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In this study, the effect of different types of aluminosilicates on the thermo-mechanical properties of metakaolinite-based geopolymer binders and composites was examined. The metakaolinite-based geopolymer binders and composites were produced from three different types of aluminosilicates (one metakaolin and two calcined claystones) and a potassium alkaline activator. Chamotte was added as a filler, amounting to 65% by volume, to create geopolymer composites. Geopolymer binders were characterized by X-ray diffraction, rotary rheometer and scanning electron microscopy. The mechanical properties, thermal dilatation and thermal conductivity were investigated on geopolymer composites with three different aluminosilicates before and after exposure to high temperatures (up to 1200 °C). The results showed that the geopolymer binders prepared from calcined claystones had a lower dynamic viscosity (787 and 588 mPa·s) compared to the geopolymer binders prepared from metakaolin (1090 mPa·s). Geopolymer composites based on metakaolin had lower shrinkage (0.6%) and higher refractoriness (1520 °C) than geopolymers from calcined claystones (0.9% and 1.5%, 1500 °C and 1470 °C). Geopolymers based on calcined kaolinitic claystones are a promising material with higher compressive (95.2 and 71.5 MPa) and flexural strength (12.4 and 10.7 MPa) compared to geopolymers based on metakaolin (compressive strength 57.7 MPa).

Metakaolinite-based geopolymer binder was prepared at room temperature by mixing calcined claystone and potassium alkaline activator. Various granular inorganic fillers were added, amounting to 65 vol % to form geopolymer composites. The effect of four types of fillers (sand quartz, chamotte, cordierite, and corundum) on the thermo-mechanical properties of metakaolinite-based geopolymer composites were investigated. The samples were also examined by an X-ray diffraction method to determine their phase composition. The pore size distributions were determined by a mercury intrusion porosimeter. The XRD revealed the crystallization of new phase (leucite) after thermal exposure at 1000 &deg, C and higher. Geopolymer binders had low mechanical properties (flexural strength 2.5 MPa and compressive strength 45 MPa) and poor thermo-mechanical properties (especially high shrinkage&mdash, total shrinkage 9%) compared to geopolymer composites (flexural strength up to 13.8 MPa, compressive strength up to 95 MPa and total shrinkage up to 1%). The addition of fillers reduced the shrinkage of geopolymers and improved their mechanical properties. The results have shown that the compressive strength tested in situ and after exposure to high temperature are in conflict. Geopolymer composites with the addition of chamotte had the best mechanical properties before and after thermal exposure (compressive strength up to 95 MPa). The average pore size diameters increased with the increasing temperature (from 10 nm to approx. 700 nm). The fillers addition decreased the pore volume (from 250 mm3/g to approx. 100 mm3/g).

A novel β-belite cement was prepared, characterized (by chemical and phase composition, particle size distribution, bulk density, specific surface area) and incorporated into mortars based on a mixed binder β-belite-metakaolinite-hydrated lime with different contents of β-belite cement (0, 20, 40, 60, 80 and 100 wt.%). The metakaoline:hydrated lime weight ratio of 1:1 and binder:sand weight ratio of 1:3 were observed in all mortars. The effect of the β-belite cement fraction on the properties of fresh mortars (water:binder ratio needed to achieve the required mortars consistency and initial setting time), on the phase composition (X-Ray diffraction phase analysis and thermogravimetric analyses) and on the structural properties of mortars (compressive strength, flexural strength, bulk density, water absorption, water absorption coefficient, shrinkage) over 1 year of curing was investigated. Freeze and thaw resistance of the mortars after 1 year of curing was also evaluated. Partial replacement of metakaolinite-hydrated lime binder with β-belite cement affected all investigated mortar properties. Significant improvements in mechanical properties and resistance to freezing and thawing cycles were the main advantages.

The low viscosity metakaolinite based geopolymer binders were prepared by mixing calcined claystone with potassium activators. The effect of the water content (30, 35, 40, 45 and 50%) and the Me:Al molar ratio (0.55, 0.70, 0.85, 1.00, 1.15 and 1.30) on the properties of binders (dynamic viscosity, applicability by ejection needles with different external diameters, compressive strength, elastic modulus and pore size distribution) was investigated. The Si:Al molar ratio was maintained at 1.5 for all geopolymer binders. Composites of geopolymer binders with 30% water with sand (1:1) were also prepared and evaluated. Geopolymer binders had a very low viscosity (8.4 mPa·s to 1.154 Pa·s), excellent mechanical properties (compressive strength up to 88.1 MPa), and all of them were applicable with injection needles having an external diameter of 1.2 mm or less. Increasing water content in the geopolymer binders led to a significant decrease in viscosity, compressive strength and modulus of elasticity and to the growth of pore volume and pore size. Geopolymers with a Me:Al molar ratio 1.0 had the best mechanical properties. The alkali content in the geopolymer binder did not have any noticeable effect on the pore volume, however dependences of the average pore size diameters on the Me:Al molar ratio had a minimum at Me:Al 0.7. The addition of sand to the binder did not have significant influence on compressive strength, but modulus of elasticity was increased 2–3 times compared to non-filled geopolymer binders.

The leaching behaviour of three metakaolinite-rich materials prepared from granulated kaolin and two kaolinitic claystones in alkaline solutions at room temperature was investigated with the aid of centrifugal separation of clear supernatant from the reaction mixture. Two types of alkaline solutions (sodium or potassium hydroxide and sodium or potassium silicate solution) with two solid/ liquid weight ratios (0.04 and 0.65) were tested in a large time interval (5 min to 336 h). The metakaolinite-rich materials were characterized by XRD, XRF, BET and MIP. Al and Si concentrations in supernatant were analysed using an inductively coupled plasma optical emission spectrometer (ICP-OES), the solid phases were identified by X-ray diffraction. All three metakaolinite-rich input materials are leachable in the applied alkaline solutions, almost independent of the character of the calcined kaolinitic materials, including both less expensive claystones. The concentrations of dissolved Al and Si were mostly higher in an alkaline solution with sodium than with potassium cations. Alkali silicate solutions showed a significantly higher extent of leaching in comparison with alkaline hydroxide solutions. The solids remaining after the leaching in hydroxide solutions showed a presence of zeolites and carbonates, which, was not the case with alkaline silicate solutions.

The degradation of DNA, resulting in information of oligonucleosomal fragments, is a characteristic feature of apoptosis, i.e., the process of programmed cell death. In this work we have developed a method for exact determination of the proportion of fragmented DNA in an apoptotic cell population. To this end we employed Sephacryl gel chromatography matrices and UV detection of DNA concentration. The disturbing effect of low-molecular-mass UV-absorbing contaminants was eliminated by insertion of a Sephacryl S-200 HR pre-column. Optimum resolution of DNA samples isolated from apoptotic cells was achieved using a triad of Sephacryl S-200 HR, Sephacryl S-500 HR and Sephacryl S-1000 SF columns.