Papers by Keyword: Geopolymer

Abstract: Environmental pollution in the construction industry is mostly caused by the manufacture of Portland cement, which releases pollutants like CO2. In this study, geopolymer bricks constructed with fly ash, GGBS, and quarry dust as fine aggregates have undergone experimental work. An activator used in the mixture of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) is also used. For each combination, the molarity of sodium hydroxide was kept constant at 1M, while the ratios of sodium silicate to sodium hydroxide solution varied between 0.25, 0.5, and 1. Brick samples of 230 mm by 110 mm by 70 mm are collected. Tests on the test specimens were performed on the brick qualities, including efflorescence, water absorption, and compressive strength.

Abstract: Iron tailings are the main component of industrial solid waste. The long-term storage and landfill of iron tailings have caused great pressure on the environment. In this paper, Anshan type high-silicon iron tailings and fly ash were used as the main raw materials to prepare geopolymer. The activity of raw materials was determined by XRD, and geopolymer was prepared by high temperature water culture. The effect of iron tailings content, liquid-solid ratio and curing temperature on geopolymer mechanics was studied. The optimal ratio was determined by regression equation analysis with compressive strength as index. The reaction process of geopolymer was studied through microscopic analysis (XRD, SEM, FTIR), and the changes before and after the reaction of geopolymer were compared to prove the reaction degree of geopolymer, and representative specimens were selected to verify the strength changes under different ratios. The durability of the prepared polymers was tested, and the relevant parameters were determined. The gelling material with good freezing resistance and chemical corrosion resistance was successfully prepared, and the industrial waste was transformed into treasure.

Abstract: In this study, we developed alkali-activated geopolymer cement (GP) using finely powdered granite waste (GW), blast furnace slag (BFS), and nano-silica (NS). NaOH and Na₂Si₂O₃ (1:1) were used as an alkaline activator to activate the GP mix and promote the alkali-activation reactions. The mechanical properties of various GP mixes were analyzed to evaluate the durability of the resulting GP when subjected to firing at temperatures up to 750°C and the destructive effects of gamma-ray irradiation. The study revealed that blending up to 30% granite powder to the GP formulation led to faster setting due to the excess soluble Si ions sourced from the granite powder which accelerated the alkali-activation reactions and increased the stiffness of the pastes. Additionally, blending the GP mix by 10 % GW improved the compression resistance by 7 to 10 % during the later curing ages. Besides, these blended mixes have thermal stability behaviors against firing up to 750°C and irradiation by gamma rays. This is related to the thermal stability and heat storage capability of GW. Amelioration of BFS/GW mix by up to 2% NS greatly improves the compression resistance at all the stages of the alkali-activation process. Furthermore, the mixes reinforced by NS exhibited better durability in the two types of deterioration studied. This is attributed to the thermal stability of GW and the filling and/or catalytic actions of the dispersed nanoparticles through GP matrix. These factors strengthen the geopolymer network, enabling it to withstand the deteriorating effects of these harsh environments.

Abstract: Red mud, a by-product of the aluminum industry, poses a threat to the environment with its high alkalinity and heavy metal content and may seep into the soil and groundwater, endangering ecology and health. Effective utilization of red mud can reduce pollution and achieve resource recycling. In this study, a metakaolin/red mud geopolymer was prepared by phosphoric acid excitation to investigate its adsorption capacity for lead ions. The ratio of metakaolin to red mud and the additions of phosphoric acid and water were optimized, and the optimal formulations were 3/7 mass ratio of metakaolin to red mud, 2.2 molar ratio of H₃PO₄/Al₂O₃, and 0.5 water-solid ratio, which demonstrated good stability and operability.

Abstract: Red mud may cause serious pollution to soil, water, and air. Lead can seriously harm biological and even human health. This chapter summarizes the adsorption properties of metakaolin/red mud base polymer for Pb (Ⅱ). Under optimized conditions, with 0.6g/L adsorbent, pH value of 5, and adsorption time of 120 minutes, the adsorption capacity reached 122.58mg/g, and the removal rate was 73.55%. This will help to mitigate the threat of red mud and lead wastewater to human health and the environment, providing an important reference for water pollution control.

Abstract: The construction industry is crucial for social and economic development, but it faces sustainability challenges. About 40% of global industrial waste comes from construction, and cement contributes approximately 8% of global CO₂ emissions. This study aims to develop more sustainable materials by reusing waste and creating a new environmentally friendly binder, geopolymer, from ignimbrite (IG) from Arequipa, Peru, and metakaolin. Metakaolin from China (MKCh) and locally calcined metakaolin (MK650 and MK750) were used. The materials were characterized by XRD, FTIR, and SEM-EDS. Cylindrical geopolymers were produced with MK and IG ratios of 100/0 and 60/40, using a 9 mol/L NaOH activator solution. Curing was performed at 25 °C for 24 h, followed by 72 h at 50 °C. The results showed that the addition of IG increased the compressive strength, with the best performance observed in the MK-IG-60-40 material, with 52.72 ± 1.02 MPa. Thus, the addition of ignimbrite demonstrated to improve the strength of the geopolymers.

Abstract: Geopolymer, with its notable benefit of low carbon dioxide emissions, holds the potential to substantially curtail environmental pollution. According to the existing related research on geopolymer materials, it is obvious that it has great development potential in many engineering application fields, and it is a new generation of green and environmentally friendly recycled materials. Nowadays, there is a growing concern regarding explosion protection. Explosions near buildings can cause catastrophic damages on the building external and internal structure, and the most important thing is that can cause injuries and loss of life to the occupants of these buildings. This study investigates the mechanical performance of the fiber-reinforced geopolymer concrete under explosive testing. Furthermore, the finite element analysis models have been established through LS-DYNA software to simulate the explosive testing using Structure-Arbitrary Lagrangian Eulerian Method (S-ALE). The model is used to assess the dynamic mechanical behavior of geopolymer materials.

Abstract: Organic soil presents significant challenges for construction due to its unsuitability as a soil type, often necessitating stabilization using conventional agents like cement. The Silica Fume (SF)-Red Mud (RM) binder mix emerges as a promising alternative stabilizer due to its low carbon footprint coupled with its superior strength-enhancing properties. In this study,we explore the feasibility of employing SF-RM based geopolymer to stabilize organic soil. To activate the collected samples, a solution of sodium hydroxide (NaOH) with molarity (M) of 6, 9, and 12 were utilized, as well as binder (SF + RM) proportions of 10%, 20%, 30%, and 40% relative to dried organic soil and alkali-to-binder (A/B) proportions of 0.5, 0.7, and 0.9, respectively. The experimental results reveal that a variety of factors, including NaOH molarity, A/B proportions, pH, and curing duration, have an effect on the unconfined compressive strength (UCS) of treated organic soil. The best combination was obtained with a binder concentration of 30%, a NaOH molarity of 9M, and an A/B proportion of 0.7. After 28 days of curing, the UCS of the treated organic soil (1714 kPa) was found to be 168 times that of the untreated organic soil (10.2kPa). Further, the production of compounds such as aluminium silicate, sodium aluminosilicate, and potassium aluminosilicate, which have been found by X-ray diffraction (XRD) research, can be ascribed to the increase in strength. Furthermore, when subjected to analysis through Field Emission Scanning Electron Microscopy (FESEM), it becomes evident that these items play a pivotal role in filling the voids within the soil-binder composite. As a consequence, they facilitate the creation of a more smoother, compact and denser structure.

Abstract: In this work, the effect of the maximum particle size and the molar concentration of the alkaline hardening solution on the mechanical response in uniaxial compression of geopolymeric mortars manufactured from the geopolymerization of Peruvian mine tailings dust was evaluated. The mechanical results found showed that the average mechanical resistance increased as the molar concentration of the hardening solution increased from 10 to 15M, on the other hand, it was possible to verify that as the particle size of sand and mine tailings is greater, the mechanical resistance values increased. The mechanical data found are in good agreement with the porosity results, that is, as the porosity values increased, the mechanical resistance gradually decreased. The stiffness values reported in the studied geopolymeric mortars showed a slight increase when the values of molar concentration and maximum particle size increased. All the mortars studied presented a similar microstructure, with fine sand particles dispersed within a continuous phase of geopolymer (geopolymerized mining tailings).

Abstract: This work deals with the effect of adding GO on the mechanical properties of fly ash-based geopolymer-GO composites. Compressive strength, water absorption, density, and flexural strength tests were carried out to investigate mechanical and physical properties of fly ash-based geopolymer-GO composites. The results showed that the addition of graphene oxide into fly ash-based geopolymer-GO composites up to threshold value (i.e., in this study, 1 gram or 1.1 wt.%) will decrease total porosity as well as a change in the total quantity of pores and their distribution due to densification of bulk matrix of the specimens. Consequently, it reduced water absorption, increased the density of the specimens, and subsequently increased mechanical properties (i.e., compressive strength and flexural strength). Conversely, the addition of graphene oxide into fly ash-based geopolymer-GO composites greater than above the threshold value will increase total porosity due to coarsening of bulk matrix of the specimens and subsequently increased water absorption and reduced density of the material. As a result, it decreased the mechanical properties (i.e., compressive strength and flexural strength) of fly ash-based geopolymer-GO composites. The present research demonstrates how graphene oxide can improve the mechanical properties of fly ash-based geopolymer-GO composites to a certain extent, which may match with industrial applications.