Improved hydration resistance of CaO granules via sol-processed metal oxide protective layers

Well-sintered CaO granules with hydration resistance are very important for the manufacturing and application of CaO-containing refractories. CaO granules with sol-processed metal oxide protective layers were prepared by granulation and surface treatment. The obtained results indicated that the usage of nano sol greatly improved the hydration resistance of CaO granules, especially when the CaO granules were treated by alumina sol. The promoting effect of nano sols in the sintering processes improved the density of CaO granules. Nanoparticles reacted with lime at lower temperature and a new phase was formed uniformly in the treated layer, which promoted densification of the treated layer. The grain size of CaO granules in the treated layer was increased obviously with the promotion of sintering. Moreover, nanoparticles were favorable for the formation of direct bonding between CaO grains by decreasing the dihedral angle.     

Gas chromatographic thermodynamics on hydration processes of magnesium chloride with low water

1　INTRODUCTIONMagnesiumchlorideisabasicmaterialforchem icalindustry ,andithaswideapplicationsinmetallur gy,architecturalmaterialandtextileindustry .Itisalsoamaterialforfire resistantproducts ,cryogenandcompoundfertilizerproductions[1] .Thefullydehy dratedmagnesiumchlorideisagoodmaterialforelec trolyticmetalmagnesium production .Becausemag nesiumchloridehasastrongadsorptiveability ,itisalsousedasadryingagent .Manysuccessfulworkshavebeendoneonthedehydrationofbischophite[2 10 ] .Butinfact,…     

Effects of molecular structure of polycarboxylate-type superplasticizer on the hydration properties of C3S

Effects of polycarboxylate-type superplasticizer(PC) molecular structure on the hydration heat of tricalcium silicate(C3S) paste and polymerization degree of hydration products(C-S-H gel) were researched by using TAM AIR isothermal microcalorimetry(TA) and 29Si nuclear magnetic resonance(NMR).Methoxy polyethylene glycol-methacrylates-based polycarboxylate superplasticizers with different side chain lengths and main chain lengths were employed.PC molecules with shorter main chain or longer side chains caused stronger retardation of C3S early hydration and lesser increase of C3S 3 d hydration degree.NMR measurement indicated that the incorporation of PC increased the hydration degree of C3S paste and the polymerization degree of silicon-oxygen tetrahedron of C-S-H gel.The tendency for C3S 7 d hydration degree to improve was more pronounced while PC molecules with longer main chain or shorter side chain were added.Whereas,PC molecules with longer main chains or longer side chains increased the 7 d polymerization degree of C-S-H gel.     

混合梁斜拉桥主梁大体积混凝土关键技术

九江长江公路大桥为主跨818 m的混合梁斜拉桥,是国内最大的整体式混凝土箱梁断面混合梁斜拉桥,混凝土箱梁采用顶底板带有小次梁的整体式单箱三室结构.介绍主梁设计及主梁大体积混凝土设计优化措施,详细分析混凝土施工和水化热控制过程.     

The influence of oleic acid on the hydration and mechanical properties of portland cement

To investigate the effects of OA on the portland cement using oleic acid （OA） as grinding aid and the effects of OA on the portland cement, we characterized the different perfermances of the cement, discussed the characteristics of properties. The results reveal that the OA can reduce the water requirement of normal consistency. With the content of OA added, setting time was extended. The OA can significantly improve the rheological properties of cement-based materials, while the compressive strength decreases.     

环己烯水合生产环己醇工艺条件优化

从有机化工反应热力学和动力学的角度研究分析了我公司环己烯水合反应生产环己醇的工艺条件，并初步讨论了该反应工艺的理论和实践间的影响与关系。     

WHDF增强密实(抗裂)剂对改进面板砼抗裂性能的影响

WHDF增强密实(抗裂)剂,是一种应用于面板堆石坝面板混凝土抗裂的高性能外加剂。笔者运用化学热力学和动力学等研究方法,从砼的微观结构着手,研究水泥水化机理,把水泥水化程度和水化产物与外加剂的抗裂作用机理结合起来研究,使得WHDF抗裂剂能促进水泥水化程度,优化水化产物和协同激发砼中活性混合材料与Ca(OH)2进行二次水化,从而提高砼中凝胶量,降低孔隙率,改善水泥石及其与骨料界面的结构,增强凝胶的粘结力,使砼具有良好的抗裂性能。湖北小溪口电站等近十个水电工程的面板混凝土掺用WHDF后,混凝土表面平滑光泽,均无收缩裂缝产生。     

粉煤灰混凝土绝热温升的试验研究

目的 研究不同粉煤灰的掺量和不同水肢比条件下粉煤灰混凝土的绝热温升和胶凝材料水化速率的发展规律．方法 利用混凝土绝热温升仪测试混凝土绝热温升．结果 在水胶比0．53条件下，混凝土的绝热温升值随着粉煤灰掺量的增加而下降；在水胶比0．25条件下。绝热温升值先随着粉煤灰掺量的增加而增大，当掺量达40％以后绝热温升值开始下降。混凝土中胶凝材料的水化速率峰值随粉煤灰掺量增加而下降．结论 粉煤灰混凝土的绝热温升受水胶比和粉煤灰掺量共同影响，低水胶比条件下只有适当增加粉煤灰的掺量才能降低粉煤灰混凝土的绝热温升；高水胶比条件下。粉煤灰混凝土的绝热温升随粉煤灰掺量增加而下降。     

Influence of ultra-fine fly ash on hydration shrinkage of cement paste

1INTRODUCTION Hydrationshrinkageisalsoknownaschemicalshrinkage[1].Thesolidvolumeincreasesafterce menthydrating,buttheabsolutevolumeofcementwatersystemreduces.Usuallythetotalamountofvolumeshrinkageofcementwatersystemis7%9%[1,2].Withthedevelopmentofthetechno logyofcementandconcrete,concretewithhighstrengthandhighperformanceisthedevelopingtendencynow.However,nowadays,comparedwithordinaryconcrete,thehydrationshrinkageofhighperformancecementconcreteincreasesobvi ouslybecauseoftheaccelerationof…     

Microstructure and Composition of Hydration Products of Ordinary Portland Cement with Ground Steel-making Slag

1　IntroductionSteel makingslagisthewasteofsteel makingindus tryandnearlysixteenmilliontonssteel makingslagisproducedinChinaperyear[1] .Justasflyashandblastfurnaceslag ,itisoneofthreekindsofdominantindustrywastesinourcountry .Eventhoughsteel makingslagce menthasdevelopedformorethantwentyyearsinCh ina[2 ,3 ] ,comparedwithothertwowastes ,thestudyandap plicationonsteel makingslagincementandconcreteareinsufficientyet.Moststeel makingslagcementsarepre paredbyinter grindingprocess ,sotheparticlesiz…