Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

The use of layered double hydroxides (LDHs) is a new direction in chemistry cement. influence calcium/aluminum (Ca-Al LDHs) and polycarboxylate ethers (PCE) on the strength development Portland limestone cement has been investigated. It shown that Ca-Al LDHs form slurry with introduction alkaline aluminate accelerator Na[Al(OH)4]. was determined this contributes to significant increase early stone. However, reduces setting time hardening, there decrease age. At an stage structuring paste addition Na[Al(OH)4], metastable high-water hydrate phases type C4AH19 ([Ca2Al(OH)6]2(ОН)2·12H2O) are formed, which, due conversion phenomenon, transform cubic C3AH6. Such processes accompanied by overall porosity decreases Stabilization LDH structure achieved introducing anions [NO3]- into interlayer space formation Ca-Al-NO3 through sol-gel technology. X-ray phase analysis, IR spectroscopy, electron microscopy proved fact synthesis AFm-phases [Ca2Al(OH)6]2(NO3)2.6H2О. When modifying such hydrates ethers, nanocomposite LDHs-РСЕ formed. found when introduced СЕМ ІІ/A-LL 42,5 R, over period 8...24 hours increases 2.0–1.5 times, and, after 2 28 days, 58 144 % standard (Rс28=62.5 MPa). obtained nanomodified refers extra rapid-hardening high-strength cement, which makes it possible solve task carrying out work rapid restoration reinforced concrete structures' elements