Preliminary Study of Alkali Activation of Basalt: Effect of NaOH Concentration on Geopolymerization of Basalt

The main objective of this study is to examine the possibility of using fresh basalt powder in the preparation of geopolymer pastes. Four NaOH concentrations of 2.5, 5, 7.5 and 10 M were used to alkali activation of basalt. In addition, effect of curing temperature at ambient, 45°C and 65°C were studied. The geopolymer pastes were investigated using FTIR, XRD and SEM-EDS techniques as well as compressive strength up to 90 days. The results were shown the compressive strength of prepared geopolymer increased with concentration of alkali activator up to 90 days. On the other hand, the compressive strength of prepared geopolymer pastes were improved with increased curing temperature. The results showed that there was a change in the chemical and mineral structure, due to the reaction of the sodium hydroxide with the different minerals of the basalt. In addition, the Na/Al and Si/Al ratios were completely different from that of the raw basalt. The geopolymerization reactions occurred at the surface basalt and the unreacted basalt particles actually play a supporting role in the geopolymer properties.

粗骨料种类对高强混凝土工作性和力学性能的影响

该文选用同级配的石灰石碎石、卵碎石和玄武岩碎石3种粗骨料,研究粗骨料种类对高强混凝土工作性和力学性能的影响。通过对高强混凝土的塌落度、扩展度、抗压强度、弹性模量等指标的测试和分析,结果表明:玄武岩组新拌混凝土的工作性稍逊于石灰石组和卵碎石组,卵碎石组最好。对于石灰石组和玄武岩组,由于骨料表面吸水导致玄武岩组早期混凝土强度较石灰石组偏低,而后期因为玄武岩强度高而使得其配制的混凝土28d强度提高。卵碎石粒形在强度上的劣势导致其28d强度最低。三种粗骨料中,骨料弹性模量越高,同等条件下配制的混凝土弹性模量也越大,但混凝土弹性模量要远小于骨料弹性模量值,且混凝土弹性模量的增幅远远小于相应粗骨料的增幅。