A performance study of hydrophobically modified coal gangue mortar
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摘要: 煤矸石物理化学特性复杂、强度低、疏松多孔的特点，限制了其在建筑材料中的大量使用。本文采用疏水溶液浸泡的方式，在非煅烧、非预湿的条件下对煤矸石进行了改性。在系统研究改性前后煤矸石基本性质的基础上，设置0%、30%、50%、70%和100%共5种疏水改性后煤矸石质量替代率，以接触角、抗折强度、抗压强度、氯离子电通量为表征参数，分析了不同疏水改性煤矸石替代率对砂浆性能的影响。研究结果表明：采用本文的制备方法，当改性煤矸石替代率低于50%时，可实现煤矸石砂浆表面的疏水状态；抗压强度随改性煤矸石替代率的增大呈现降低的趋势，最大降低率为不掺加改性煤矸石时的15.7%；替代率为30%时，28 d抗压强度为58.5 MPa。不同改性煤矸石替代率下砂浆电通量均小于250 C，表现出优秀的抗氯离子渗透性。替代率为30%时电通量最小，为130 C。采用本研究提出的疏水改性的方法，可以使煤矸石在非煅烧、非预湿的条件下，保证砂浆良好的力学强度和抗氯离子渗透性能，实现煤矸石的充分利用。Abstract: Coal gangue has the characteristics of complex physical and chemical properties, low strength, loose and porous, which limit its extensive use in building materials. In this paper, coal gangue was modified by soaking in hydrophobic solution under uncalcining and non-prewetting conditions. The basic characteristics of coal gangue before and after modification was systematically studied, and hydrophobically modified coal gangue mass substitution rates of 0%, 30%, 50%, 70% and 100% were set. Contact angel, flexural strength, compressive strength, electric flux were used as characteristic parameters to evaluate the influence of modified coal gangue replacement rate on the basic properties of mortar under different substitution rates.Results showed that, by using the binary cooperative complementary method, when the replacement rate of modified coal gangue was lss than 50%, the hydrophobic state of the surface of coal gangue mortar could be achieved. As the replacement rate of modified coal gangue increases, the compressive strength showed a decreasing trend, the maximum decrease was 15.7% compared with none modified coal gangue added. The 28 d compressive strength was 58.5 MPa with 30% replacement rate of modified coal gangue. The electric flux was less than 250 C under different modified coal gangue replacement rate, which indicated excellent resistance to chloride permeability. When the modified coal gangue replacement rate is 30%, the electric flux was the smallest (130 C). The hydrophobic modification method could ensure good mechanical strength and resistance to chloride penetration under the condition of uncalcined and non-prewetted coal gangue, which fully utilizes coal gangue.
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Key words:
- coal gangue /
- hydrophobic modification /
- contact angle /
- chloride permeability /
- mortar
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图 5 疏水处理后的煤矸石表面接触角
Figure 5. Surface contact angle of coal gangue after hydrophobic treatment
图 6 煤矸石表面水滴形貌
Figure 6. Appearance of water droplets on the surface of coal gangue particles
图 7 不同煤矸石替代率下砂浆表面接触角
Figure 7. Surface contact angle of mortar with different coal gangue replacement ratio
图 11 疏水改性前后净浆7 d、28 d龄期的FTIR图谱
Figure 11. FTIR spectra of cement-sillica fume paste before and after hydrophobically modified at 7 and 28 days
表 1 煤矸石细骨料的压碎指标
Table 1. The crush index of coal gangue fine aggregates
编号 粒级/mm 压碎指标实测值/% 平均值/% CCG 0.60~1.18 20 20 20 20 FCG 0.30~0.60 21 23 25 21 
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表 2 骨料的堆积密度和表观密度
Table 2. The bulk density and apparent density of aggregates
编号 疏水处理 堆积密度/(kg·m-3) 表观密度/(kg·m-3) CQS 未处理 1 328 2 628 FQS 1 337 2 629 CCG 1 234 2 307 FCG 1 246 2 442 HTCCG 处理后 1 054 2 093 HTFCG 1 086 1 866
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表 3 砂浆配合比
Table 3. Mix proportion of mortar
试样名称 水泥/g 硅灰/g 疏水溶液/g 煤矸石/g 替代率/% 石英砂/g PCA/g 粗 细 粗 细 CGM0 650 32.5 136.5 0 0 0 364.0 182.0 17.2 CGM30 650 32.5 136.5 109.2 54.6 30 254.8 127.4 19.6 CGM50 650 32.5 136.5 182.0 91.0 50 182.0 91.0 22.2 CGM70 650 32.5 136.5 254.8 127.4 70 109.2 54.6 23.8 CGM100 650 32.5 136.5 364.0 182.0 100 0 0 25.4
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