Production and Evaluation of Porous Photocatalyst Concrete Filter (deNOx PCF) for NOx Reduction

A porous photocatalyst concrete filter (deNOx PCF) is successfully manufactured to reduce NOx by mixing TiO2 photocatalyst with lightweight aerated concrete. From the results, 4% infusion rate of each foaming agent provided the smallest change of the height, and the optimal quality of the air bubbles can be produced by using foaming agent B with 4% of infusion rate. When 3% of TiO2 photocatalyst was mixed, less irregular and relatively homogeneous pores were formed on the surface with white color due to the proper amount of photocatalyst applied. For 3% of photocatalyst mixed with deNOx PCF, 1.03 μmol/hr of NO was reduced equivalent to 10.99% of NO reduction, suggesting that the TiO2 photocatalyst dispersed in the continuous and well-developed pores inside the specimen successfully performed the removal of NO flowing through deNOx PCF using synergistic effects of adsorption and photodegradation reaction. Finally, the specimen of porous deNOx PCF for reducing NOx developed in this study can be applied to various construction sites and the air quality can be solved by reducing NOx contributing to the formation of fine particles.

Influence of Aluminium and Autoclaving Temperature on the Properties of Autoclaved Aerated Concrete

Autoclaved aerated concrete (AAC) prepared by the mixing of ordinary Portland cement, lime powder, sand, aluminium powder and water. This study covers the variation of physical, mechanical and functional properties of autoclaved aerated concrete with autoclaving temperature and aluminium content and compared with that of normal weight cement mortar sample. In this work, two dosage of aluminium content of 0.4% and 0.8% of the dry weight of ordinary Portland cement and three different autoclaving temperature of 160oC, 180oC and 200oC were used. AAC sample with 0.8% aluminium and 160oC temperature had unit weight of 1490kg/m3 which was lowest among all samples including the control or normal weight cement blocks. Weight reduction of AAC sample was 31.53%. AAC sample with 0.4% aluminium and 200oC autoclaving temperature gave maximum compressive and tensile strength of 19.4MPa and 1.81MPa respectively which were close to that of normal weight concrete and strength of AAC increased with autoclaving temperature and decreased with aluminium content. In this research, the functional propertiesof AAC, absorption capacity was much higher than normal weight concrete and this capacity was increased with aluminium content and with decreasing autoclaving temperature and unit weight of AAC. For AAC with 0.8% aluminium and 160oC temperature gave maximum water absorption capacity (=9.93%). Again, surface absorption rate was higher for first 12hours and with time it would be constant because of its saturated position. Journal of Engineering Science 12(3), 2021, 11-17

The Physical and Mechanical Properties of Autoclaved Aerated Concrete (AAC) with Recycled AAC as a Partial Replacement for Sand

The application of AAC has increased considerably in Malaysia since the 1990s. The usage of AAC has some advantages, but it also has negative environmental impacts since rejected concrete will become landfill. This study aimed to use AAC waste powder as a material that would partially replace the sand content to produce a new form of Autoclaved Aerated Concrete (AAC). The physical and mechanical properties of the newly developed AAC were investigated. This paper presents improved mechanical and physical properties of the new form of recycled AAC concrete. Besides these improvements, using recycled AAC could lower production costs. Furthermore, the usage of this recycled waste powder is both economically and environmentally advantageous. This study found that when recycled AAC was substituted for sand, AAC with a fine recycled powder content of 30% had a compressive strength that was around 16% higher than conventional AAC and between 29% and 156% higher than any value attained utilizing an industrial waste product. This study also confirmed that the greater strength could be identical to a higher tobermorite phase and that the recycled AAC surface showed a finer crystalline morphology.

Influence of Waste Tire Particles on Freeze–Thaw Resistance and Impermeability Performance of Waste Tires/Sand-Based Autoclaved Aerated Concrete Composites

Waste tires/sand-based autoclaved aerated concrete (SAAC) composites were prepared by mixing waste tires, which have different particle sizes and content. The physical performance, mechanical properties, freeze–thaw resistance, impermeability performance, phase composition, and microstructure of waste tires/sand-based autoclaved aerated concrete composite materials were examined. The results demonstrated that the 750-μm-sized waste tire particles on the surface of the SAAC composite did not agglomerate. Moreover, these particles did not damage the pore structure of the composites. The SAAC composites, with a relatively high compressive strength and low mass-loss rate, were obtained when the contents of waste tire particles ranged from 1.0 to 2.5 wt.%. For composites prepared with 2.0 wt.% of 750-μm-sized waste tire particles, the optimal compressive and flexural strength values were 3.20 and 0.95 MPa, respectively. The increase in the rate of water absorption on SAAC composites was lowest (i.e., 16.3%) when the soaking time was from 24 to 120 h.

Effect of modifiers and mineral additives from industrial waste on the quality of aerated concrete products

The given article is devoted to research of influence of polymer modifiers and mineral additives on quality of composite aerated concrete products. When selecting the composition of composite aerated concrete local raw materials and components were used: portland cement, sand, aluminum powder, polyvinyl acetate, fly ash, post-alcoholic bard and whey of milk. Preliminary polyvinyl acetate was combined with binder mixing water at a temperature above 55ºC to obtain a readily soluble polymer emulsion. Dispersion was carried out with a rotary-pulsation apparatus at a pressure of 0.5-1.0 MPa and a rotor speed of ~1200 rpm. In the same apparatus the complex modifier was produced. The offered technology of production of a complex modifier seems to be the most effective for composite aerated concrete. It made it possible to reduce water absorption and capillary suction of composite aerated concrete by an average of 25% and 45%, respectively. Moreover, different combinations of fly ash, polymer and modifier made it possible to achieve optimal values of thermal conductivity, compressive strength and frost resistance of composite aerated concrete.

Block catalytic system for neutralization of carbon monoxide based on aerated concrete

The paper presents the results of a study of catalysts for the conversion of carbon monoxide based on aerated concrete, modified with magnetite and chromium ferrite separately and in aggregate. It was found that at a consumption of 100 g of catalyst powder per 1 dm3 of a typical mixture for producing aerated concrete and obtaining blocks of modified aerated concrete according to the traditional technology, their efficiency is 70-85% at 400 °C and decreases to 9-13% at 200 °C. In terms of strength and physicochemical properties, aerated concrete samples differ little from standard ones, and in some cases even exceed them. The proposed method for fixing catalyst particles in blocks of aerated concrete makes it possible to build fundamentally new schemes for neutralizing carbon monoxide when placing modified blocks directly at the loading of electrode raw materials in furnaces. This greatly simplifies the conversion process and its control system.

Ballistic strength of aerated concrete

In regional studies conducted by the Law Enforcement Agency and the Armed Forces within the scope of counter-terrorism activities, to ensure peace and security throughout the country and for the police and military personnel to provide security services, the need to produce different solutions has arisen in the face of attacks on the security points established at many important points, especially at the entrance and exit points of the cities. In this context, by changing the direction and angle of the wall types made of aerated concrete used in construction techniques, 7 variations were tested on these wall types with materials formed with adhesive mortar+plaster, monolithic elastomer polyurea, and non-Newtonian fluid, and the strength of these materials were tested with BR6 and BR7 bullets. The main purpose of this study was to determine the most suitable material in terms of security parameters in the shortest time and at a low cost and to create a reliable structure for security cabins. At the end of the study, the best results were obtained with the shots made on the narrow surface of the aerated concrete and the shots made on the platform formed with non-Newtonian fluid.

Experimental and Numerical Studies on the Behaviors of Autoclaved Aerated Concrete Panels with Insulation Boards Subjected to Wind Loading

Autoclaved aerated concrete panels (AACP) are lightweight elements in civil engineering design. In this paper, experiments and numerical analyses were conducted to study the flexural behavior of an enclosure system that consisted of AACPs and a decorative plate. A full-scale test was conducted to investigate the behavior of the enclosure system under wind suction. Load–deflection curves and load–strain relationships under different wind pressures were recorded and discussed. The effects of thickness, reinforcement ratio, and strength grade on the flexural behavior of AACPs were numerically investigated. Based on the numerical results, we found that the flexural behavior of AACPs can be improved by increasing the thickness or the reinforcement ratio. A comparison of finite element and theoretical results calculated using American and Chinese design formulae was conducted, and the results indicated the existing design formulae can conservatively estimate the major mechanical indices of AACPs.

Evaluation of Non-Autoclaved Aerated Concrete for Energy Behaviors of a Residential House in Nur-Sultan, Kazakhstan

Autoclaved aerated concrete (AAC) is commonly used as a modern, energy-efficient construction material in Nur-Sultan, Kazakhstan—the second-coldest national capital in the world after Ulaanbaatar, Mongolia. The autoclave curing method used to manufacture the AAC has potential risks and is environmentally costly because of its high-pressure and -temperature operation. Therefore, for phase I and II studies, non-autoclaved aerated concrete (NAAC) was cast, and its properties were evaluated in terms of compressive strength, density, porosity, and thermal conductivity. Moreover, the thermal conductivity prediction model of NAAC was successfully developed. In this Phase III study, the energy behavior of the NAAC was evaluated by energy simulation for a typical two-story residential house model in Kazakhstan. Different wall materials, such as fired brick and normal concrete, were adapted to compare the energy performance of NAAC. Finally, the annual heat loss and amount of heat transferred through the wall of the house were calculated to cross-check the energy-saving effect of NAAC. It was found that the NAAC conserved energy, because the heating and cooling loads, annual heat loss, and amount of heat transfer of NACC were lower than those of fired brick and normal concrete.