such as drying shrinkage, freeze-thaw and carbonation, et cetera) have been studied here comprehensively by the simulation weathering examination. Meanwhile, the influences of additives of alkali paste and gypsum on the mechanical properties and pore structure of the compacts have been investigated and discussed, and the effects of interface texture on the mechanical properties have been discussed also. The results suggest that the weathering resistance of the system studied can be improved effectively by means of controlling the fraction of effective calcium oxide (EF_cao) and additives, in turn, to improve the interface interlinking. The optimum fraction of EF_cao is ∼15.3%, alkali paste is about 3.0% and gypsum is 1.7∼2.6% (account by SO₃%) if the as-received low calcium-bearing fly ash with low carbon content (<6.0%) has been selected.