增钙灰在商品混凝土中应用的试验研究

本文通过对增钙灰的品质分析，增钙灰－水泥体积安定性和增钙灰对混凝土性能影响的试验研究，得出它是一种火山灰活性优于普通粉煤灰的掺合料，一般具有减水塑化作用，可用来配制C20－C50级商品混凝土，各项性能不亚于基准混凝土。提出配制增钙灰混凝土时，应以安定性合格为前提，遵循等稠、等强的原则、水胶比宜比基准混凝土适当降低，为安全合理应用增钙灰混凝土，增钙灰在不同水泥中掺量宜有限制，其生产单位和使用单位要分别对体积安全性采取控制措施。     

粉煤灰取代水泥率及超量系数对砼性能的影响

本文就粉煤灰取代水泥率及超量系数二因素探讨粉煤灰对混凝土性能的影响。大量试验结果表明，粉煤灰取代水泥能提高砼和易性，而采取合适的取代水泥率及超量系数能配制出３天、２８天强度接近普通砼的粉煤灰砼。     

高强轻集料混凝土力学性能试验研究

本文采用页岩陶粒，掺入粉煤灰和高效减水剂配制高强轻集科混凝土，试验研究水胶比、砂率和粉煤灰取代率对轻集科混凝土力学性能和表观密度的影响，并得出了一个合理的轻集料混凝土配合比。结果表明：轻集料混凝土强度与水胶比成反比；而对于砂率和粉煤灰取代率，存在一个最优的砂率和粉煤灰取代率。     

粉煤灰超量取代技术在水利工程混凝土中的研究与应用

在拌合混凝土时加入适量粉煤灰取代水泥，是化废为利、节约水泥、降低成本、改进混凝土性能的简便措施。国外研究工作始于３０年代，４０～７０年代推广应用，８０年代进入了粉煤灰资源化、产品化、商品化研究利用新时期。普遍开展了粉煤灰的分选利用；高性能粉煤灰作为功能材料，已为配制高强、高性能混凝土（ＨＰＣ）的重要组成材料。本项研究始于１９７３年，是在建设广西大化水电站时，由北京水利水电科学院、广西水电工程局、广西电力工程勘察设计研究院等合作完成。以往在混凝土中掺用粉煤灰，普遍采用容易获得的原状普通粉煤灰，并据…     

用粉煤灰取代砂对混凝土早龄期强度和长期抗锈性的影响

用粉煤灰取代砂对混凝土早龄期强度和长期抗锈性的影响徐峰编译（安徽省建科所）粉煤灰混凝土的配合比设计有两种方法，一是用粉煤灰等量取代部分水泥；二是用粉煤灰取代部分骨料。用前一种方法配制的混凝土其早龄期强度较低；用后一种方法配制的混凝土其强度等于或超过普...     

HAS粉煤灰高强砂浆粉性能的研究

对HAS粉煤灰高强砂浆粉配制的砂浆与水泥配制的砂浆的性能进行对比研究。研究结果表明,前者性能明显优于后者,HAS砂浆料可完全取代水泥、石灰膏配制砂浆。     

Ⅲ级粉煤灰混凝土抗压强度研究

Ⅲ级粉煤灰混凝土抗压强度研究贺鸿珠上海市建筑科学研究院１前言且级粉煤灰的主要指标—需水量比和抗压强度比，通过掺加外加剂或高钙灰改性可达到了五级灰及Ⅲ级灰以上的粉煤灰的品质要求，故对其配制的皿级粉煤灰混凝土也应是可行的。２原材料２．１水泥：５２５号硅酸...     

粉煤灰取代水泥率及超量系数对混凝土性能的影响

本文就粉煤灰取代水泥率及超量系数二因素探讨粉煤灰对混凝土性能的影响。大量试验结果表明,粉煤灰取代水泥能提高砼和易性,而采取合适的取代水泥率及超量系数能配制出３天、２８天强度接近普通砼的粉煤灰砼。     

C80高强粉煤灰混凝土及其应用

本文研究了粉煤灰替代部分水泥配制Ｃ８０砼的压蒸工艺技术，结果表明，采用此技术可以稳定生产Ｃ８０混凝土和高强预应力混凝土管桩（简称ＰＨＣ桩）。     

无砂大孔粉煤灰陶粒混凝土

通过对无砂大孔粉煤灰陶粒混凝土的试验研究 ,阐明用粉煤灰陶粒、水泥和外加剂 ,可以配制出轻质高强新型轻骨料混凝土。其技术性能符合结构保温轻骨料混凝土指标要求     

Properties of high-volume fly ash concrete incorporating nano-SiO2

This paper presents a laboratory study on the properties of high-volume fly ash high-strength concrete incorporating nano-SiO₂ (SHFAC). The results were compared with those of control Portland cement concrete (PCC) and of high-volume fly ash high-strength concrete (HFAC). Assessments of these concrete mixes were based on short- and long-term performance. These included compressive strength and pore size distribution. Significant strength increases of SHFAC compared to the high-volume fly ash high-strength were observed as early as after 3 days curing, and improvements in the pore size distribution of SHFAC were also observed. In this work, the hydration heat of nano-SiO₂ fly ash cement systems was also studied in comparison to the fly ash-cement systems and to the pure cement systems. In addition, the weight change of fly ash incorporating nano-SiO₂, fly ash, and nano-SiO₂ alone after immersed in saturated lime solution was also studied.     

Use of ground coarse fly ash as a replacement of condensed silica fume in producing high-strength concrete

This paper presents a method of improving coarse fly ash in order to replace condensed silica fume in making high-strength concrete. The coarse fly ash, having the average median diameter about 90-100 μm, yields a very low pozzolanic reaction and should not be used in concrete. In order to improve its quality, the coarse fly ash was ground until the average particle size was reduced to 3.8 μm. Then, it was used to replace Portland cement type I by weights of 0%, 15%, 25%, 35%, and 50% to produce high-strength concrete. It was found that concrete containing the ground coarse fly ash (FAG) replacement between 15% and 50% can produce high-strength concrete and 25% cement replacement gave the highest compressive strength. In addition, the concrete containing FAG of 15-35% as cement replacement exhibited equal or higher compressive strengths after 60 days than those of condensed silica fume concretes. The results, therefore, suggest that the FAG with high fineness is suitable to use to replace condensed silica fume in producing high-strength concrete.     

高钙粉煤灰在小石峡水电站中的应用研究

研究了高钙粉煤灰不同掺量情况下混凝土的体积安定性及高钙粉煤灰的最大掺量情况下,在不同水胶比、不同掺量情况下混凝土的力学性能及耐久性性能。研究发现：掺高钙粉煤灰混凝土的安定性可通过测定其胶凝材料的安定性来评定,掺加25%左右的高钙灰,所配制的混凝土的强度性能和体积稳定性都较好,随着水胶比的降低,掺高钙粉煤灰混凝土同龄期的抗压强度逐渐增大：掺高钙粉煤灰灰混凝土具有良好的抗渗性能及良好的抗冻性能。     

Effect of lime putty addition on structural and durability properties of concrete

The effect of lime putty addition on main structural and durability properties of concrete was studied. Different types of cement were used for concrete preparation: a Portland cement, a pozzolanic cement and a Portland cement with the addition of 20% fly ash. The measured concrete properties were compressive strength, setting times, length change, porosity, carbonation depth and degree of steel bar corrosion. It was found that the lime putty addition has a positive effect on the properties of concrete that contain pozzolans and a slightly negative effect on the properties of pure Portland cement. This behavior was correlated with the availability of active silica of cementitious materials. The active silica of pozzolans reacts with the added calcium hydroxide giving constituents, which improve the concrete stability and durability.     

纳米颗粒对道路粉煤灰混凝土耐磨性能的影响及作用机理

为探讨纳米颗粒对道路粉煤灰混凝土耐磨性能的影响,采用纳米材料和超细粉煤灰等量取代水泥制备了纳米改性粉煤灰水泥砂浆,在此基础上制备出三种纳米改性道路粉煤灰混凝土:纳米SiO2 (NS)混凝土、纳米SiC(NC)混凝土和纳米复掺混凝土,并研究了两种纳米材料对粉煤灰水泥砂浆力学性能和道路粉煤灰混凝土耐磨性能的影响及作用机理.结果表明:混凝土中掺入纳米材料能显著提高其耐磨性能.单掺NS混凝土中NS最优掺量为2％,单掺NC混凝土中NC最优掺量为3％;而复掺2％ NS、2％ NC时,纳米复掺混凝土耐磨性最佳,与基准混凝土相比,磨损量降低了75％.分析认为:纳米材料的表面效应、活性效应和微集料填充效应使其具有较大的表面能,在水泥浆体中与Ca(OH)2晶体发生二次水化反应,改善了Ca(OH)2的取向程度,强化了水泥石微细观结构,优化了水泥基体内孔径分布与孔结构,使其更加密实,从而提高了道路粉煤灰混凝土的耐磨性能.     

掺合料对硫铝酸盐水泥基混凝土耐久性影响的研究

研究了掺合料复掺(矿渣∶粉煤灰=2∶1)、单掺矿渣、单掺粉煤灰对硫铝酸盐水泥基混凝土强度、抗渗性、抗冻性的影响,并与相同水灰比下掺合料复掺对普通硅酸盐水泥基混凝土对应性能的影响进行对比。结果表明:在硫铝酸盐水泥基混凝土中,掺合料的加入使混凝土的早期和后期强度都明显降低,抗渗性稍微降低,抗冻性明显降低,且掺量越高,其强度、抗渗性、抗冻性降低越明显;但复掺时的效果比单掺时的效果好,粉煤灰的效果最差;而在普通硅酸盐水泥基混凝土中,掺合料的加入使混凝土的早期强度降低,但后期强度超过空白样的强度,抗渗性、抗冻性明显提高,但是,在无掺合料时其抗渗性、抗冻性大大低于相同水灰比下硫铝酸盐水泥基混凝土的抗渗性、抗冻性。     

Modeling the hydration of concrete incorporating fly ash or slag

Granulated slag from metal industries and fly ash from the combustion of coal are industrial by-products that have been widely used as mineral admixtures in normal and high strength concrete. Due to the reaction between calcium hydroxide and fly ash or slag, the hydration of concrete containing fly ash or slag is much more complex compared with that of Portland cement. In this paper, the production of calcium hydroxide in cement hydration and its consumption in the reaction of mineral admixtures is considered in order to develop a numerical model that simulates the hydration of concrete containing fly ash or slag. The heat evolution rates of fly ash- or slag-blended concrete is determined by the contribution of both cement hydration and the reaction of the mineral admixtures. The proposed model is verified through experimental data on concrete with different water-to-cement ratios and mineral admixture substitution ratios.     

粉煤灰制备轻质高强混凝土的试验研究

以烧结粉煤灰陶粒作为粗骨料,复掺超细粉煤灰与一级粉煤灰部分替代水泥作为胶凝材料,制备轻质高强混凝土.主要研究了两种粉煤灰的掺配比例与总掺量对轻骨料混凝土力学性能、干表观密度及微观形貌的影响.试验结果表明:掺超细粉煤灰能够细化水泥水化产物的晶体尺寸,打乱氢氧化钙的生长取向,减少混凝土内部结构缺陷,使胶凝材料浆体更均匀;当超细粉煤灰与一级粉煤灰的比例为1:1,粉煤灰的总掺量为40%时,可以配制出28 d抗压强度为58.6 MPa,干表观密度为1900 kg/m3的LC50轻质高强轻骨料混凝土.     

Strength properties of high-volume fly ash roller compacted and workable concrete, and influence of curing condition

A laboratory investigation was carried out to evaluate the strength properties of high-volume fly ash (HVFA) roller compacted and superplasticised workable concrete cured at moist and dry curing conditions. Concrete mixtures made with 0%, 50% and 70% replacement of normal Portland cement (NPC) with two different low-lime Class F fly ashes, good and low quality, were prepared. Water-cementitious material ratios ranged from 0.28 to 0.43. The compressive, flexural tensile and cylinder splitting tensile strengths were measured and presented. The relationship between the flexural tensile and compressive strengths was discussed. The influence of loss on ignition (LOI) content of fly ash on water demand and the strength of concrete was also discussed. The influence of moist and dry curing conditions on the high-volume fly ash (HVFA) concrete system was assessed through a proposed simple efficiency factor. The study showed that producing high-strength concrete was possible with high-volume fly ash content. LOI content increased the water demand of fresh concrete. HVFA concrete was found to be more vulnerable to dry curing conditions than was NPC concrete. It was concluded that HVFA concrete was an adequate material for both structural and pavement applications.     

Cl-对高钙粉煤灰硬化水泥浆体的影响

研究了高钙粉煤灰硬化水泥浆体中Cl^-的扩散和渗透规律，以及Cl^-对高钙粉煤灰硬化水泥浆体性能的影响，并探讨了氯盐对高钙粉煤灰水泥浆体产生破坏的机理。试验结果表明，高钙粉煤灰的掺量以及水灰比和水化时间对Cl^-的扩散都有影响。