共查询到18条相似文献,搜索用时 171 毫秒
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研究湿排粉煤灰在水泥工业生产中的应用,结果表明:湿排烘干粉煤灰的比表面积与需水量随着粉磨时间的延长而增大,综合考虑粉磨时间对湿排烘干粉煤灰粒度分布、活性指数及电耗成本的影响,确定湿排烘干粉煤灰的粉磨细度为550m2/kg;湿排烘干粉煤灰掺量的增加会导致水泥标准稠度用水量增加,凝结时间的延长及抗折、抗压强度下降;但通过不同掺量的湿排烘干粉煤灰,可以生产不同强度等级的复合硅酸盐水泥;生石灰与水泥激发剂的叠加作用可以显著激发湿排粉煤灰的潜在活性(活性指数可达140%),湿排粉煤灰的复合活化剂的适宜配比为:生石灰35%~40%,复合激发剂2.0%。 相似文献
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研究了海水环境下掺入硅灰、粉煤灰、矿渣对硫铝酸盐水泥抗压强度、化学收缩和水化产物的影响规律.结果表明:当硅灰的掺量为2.5%时,水泥浆体的抗压强度比空白组高.矿渣掺量为10%的水泥浆体28 d抗压强度明显超过掺入硅灰和粉煤灰时的强度,60 d强度高于空白组.掺入2.5%硅灰后,水泥浆体的化学收缩增大;在水化早期,粉煤灰和矿渣的火山灰活性很低,导致水泥浆体的化学收缩降低.掺入10%硅灰加快了硫铝酸盐水泥3 d水化反应,钙矾石生成量增多,水泥浆体早期强度比掺其它掺合料有所提高,但体积过快膨胀会破坏其内部结构,对水泥浆体的强度发展不利. 相似文献
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为了拓展氯氧镁水泥(MOC)材料的应用领域,以盐湖提钾肥副产物水氯镁石、轻烧氧化镁和粉煤灰为胶凝材料,制备了不同粉煤灰掺量的氯氧镁水泥混凝土(MOCC)。研究了粉煤灰掺量对MOCC抗压强度、物相组成、微观形貌和孔结构的影响。结果表明:随着粉煤灰掺量的增加,MOCC的抗压强度逐渐降低,当粉煤灰掺量为40%(质量分数)时,其300 d抗压强度降低至39.99 MPa,降低了22.52%。MOCC的主要水化产物为5Mg(OH)2·MgCl2·8H2O(5·1·8)和Mg(OH)2,掺加粉煤灰并没有产生新的晶相。掺入粉煤灰增加了MOCC的孔隙率和有害孔体积,从而降低了其抗压强度。采用相同水灰比制备了普通硅酸盐水泥混凝土,抗压强度对比测试结果表明:掺40%的粉煤灰MOCC的抗压强度虽然比未掺粉煤灰MOCC抗压强度低,但仍比普通硅酸盐水泥混凝土300 d龄期的抗压强度(33.42 MPa)高出19.66%,说明MOCC比普通硅酸盐水泥混凝土具有较高的抗压强度。 相似文献
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研究了粉煤灰掺量分别为0、20%和40%,水胶比为0.4的水泥浆体的抗压强度、电阻率、化学收缩以及水化产物的变化规律.电阻率采用无电极电阻率法进行测试,化学收缩采用ASTM C1608-12规定的膨胀测定法进行测试.结果表明,在250 d龄期时,粉煤灰掺量为20%的硬化水泥浆体抗压强度仅比空白组低5%;当粉煤灰掺量增大时,水泥浆体在3 d龄期时的强度、电阻率和化学收缩均减小,抗压强度与电阻率之间具有很好的线性关系.XRD及热重分析表明,随着粉煤灰掺量增加,水化硅酸钙含量减少,在3 d龄期时水化产物中出现了钙矾石. 相似文献
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Jatuphon Tangpagasit Chai Jaturapitakkul Kraiwood Kiattikomol 《Cement and Concrete Research》2005,35(6):1145-1151
This research is to study the effect of particle size of fly ash on packing effect and pozzolanic reaction of mortar when 20% of fly ash is used to replace Portland cement type I. Both effects can be determined by using fly ash and insoluble material which have almost the same particle size to replace Portland cement type I. Normally, the compressive strength of fly ash mortar is contributed from hydration reaction, packing effect, and pozzolanic reaction. For mortar mixed with insoluble material, the compressive strength is due to hydration reaction and packing effect. Thus, compressive strength due to pozzolanic reaction can be determined from the difference in compressive strength between fly ash mortar and insoluble material mortar. The results show that the strength activity index of fly ash mortar depends on the median particle size of fly ash and curing ages of mortar samples. At early ages, the strength activity index of fly ash mortar due to packing effect is higher than that due to pozzolanic reaction. At the ages of 3 to 90 days, the difference in strength activity index due to packing effect of fly ashes with median particle size of 2.7 and 160 μm is almost constant about 22% of the strength of standard mortar (STD). The differences in strength activity index due to pozzolanic reaction of fly ashes with median particle size of 2.7 and 160 μm are 3%, 20%, and 27%, respectively, at the ages of 3, 28, and 90 days. 相似文献
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通过凝结时间、抗压强度和电阻率等分析手段,研究了Ca(OH)2对硫铝酸盐水泥-粉煤灰复合胶凝材料水化过程的影响.结果表明,掺入Ca(OH)2明显缩短了硫铝酸盐水泥-粉煤灰复合胶凝材料的凝结时间;当Ca(OH)2掺量为0.5%时,初凝时间最短,1 d、28 d强度均明显提高;当Ca(OH)2的掺量为2%时,28 d强度相比空白样提高了61.9%;掺入Ca(OH)2后,硫铝酸盐水泥-粉煤灰复合胶凝材料的1 d电阻率减小,随着Ca(OH)2掺量增大,电阻率逐渐减小,电阻率变化率极大值提前,说明Ca(OH)2加快了该复合胶凝材料的早期水化进程.XRD分析表明,掺入Ca(OH)2后,水化1 d时钙矾石的生成量增多,消耗无水硫铝酸钙的量增多;水化28 d时钙矾石的生成量相对变化较小,但强度明显增大,粉煤灰对硫铝酸盐水泥强度的贡献较为明显. 相似文献
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To enable commercial use of alkali-activated fly ash concrete, its durability must be better understood. Alkali–silica reaction is a primary concern since highly alkaline solutions are generally used for activation. This study investigated the effect of NaOH activating solution concentration on pore solution alkalinity and subsequent alkali–silica reaction in alkali-activated fly ash concrete. It was found that pore solution alkalinity increased with increasing activating solution NaOH concentration, and this effect was amplified at concentrations above an optimum, defined as the concentration that resulted in the highest mortar compressive strength. Expansion of concrete prisms containing highly reactive fine aggregate and activating solution concentrations above the optimum concentration was approximately three times that of concrete with optimum activating solution concentrations, but only about 5% of the expansion observed in the ordinary portland cement control. The low expansion may be attributed to the low calcium levels in the alkali-activated fly ash concrete. 相似文献
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利用粉煤灰微珠按10%、20%和30%(质量分数)部分替代水泥制备了混凝土试样,并对混凝土试样的抗压强度、弹性模量和徐变进行了测试,同时通过压汞孔隙率实验对试样的微观结构进行了研究。结果表明,粉煤灰微珠会使混凝土的早期抗压强度和弹性模量下降,但是对混凝土长期强度增长和弹性模量增长有明显的促进作用,在90 d时粉煤灰微珠掺量为20%的试样强度和弹性模量最高。掺入20%的粉煤灰微珠可以降低混凝土的比徐变,但是过多的粉煤灰微珠反而会增加混凝土的徐变变形。孔隙分析结果表明,总孔隙体积较高时,混凝土的强度较低,徐变变形较大;而加入20%粉煤灰微珠会降低混凝土的中孔隙、大孔隙和总孔隙体积,从而改善混凝土的强度和徐变特性。 相似文献