Thermo-mechanical and microstructural characterisation of sodium-poly(sialate-siloxo) (Na-PSS) geopolymers

Effect of synthesis parameters on the compressive strength of low-calcium ferronickel slag inorganic polymers

“…Each specimen lost in total 4, 7, 6.5 and 5% water, of which approximately 2, 5, 4.5 and 3.5%, respectively, is absorbed water lost at temperatures lower than 200 • C. The water loss at around 550 • C is probably due to dehydroxylation of kaolin. The remaining water is less able to diffuse to the surface or bound tightly [63] and continues to evaporate slowly at temperatures higher than 200 • C. The continuous mass loss up to about 550 • C is due to the loss of hygroscopic water or water residing in the channels [64]. As it has been mentioned earlier an optimum water content should be present in the initial paste so that an adequate compressive strength is acquired; specimen T3 reaches 53 MPa, while specimen T1 only 1.5 MPa.…”

Synthesis of thermostable geopolymer from circulating fluidized bed combustion (CFBC) bottom ashes

“…Compared with conventional ordinary Portland cement (OPC), geopolymers have demonstrated quite a few advantages, such as high mechanical strength, excellent chemical resistance, inherent fire and heat resistance, low thermal conductivity, no toxic fume emission when heated, low shrinkage and deleterious alkali aggregate effect, rapid controllable setting and hardening, as well as precise mouldability [3,5,6]. The intrinsic fire and heat resistances of geopolymeric materials are of interests [7,8]. While most organic polymers soften and ignite at 400-600 • C [7], and OPC experiences decomposition of its Ca(OH) 2 content at around 500 • C [9], geopolymers are found to be nonflammable and heat resistant at high temperatures up to 1000 • C [5,10], making them a promising material for a variety of applications, such as commercial aerocrafts, marine ships and platforms, ground transportations, etc., where fire hazard and heat resistance are important design considerations due to restriction of egress.…”

“…fly ashes, blast furnace slags, and metakaolinites, generally show higher compressive strength than those derived from classic non-calcined ones, such as kaolinites, albites, stilbites, and mine tailings, suggesting that calcined source materials lead to higher geopolymerization degrees. Therefore, non-calcined aluminosilicate sources are usually subjected to calcinations at 500-750 • C for several hours prior to geopolymerization [8,12], which requires remarkable energy consumption. On the other hand, the calcined source materials, except for metakaolinites, are predominantly industrial wastes, whereas the non-calcined ones are largely natural minerals.…”

“…1200-1400 • C) [19,20]. Besides, CBAs have a retention time of several hours at the heating temperature, which represents an almost ideal condition needed for thermal activation of kaolinic source materials [8,12].…”

Properties of lightweight high calcium fly ash geopolymer concretes containing recycled packaging foam

“…For example, the values of thermal conductivity at the age of 28-day with volumes of foam of 0, 0.85, 0.90, 0.95, 1.00, and 1.05 were 0.77, 0.35, 0.33, 0.30, 0.29 and 0.27 W/mK, respectively. The thermal conductivity values of lightweight aggregate foamed geopolymer concrete were reported to be 0.47-0.58 W/mK [43] and those of metakaolin geopolymers were 0.55-0.65 W/mK and increased to 0.91 W/mK with the addition of quartz sand [44]. These values were comparable to the obtained results of 0.27-0.35 W/mK for lightweight geopolymer concretes and 0.77 W/mK for normal weight geopolymer concrete.…”