EFFECTS OF WATER GLASS MODULI AND SOLID CONTENT ON SETTING TIME AND COMOURESSIVE STRENGTH FOR FLY ASH -BASED GEOPOLYMER
It is generally believed that fly ash alone to make geopomyer at room temperature will have long setting times and low 28-day compressive strength,below 10 MPa.The typical approach to fix these issues is to blend fly ash with slag or cured at higher temperature,such as 35-80℃.The typical water glass moduli and sold contents reported in literature are in the range of 1.0 to 2.0 and 30 to 40%,respectively.In general,higher solid content is believed to have higher strength and longer setting time due to higher pH to dissolve more monomers from fly ash to build a stronger final structure,but produce more dimers and trimmers to delay gelation.Higher modulus is believed to have shorter setting time but higher strength due to higher initial silicate concentration from water glass to cause faster gelation and form a stronger structure.The effects of water glass moduli from 0.6 to 2.4 and solid contents from 11.5% to 46% on setting times and compressive strengths were studied.Two peak setting time and strength values were found in our studied ranges.The above rules do not seem to apply universally.An optimal modulus at a given solid content or vice versa is required to achieve the desired setting time and form a stronger final structure.Fly ash-based geopolymer cured at room temperature can achieve the 28-day compressive strength up to 32 MPa with setting times longer than 20 minutes at modulus of 2.4 and solid content of 46%.To obtain desired setting times,such as 10 to 20 minutes,for certain applications,the solid content range of 34.5%-42% at modulus of 2.4 or the modulus rang of 1.2-2.4 at solid content of 34.5% are recommended to achieve better 28-day strength of 14-28
water glass fly ash geopolymer compressive strength setting time
Qiao Li Yongbin Zhao Jinder Jow Shih-yaw Lai
National Institute of Clean-and-low-carbon Energy (NICE),Beijing,China
国际会议
长沙
英文
107-115
2014-06-01（万方平台首次上网日期，不代表论文的发表时间）