聚合物胶凝材料-地聚合物

地聚合物是一类新型的高性能无机聚合物材料,它与水泥基材料相比具有更高的强度、更优良的耐久性、无污染等特点。它在工业、民用、军事、高科技等领域都具有广阔的应用前景。本文详细介绍了地聚合物的性能、发展状况以及应用前景,分析和讨论了其主要优缺点和适用范围,并指出这一领域中值得进一步研究的一些问题和可能发展的方向。     

富镁镍渣-粉煤灰基地质聚合物的制备与性能表征

以工业固体废弃物富镁镍渣和粉煤灰为原料,以水玻璃和NaOH为碱激发剂,制备了一系列富镁镍渣-粉煤灰基地质聚合物。研究了不同粉煤灰掺量对地质聚合物力学性能的影响,并测定地质聚合物的线性收缩和碱溶出,通过XRD、IR、DTA等手段对产物进行表征。结果表明:富镁镍渣-粉煤灰基地质聚合物的强度随粉煤灰的掺入先升高后降低,当掺量为30%(质量分数)时,地质聚合物的抗压强度可达最高值22.15 MPa,较镍渣基地质聚合物强度提高42.2%;XRD分析表明富镁镍渣中MgO以镁橄榄石相存在,而非游离态,故地质聚合物具有良好的体积安定性。     

新型节能无机矿物聚合建筑材料研究概况

无机矿物聚合材料是一种新型节能建筑材料,其化学组成与沸石相近,物理形态上呈三维网状结构.由于无机矿物聚合材料具有良好的力学性能,并且耐腐蚀性强,抗渗性好等优点,备受各国关注.介绍了无机矿物聚合材料的国内外发展现状,反应机理以及理化性能,并展望其应用前景.     

Development of mix design method based on statistical analysis of different factors for geopolymer concrete

The present study proposes the mix design method of Fly Ash (FA) based geopolymer concrete using Response Surface Methodology (RSM). In this method, different factors, including binder content, alkali/binder ratio, NS/NH ratio (sodium silicate/sodium hydroxide), NH molarity, and water/solids ratio were considered for the mix design of geopolymer concrete. The 2D contour plots were used to setup the mix design method to achieve the target compressive strength. The proposed mix design method of geopolymer concrete is divided into three categories based on curing regime, specifically one ambient curing (25 °C) and two heat curing (60 and 90 °C). The proposed mix design method of geopolymer concrete was validated through experimentation of M30, M50, and M70 concrete mixes at all curing regimes. The observed experimental compressive strength results validate the mix design method by more than 90% of their target strength. Furthermore, the current study concluded that the required compressive strength can be achieved by varying any factor in the mix design. In addition, the factor analysis revealed that the NS/NH ratio significantly affects the compressive strength of geopolymer concrete.     

Effect of fibre characteristics on physical,mechanical and microstructural properties of geopolymer concrete: A comparative experimental investigation

The main aim of this work is to comparatively reveal the effect of fibre type, length and content on compressive strength and microstructure of structural geopolymer concrete (GPC) produced under constant mixture and curing parameters in order to address the significant gap in present literature. Firstly, GPCs with different NaOH concentrations (i.e., 6, 9, 12 and 15 M) and activator solution/binder (a/b) ratios (i.e., 0.45 and 0.55) were produced in ambient curing condition, and optimum production parameters were determined based on the preliminary evaluations. Then, glass and polypropylene fibres in 6-mm length (GS6 and PP6) and polyamide and polypropylene fibres in 12-mm length (PY12 and PP12) were included in GPCs at ratio of 0.4%, 0.8% and 1.2% (by volume). Compressive strength, apparent porosity, bulk density, ultrasonic pulse velocity (UPV), X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis of GPC samples were carried out comparatively. The inclusion of GS6 fibre enhanced the compressive strength thanks to fibre surface being covered by geopolymer gel and the strong adhesion between GS fibre and geopolymer matrix. SEM images of fibre reinforced GPC (FRGPC) also confirmed the experimental findings, which were attributed to improvement in compressive strength. Regardless of the fibre type, the maximum compressive value strength was obtained from GPC specimens with 0.4% fibre and then decreased. Higher fibre inclusions led to poor compaction, workability issues and inhomogeneous fibre dispersions. A very good relation (R² = 0.98) was acquired between UPV and compressive strength values of GPC/FRGPC samples.     

Effect of granite flour proportion on the strength properties of geopolymer mortar based on fly ash

Given global trends and challenges, the development of binders for the production of geopolymer concretes has become a topical area of building science. The purpose of this study is to determine whether granite can replace traditional construction aggregate, such as river sand, during geopolymer production, as well as to demonstrate the effect of the proportion of granite flour on the strength properties of fly ash-based geopolymer mortar. A combination of granite flour, quartz sand, and fly ash in various proportions was used as an aluminosilicate precursor. The scope of the study includes density measurements, compressive and flexural strength tests, abrasion by the Boehme method, and microstructural observations. Based on the obtained results, it can be concluded that granite can be successfully used as a replacement for quartz sand during the production of fly ash-based geopolymers. Moreover, the addition of granite makes it possible to improve the strength properties of geopolymers, compared to a geopolymer composite containing quartz sand.     

高钙粉煤灰地聚合物固化/稳定重金属的试验研究

利用高钙粉煤灰研制地聚合物来固化/稳定重金属,采用静态和动态浸出试验研究了高钙粉煤灰地聚合物对重金属的固化/稳定效果,并进一步探索了重金属的迁移机制和长期安全性.研究表明:高钙粉煤灰地聚合物分别固化/稳定0.025％的铅,0.025％的铬和0.01％的汞后,经静态浸出试验,重金属浸出浓度远低于规定的上限值,且固化率均在98％以上.经动态浸出试验,重金属的实时浸出浓度低于规定的上限值,累积浸出浓度在72 h后趋于稳定;固化体中重金属的径向分布相似;重金属的有效扩散系数和浸出率非常低,长期安全性优良.     

Synthesis of novel low‐cost porous gangue microsphere/geopolymer composites and their adsorption properties for dyes

A novel porous coal gangue microsphere/geopolymer (CG/KGP) composite was firstly synthesized by adding gangue microspheres into geopolymer matrix. Effects of precalcined temperature of CG microspheres on the microstructure and specific surface area of the porous CG/KGP particles were systematically investigated. Adsorption properties of the CG/KGP composites were also reported. Results showed that the CG/KGP composites contained mainly amorphous phase and many functional groups were on the particle surface. The precalcined CG microspheres were dispersed homogenously and bonded well with the KGP matrix. The CG900/KGP samples showed better adsorption properties than the pure KGP. As for the dosage of 4 g/L (starting concentration, 100 mg/L), adsorption capacity achieved the highest value of 24.6 mg/g and the removal efficiency reached 98%. Adsorption of MB onto CG900/KGP particles followed the pseudo‐second‐order kinetic model. The novel porous CG/KGP composite has potential application in wastewater filtration and adsorption treatment.     

Highly porous mullite ceramics from engineered alkali activated suspensions

Air may be easily incorporated by vigorous mechanical stirring, with the help of surfactants, of activated geopolymer‐yielding suspensions. The cellular structure is stabilized by the viscosity increase caused by curing reactions, configuring an “inorganic gel casting”. The present paper is aimed at extending this approach to mullite foams, obtained by the thermal treatment of engineered alkali activated suspensions. “Green” foams were first obtained by gel casting of a suspension for Na‐geopolymer enriched with reactive γ‐Al₂O₃ powders. Sodium was later extracted by ionic exchange with ammonium salts. In particular, the removal of Na⁺ ions was achieved by immersion in ammonium nitrate solution overnight, with retention of the cellular structure. Finally, the ion‐exchanged foams were successfully converted into pure mullite foams by application of a firing treatment at 1300°C, for 1 hour. Preliminary results concerning the extension of the concept to mullite three‐dimensional scaffolds are presented as well.