磷石膏改性二灰稳定磷渣基层材料的研究

磷渣不宜用水泥或石灰单独进行稳定 ,用石灰粉煤灰稳定磷渣 ,能获得较高的强度 ,其 7d强度满足高速以及一级公路二灰稳定类基层强度要求。掺加 6 %的磷石膏 ,能够提高石灰粉煤灰稳定磷渣的强度。SEM观察发现 ,磷渣表面有明显的反应 ,这一点有利于材料强度的形成     

Relationships between modified methylene blue value of microfines in manufactured sand and concrete properties

To better understand and assess the effect of microfines on concrete properties, the synergetic effect of methylene blue value and content of microfines on properties of low and high strength concrete was studied and then the relationships between the index of modified methylene blue value (MMBV) and concrete properties were investigated. The results show that relationships between MMBV and fresh and hardened properties of concrete can be fully established, and the correlation between MMBV and C60 concrete property is higher than the correlation between MMBV and C30 concrete. With the increase of MMBV, concrete workability and frost resistance decrease while drying shrinkage decreases; however, compressive strength and chloride-ion penetration resistance of C30 concrete have not been negatively affected whereas those of C60 concrete are significantly deteriorated when MMBV exceeds 100. To make use of microfines without remarkably damaging concrete quality, it is suggested that MMBV of microfines in MS used in C30 and C60 concrete be no more than 100.     

Leaching behavior and mechanism of cement solidified heavy metal Pb in acid medium

The relationship between Pb leaching concentration and the solution’s pH with time was analyzed when cement in its solidified form was leached in an acid medium. The effects of the particle size of the solidified form, the cement adding method, and the hydration degree on Pb solidification were also investigated. The experimental results indicate that cement is quickly dissolved and hydrated in the acid medium, forming a C-S-H gel or silicic acid sol with good adsorption. When cement-Pb solidified form is leached in an acetate solution, the hydrated product erodes with time, so the Pb concentration increases slightly in the beginning. Then, some of the Pb ions are absorbed by the newly generated silicic acid sol, C-S-H. Others produce Pb(OH)₂ precipitation for secondary solidification, leading to a gradual decrease in the Pb concentration in a leaching time of more than two hours. Moreover, the particle size of the solidified form has important effects on the Pb dissolution. When the amount of added cement is low, with a pH of less than 9.5, the solidification affects the sequence of the original cement powder, the cement hydrated powder, and the cement-Pb solidified form. When the added amount of cement increases with a pH of more than 11, the effect of adding methods on solidification decreases, and the solidified form is a little better than others.     

水泥粉煤灰稳定碎石基层在赤通高速公路中的应用

通过对水泥粉煤灰稳定碎石路面基层材料试验表明:粉煤灰的最佳掺量10%为宜;工程应用证明水泥粉煤灰稳定碎石是一种具备优良路用性能和推广前景的基层材料.     

补偿收缩混凝土的应用与研究

中国工程院院士、著名建筑环境专家、清华大学教授江亿不久前接受了《经济日报》记者的专访，就我国建筑节能发展潜力及相关问题回答了记者的提问，现摘编如下，已飨读者。     

改性生石灰稳定磷渣路面基层材料研究

对改性生石灰稳定磷渣路面基层材料进行了试验研究。研究结果表明:改性生石灰适宜用于磷渣稳定;原材料对混合料的早、后期强度影响较小;粉煤灰掺量为30%时,混合料7d强度可达1.39MPa,满足高速以及一级公路石灰粉煤灰稳定类基层材料的强度要求。     

聚丙烯纤维混凝土在桥面铺装中的应用与施工

针对巴东长江大桥桥面铺装层的设计要求,80mm厚C40防水混凝土,进行了微膨胀聚丙烯纤维混凝土的配合比设计、性能试验和桥面铺装施工措施研究。结果显示,采用UEA-I膨胀剂补偿收缩和聚丙烯纤维增强的混凝土,具有优良的抗裂、抗渗、耐磨、抗冲击、抗疲劳等性能。通过在巴东长江大桥桥面铺装层中进行全面施工应用,效果十分理想。     

机制砂中石粉对不同强度等级混凝土性能的影响研究

机制砂生产中不可避免地产生一定数量的粒径小于75 μm的石粉颗粒.针对国家标准GB/T 14684-2001<建筑用砂>对强度等级低于C30、C30-C60、高于C60的混凝土用机制砂石粉含量限值分别为7%、5%、3%的规定,试验研究了超过国标规定上限的石粉含量分别对C30、C60、C80机制砂混凝土工作性、强度、干缩及氯离子扩散系数、抗冻等性能的影响,据此提出了混凝土用机制砂石粉含量限值可以进一步放宽的建议.     

工业固体废弃物胶凝材料水化热力学研究

根据工业固体废弃物的特性将其分为6类,又根据6类工业固体废弃物之间以及固体废弃物与人造胶凝材料(水泥熟料、石灰、石膏)之间的有效组配形式将工业固体废弃物胶凝材料分为6种不同的胶凝材料体系.列出各体系可能的水化反应形式,并通过收集文献中的各物质的热力学常数计算了相应反应的热力学参数,分析了工业固体废弃物胶凝材料的水化过程的反应推动力,以及各种水化最终产物及其稳定性,探讨了工业固体废弃物的活性及改善途径.     

饱水轻集料内养护对高性能混凝土收缩的影响

混凝土内养护可以明显改善高性能混凝土自收缩,阐述了饱水轻集料内养护的作用机理,研究了饱水轻集料取代粗骨料对混凝土收缩的影响,试验结果表明:10%、30%、50%等体积取代粗骨料,有效降低混凝土自收缩和干缩, 1 d自收缩分别降低了12.5%、35%和65%,28 d自收缩分别降低了9%、29%和49%;混凝土干缩降低幅度随轻集料取代率的增加而增加,50%等体积取代时,1 d、3 d、7 d、14 d和28 d干缩分别降低了21%、26%、25%、26%和24%.