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掺和钢炉渣的新型混合水泥土强度特性试验研究
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作者 王丽艳 符仁建 +1 位作者 胡霖森 杜晓雷 《施工技术》 CAS 北大核心 2014年第17期97-101,122,共6页
掺和废弃钢炉渣的混合土是一种新混合填土路基材料,在常规不固结不排水三轴压缩试验基础上研究了混合轻质黏土的强度特性,分析了钢炉渣掺入比以及龄期分别对应力应变特性、破坏形式及抗剪强度的影响规律,得出了应力应变特性、破坏形式... 掺和废弃钢炉渣的混合土是一种新混合填土路基材料,在常规不固结不排水三轴压缩试验基础上研究了混合轻质黏土的强度特性,分析了钢炉渣掺入比以及龄期分别对应力应变特性、破坏形式及抗剪强度的影响规律,得出了应力应变特性、破坏形式及抗剪强度随钢炉渣掺入比以及龄期变化的规律是基本一致的,钢炉渣掺入比越大,混合水泥土的早期强度越低,但随着龄期的增长,后期强度增长越明显,研究得出的混合水泥土理想的钢炉渣施工掺入比在能源节约、环境保护方面可以有一定的应用前景。 展开更多
关键词 公路工程 路基 混合水泥土 应力 应变
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不同水泥土混合桩周围土体的扰动与强度恢复 被引量:8
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作者 沈水龙 唐翠萍 庞晓明 《岩土力学》 EI CAS CSCD 北大核心 2006年第10期1827-1830,共4页
针对由深层搅拌法或高压旋喷法施工的水泥土混合桩周围土体的扰动与强度恢复的问题,采用两种常用的施工法:高压旋喷混合法(简称旋喷法)和水泥浆搅拌混合法(简称湿法),在日本有明黏土中施工以观测周围土体力学特性的变化。测试结果表明,... 针对由深层搅拌法或高压旋喷法施工的水泥土混合桩周围土体的扰动与强度恢复的问题,采用两种常用的施工法:高压旋喷混合法(简称旋喷法)和水泥浆搅拌混合法(简称湿法),在日本有明黏土中施工以观测周围土体力学特性的变化。测试结果表明,水泥土混合桩周围土体的扰动程度与其施工方法有关;两种不同施工方法施工后周围土体的当日强度与原状土的强度之比分别是0.42(旋喷法)和0.68(湿法),施工30d后,旋喷法有44%,湿法有40%的初始强度得到恢复。结果亦表明周围土体模量恢复要慢于强度恢复的速度。 展开更多
关键词 泥土混合 高压旋喷法 泥浆搅拌法 力学性质变化
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Influence of ultra-fine fly ash on hydration shrinkage of cement paste 被引量:15
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作者 高英力 周士琼 《Journal of Central South University of Technology》 EI 2005年第5期596-600,共5页
Hydration shrinkage generated by cement hydration is the cause of autogenous shrinkage of high strength concrete. It may result in the volume change and even cracking of mortar and concrete. According to the data anal... Hydration shrinkage generated by cement hydration is the cause of autogenous shrinkage of high strength concrete. It may result in the volume change and even cracking of mortar and concrete. According to the data analysis in a series of experimental studies, the influence of ultra-fine fly ash on the hydration shrinkage of composite cementitious materials was investigated. It is found that ultra-fine fly ash can reduce the hydration shrinkage of cement paste effectively, and the more the ultra-fine fly ash, the less the hydration shrinkage. Compared with cement paste without the ultra-fine fly ash, the shrinkage ratio of cement paste reduces from 23.4% to 39.7% when the ultra-fine fly ash replaces cement from 20% to 50%. Moreover, the microscopic mechanism of the ultra-fine fly ash restraining the hydration shrinkage was also studied by scanning electron microscopy, X-ray diffraction and hydrated equations. The results show that the hydration shrinkage can be restrained to a certain degree because the ultra-fine fly ash does not participate in the hydration at the early stage and the secondary hydration products are different at the later stage. 展开更多
关键词 ultra-fine fly ash cement paste hydration shrinkage MECHANISM
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土质因素对TRD防渗墙工作性能影响的机理分析 被引量:1
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作者 邢政华 顾海荣 +3 位作者 刘东华 芮凯军 张鹏 李俊才 《山西建筑》 2018年第36期61-62,共2页
TRD工法是一种新型水泥土防渗墙施工工艺,广泛用于大坝围堰、库岸堤坝和地下工程的止水帷幕结构。TRD工法是将各地层的土体混合后与水泥浆搅拌形成等厚连续的混合土质水泥土地下连续墙,所以不同地层土质混合差异对其水泥土防渗墙的工作... TRD工法是一种新型水泥土防渗墙施工工艺,广泛用于大坝围堰、库岸堤坝和地下工程的止水帷幕结构。TRD工法是将各地层的土体混合后与水泥浆搅拌形成等厚连续的混合土质水泥土地下连续墙,所以不同地层土质混合差异对其水泥土防渗墙的工作性能具有明显差别。系统研究水泥混合土土的渗透系数,讨论土质因素对水泥混合土工程性能的影响。研究表明混合土质水泥土的防渗性能受混合土质中渗透性强的土质含量占比所控制。上述研究对判断不同地层条件的TRD工法防渗效果与工作性能具有一定的参考意义。 展开更多
关键词 TRD工法 混合土质泥土 渗透系数
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Utilization of Concrete Waste Aggregates Using Geopolymer Cement 被引量:1
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作者 Sotya Astutiningsih Henki Wibowo Ashadi +2 位作者 Hendra Widhatra Kresnadya Desha Rousstia Maria Elizabeth Suryatriyastuti 《Journal of Civil Engineering and Architecture》 2010年第6期11-15,共5页
Reuse of concrete waste, especially in large quantity, can save not only material but also cost for its disposal. This paper presents experiment results on the use of fine and coarse aggregates from concrete waste in ... Reuse of concrete waste, especially in large quantity, can save not only material but also cost for its disposal. This paper presents experiment results on the use of fine and coarse aggregates from concrete waste in geopolymer mortars and concretes. Geopolymeric cement is an inorganic compounds of aluminosilicates synthesized from precursors with high content of silica and alumina activated by alkali silicate solutions. Geopolymer in this experiment was synthesized from fly ash as the precursor and sodium silicate solution as the activator. Hardening of geopolymers was performed by heating the casted paste in an oven at -60~Cfor 3 to 36 hours. Compressive strength of geopolymer pastes and mortars using either fresh or waste fine aggregates were in the range of 19-26 MPa. Hardening time of 3 hours at 60~C followed by leaving the test pieces at room temperature for 7 day before testing results in similar strength to that of mortars cured for 36 hours at 60~C followed by leaving the samples at room temperature for 3 days. It suggests that optimum strength can be achieved by combination of heating time and rest period before testing, i.e the specimens age. Applying mix design with a target strength of 40 MPa, conventional Portland cement concretes using fresh aggregates reached 70% of its target strength at day-7. Compressive strength of geopolymer concretes with waste aggregates was -25 MPa at day-3 while geopolymer concretes with fresh aggregates achieved -39 MPa at day-3. It can be concluded that geopolymer concretes can achieve the target strength in only 3 days. However, the expected reinforcing effect of coarse aggregates in concrete was ineffective if waste coarse aggregates were used as the strength of the concretes did not increase significantly from that of the mortars. On the other hand, waste fine aggregates can be reused for making geopolymer mortars having the same strength as the geopolymer mortars using fresh aggregates. 展开更多
关键词 GEOPOLYMER concrete waste aggregates MORTAR CONCRETE compressive strength.
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Seismic behaviors of steel reinforced ECC/RC composite columns under low-cyclic loading 被引量:8
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作者 Pan Jinlong Mo Chuang +1 位作者 Xu Li Chen Junhan 《Journal of Southeast University(English Edition)》 EI CAS 2017年第1期70-78,共9页
To improve the seismic performance of columns, engineered cementitious composite (ECC) is introduced to partially substitute concrete at the base of the columns to form ECC,/reinforced concrete ( RC) composite col... To improve the seismic performance of columns, engineered cementitious composite (ECC) is introduced to partially substitute concrete at the base of the columns to form ECC,/reinforced concrete ( RC) composite columns. The mechanical behaviors of the ECC/RC composite columns are numerically studied under low-cyclic loading with the finite element analysis softwareof MSC. MARC. It is found that the ECC/RC composite columns can significantly enhance the load capacity, the ductility ad energy dissipation of columns. Then, the effects of the height of the ECC, the axial compression ratio and the longitudinal reinforcement ratio on the seismic behaviors of the composite columns are parametrically studied. The results show that the ECC/RC composite column with a height of the ECC layer of 0. Sh(h is the height to the cross-section) can achieve similar seismic performance of a full ECC column. The peak load of the composite column increases significantly while the ductility decreases with the increase of the axial compression ratio. Increasing the longitudinal reinforcement ratio within a certain range can improve the ductility and energy dissipation capacity and almost has no effect on load capacity. The aalysis results ae instructive and valuable for reference in designing ECC structures. 展开更多
关键词 engineered cementitious composites ECC) ECC/RC composite columns hysteretic curves DUCTILITY energy dissipation parametric analysis
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Experimental study on improving collapsible loess with cement 被引量:2
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作者 SHAN Bo WANG Changming +3 位作者 DONG Quanyang TANG Ling ZHANG Guangyi WEI Jiaming 《Global Geology》 2010年第2期79-84,共6页
The collapsibility of loess ground can directly affect stability of subgrade. Therefore, how to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation ... The collapsibility of loess ground can directly affect stability of subgrade. Therefore, how to adopt practical technical measures to reduce or eliminate its collapse deformation is an important content in foundation design in collapsible loess zone. Selecting collapsible loess from Fuxin-Chaoyang highway in Liaoning, the authors conducted a series of tests for improving loess with cement. The loess in different water content was mixed with the cement in varying proportions, unconfined compression strength for the samples at four different curing periods were tested, and the relationships of improved soil strength among cement mixture ratio and curing periods were analyzed. When the curing periods are certain, the strength of loess increases along with the mixture ratio increases; when the cement mixture ratio is 5%-15%, the scope of increases is quite obvious; when the mixture ratio is greater than 15%, the tendency of intensity increases turns slow. When the mixture ratio for the specimen is certain, the intensity of the test specimen increases along with the curing period increases, the intensity grows obviously in 28 days, and the growth rate is small in 28-90 days, the intensity tends to be steady in the curing period of 90 days. 展开更多
关键词 collapsible loess CEMENT unconfined compression strength
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Flexural response of reinforced concrete beams strengthened with post-poured ultra high toughness cementitious composites layer 被引量:6
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作者 王楠 徐世烺 《Journal of Central South University》 SCIE EI CAS 2011年第3期932-939,共8页
Four-point bending tests were conducted up to failure on eleven reinforced concrete (RC) beams and strengthening beams to study the effectiveness of externally pouring ultra high toughness cementitious composites (UHT... Four-point bending tests were conducted up to failure on eleven reinforced concrete (RC) beams and strengthening beams to study the effectiveness of externally pouring ultra high toughness cementitious composites (UHTCC) on improving the flexural behavior of existing RC beams.The strengthening materials included UHTCC and high strength grade concrete.The parameters,such as thickness and length of strengthening layer and reinforcement in post-poured layer,were analyzed.The flexural behavior,failure mode and crack propagation of composite beams were investigated.The test results show that the strengthening layer improves the cracking and ultimate load by increasing the cross section area.Introducing UHTCC material into strengthening not only improves the bearing capacity of the original specimens,but also disperses larger cracks in upper concrete into multiple tightly-spaced fine cracks,thus prolonging the appearance of harm surface cracks and increasing the durability of existing structures.Compared with post-poured concrete,UHTCC is more suitable for working together with reinforcement.The load?deflection plots obtained from three-dimensional finite-element model (FEM) analyses are compared with those obtained from the experimental results,and show close correlation. 展开更多
关键词 ultra high toughness cementitious composities strengthening beams flexural behavior post-poured layer
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Experimental Study of Concrete Column Shape Modification Using Fiber Reinforced Polymer Composite Shells and Expansive Cement Concrete
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作者 Zihan Yan Chris P. Pantelides 《Journal of Civil Engineering and Architecture》 2010年第2期1-7,共7页
Fiber Reinforced Polymer (FRP) composites are an effective material for strengthening circular concrete columns. The effectiveness of FRP confinement for square and rectangular columns is greatly reduced due to stre... Fiber Reinforced Polymer (FRP) composites are an effective material for strengthening circular concrete columns. The effectiveness of FRP confinement for square and rectangular columns is greatly reduced due to stress concentrations at the sharp comers and loss of the membrane effect at the fiat sides of the cross-section. Shape modification can eliminate the effects of column comers and flat sides, and thereby restore the membrane effect and improve the compressive behavior of FRP-confined square and rectangular concrete columns. Shape modification using chemical post-tensioning, achieved by using expansive cement concrete, is described and several mix designs for obtaining the optimal level of expansion are presented. In addition, parametric studies regarding the optimal geometry of the shape-modified cross-section are presented utilizing the analytical model. 展开更多
关键词 Chemical post-tensioning concrete columns CONFINEMENT expansive cement concrete fiber reinforced polymers post tensioning stress strain relations.
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Concrete Based on Fly Ash Alumosilicate Polymers
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作者 R. Sulc T. Strnad +4 位作者 F. Skvara P. Svoboda Z. Bittnar V. Smilauer L. Kopecky 《Journal of Environmental Science and Engineering》 2011年第6期728-735,共8页
Concretes on the basis of the alumosilicate polymer can be prepared by alkali activation (NaOH, sodium water glass) of waste brown coal fly ash. The preparation is possible: (1) by using a short-term heating of t... Concretes on the basis of the alumosilicate polymer can be prepared by alkali activation (NaOH, sodium water glass) of waste brown coal fly ash. The preparation is possible: (1) by using a short-term heating of the concrete mix (to 80 ℃); or (2) by allowing the mix to harden spontaneously at a temperature of 20 ℃. The concretes prepared by short-time heating attain high strength values after their preparation; the values are comparable to those characterizing concretes obtained on the basis of Portland cement. The strength development of concretes hardening at 20 ℃ is substantially less steep but, nevertheless, the strength attained after about 60 days is practically identical with that of the concretes exposed to a short-time heating. The shrinkage of concretes prepared by short-time heating is very small as compared with the concretes allowed to harden spontaneously; the shrinkage of latter concretes is larger than that of the concretes on the basis of Portland cement. The concretes on the basis of alumosilicate polymer exhibit much better resistance to the corrosive action of the environment as compared with those prepared on the basis of Portland cement. 展开更多
关键词 Alumosilicate polymer GEOPOLYMER CONCRETE fly ash
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Experimental Study on the Use of Trass as a Supplementary Cementitious Material in Pervious Concrete
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作者 Alireza Joshaghani Alireza Moazenian Richard Abubakar Shuaibu 《Journal of Environmental Science and Engineering(A)》 2017年第1期39-52,共14页
Abstract: The purpose of this paper is to evaluate the suitability of using trass as a supplementary cementing material in pervious concrete. OPC (Ordinary Portland Cement) was replaced in the concrete mix by 15%, ... Abstract: The purpose of this paper is to evaluate the suitability of using trass as a supplementary cementing material in pervious concrete. OPC (Ordinary Portland Cement) was replaced in the concrete mix by 15%, 25% and 35% weight percentages and the results were compared with reference mixtures with 100% Portland cement. The variables in this study were trass content, aggregate size and water to cement ratio. Sixteen eases of concrete mixtures were tested to study physical and mechanical properties of hardened concrete, including porosity, permeability, compressive strength, splitting-tensile strength and flexural strength at various ages. Results indicated that mechanical properties of the pervious concrete marginally decreased with the increased content of trass when compared to the reference mixtures. However, at later ages the differences were insignificant. 展开更多
关键词 Pervious concrete TRASS supplementary cementitious material PERMEABILITY STRENGTH natural pozzolans.
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Analysis of Harnessing Waste Fine Aggregate for Sustainable Production of Concrete Elements
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作者 Jacek Katzer Janusz Kobaka 《Journal of Civil Engineering and Architecture》 2010年第7期42-48,共7页
This paper focuses on cement composites based on waste fine aggregate obtained from hydroclassification all-in-aggregate in the Central Pomerania region in northern Poland. In the world there are regions with poor sup... This paper focuses on cement composites based on waste fine aggregate obtained from hydroclassification all-in-aggregate in the Central Pomerania region in northern Poland. In the world there are regions with poor supplies of coarse aggregate, which is one of the most essential raw materials used for production of ordinary concrete. In these regions, instead of coarse aggregate, there are often very large deposits of fine aggregate such as natural sand and fine all-in-aggregate. These raw materials may be used for concrete production of standard mechanical properties. Manufacturing concrete based on locally available fine aggregate is inexpensive which encourages the local production of fine aggregate cement composites instead of ordinary concrete, requiring gravel transported from distant places. 展开更多
关键词 AGGREGATE fine aggregate waste aggregate cement composite
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Numerical study on flexural behaviors of steel reinforced engineered cementitious composite(ECC) and ECC/concrete composite beams 被引量:13
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作者 YUAN Fang PAN JinLong WU YuFei 《Science China(Technological Sciences)》 SCIE EI CAS 2014年第3期637-645,共9页
Engineered cementitious composite(ECC)is a class of high performance cementitious composites with pseudo strain-hardening behavior and excellent crack control capacity.Substitution of concrete with ECC can largely red... Engineered cementitious composite(ECC)is a class of high performance cementitious composites with pseudo strain-hardening behavior and excellent crack control capacity.Substitution of concrete with ECC can largely reduce the cracking and durability problems associated with brittleness of concrete.In this paper,a simplified constitutive model of the ECC material was applied to simulate the flexural behaviors of the steel reinforced ECC and ECC/concrete composite beams with finite element method.The simulation results are found to be in good agreement with test results,indicating that the finite element model is reasonably accurate in simulating the flexural behaviors of the steel reinforced ECC flexural members.The effects of the ECC modulus,ECC tensile ductility,ECC thickness and ECC position on flexural behaviors in terms of ultimate moment,deflection and the maximum crack width of the steel reinforced ECC or ECC/concrete composite beam are hence evaluated. 展开更多
关键词 engineered cementitious composite(ECC) constitutive model flexural behavior finite element
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Properties prediction of fly ash blended concrete using hydration model 被引量:1
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作者 WANG XiaoYong 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第9期2317-2325,共9页
Fly ash is an industrial by-product from coal combustion and has been widely used as mineral admixture in normal and high strength concretes. Owing to the pozzolanic reaction between calcium hydroxide and fly ash, com... Fly ash is an industrial by-product from coal combustion and has been widely used as mineral admixture in normal and high strength concretes. Owing to the pozzolanic reaction between calcium hydroxide and fly ash, compared with Portland cement, the hydration of concrete containing fly ash is much more complex. In this paper, by considering the production of calcium hydroxide in cement hydration and its consumption in the pozzolanic reaction, a numerical model is proposed to simulate the hydration of concrete containing fly ash. Similar to the hydration reaction of cement, fly ash activity is divided into three processes: an initial dormant period, a phase-boundary reaction process and a diffusion process. The mutual interactions between the cement hydration and fly ash reaction are considered through the available calcium hydroxide amount and available capillary water amount in the system. The properties of hardening fly ash blended concrete, such as the reaction degree of fly ash, chemically bound water, calcium hydroxide, and compressive strength, are determined from the contributions of cement hydration and fly ash pozzolanic reaction. The evaluated results show good accordance with the experimental results. 展开更多
关键词 CEMENT fly ash HYDRATION MODEL
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