Effect Of Sulfate Solution Research Articles

Hybrid slag geopolymer composites with durable characteristics activated by cement kiln dust

The effect of sulfate solution on the geopolymer formed from different type of slag as arc slag (EAFS) and granulated blast furnace slag (GGBFS) as well as cement kiln dust (CKD) was studied. Activation was carried upon usage of 25% CKD, as it bears high alkali content that can initiate and propagate the polymerization process. The formed geopolymer composites were immersed in 5% MgSO4 solution to determine the stability upon sulfate attack. FTIR, XRD, SEM, compressive strength and water absorption analysis were utilized to examine the obtained geopolymer under sulfate attack. Results clarified an optimization of strength values by EAFS increase up to 50%, followed by lowering in strength with EAFS increase, possessing stability up to 12 months. Data elucidated a good stability and resistance of mix containing slag substitution by 50% EAFS and 25% GGBFS and resulted in further enhancement in both mechanical and micro-structural characteristics by increasing matrix compaction and cohesion than the non-immersed samples (28 days).

Impact of electric arc furnace slag on geopolymer composites exposed to sulphate solution

Effect of sulfate solution on the geopolymer formed from electric arc furnace slag (EAF) along with water cooled slag and cement kiln dust was studied. Activation was carried up on usage of 25% CKD as it bears high alkali content that can initiate and propagate the polymerization process. The formed geopolymer products were immersed in 5% MgSO4 solution to determine the stability up on sulfate attack. FTIR, XRD, SEM, compressive strength and water absorption were utilized to examine the resulted geopolymer product under sulfate attack. Results showed that, the compressive strength of geopolymer specimens increase with EAF slag up to 50% then decrease with further slag increase, possessing stability up 12 months and giving an increased compressive strength than the control mix that has not EAFS by 6.53%, 14.72%, 47.44% and -4.89 % after immersing ages of 3 months and 2.26, 14.26, 43.97 and 19.98 % after immersing age of 12 months for replacement by 10, 25, 50 and 75% of EAFS, respectively. Data elucidated a good stability and resistance of mix containing slag substitution by 50 % EAF and 25 % GGBFS and results in further enhancement in both mechanical and microstructural characteristics than the non-immersed samples (28days).

Impact of electric arc furnace slag on geopolymer composites exposed to sulphate solution

Effect of sulfate solution on the geopolymer formed from electric arc furnace slag (EAF) along with water cooled slag and cement kiln dust was studied. Activation was carried up on usage of 25% CKD as it bears high alkali content that can initiate and propagate the polymerization process. The formed geopolymer products were immersed in 5% MgSO4 solution to determine the stability up on sulfate attack. FTIR, XRD, SEM, compressive strength and water absorption were utilized to examine the resulted geopolymer product under sulfate attack. Results showed that, the compressive strength of geopolymer specimens increase with EAF slag up to 50% then decrease with further slag increase, possessing stability up 12 months and giving an increased compressive strength than the control mix that has not EAFS by 6.53%, 14.72%, 47.44% and -4.89 % after immersing ages of 3 months and 2.26, 14.26, 43.97 and 19.98 % after immersing age of 12 months for replacement by 10, 25, 50 and 75% of EAFS, respectively. Data elucidated a good stability and resistance of mix containing slag substitution by 50 % EAF and 25 % GGBFS and results in further enhancement in both mechanical and microstructural characteristics than the non-immersed samples (28days).

Effect of sulfate solution on the frost resistance of concrete with and without steel fiber reinforcement

Properties of plain concrete (PC) and steel fiber reinforced concrete(SFRC) (with water/cement ratio of 0.44, 0.32 and 0.26) subjected to freeze–thaw cycles in 5.0% sodium sulfate solution were investigated in this paper. It was found that during the initial 300 freeze–thaw cycles, sulfate solution had little effect on the relative dynamic modulus of elasticity (Ed) of concrete. In further freeze–thaw cycling, the effect of sulfate solution on Ed was much more obvious. Both PC and SFRC specimens with w/c of 0.44 failed before 300 cycles and exhibited similar developing trends of the Ed whether freezing and thawing in sulfate solution or in fresh water. As for the concrete specimens with w/c of 0.26, the decline of Ed was more serious when freezing and thawing in sulfate solution than that in fresh water after 300 cycles. The adoption of steel fiber greatly restrained the decline of Ed and changed the failure mode of the specimen from brittle crack in midspan of PC to gradually decline of Ed up to failure under the combined action of freeze–thaw cycles and sulfate attack. Test results also demonstrated that there was an interaction effect between the action of freeze–thaw cycles and sulfate attack.

Effect of sulphate solutions on normal and sulphate‐resisting portland cement

AbstractThe expansion and changes in phase composition of dilute paste and mortar bars of normal and sulphate‐resisting Portland cement exposed to various sulphate solutions were studied over a period of time. Although strong expansion was usually associated with the presence of considerable amounts of calcium sulphoaluminate, there was no quantitative correlation between expansion and the concentration of crystalline calcium sulphoaluminate. Similar quantities of this compound were found in corresponding samples of normal and sulphate‐resisting cement. It was inferred that, on continued corrosion, calcium sulphoaluminate partially passes into a gel phase which may determine the properties of the cement.In the presence of magnesium ions the bars disintegrated before excessive expansion occurred, since these ions reacted with hydrating cement with the precipitation of magnesium hydroxide, which tends to block the pores and channels, thus preventing penetration of the solutions. Chloride ions increased expansion by forming calcium chloroaluminate. Under the static conditions of the experiments protective surface films developed.