碱激发剂浓度及模数对碱矿渣胶凝材料抗压性能及水化产物的影响研究

采用水玻璃(复掺氢氧化钠调整模数)激发粒化高炉矿渣活性制备碱矿渣净浆试样.采用抗压强度测试、X-射线衍射(XRD)、综合热分析(TG-DSC)等技术手段研究了激发剂碱浓度(4%、6%、8%)及模数(0.75、1.00、1.50、2.00)对碱矿渣胶凝材料抗压性能及水化产物的影响.研究结果表明:激发剂模数较低时(0.75和1.00),碱矿渣胶凝材料抗压强度随着碱浓度的增加而呈下降趋势;激发剂模数较高时(1.50和2.00),试件强度在碱浓度为6%时达到最大值.在相同碱浓度下,激发剂模数为1.50时试件抗压强度值最大.碱矿渣胶凝材料主要水化产物为C-S-H凝胶,同时伴有C-A-S-H凝胶生成.另外观测到少量斜方钙沸石(CaAl2Si2O8· 4H2O)的生成.在部分配合比中还观测到水滑石(Mg6Al2(OH)16CO3· 4H2O)的存在.碱浓度较高的碱矿渣胶凝材料中生成了较多的C-S-H水化产物.激发剂模数较高时(1.50和2.00),更有利于碱矿渣中C-S-H水化产物的生成.碱浓度/模数较低时, C-S-H产物结晶度有所提高.相较于C-S-H凝胶结晶度,其生成量对碱矿渣胶凝材料抗压强度的影响更为显著.     

矿渣掺量对热养护粉煤灰基地聚物收缩和抗压强度的影响及机理分析

本文通过数字图像相关(DIC)方法研究了0%、10%、20%、30%、40%、50%六种矿渣掺量(质量分数,下同)对粉煤灰基地聚物(FAGP)混凝土热养护过程中收缩的影响,测试了热养护后混凝土和净浆的抗压强度,并且结合同步热分析(TGA-DSC)、X射线衍射(XRD)和扫描电子显微镜(SEM)对微观机理进行了分析。结果表明：随着矿渣掺量的增加,FAGP的收缩量和收缩速率均先减小后增大,抗压强度先增大后减小,水化程度增大,微裂缝数量增加;当矿渣掺量为40%时,FAGP混凝土的收缩量最小,抗压强度最大;当矿渣掺量较低时,地聚物水化程度小,微裂缝少,地聚物收缩的主要原因是热养护初期的弹性模量较低;当矿渣掺量较高时,地聚物水化程度大,微裂缝较多,地聚物收缩主要由较强烈的化学反应引起。     

碱激发矿渣混凝土制备及性能研究

本文主要分析不同模数和掺量的水玻璃对矿渣及粉煤灰潜在活性激发效果,同时对碱激发矿渣混凝土配合比进行试验研究,结果表明适当模数及掺量的水玻璃可以有效激发矿渣潜在活性;采用粉煤灰替代部分矿渣可以改善料浆的流动性,但其潜在活性低于矿渣,不利于强度发展;碱矿渣混凝土属于绿色环保型建材,具有显著经济社会效益,本次试验成功配制出C50碱激发矿渣混凝土。     

碱矿渣水泥基胶凝材料的碳化特征研究

抗碳化性能是混凝土耐久性的重要方面.以水玻璃与氢氧化钠(NaOH)为碱组分,粒化高炉矿渣为胶凝材料,研究了碱矿渣水泥的抗碳化性能,并分析了碱矿渣水泥易于发生碳化的主要原因.结果表明:与硅酸盐水泥相比,碱矿渣砂浆的碳化程度较大,碳化未引起碱矿渣水泥石干燥收缩的增加.碱矿渣水泥基胶凝材料硬化体碳化程度较大的主要原因是其水化产物不存在Ca(OH)2、硬化体孔溶液的高碱性及较大的干燥收缩.     

碱矿渣粉煤灰胶凝体系的温度激发特性研究

为探究不同温度状态下的碱激发剂对矿渣、粉煤灰的活性激发效果,将NaOH、Na2CO3以复合掺的方式得到了碱激发剂,并以碱激发剂溶液的温度t为试验设计参数,在t=20、30、40、50、60、70、80、95℃状态下,制备了粉煤灰与矿渣的比值为0.6、碱掺量为6.0%、复合碱组分间的比例n=1.3、胶水比为3.2的净浆试...     

钢渣矿渣基全固废胶凝材料的化学活化

为了促进钢铁冶金渣的高附加值应用,以钢渣、矿渣和脱硫石膏为原料制备胶凝材料,研究了不同掺量CaO或Na2SO4对胶凝材料的化学活化作用,并利用XRD、SEM对掺入激发剂胶凝材料的水化产物进行了分析.结果表明,掺入少量CaO或者 Na2SO4的胶凝材料净浆试块早期抗压强度会有一定的提高,后期强度变化不大;但当Na2SO4掺量超过2%时,净浆试块的抗压强度会降低.掺入激发剂对胶凝材料的水化产物种类不会造成影响,其水化产物主要包括钙矾石(AFt)、水化硅酸钙(C-S-H)凝胶和氢氧化钙(CH).     

偏高岭土对蒸养混凝土强度和毛细吸水性的影响

采用偏高岭土等矿物掺合料等量取代30%水泥研究了蒸养混凝土强度和毛细吸水性,并通过热重、差热分析和电镜探讨了作用机理。结果表明,偏高岭土对提高蒸养混凝土的脱模强度效果显著,复掺10%粉煤灰和20%偏高岭土的蒸养混凝土脱模强度比空白蒸养混凝土强度高23%,比复掺粉煤灰和矿渣的高17%;掺入粉煤灰、矿渣和偏高岭土都降低了混凝土的毛细吸水性,且掺偏高岭土混凝土试件的早期水吸附速率及总的吸水量均为最低;热分析和电镜观察表明,在蒸养60℃温度的热激发下,偏高岭土早期与水泥水化产物氢氧化钙发生火山灰反应是脱模强度高的主要原因,火山灰反应消耗了氢氧化钙,生成了更多的水化产物,混凝土更为致密。     

碱矿渣水泥化学收缩研究

研究了矿渣的种类、细度以及碱组分种类、碱溶液浓度等对碱矿渣水泥化学收缩的影响.结果表明,当碱组分为NaOH时,碱矿渣水泥28d龄期的化学收缩约为6～10ml/100g,与硅酸盐水泥(7～9ml/100g)的相当;当碱组分为水玻璃时,其收缩量约为3～6ml/100g,比硅酸盐水泥的小.     

碱激发矿渣水泥水化C-A-S-H凝胶微观结构的研究

通过核磁共振、扫描电镜和纳米压痕技术研究了普通波特兰水泥和碱激发矿渣水泥水化28 d形成的C-S-H和C-A-S-H凝胶的微观结构.结果表明,波特兰水泥水化形成的C-S-H凝胶的结构主要由5链14 nm的托贝莫来石(60％)和2链硅钙石(40％)组成;碱激发矿渣水泥的主要水化产物是C-A-S-H凝胶,随激发剂的性质不同而具有不同的组成和结构:当激发剂为NaOH溶液(Na2 O含量为矿渣质量的4％)时,形成的C-A-S-H凝胶是介于5链14 nm和14链11 nm的托贝莫来石之间的中间结构;当激发剂为水玻璃溶液(Na2 O含量为矿渣质量的4％)时,C-A-S-H凝胶的结构主要由11链14 nm和14链11 nm的托贝莫来石组成,与NaOH作激发剂一样,以水玻璃作激发剂的碱激发矿渣水泥水化的C-A-S-H凝胶不具有超高密度状态.     

碳酸钠、氢氧化钠与水玻璃复合激发对地聚物胶凝材料性能的影响

采用碳酸钠替代氢氧化钠调节水玻璃模数制备复合碱激发剂,研究不同碱掺量下碳酸钠掺入比例对地聚物胶凝材料净浆流动度、凝结时间及抗压强度的影响,并通过FT-IR、XRD和SEM试验分析地聚物胶凝材料水化产物的物相组成及微观形貌。结果表明,氢氧化钠与碳酸钠共同复合水玻璃的激发剂激发效果优于二者单独与水玻璃复合的激发剂,当碱掺量为6%(质量分数)、碳酸钠替代比例为40%(质量分数)时,地聚物胶凝材料净浆流动度为185 mm, 28 d抗压强度为94.4 MPa。碳酸钠替代比例增加可延长地聚物胶凝材料凝结时间,当替代比例为100%时,地聚物胶凝材料初凝时间、终凝时间可达372和420 min。不同碱组分激发剂作用时,地聚物胶凝材料水化产物相似,均以无定形铝硅酸盐C-(A)-S-H凝胶为主。     

Immobilization of Cr, Cd, Zn and Pb in alkali-activated slag binders

Granulated blast furnace slag is the main component of alkali-activated slag cementitious materials (AASCs). Calcium silicate hydrates with a low Ca/Si ratio, hydrotalcite-type phase, some amounts of hydrogarnets and sodium zeolites form as main AASC hydration products. The microstructure of alkali-activated slag pastes shows a higher amount of gel pore content compared to OPC pastes and, simultaneously, significantly lower amount of capillary pores. The microstructure and phase composition of hydrated slag indicate that they can play an essential role in the immobilization of heavy metals. The properties of alkali-activated slag pastes in the presence of Zn, Cd, Cr and Pb ions were studied. The leaching TANK test was used to evaluate the level of immobilization of particular elements in mortars made containing these elements. It was found that the degree of Cd, Zn and Pb ion immobilization was very high (exceeding 99.9%). The values for Cr⁶⁺ were lower (ca. 99.0%). The strength development as well as microstructure observations are presented in the paper.     

MgO和CaO对碱矿渣混凝土抗碳化性能的影响

与普通硅酸盐水泥(OPC)混凝土相比,碱矿渣混凝土(AASC)的抗碳化性能较差。为了提高AASC的抗碳化性能,本文采用MgO和CaO代替部分矿渣制备AASC,研究了加速碳化环境下掺MgO和CaO的AASC在不同碳化龄期的抗压强度和碳化深度,并结合 X 射线衍射(XRD)、同步热分析(TG-DTG)和扫描电镜-能谱(SEM-EDS)等技术分析了MgO和CaO对AASC抗碳化性能的改性机理。结果表明,MgO和CaO分别促进了AASC中Mg-Al水滑石和Ca-Al层状结构的生成,这两种水化产物在碳化过程中会吸收和消耗CO₂,缓解C-S-H的碳化分解。此外,加速碳化后,掺入MgO的AASC中有碳酸钙镁和碳酸镁生成,掺入CaO的AASC中碳酸钙的量明显增多,这些碳化产物可有效填充孔隙,阻碍CO₂向内部进一步的扩散。因此,在碳化环境下,掺MgO和CaO的AASC抗压强度保留率更高,碳化深度更低,表现出更好的抗碳化性能。     

Influence of nucleation seeding on the hydration kinetics and compressive strength of alkali activated slag paste

Addition of pure calcium silicate hydrate (C–S–H) to alkali-activated slag (AAS) paste resulted in an earlier and larger hydration rate peak measured with isothermal calorimetry and a much higher compressive strength after 1 d of curing. This is attributed to a nucleation seeding effect, as was previously established for Portland cement and tricalcium silicate pastes. The acceleration of AAS hydration by seeding indicates that the early hydration rate is controlled by nucleation and growth. For the experiments reported here, the effect of C–S–H seed on the strength development of AAS paste between 1 d and 14 d of curing depended strongly on the curing method. With sealed curing the strength continued to increase, but with underwater curing the strength decreased due to cracking. This cracking is attributed to differential stresses arising from chemical and autogenous shrinkage. Similar experiments were also performed on Portland cement paste.     

The role of alumina on performance of alkali-activated slag paste exposed to 50 °C

The strength and microstructural evolution of two alkali-activated slags, with distinct alumina content, exposed to 50 °C have been investigated. These two slags are ground-granulated blast furnace slag (containing 13% (wt.) alumina) and phosphorous slag (containing 3% (wt.) alumina). They were hydrated in the presence of a combination of sodium hydroxide and sodium silicate solution at different ratios. The microstructure of the resultant slag pastes was assessed by X-ray diffraction, differential thermogravimetric analysis, and scanning electron microscopy. The results obtained from these techniques reveal the presence of hexagonal hydrates: CAH₁₀ and C₄AH₁₃ in all alkali-activated ground-granulated blast-furnace slag pastes (AAGBS). These hydrates are not observed in pastes formed by alkali-activated ground phosphorous slag (AAGPS). Upon exposure to 50 °C, the aforementioned hydration products of AAGBS pastes convert to C₃AH₆, leading to a rapid deterioration in the strength of the paste. In contrast, no strength loss was detected in AAGPS pastes following exposure to 50 °C.     

碱-磷渣-粉煤灰胶凝材料的性能与硬化浆体结构

为充分利用磷渣和粉煤灰两种工业废渣生产高性能胶凝材料,研究了不同磷渣/粉煤灰配合比的碱-磷渣-粉煤灰胶凝材料性能,并用扫描电子显微镜和压汞仪分析了硬化浆体的细观结构和孔结构.结果表明:碱-磷渣-粉煤灰胶凝材料的凝结时间正常,在粉煤灰掺量为0～30 %(质量分数)范围内,随粉煤灰的掺量的增加,碱-磷渣-粉煤灰胶凝材料的凝结时间略有延长.与普通硅酸盐水泥相比,碱-磷渣胶凝材料的抗压强度较高,其3d和28d抗压强度分别可达到30.9MPa和98.8MPa,但其抗折强度相对较低.掺加粉煤灰后碱胶凝材料的抗压强度降低,而抗折强度提高.碱-磷渣-粉煤灰胶凝材料的耐蚀性和抗冻性能均显著优于硅酸盐水泥,其干缩比硅酸盐水泥的大.用部分粉煤灰取代磷渣粉可一定程度减小干缩.碱-磷渣-粉煤灰胶凝材料硬化浆体的结构非常致密,其孔隙率和平均孔径均小于普通硅酸盐水泥硬化浆体.     

碱-矿渣水泥的水化、力学及干缩性能研究进展

碱-矿渣水泥是一种优良的绿色胶凝材料,由矿渣部分或全部取代水泥而制成。在碱激发剂的作用下矿渣水化产生活性,并且由于其独特的玻璃体分相结构导致碱-矿渣水泥的水化硬化产物表现出不同于普通硅酸盐水泥基材料的性能。本文介绍了矿渣的组成与结构,从理论层面解释碱-矿渣水泥具有潜在活性的原因,探讨了不同激发剂作用下碱-矿渣水泥的水化机理,并在此基础上综述其基本力学性能和干缩特性,为其在工程实践中的应用和推广提供依据。结合相关文献,总结了现有研究的不足并对今后的发展提出了建议。     

Effect of shrinkage-reducing admixtures on the properties of alkali-activated slag mortars and pastes

The effect of a shrinkage-reducing admixture (SRA) based on polypropylenglycol on the dimensional stability of waterglass-activated slag mortars was studied. The analysis also showed the effect of the admixture on pore structure of the mortars as well as on the mineralogical composition and microstructure of the alkali-activated slag pastes.The SRA reduced the shrinkage by up to 85 and 50% when the alkali-activated slag mortar specimens were cured at relative humidities of 99 and 50%, respectively. The mechanism primarily involved in shrinkage reduction is the decrease in the surface tension of pore water prompted by the admixture. The SRA also modified the pore structure - under both curing conditions - increasing the percentage of pores with diameters ranging from 1.0 to 0.1 μm. Capillary stress is much lower in these pores than in the smaller capillaries prevailing in mortars prepared without admixtures.Microstructurally, the SRA occasioned a slight increase in the proportion of Si units Q² in the CSH gel and a decrease in the percentage of Al replacing the Si in the gel structure. The admixture did not, however, modify the mineralogical composition of the pastes.Finally, the SRA admixture retarded the alkaline activation of the slag, more intensely at higher admixture dosages. While the admixture did not significantly alter the degree of reaction in pastes cured for 7 days at RH = 99%, the value of this parameter dropped by 7% in the presence of the admixture in pastes cured at 50% relative humidity.     

SAP内养护对碱激发矿渣胶凝材料性能的影响

碱激发矿渣(AAS)胶凝材料存在早期收缩大、开裂风险高的问题,限制了其工程应用。本文采用TAM、TGA、MIP等方法研究了高吸水性树脂(SAP)内养护对AAS胶凝材料水化热、水化产物及孔结构的影响,同时研究了SAP对AAS胶凝材料抗压强度及自收缩的影响规律。结果表明,SAP的加入会增加基体的孔隙率,降低AAS浆体的抗压强度,但是随着水化时间的延长,SAP的内养护作用可以促进矿渣水化,抗压强度的降低幅度逐渐减小。SAP的加入对AAS胶凝材料的水化放热过程有一定的延迟作用,表现为诱导期延长,第二放热峰滞后。SAP的加入使AAS胶凝材料水化产物总量增加,增加程度随着模数的增加而提高。此外,SAP抑制AAS浆体自收缩效果明显,添加SAP之后自收缩降低率最高可达81%。     

Effect of binder content on the performance of alkali-activated slag concretes

This paper assesses the mechanical and durability performance of concretes produced using alkali silicate-activated ground granulated blast furnace slag as sole binder. Alkali-activated concretes are formulated with 300, 400 and 500 kg slag per m³ of fresh concrete, and their performance is compared with reference concretes produced using Portland cement (OPCC). Regardless of the binder content, the alkali-activated slag concretes (AASC) develop higher compressive strength than the comparable reference concretes. A higher binder content leads to increased strength in both AASC and OPCC at 28 days. However, at 90 days, the performance penalty for low binder content is more significant in the OPCC than AASC samples. Permeability, water sorption and carbonation resistance properties are also improved at higher binder contents. By controlling mix design parameters, it is possible to produce AASC with mechanical strength and durability comparable to conventional Portland cement concretes.     

粉煤灰掺量对碱激发矿渣砂浆减缩特性研究

研究粉煤灰掺量对碱激发矿渣砂浆的凝结时间、抗压强度、化学收缩和自收缩的影响因素和影响规律.结果表明,加入粉煤灰不仅能有效改善碱激发矿渣砂浆凝结快,收缩变形大的问题,同时也能够解决碱激发粉煤灰砂浆在常温条件下早期强度低和强度发展缓慢等问题.配比不同掺量的粉煤灰,以寻求最佳的掺量,在保证碱激发矿渣砂浆强度的同时提高减缩效果.