绿色环保胶凝材料混凝土两种力学性能研究

利用废弃矿渣与水泥加工的绿色环保胶凝材料来配置绿色混凝土,为探究C30、C50两种强度下不同绿色环保胶凝材料取代率的混凝土力学强度变化规律,从抗压强度与劈裂抗拉强度两个方面设计力学实验,研究绿色环保胶凝材料混凝土在7d和28d两种不同养护时间下试件的力学强度变化。由结果可得,C30强度混凝土7d和28d养护的抗压强度整体随着绿色环保胶凝材料取代率的逐渐增高而逐渐降低,呈现一种负相关趋势;C50强度的绿色环保胶凝材料混凝土相对于C30强度的降低趋势更加明显。C30强度混凝土7d和28d养护的劈裂抗拉强度整体随着绿色环保胶凝材料取代率的逐渐增高而逐渐降低,同样呈现一种负相关趋势;C50强度的绿色环保胶凝材料混凝土与C30强度的降低趋势基本相同。     

一类新型胶凝材料及其组成设计

本文从材料设计的基本观点出发，对一类新型胶凝材料从组份的确定，到组成的设计进行了大量的工作，重点介绍了这类胶凝材料设计的基本思想，以及胶凝材料最佳组成范围和胶凝材料的力学性能。     

含有复合胶凝材料的砼力学性能及其微观结构机理分析

通过研究单掺和复合掺入粉煤灰、矿粉、复合膨胀组元后，对混凝土和砂浆力学性能的影响，并通过X射线衍射（XPD）和扫描电镜（SEM）等微观结构分析，阐明了三者各自的作用效果以及复合后的优势互补作用原理，在此基础上研制成的新型高性能复合胶凝材料。研究表明这种高性能复合胶凝材料具有低水化热、高强、优良补偿收缩效果的特性，能有效控制混凝土的收缩裂缝，提高混凝土的耐久性。     

高性能胶凝材料中石膏的优化

高性能胶凝材料主要用于高性能混凝土,具有强度高、需水量小、水化垫低和收缩小等特点。按掺高效减水剂的胶凝材料的流变性能来优化石膏的掺量是高性能胶凝材料的特有技术之一。试验研究了石膏的掺量对高性能胶凝材料的需水量、凝结时间、强度、收缩性的影响,以此作为优化石膏掺量的依据。     

利用炼铁高炉渣制备胶凝材料的研究

以高炉渣微粉和偏高岭土为主要原料,NaOH和Na2SiO3为复合激发剂,制备了碱激发矿渣胶凝材料,研究了炉渣粒度、碱添加量及养护制度对矿渣胶凝材料性能的影响.结果表明,炉渣粉磨至10 μm,在室温下养护,激发剂含量为12%时,样品的1 d抗压强度为17.66 MPa;当碱激发剂含量达到16%时,样品的1 d抗压强度为27.91 MPa;随着养护时间的延长,胶凝材料的抗压强度有提高的趋势,80 ℃养护可以提高胶凝材料的早期强度,但养护温度不宜过高.     

高钙粉煤灰作为添加剂制备赤泥偏高岭土胶凝材料

采用XRD、IR、SEM、和EDS等分析手段,研究了高钙粉煤灰作为添加剂制备的赤泥偏高岭土胶凝材料的力学性能和水化产物.结果表明:合适掺量的高钙粉煤灰(<14%)有助于试样力学性能的提高;高钙粉煤灰作为添加剂所制备的赤泥偏高岭土胶凝材料,其水化产物主要有水化硅酸铝钙、沸石相、羟基硅酸铝、钙长石、蓝晶石、水化硅酸钙和叙永石. 随着试样养护龄期的增长胶凝材料结构更密实,形成PSS型结构.     

FKJ胶凝材料的耐化学介质特性

通过FKJ砂浆试件在碱、酸及盐溶液中浸泡后强度变化，试验其耐化学腐蚀能力。FKJ砂浆试件在几种化学介质中耐蚀系数值较高，可用于海水工程、盐类化工工程和污水处理工程等。与普通水泥混凝土相比，具有较好的耐久性。     

脱硫石膏制备超硫胶凝材料

研究旨在开发一种以烟气脱硫石膏为主要原料,矿渣粉为活性成分,熟料、钢渣作为碱性激发剂的超硫水硬性胶凝材料。该胶凝体系脱硫石膏掺量高达45%,且以2%熟料激发时,3d抗压强度达20.5MPa,28d为48.7MPa;而以8%钢渣激发,分别达15.8MPa和50.7MPa。XRD和SEM分析表明,脱硫石膏-矿渣-激发剂体系的水化产物主要是钙矾石和C-S-H凝胶。脱硫石膏在水化过程中一部分参与水化形成水化产物钙矾石,其余部分被水化产物所包裹起集料骨架作用。     

Mechanical properties of gangue-containing aluminosilicate based cementitious materials

High performance aluminosilicate based cementitious materials were produced using calcined gangue as one of the major raw materials. The gangue was calcined at 500℃. The main constituent was calcined gangue, fly ash and slag, while alkali-silicate solutions were used as the diagenetic agent. The structure of gangue-containing aluminosilicate based cementitious materials was studied by the methods of IR, NMR and SEM. The results show that the mechanical properties are affected by the mass ratio between the gangue, slag and fly ash, the kind of activator and additional salt. For 28-day curing time, the compressive strength of the sample with a mass proportion of 2：1：1 （gangue： slag： fly ash） is 58.9 MPa, while the compressive strength of the sample containing 80wt% gangue can still be up to 52.3 MPa. The larger K^＋ favors the formation of large silicate oligomers with which AI（OH）4- prefers to bind. Therefore, in Na-K compounding activator solutions more oligomers exist which result in a stronger compressive strength of aluminosilicate-based cementitious materials than in the case of Na-containing activator. The reasons for this were found through IR and NMR analysis. Glauber＇s salt reduces the 3-day compressive strength of the paste, but increases its 7-day and 28-day compressive strengths.     

Optimization of SO<Subscript>3</Subscript> content in blended cementitious materials

Experimental investigation was conducted on the effects of gypsum types and SO₃ content on the fluidity and strengths of different cementitious systems. The experimental results show that influences of gypsum in various cementitious materials are different. For cementitious materials blended with various proportions of slag-fly ash and 5% gypsum content, influences of gypsum and calcined gypsum on the fluidity and flexural/compressive strength are similar. It is revealed that “combination effect” and “synergistic effect” of slag and fly ash play an important role during hydration. For cementitious materials with 45% clinkers, 30% slag, 20% fly ash and 5% limestone, the optimized SO₃ contents in gypsum and calcined gypsum are 3.13% and 3.51% respectively and the optimized gypsum content is 6.5%. While both of them are blended, the optimum ratio of gypsum to calcined gypsum is 40%:60% (total gypsum content 6.5%), correspondingly the optimum ratio of SO₃ is 19.3%:32. 4%. CHEN Mei-zhu : Born in 1974 Funded by Hubei Bureau of Science and Technology of China (981P0202)     

粉煤灰混凝土抗压性能试验与分析

为了得到不同掺量、不同侵蚀环境下粉煤灰混凝土的抗压性能,研究干湿循环和全浸泡侵蚀环境下,粉煤灰掺量分别为0、10%、20%、30%的粉煤灰混凝土的抗压强度.结果表明:全浸泡和干湿循环环境对比,粉煤灰混凝土抗压强度相差不大;随着粉煤灰掺量的增加,其抗压强度呈下降趋势;全浸泡和干湿循环环境下的粉煤灰掺量均不宜过大,且粉煤灰掺量在10%较为适宜.     

Effect of alkali-activation on aluminosilicate-based cementitious materials

High-performance aluminosilieate-based eementitious materials were produced with fly ash from a coal power plant as one of the major raw materials.The structures of fly ash containing aluminosilicate-based cementitious materials were compared before and after treatment by the methods of nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM).During the 28 d curing time,the compressive strength of water glass and fly ash samples increased from 9.08 MPa to 26.75 MPa.The results show that most of the stiff shells are destroyed after mechanical grinding and chemical activation.Magic angle spinning (MAS)NMR of 27Al shows that the wide peak becomes narrow and the main peak shifts to the direction of low field,indicating the decrease of polymerization degree,the enhancing of activity,the decrease of six-coordination structure,and the increase of small and symmetrical four-coordination polyhedron structure within the aluminum-oxygen polyhedron network.Comparisons between MAS NMR of 29Si with different treatments suggest that Q0 disappears,the quantity of Q2 increases,and the quantity of Q4 decreases.The polym     

养护温度对高延性水泥基材料力学性能的影响

研究养护温度对高延性水泥基复合材料性能的影响,分析养护温度在20、40、60和80℃时水泥基复合材料的抗弯性能、抗压强度、抗折强度及裂缝分布特点.结果表明,养护温度越高,高延性水泥基复合材料的早期跨中挠度越小;养护温度高于40℃时,试件的跨中挠度和韧性指数随龄期延长无明显变化;高养护温度能显著提高高延性水泥基复合材料的早期抗压强度和抗折强度,龄期对高温养护条件下高延性水泥基复合材料的抗压、抗折强度影响不大;粉煤灰掺量相同时,常温养护下高延性水泥基复合材料的裂缝更加细密均匀;养护温度为60℃时,粉煤灰掺量提高至80%,高延性水泥基复合材料的韧性显著提高,28d抗压强度可达70MPa.     

Impact properties of engineered cementitious composites with high volume fly ash using SHPB test

The split Hopkinson pressure bar (SHPB) testing with diameter 40 mm was used to investigate the dynamic mechanical properties of engineered cementitious composites (ECCs) with different fly ash content. The basic properties including deformation, energy absorption capacity, strain-stress relationship and failure patterns were discussed. The ECCs showed strain-rate dependency and kept better plastic flow during impact process compared with reactive powder concrete (RPC) and concrete, but the critical compressive strength was lower than that of RPC and concrete. The bridging effect of PVA fiber and addition of fly ash can significantly improve the deformation and energy absorption capacities of ECCs. With the increase of fly ash content in ECCs, the static and dynamic compressive strength lowered and the dynamic increase factor enhanced. Therefore, to meet different engineering needs, the content of fly ash can be an important index to control the static and dynamic mechanical properties of ECCs.     

考虑界面过渡区及集料因素的水泥基材料碳化模型

集料和界面过渡区对水泥基材料抗碳化性能有显著影响。基于Fick第二定律,提出一种考虑集料和界面过渡区影响的CO₂扩散模型,模型中首次引入界面过渡区的扩散系数并给出相应参数的计算方法,并基于质量守恒定律给出CO₂反应模型,利用该模型研究荷载作用下C30和C50混凝土中CO₂的浓度分布。结果表明,考虑集料和界面过渡区影响能更准确地计算CO₂在水泥基材料中的扩散系数及碳化深度值。通过与文献中的试验数据进行比较,进一步验证了理论模型的可靠性。模型将集料和界面过渡区作为评价混凝土耐久性的重要因素,为钢筋混凝土结构的设计和寿命预测提供依据。     

夏热冬冷地区不同墙体材料节能冬季试验研究

对利用两淮矿区固体废弃物制备的夏热冬冷地区常用的三种新型墙体材料（粉煤灰蒸压加气混凝土砌块、粉煤灰混凝土空心砌块、烧结煤矸石空心砖）与传统粘土实心砖进行了冬季同环境下的能耗评价、环境评价等技术方面的对比试验研究.结果表明,新型墙体材料节能降耗指标均优于传统粘土实心砖,其中粉煤灰蒸压加气混凝土砌块相对较好.     

CFG桩复合地基桩身材料性能研究

通过对大掺量IIIa级粉煤灰混凝土构成的CFG桩身材料进行力学性能方面的室内试验,讨论了抗压强度与材料配合比、龄期之间的关系,并探讨了桩身材料性能对CFG桩承载力的影响.结果显示抗压强度均随着胶凝效率的增大而减小,粉煤灰替代水泥率超过40%后抗压强度仍能满足设计要求,随着龄期的增长,每一类型、一定胶凝效率试件的抗压强度都有显著提高.