固硫灰泡沫混凝土的基材研究

以熟料(30%)-固硫灰(70%)做基体,研究了在不同养护方式下,生石灰、铝酸盐水泥单掺及复掺时对基体强度、凝结时间、膨胀性能的影响。结果表明,在熟料-固硫灰系统中加入生石灰可激发固硫灰活性、加快浆体稠化,提高后期强度并增加膨胀。单掺2%铝酸盐水泥的基体强度最高,但当与生石灰复掺时,基体凝结时间会进一步缩短且强度降低,但膨胀增加显著。蒸养有利于基体强度发展并能有效限制膨胀,其膨胀率约为标养的20%。在生石灰掺量为8%,铝酸盐水泥掺量为2%和60℃蒸气养护1d的条件下,可以制备出容重为393kg/m3,强度2.1MPa且性能合格的固硫灰泡沫混凝土。     

偏高岭土和硅灰影响砂浆干燥收缩的对比研究

采用偏高岭土、硅灰取代水泥制备砂浆,经不同预养护时间后测试砂浆干燥过程中的收缩和质量损失,对比分析偏高岭土和硅灰对砂浆干缩的影响。结果表明,偏高岭土和硅灰均减小了砂浆90d干缩,偏高岭土改善砂浆抗干缩性更优,延长预养护时间有利于提高偏高岭土和硅灰降低砂浆干缩的效果;在一定掺量范围内,随掺量上升,掺偏高岭土砂浆干缩不断变小,掺硅灰砂浆则先变小后变大;硅灰和偏高岭土砂浆中复掺粉煤灰能进一步改善砂浆抗干缩性,而复掺矿粉则不利于降低砂浆干缩。预养护3d的偏高岭土砂浆和硅灰砂浆质量损失在一定范围内与干缩呈线性关系,粉煤灰和矿粉的加入降低了线性拟合度;预养护14d的砂浆干燥质量损失与干缩线性关系良好。     

矿物掺合料对自密实混凝土基本性能的影响

为探讨粉煤灰、硅灰掺量对自密实混凝土工作性能和力学性能的影响,对单掺粉煤灰自密实混凝土和复掺粉煤灰硅灰自密实混凝土进行了工作性能测试、抗压强度和抗折强度试验.结果表明:粉煤灰和硅灰的掺入可以提高水泥浆体的流动性,改善自密实混凝土的填充性、间隙通过能力和抗离析性能;3d龄期时,自密实混凝土的抗压强度和抗折强度随粉煤灰掺量...     

利用固硫灰制备高强混凝土及耐久性研究

固硫灰是循环流化床燃煤发电产生的废渣,其排放堆积严重威胁环境,而将固硫灰作为混凝土矿物掺合料应用于建材领域是实现其资源化利用的最佳途径之一。通过研究掺固硫灰混凝土的抗压强度、抗冻性以及抗硫酸盐侵蚀性能,并与掺硅灰和掺粉煤灰组对比,得出了固硫灰作为矿物掺合料对高强混凝土性能的影响。结果表明,固硫灰的掺入有利于混凝土抗压强度、抗冻性以及抗硫酸盐侵蚀性能的提高,且用固硫灰制备高强混凝土可充分利用固硫灰的膨胀性优势,提高混凝土密实性,改善混凝土的微观结构,从而提高混凝土的耐久性。     

化学激发固硫灰的早期水化活性

采用激发剂单掺和复掺的方式对固硫灰的火山灰活性和自硬性进行激活,对比分析了固硫灰7d和28 d的抗压强度,同时利用水化热测量、XRD和红外(FT-IR)分析等方法分析激发剂对固硫灰早期水化活性的影响.结果表明:不同种类激发剂激发固硫灰早期活性的顺序为:生石灰＞水玻璃＞三乙醇胺＞Na2SO4;Na2SO4能够有效地促进固硫灰中硬石膏的溶解析晶,当Na2SO4与TEA复掺时,可以避免Na2SO4激发固硫灰后期强度发展缓慢的缺点;在固硫灰中添加适量生石灰可以显著提高固硫灰活性;4种激发剂复掺时,固硫灰7d和28 d强度分别达到7 MPa和22 MPa,推荐采用复合激活方法激发固硫灰活性.     

固硫灰免蒸压加气混凝土性能影响因素的研究

利用循环流化床燃煤固硫灰制备了免蒸压无水泥加气混凝土,并对影响其性能的因素进行了研究。讨论了石灰掺量、激发剂掺量、料浆初始温度、养护制度、固硫灰细度、铝粉掺量等因素对无水泥固硫灰免蒸压加气混凝土性能的影响;并使用SEM和XRD等手段对制品的水化产物进行了形貌和矿物成分分析。研究结果表明:激发剂掺量是影响加气混凝土性能的主要因素;在生石灰掺量为12%,激发剂掺量为2.1%和60℃蒸汽养护1d的条件下,可以制备出容重为705kg/m3,强度达5.44MPa的无水泥固硫灰免蒸压加气混凝土。     

地下水强酸盐复合腐蚀环境下不同矿物掺合料对水泥砂浆耐腐蚀性能的影响

模拟了贵州地区地下水强酸盐复合腐蚀环境,系统研究了粉煤灰、矿渣粉和硅灰3种矿物掺合料单掺与复掺对水泥砂浆耐腐蚀性能,如耐蚀系数、质量变化率、氯离子相对扩散系数的影响规律,并探讨了地下水强酸盐复合腐蚀环境下水泥砂浆的腐蚀机理。结果表明,与基准砂浆相比,单掺与复掺矿物掺合料均提高了砂浆的耐蚀系数,降低了砂浆后期氯离子相对扩散系数,但增大了砂浆质量损失率。这3项指标从不同角度反映了地下水复合腐蚀环境下水泥砂浆的耐腐蚀性能。     

保温砂浆强度与容重随粉煤灰和矿粉掺量变化的研究

通过对在保温砂浆中复掺矿粉与粉煤灰的实验研究,建立强度与容重之间的关系,寻找出保温与强度相对较好的砂浆配比.研究结果表明:随着粉煤灰与矿粉掺量的增加,保温砂浆早期强度下降,后期强度增长较快,而容重不断增长,但在矿粉掺量为10%、粉煤灰掺量为20%时,保温砂浆强度相对较高,容重相对较低,这即是要找的平衡砂浆强度与容重矛盾的最优掺量.     

硅灰-粉煤灰-废石粉对透水混凝土性能的影响

采用硅灰、粉煤灰、废石粉单掺及三元复合等质量代替部分水泥, 研究其对透水混凝土力学性能、透水系数及砂浆流动性的影响。结果表明: 随着硅灰掺量增加, 砂浆流动度先增加后减小, 透水混凝土强度逐渐增大, 透水系数先减小后增大, 当硅灰掺量超过6%时, 强度不再增加, 透水系数增大, 砂浆流动度 下降; 随着粉煤灰掺量的增加, 砂浆流动度不断增加, 透水混凝土强度与透水系数不断降低, 单掺粉煤灰时, 掺量不宜超过10%; 随着废石粉掺量的增加, 透水混凝土的抗压强度先增加后减少, 透水系数一直减小, 在掺量为 15%时强度最高。硅灰-粉煤灰-废石粉三元复合体系中, 掺6%硅灰、10%粉煤灰、10%废石粉的透水混凝土, 砂浆流动度为162mm, 28d 强度达到38. 4 MPa, 透水系数达到 4. 4 mm/ s。SEM 分析发现, 三元复合体系主要水化产物有水化硅酸钙凝胶和板状氢氧化钙, 还有少量针状钙矾石, 各水化产物之间连接较好, 浆体密实,水化产物发育较好, 浆体水化较完全。     

矿物外加剂对铁尾矿砂活性粉末混凝土性能的影响研究

利用铁尾矿作为活性粉末混凝土(RPC)的细骨料,对水胶比、减水剂掺量和矿物外加剂掺量进行优化,通过加压成型和蒸汽养护,制备出铁尾矿活性粉末混凝土(RPC).详细研究了粉煤灰、硅灰等矿物外加剂对RPC性能的影响,研究表明,当硅灰掺量为10%和粉煤灰掺量为15%复掺时,RPC的抗压强度可以到达176MPa,抗折强度达到38MPa,符合经济型活性粉末混凝土设计要求.     

机制砂颗粒级配对砌筑干混砂浆力学性能的影响

目前,对干混砂浆的研究主要集中在天然砂配制的干混砂浆的品种和性能上,对机制砂干混砂浆的研究还很少.针对机制砂在生产过程中颗粒级配的可控优势,研究了8种不同粒组含量的机制砂对干混砂浆力学性能的影响.试验结果表明,砂浆的稠度值随石粉含量的减小呈现逐渐增大的趋势,其中石粉含量小于20%时砂浆的稠度值较好.砂浆的抗压和抗折强度值随石粉含量的减小及较大颗粒含量的增加呈现逐渐减小的趋势.砂浆的压折比总体上呈下降趋势,石粉含量小于20%时砂浆的压折比小于等于3,说明砂浆的柔韧性较好.砂浆与聚苯板和瓷砖的黏结强度随石粉含量的减小总体上呈先增大后减小趋势,石粉含量为5%到20%时砂浆的黏结强度值较高.因此,机制砂颗粒级配在石粉含量为15%²0%时,粒组所配砂浆的总体性能优良.     

Adsorption mechanism of polycarboxylate-based superplasticizer in CFBC ash-Portland cement paste

Circulating fluidized bed combustion （CFBC） ash exhibits the desirable pozzolanic activity which makes it a potential supplementary cementitious material to replace cement for concrete production. However, the high unburnt carbon content and porous surface structure of CFBC ash may adsorb water reducer and thereby significantly reduce the efficiency of water-reducing agents. The adsorption mechanism of polycarboxylate superplasticizer in CFBC ash-Portland cement paste was investigated by ultraviolet-visible spectrophotometer, and the conception of ＂invalid adsorption site＂ of CFBC ash was presented. The results show that the adsorption behavior of polycarboxylate superplasticizer in coal ash-Portland cement paste can be described by Langmuir isothermal adsorption equation. The adsorption capacity of CFBC ash-Portland cement paste is higher than that of pulverized coal combustion （PCC） fly ash-Portland cement paste. Moreover, the adsorption amount of polycarboxylate superplasticizer increases with the ratio of ash-to-cement in the paste. At last, the fluidity of CFBC ash-Portland cement paste is lower than that of the PCC fly ash paste. This work suggests that when CFBC ash is used as concrete admixture, the poor flowability of the cementitious system due to the high adsorption of water and water-reducing agent should be taken into consideration.     

Properties and mechanism of CFBC fly ash-cement based stabilizers for lake sludge

Circulating fluidized bed combustion(CFBC) fly ash was mixed with cement or lime at a different ratio as a stabilizer to stabilize lake sludge.In order to understand the influences of stabilizers on the lake sludge properties,tests unconfined compressive strength,water stability and SEM observation were performed.The experimental results show that with the increase of the curing time,the strength of all the stabilized specimens increase,especially the samples containing cement.The strength of the specimens is decreased with the increasing of the CFBC fly ash/cement ratio,the optimum ratio between CFBC fly ash and cement is 2:3.The water stability of CFBC fly ash-cement based stabilizers is higher than those of cement and lime.Moreover,the lake sludge stabilization mechanism of CFBC fly ash-cement based stabilizers includes gelation and filling of the hydration products,i e,C-S-H gel and the AFt crystal,which act as benders to solidify those particles together and fill in the packing void of the aggregates.     

EPS保温砂浆性能试验研究

为了系统研究不同组分对聚苯乙烯泡沫(EPS)保温砂浆性能影响,通过试验探讨了EPS体积掺量、粘结剂、引气剂和粉煤灰掺量对EPS保温砂浆和易性、力学性能、导热系数及吸水率和软化系数的影响.试验结果表明,对于配制高性能EPS保温砂浆,EPS体积掺量适宜控制为80％～82％,含气量在20％左右,粉煤灰掺量为20％.掺入适量市售白乳胶能提高EPS保温砂浆的粘结强度和抗折强度,适量粉煤灰掺量能显著降低EPS保温砂浆的干缩率和导热系数,提高EPS保温砂浆综合性能.     

矿物掺合料对机制砂水泥基自流平砂浆性能的影响

试验选用普通硅酸盐水泥、硫铝酸盐水泥与半水石膏的三元胶凝体系,选用机制砂作为细集料,制备全机制砂水泥基自流平砂浆.选用粉煤灰、石粉与硅灰作为矿物掺合料,并研究矿物掺合料对全机制砂制水泥基自流平砂浆流动度、抗压抗折强度与尺寸变化率的影响.研究结果表明:矿物掺合料的火山灰效应对自流平砂浆力学性能的发展产生积极影响,自流平砂...     

橡胶粉、粉煤灰对再生砂浆力学性能影响的试验研究

为了更有效地处理及再利用废橡胶和废弃混凝土,对橡胶粉再生砂浆的力学性能进行了试验研究.选取60目精细胶粉与I级粉煤灰直接掺入到再生砂浆中,通过与素再生砂浆、普通砂浆的对比,研究了其对再生砂浆抗折强度与抗压强度的影响,并探讨了橡胶粉和粉煤灰的作用机理.结果表明:橡胶粉掺量为4%、粉煤灰掺量为15%时,有利于改善再生砂浆的力学性能.     

超细粉煤灰与原灰在水泥砂浆中的水化特征对比研究

主要对比研究了粉煤灰原灰颗粒和超细粉磨后的粉煤灰颗粒在水泥砂浆中的水化过程,利用SEM对水化行为进行了微观观察,并结合砂浆试块3 d7、d、28d抗折、抗压强度.结果表明:粉煤灰的细度对试块的强度影响最大,尤其是后期对抗压强度,在相同掺量下,强度相差达2倍左右;粒径在5μm左右的粉煤灰颗粒在养护初期就已经开始水化,且水化速率较快,在28 d时水化程度已经很充分,粉煤灰原灰颗粒即使养护到28 d龄期时,水化程度仍然很低;掺入细灰的试体各个龄期的结构均比原灰的要致密,且钙矾石的生长更快.     

Effect of curing conditions on the hydration and performance of CFBC ash cementitious system

Circulating fluidized bed combustion （CFBC） ash can be used as supplementary cementitious material for concrete production for its high pozzolanic activity. We investigated the effect of curing conditions on the hydration and performance of CFBC ash-Portland cement system （30： 70, by mass） including hydration products, paste microstructure, linear expansion ratio, chemically combined water content and compressive strength. The results show that tobermorite rather than ettringite is generated under the condition of autoclaved curing. The expansion and mortar strength of the system cured in water is higher than those cured in air at a given age, and the strength and bulk volume may retract under the condition of air curing. In addition, autoclaved curing facilitates the increase of strength gain at early curing ages （the increase rate lowers down in the following ages） and the improvement of system volume stability. It is suggested that sufficient water is necessary for the curing of CFBC ash cementitious system, and autoclaved curing may be considered where volume stability is a primary concern.     

The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength

The influence of mineral admixtures on bending strength of mortar on the premise of equal compressive strength was investigated. Three mineral admixtures (fly ash, ground granulated blast-furnace slag and steel slag) were used. The adding amount of mineral admixture in this study ranges from 22.5% to 60%, and the water-to-binder ratio ranges from 0.34 to 0.50. With equal compressive strength, different mortars can be arranged in such a descending order with their bending strength: cement-fly ash mortar, cement mortar, cement-GGBS mortar, and cement-steel slag mortar. With the same compressive strength, the higher the steel slag content and water-to-binder ratio, the lower the bending strength of mortars. However, the effect of mineral mixture content and water-to-binder ratio on the bending strength of cement-fly ash mortar and cement-GGBS mortar is far inconspicuous.     

保温砌筑砂浆的试验研究

保温砌筑砂浆是以粉煤灰、普通硅酸盐水泥，轻骨料为主要材料，配以各种外加剂而制成，具有重量轻，导热系数小，抗冻性高，粉煤灰掺量大，使用方便等优点，消除了保温砌块因灰缝产生冷桥而造成的热耗，是一种理想的保温节能材料。