Beneficiation of stockpiled fluidized bed coal ash in road base course construction

The presented paper investigates the potential for the utilization of unprocessed, as excavated (i.e. unground), stockpiled coal combustion fluidized bed ash in road base course construction. In addition to functioning as a stabilizer of the fines in the stockpiled material, this ash also permits treating the stockpiled ash agglomerates as an aggregate. Both untreated and cement-treated mix designs were evaluated. The laboratory program included unconfined strength measurements, triaxial, volumetric swell, and moisture susceptibility testing protocols performed on cylindrical specimens compacted at their optimum moisture content.The results have shown that, without breaking down the agglomerates by grinding, the unstabilized stockpiled ash possesses very little residual cementitious activity; whereas, if treated with small amounts of cement (3%), it meets the required strength criteria for cement-treated base courses while minimizing the volumetric swell characteristics.     

Potential use of stockpiled circulating fluidized bed combustion ashes in controlled low strength material (CLSM) mixture

This paper presents the results of an experimental investigation carried out to evaluate the potential use of stockpiled circulating fluidized bed combustion (CFBC) ashes in developing controlled low strength material (CLSM) in which stockpiled CFBC ash was partially or fully replaced with Class F fly ash. Prior to develop CLSM mixture, basic material characterization of stockpiled CFBC ash was executed to identify the physical, chemical, and mineralogical changes due to aging process of the stockpiled ashes. For CLSM mixture, stockpiled CFBC ash was replaced with five different percentages of Class F fly ash by weight (20%, 40%, 60%, 80%, and 100%). Tests were performed to measure fresh and hardened properties of CLSM mixtures. It was found that the stockpiled CFBC ash can be effectively used in developing CLSM mixtures with restricted use of portland cement and fly ash in the direction of sustainable development.     

利用流化床燃煤固硫灰制备混凝土膨胀剂的研究

利用固硫灰、烧铝矾土、硬石膏为原料制备了混凝土膨胀剂。结果表明,固硫灰、烧铝矾土和硬石膏按照质量比35:15:50能制备出满足GB23439-2009《混凝土膨胀剂》要求的Ⅰ型膨胀剂。运用SEM电镜扫描、XRD衍射分析研究了混凝土膨胀剂掺入水泥的水化反应,结果表明,随着水化龄期的延长,钙矾石含量增多。制备的膨胀剂是以钙矾石为主要膨胀源的混凝土膨胀剂。     

黑液粉煤灰烧结砖的研制

本文以粉煤灰为主要原料、少量粘土为粘结剂、改性黑液为成型剂进行了烧结砖研制。讨论了粉煤灰与黑液用量对烧结砖性能的影响 ,并通过正交试验求出最佳配比与工艺参数。试验结果表明 ,这种烧结砖可达到GB50 10— 85标准中MU15级的要求 ,且比普通粘土烧结砖质量轻、保温性能好。     

火力发电产生的高钙粉煤灰的改性研究

本文以电厂发电采用的循环流化床燃烧煤产生的高钙粉煤灰作为研究的对象,主要是为了找到高钙灰降钙的方法,在此基础上改善高钙灰的性能,然后把这种高钙灰利用到水泥生产或混凝土中,变废为宝,变害为利,合理综合利用。     

利用高钙固硫灰生产蒸压砖的研究

对高钙固硫灰生产蒸压砖的生产工艺进行了研究,提出了重点解决循环流化床锅炉粉煤灰的高钙、高硫、低硅难题的有效途径。     

循环流化床灰对水泥基胶凝材料及碾压混凝土工作性的影响

作为燃煤灰渣之一的循环流化床灰,成分比煤粉炉粉煤灰更加特殊和复杂,综合利用程度低。当将其作为水泥混凝土用辅助胶凝材料时,明显增加水泥基胶凝材料的标准稠度用水量,降低胶砂流动度。相对于普通塑性混凝土,循环流化床灰更适用于碾压混凝土这种干硬性混凝土体系。     

古建筑修复用熟石灰性能优化及机理研究

研究了矿渣、循环流化床锅炉燃烧脱硫灰(CFBC脱硫灰)和硅灰对熟石灰性能的影响及作用机理,并与理想的古建筑修复材料——强度等级为NHL2的天然水硬性石灰(简写为NHL2)进行性能对比,探讨了改性熟石灰用于古建筑修复的合理性.结果表明:由于火山灰反应及对熟石灰微观结构的影响,矿渣、CFBC脱硫灰和硅灰均可明显改善熟石灰的力学性能、防水性和耐候性;与NHL2相比,掺矿渣的熟石灰力学性能、防水性、耐候性和柔性均有所提高,掺CFBC脱硫灰的熟石灰性能优势较小,掺硅灰的熟石灰抗压强度和耐候性能较好,但防水性和柔性较差.在古建筑修复中,可利用质量分数为20%的矿渣作为熟石灰的添加剂.     

Engineering characteristics of the compressed-stabilized earth brick

Utilization of lime and rice husk ash for soil stabilization produced considerable strength gain and other geotechnical properties of the stabilized soils. Its application could be also superior for construction materials as compressed-stabilized earth (CSE) or unfired-brick. This paper presents the investigation result of the application of lime and rice husk for unfired brick or compressed stabilized earth. The compressive and three-point flexural strength tests including compressive strength after water submersion were carried out in this present study. The investigation results show that compressive and flexural strength of clay brick are improved by adding of lime and RHA. The best quantity of lime and RHA in this study, is obtained by ratio 1:1 of lime and RHA. The addition of sand in stabilized clay resulted in more improvement in the water retention ability.     

循环流化床粉煤灰对水泥性能的影响

检验了循环流化床粉煤灰和炉渣的技术性能指标.通过调整复合硅酸盐水泥中钢渣、炉渣和粉煤灰的配比,研究了循环流化床粉煤灰对水泥强度的影响.     

Influence of pozzolan from various by-product materials on mechanical properties of high-strength concrete

This paper presents experimentally investigated the effects of pozzolan made from various by-product materials on mechanical properties of high-strength concrete. Ground pulverized coal combustion fly ash (FA), ground fluidized bed combustion fly ash (FB), ground rice husk–bark ash (RHBA), and ground palm oil fuel ash (POFA) having median particle sizes less than 11 μm were used to partially replace Portland cement type I to cast high-strength concrete. The results suggest that concretes containing FA, FB, RHBA, and POFA can be used as pozzolanic materials in making high-strength concrete with 28-day compressive strengths higher than 80 MPa. After 7 days of curing, the concretes containing 10–40% FA or FB and 10–30% RHBA or POFA exhibited higher compressive strengths than that of the control concrete (CT). The use of FA, FB, RHBA, and POFA to partially replace Portland cement type I has no significant effect on the splitting tensile strength and modulus of elasticity as compared to control concrete or silica fume concretes. This results suggest that the by-products from industries can be used to substitute Portland cement to produce high-strength concrete without alteration the mechanical properties of concrete.     

蒸压灰渣页岩砖砌体抗压及抗剪性能试验研究

通过对3种砂浆砌筑的24件蒸压灰渣页岩砖砌体试件的轴心抗压试验与通缝抗剪试验,分别对该砌体在轴心压力与剪力作用下的抗压性能与抗剪性能进行试验研究,分析了该砌体的破坏特征、抗压能力与抗剪性能。研究表明：轴压试验中,与黏土砖相比蒸压灰渣页岩砖砌体的初始裂缝出现较早,砌体的抗压强度随着砂浆强度的提高而提高。砌体通缝抗剪试验试...     

Chemical resistance of pozzolanic plaster for earthen walls

Earth is an economical and ancient construction material. Historical earthen architecture is a heritage that must be handed over to the next generations but experience shows that these historical structures do not stand up well against the destructive action of rain. In this study, fly ash, powdered brick, hydrated lime and water were mixed to develop a pozzolanic plaster for use in conservation of earthen walls. Chemical durability, such as sulfate, salt and acid resistance of this pozzolanic plaster also was investigated. The chemical compounds employed in these tests were 2000 and 5000 ppm sodium sulfate and ammonium nitrate solutions for sulfate and salt attack. Also, the acidic media were with 1%, 5% and 10% concentrations of sulfuric acid and hydrochloric acid. All test results indicated that incorporation of fly ash in pozzolanic plaster provides a satisfactory resistance to aggressive chemicals such as sulfate, salts and acids. The developed plaster seems to be a suitable material for preservation of earthen walls since it has adequate mechanical and chemical properties in comparison with soil.     

Stabilization of marginal aggregates with hydraulic and puzzolanic binders based on waste materials

Natural sand deposits and waste screenings from gravel pits and quarries are abundant in parts of Sweden. Investigations have been made to stabilize such materials with binders based on waste materials. Both laboratory work and test roads have been performed. In the latter case, mainly secondary roads have been strengthened with a plant-mixed bases. Good results have been achieved with a binder made of milled granulated blast furnace slag, activated with lime or especially with both lime and waste gypsum. Sand and screenings from gravel often contain organic material, deleterous with the binders studied. In such cases, the gypsum addition also seems to counteract the negative effect of the organic material. Fly ash has recently been available in Sweden. Tests made with fly ash-lime, as often used for stabilization abroad, have shown too slow binding for a rather cold climate. Addition of waste gypsum, calcium chloride, alkali-salts or use of an alkali-rich cement kiln dust instead of commercial lime can improve the binding properties. Different fly ashes, however, react in different ways. It is often more suitable to use fly ash-cement as a binder, especially with poorly graded aggregates. The fly ash, added in an optimum amount, work as a filler and high immediate stabilities can be achieved at a correct water content. The puzzolanic properties of the fly ash, at the same time, makes it possible to reduce the cement content considerably in comparison with the case when only portland cement is used as a binder. Promising laboratory work has also been done with binders consisting of condensed silica fume or ash from fluidized bed coal combustion, both in combination with lime.     

利用电石渣改性固硫灰制备胶凝材料的研究

基于固硫灰自身的火山灰活性和自硬性,提出用钙质激发剂激发固硫灰活性制备固硫灰基胶凝材料。实验研究表明在激发剂的作用下,掺入偏高岭土后胶凝材料强度提高80%以上。用内掺50%偏高岭土的固硫灰,采用电石渣或熟石灰复合水玻璃作为激发剂制备胶凝材料都在体系的碱含量为30%,水玻璃的模数为2.0,养护温度为60℃时强度达到最大,两种激发剂对强度的影响差异不大,而采用电石渣作为激发剂更节约成本,更具优势。     

火山灰质材料活性的快速评定方法

用加热回流的方法测定了不同火山灰材料的活性率Ka（在饱和石灰水中反应的SiO2和Al2O3总量占该材料全部SiO2和Al2O3总量的百分比）。结果表明,Ka与标准胶砂强度比具有较好的相关关系,当细度变化时,同种火山灰材料的Ka和胶砂强度比有着相同的变化规律;改变循环流化床含硫废渣中的SO3含量,其对Ka和胶砂强度比的影响也相同,验证试验表明,活性率Ka能反映其他因素对材料活性的影响,经闭合试验及对影响测试结果的因素所进行的正交实验结果表明,活性率测定方法可靠,测定时间只需几小时。     

蓄能保温砖的制备和保温性能实验

基材砖体以粉煤灰和硅酸钠为主要原料制备,砖体内部填充定量的水合盐相变储能包覆材料后,制备了一种新型复合储能建材——粉煤灰胶体保温蓄能砖(PCM砖)。对该砖体进行了48h的仿真环境热学性能试验,与普通红砖进行了对比,试验结果表明,由于储能的作用,PCM砖起到了调节温度热波动的作用。热流的波动幅度被削弱,作用的时间被推后,将温度变化维持在较小的范围内,可作为保温墙体材料进行应用。     

蒸压钢纤维粉煤灰砖长龄期抗折性能试验分析

为研究蒸压钢纤维粉煤灰砖长龄期的力学性能,自然环境下养护1000d后对不同钢纤维体积掺量的蒸压钢纤维粉煤灰砖进行抗折强度试验。试验结果表明,钢纤维体积掺量为0.4%、0.6%和0.8%时,相比蒸压粉煤灰砖,蒸压钢纤维粉煤灰砖的抗折强度分别提高了16.1%、38.7%和24.2%,钢纤维的加入能提高长龄期抗折强度并能改善砖体的破坏形态;0.6%钢纤维体积掺量时,砖试件在抗折强度和破坏形态上均表现出较好的特性,是钢纤维的合理体积掺量。钢纤维锈蚀是影响蒸压钢纤维粉煤灰砖长龄期抗折强度的主要因素。     

蒸压粉煤灰实心砖砌体受压变形性能试验研究

为研究蒸压粉煤灰砖砌体受压变形性能,以砂浆强度为主要参数,对18个蒸压粉煤灰实心砖砌体试件及15个普通粘土砖砌体试件进行轴心受压试验,对试件的受力状况及其应力-应变关系进行分析研究。试验表明,蒸压粉煤灰砖砌体弹性模量值低于普通粘土砖值且实测值高于规范值。弹性模量随荷载增大有明显降低,且有较强的非线性特征。泊松比实测值与普通粘土砖值相近。给出蒸压粉煤灰砖砌体的应力-应变关系表达式及其弹性模量、泊松比的建议计算公式。     

固硫灰对水泥基自流平砂浆水化产物和性能的影响

研究了固硫灰细度和掺量对水泥基自流平砂浆性能的影响.研究发现固硫灰细度越细,砂浆1d、3d、28d抗折和抗压强度越高,收缩则先减小后增大.掺加粉磨后固硫灰砂浆的收缩均较掺原灰砂浆的收缩小.随着固硫灰掺量增大,水泥基自流平砂浆的1d和3d强度先增大后减小,28d强度呈减小趋势,收缩随着固硫灰掺量增大而减小.固硫灰取代硅酸盐水泥的40%～60%时,砂浆的强度和收缩性较好,取代率为50%时性能最佳.