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1.
考察了水泥组成对水泥胶砂流动度经时损失的影响.实验结果表明,水化初期水泥浆体中迅速析出钙矾石,是胶砂流动度损失的主要原因.在不改变熟料的条件下,通过调整水泥组成,可以有效地改善水泥胶砂流动度经时损失.  相似文献   

2.
本文从水泥、粉煤炭、高效减水剂的作用机理出发,对该体系进行了相容性研究,提出用饱和点、流动度的经时损失和胶砂强度三个指标来检测和评价水泥、粉煤灰、高效减水剂的相容性问题.  相似文献   

3.
将尾矿砂以不同比例代替天然砂,研究其对水泥胶砂性能的影响。试验结果表明,尾矿砂的掺入能够满足水泥胶砂流动度和强度的要求,与天然砂相比,掺加尾矿砂可以提高水泥胶砂的流动度,并使水泥胶砂3d抗折强度和抗压强度略有降低,但可以提高水泥胶砂28d抗折强度和抗压强度。  相似文献   

4.
通过制备氧化石墨烯(GO)水泥胶砂,研究了GO对水泥胶砂流动度以及力学性能的影响。结果表明:水泥胶砂流动度随着GO掺量的增大而减小;每增加0.01%的GO需要增加0.1%的聚羧酸高性能减水剂(PC)以保持水泥胶砂流动度在210±10 mm范围内;当GO/PC掺量为0.02%/0.17%时,对水泥胶砂抗折强度、抗压强度的提升效果最好,最大提升率分别为15.9%、13.7%;GO对水泥胶砂抗折强度的提升比抗压强度大,并且对水泥胶砂早期力学性能的提升更显著。  相似文献   

5.
实验结果表明,少量CaCl_2将增大硅酸盐水泥浆体的流动度经时损失。由于CaCl_2降低二水石膏在Ca(OH)_2饱和溶液中的溶解速度并增大其溶解度,使早期硅酸盐水泥浆体的液相组成发生了变化,浆体中水化产物生成量增加,自由水减少,从而导致浆体流动度经时损失增大。  相似文献   

6.
实验结果表明,少量CaCl2将增大硅酸盐水泥浆体的流动度经时损失.由于CaCl2降低二水石膏在Ca(OH)2饱和溶液中的溶解速度并增大其溶解度,使早期硅酸盐水泥浆体的液相组成发生了变化,浆体中水化产物生成量增加,自由水减少,从而导致浆体流动度经时损失增大.  相似文献   

7.
梁建华 《科技资讯》2011,(22):249-249,251
在总掺量一定的情况下,就萘系高效减水剂与缓凝剂葡萄糖酸钠的复合后对水泥净浆流动度、流动度经时损失等性能的影响作用进行了试验分析,结果表明不同掺量的缓凝组分的相容性不同,复合效应也存在差别。  相似文献   

8.
颗粒分布对水泥与减水剂相容性的影响   总被引:1,自引:0,他引:1  
采用Marsh筒法与净浆流动度法研究了相同熟料制备的不同颗粒分布的水泥样品与减水剂的相容性,揭示了粉体比表面积、均匀性系数(n)、特征粒径(x′)、堆积孔隙率与相容性的关系。结果表明:样品比表面积越大, n越大,x′越小,堆积空隙率越大,水泥与减水剂的相容性越差。当比表面积与x′ 相近时,n越大,浆体的流动性越差,饱和点掺量越大或饱和点Marsh时间越长,流动度经时损失越小。随着样品比表面积增大,饱和点掺量增大,流动度减小,流动度经时损失增大,与减水剂相容性变差,且对于n越大的样品,比表面积增大对相容性的不利影响越显著。凡是能降低堆积空隙率,使水泥颗粒分布连续而较宽,且自身需水性较低的微细粉体,均有利于改善水泥与减水剂的相容性。  相似文献   

9.
氨基磺酸系高效减水剂(简称AH)与目前广泛使用的萘系高效减水剂(FDN)相比,具有更加优异的性能。表现为:在掺量很少的情况下,水泥净浆就具有较高的流动度,当掺量相同时,其对水泥净浆流动度远超FDN。此外,它还具有明显抑制水泥净浆流动度经时损失的性能,是一种缓凝型的高效减水剂,与水泥的相容性好,对混凝土也能表现出显著的减...  相似文献   

10.
浆液流动性指标试验方法对不同性质浆液的适用性存在差异,多种流动性指标与试验方法的组合运用能够准确、合理地反映浆液的经时变化。通过稠度试验、孔道压浆流动度试验和胶砂流动度试验,对常规快硬型单液活性浆液的流动性指标进行了对比试验量测,探讨了不同的试验方法对浆液流动性的适用性和合理性,分析了浆液流动性的经时变化,提出了浆液流动性指标的控制范围,为盾构同步注浆施工提供参考。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

13.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

14.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。  相似文献   

18.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

19.
20.
The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to  相似文献   

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