Akademik Veri Yönetim Sistemi
5th International Conference on Engineering Technologies in Konya/Turkey (ICENTE 2021), Konya, Türkiye, 18 - 21 Kasım 2021, ss.186
Portland
cement, which is used as a binding material in traditional concrete, continues
to have a market advantage in the construction industry in the past and still
thanks to its cheap and easily available raw materials (limestone and clay).
Although Portland cement continues to be the most used binder material in the
concrete industry today, due to the high energy requirement during the
production of cement and the harmful effect of the CO₂ gas released on the
atmosphere, some studies have been carried out for the production of
alternative binder building materials to cement in recent years. In this study,
while producing geopolymer mortars, metakaolin as a binder, baked stone dust
waste at 15%, 30%, 45% replacement ratios as substitute material, colemanite
mineral at 10%, 20%, 30% replacement ratios as substitute material, borax penta
hydrate mineral at 10%, 20%, 30% replacement ratios as substitute material, borax
deca hydrate mineral is used at 10%, 20%, 30% replacement rates. At the same
time, metakaolin as a binder, colemanite mineral as an additive at 10%, 15%,
20% additive rates, borax penta hydrate mineral at 10%, 15%, 20% additive
rates, and borax deca hydrate mineral was used in 10%, 15%, 20% additive
ratios. In mortar production, 50% of 10M sodium hydroxide (NaOH) and 50% of 2
Module sodium silicate Na₂SiO₃ were used as alkali activators. Geopolymer
mortars produced using a liquid/binder ratio of 1, a water/binder ratio of
0.60, and a sand/binder ratio of 2.25 were cured for 24 hours at room
temperature and 60 ℃ curing conditions. When the dispersion values of the
produced geopolymer mortars were examined, it was observed that the dispersion
value increased with the increase of the replacement rate of the baked stone
dust waste substituted for the metakaolin as a binder, and the dispersion
values increased with the increase of the substitution rate of colemanite,
borax penta hydrate and borax deca hydrate substituted for the metakaolin. When
the mechanical properties of geopolymer mortars were examined at different
curing temperatures, it was observed that the 7 and 28-days flexural and
compressive strengths of the samples containing only metakaolin as a binder at
room temperature and 60 ℃ curing temperature did not differ. It was observed
that the best results were obtained at 30% substitution rate in 7-days flexural
and compressive strengths at room temperature and 60 ℃ curing temperature in
the samples using baked stone dust waste as a substitute material, while the
samples using only metakaolin gave the best results in the 28-days compressive
strength. In the samples using colemanite mineral as a substitute material for
metakaolin, it was observed that the best values in flexural and compressive
strength of 7 and 28 days at room temperature curing were found only in the
samples using metakaolin. In the samples cured at 60 ℃, it was observed that
the best strength value in 7-days flexural and compressive strength was
obtained in 10% colemanite mineral substitution. Likewise, considering the
28-days compressive strength of the samples cured at 60 ℃, the best values were
obtained in the samples using only metakaolin as a binder. On the other hand,
in the samples where borax penta hydrate and borax deca hydrate mineral were
used as substitute materials instead of metakaolin as binder, it was observed
that the best strength values were obtained in the samples produced using only
metakaolin at both room temperature and 60 ℃ curing temperature. When
colemanite mineral was used as an additive to metakaolin binder geopolymer
mortars, it was observed that the best results at room temperature curing were
obtained only in samples using metakaolin. At 60 ℃ curing temperature, it was
observed that the best value in 7-days flexural and compressive strength was
observed in the samples using 20% colemanite mineral, while in the 28-days
compressive strength, only metakaolin was used as a binder. When borax penta
hydrate mineral is used as an additive to metakaolin binder geopolymer mortars
in mortar production, it has been observed that the best value in 7-days
flexural and compressive strength at 60 ℃ curing temperature is obtained with
10% additive, while 28-days compressive strength is obtained in samples
produced using only metakaolin. Likewise, in the samples using the mineral
borax deca hydrate as additive material, it was observed that the best values
in the flexural and compressive strength of 7 and 28 days at room temperature
curing and 60 ℃ curing temperature were found only in the samples using
metakaolin. As a result, it has been seen that metakaolin should be used as the
main binder in the production of geopolymer mortar and that metakaolin gains
strength at room temperature. It has been observed that up to 30% baked stone
dust waste can be used as a metakaolin replacement material in geopolymer
mortars, especially in early strength conditions. It has been observed that
boron minerals cannot be used as a substitute material in geopolymer mortars in
any way, and it has been observed that colemanite and borax penta hydrate
minerals can be used up to 10% to 20%, especially in early strength conditions,
in terms of additive material.