PREPARATION OF PUZZOLANA ACTIVE TWO COMPONENT COMPOSITE FOR LATENT HEAT STORAGE

Application of Phase Change Materials (PCMs) represents promising way for an increase of energy efficiency of industrial devices, reduction of energy demands for heating and cooling, waste heat recovery, solar energy storage and smart control of buildings interior climate. In this paper, the potential of diatomite as the bearer for the shape stable PCM was studied in order to develop material applicable in the mix composition of composite materials. Considering availability, endurance and compatibility of diatomite with the cement and lime based materials, preparation of diatomite/wax composite brings pozzolana active PCM with great promises at a reasonable cost. Prepared composite was analysed in detail using laser diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. Also the pozzolanic activity was measured. The prepared two components composite exhibits high latent heat storage and particle size distribution compatible with cement and hydrated lime

PREPARATION OF PUZZOLANA ACTIVE TWO COMPONENT COMPOSITE FOR LATENT HEAT STORAGE

Application of Phase Change Materials (PCMs) represents promising way for an increase of energy efficiency of industrial devices, reduction of energy demands for heating and cooling, waste heat recovery, solar energy storage and smart control of buildings interior climate. In this paper, the potential of diatomite as the bearer for the shape stable PCM was studied in order to develop material applicable in the mix composition of composite materials. Considering availability, endurance and compatibility of diatomite with the cement and lime based materials, preparation of diatomite/wax composite brings pozzolana active PCM with great promises at a reasonable cost. Prepared composite was analysed in detail using laser diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and differential scanning calorimetry. Also the pozzolanic activity was measured. The prepared two components composite exhibits high latent heat storage and particle size distribution compatible with cement and hydrated lime

LIGHTWEIGHT CONCRETE MADE WITH WASTE EXPANDED POLYPROPYLENE-BASED AGGREGATE AND SYNTHETIC COAGULATED AMORPHOUS SILICA

Recycled plastic aggregate can be used as an alternative material to produce lightweight concrete with low environmental impact. Polypropylene is one of the least recycled post-consumer plastics. In the present study we focused at waste expanded polypropylene (EPP) aggregate that is used for partial replacement of natural aggregate to produce lightweight cement-based composites. Coagulated silica was used as admixture for improvement of dispersion of EPP particles in the cement-based matrix. At first, natural and EPP aggregates were examined. Coagulated silica was characterized by SEM, EDS, XRF, particles size distribution and pozzolanic activity. Analysis of the microstructure of lightweight concrete was performed using an optical microscope, SEM imaging and EDS. For the developed lightweight concrete, basic physical, mechanical and hygric properties were examined. Specific attention was paid to thermal properties. The results show, using of plastic waste aggregate led to a sufficient mechanical resistance, whereas the thermal insulation performance of the developed concrete was markedly improved. Composite with incorporated PP waste aggregates was found to be prospective material for non-structural applications in building industry, which allows the development of buildings with optimum energy performance as well as reduce the growing environmental impact of waste polymers and saving the natural aggregates

THE EFFECT OF THE SODIUM SULPHATE SOLUTION EXPOSURE ON PROPERTIES AND MECHANICAL RESISTANCE OF DIFFERENT KINDS OF RENDERS

The effect of 5% water solution of the sodium sulphate and the reference environment of distilled water on changes in mechanical resistance of the commercial dry render mixes was researched in the paper. The prism-shaped specimens cured 28 days in humid and stable conditions were immersed in water or sodium sulphate water solution. At chosen time, the particular specimens were collected, dried to constant mass, and subjected to tests. The maximum time of specimen exposure to moisture or salt action was 168 days. Within the performed experiments, length changes, mass gain, mechanical and basic properties were measured in order to reveal the effect of sulphate corrosion on researched materials. Additionally, pore size distribution measurement and X-Ray CT analysis for the most damaged render were done, in order to characterize the disruptive impact of sulphate solution on porous microstructure of lime-metakaolin-based render. The obtained data revealed the high capacity of porous space of the tested renders for salt storage. For shorter times of exposure to salt action, most of the studied renders exhibited improvement in mechanical resistance. On the other hand, after the full filling of the porous space, the evoked crystallization pressures led to the decrease in mechanical resistance and materials damage. However, one type of studied renders originally designed for restoration of salt laden masonry maintained its excellent mechanical properties even after 168 days of sulphate exposur

GRAPHENE- AND GRAPHITE OXIDE-REINFORCED MAGNESIUM OXYCHLORIDE CEMENT COMPOSITES FOR THE CONSTRUCTION USE

Graphene and graphite oxide reinforced magnesium oxychloride cement (MOC) pastes were researched. To produce MOC pastes, the light-burnt magnesium oxide was added and dispersed in the magnesium chloride solution. The graphene powder, graphite oxide powder, and their combination were incorporated in the solution. The total amount of the nano additives was 0.5% by the weight of the magnesium oxychloride binder. The morphology and microstructure of the hardened materials were studied using scanning electron microscopy (SEM). The phase composition of precipitated MOC-based products was investigated using X ray diffraction (XRD). The macrostructural parameters of the composites such as bulk density, specific density, and open porosity were evaluated. Mechanical strength and stiffness were analyzed by the measurement of flexural and compressive strength and dynamic elastic modulus. The electrical properties were examined by the use of impedance spectroscopy (IS). From the experimental results the model of the transport of electric charge in researched materials dispersion was estimated. The use of graphene- and graphite oxide-reinforcement of MOC matrix gave highly dense materials of low porosity, high mechanical resistance, whereas the used nano-additives enabled the produce of composites of high strength efficiency index. The addition of graphene particles and the formation of graphite agglomerates significantly decreased electrical resistivity of the MOC matrix which was originally characterized by low electrical conductivity

STUDY ON POZZOLANA ACTIVITY OF WHEAT STRAW ASH AS POTENTIAL ADMIXTURE FOR BLENDED CEMENTS

Wheat straw ash coming from combustion of packed wheat straw was studied as a potential pozzolana active admixture for blended cements. X-Ray fluorescence, X-Ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy were used to examine chemical and mineralogical composition, morphology and elemental distribution of a raw untreated ash. Due to high carbon content, the wheat straw ash was thermally treated for 2 hours at 700 °C and analyzed again using the same analytic techniques. Thermal treatment process was monitored using simultaneous thermal analysis and Fourier Transform infrared spectroscopy. The pozzolana activity was assessed using Chapelle and Frattini tests. In the next step, wheat straw ash was used for preparation of blended cement pastes. The content of ash in the blends was 10, 15, and 20% by mass. For the hardened pastes, basic physical properties, mechanical parameters, and pore size distribution were measured. For fresh past mixes, workability was tested. Moreover, leachability of chlorides, nitrates, sulfates and alkalis from paste samples was studied. The experimentally obtained data pointed to the high pozzolana activity of wheat straw ash and sufficient mechanical properties of cement pastes with the ash content up to 20 mass% of cement. In summary, the analyzed waste product from biomass combustion was found to be applicable as a part of cement-based blended binder providing economic and environmental benefits for concrete industry