"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference"最新文献_第2页

Biogenic Sulphuric Acid Attack of Concrete Sewer Pipes: A Prediction of the Corrosion Rate 混凝土下水管道的生物硫酸侵蚀:腐蚀速率的预测

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10604

A. Beeldens, D. Gemert

{"title":"Biogenic Sulphuric Acid Attack of Concrete Sewer Pipes: A Prediction of the Corrosion Rate","authors":"A. Beeldens, D. Gemert","doi":"10.14359/10604","DOIUrl":"https://doi.org/10.14359/10604","url":null,"abstract":"Biogenic sulphuric acid corrosion is a phenomenon which occurs mainly in sewer pipes. The process consists of four stages: the reduction of sulphate to sulphide; the transition of sulphide to hydrogen sulphide gas in the sewer atmosphere; the re-oxidation of the sulphide gas to sulphuric acid in an oxidizing environment of the sewer pipe and finally concrete attack by sulphuric acid. Different models are developed to predict the sulphide formation and the corrosion rate. The model of Pomeroy, according to which the rate of sulphur production and the rate of corrosion can be calculated, is used in this paper. Different parameters are taken into account and case studies are described. Comparison of the calculated corrosion and the measured corrosion indicates the accuracy of the formula. In addition, a sensitivity study is carried out on the formulae to distinguish the influence of the different parameters. A realistic variation of the different parameters is made, based on measurements at the inlet of purification plants. The most influencing parameters for the model were the temperature, the BOD-content and the pH-value of the waste water, the depth of flow and the detention time.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125511752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

High Quality Recycled Aggregate Concrete (HiRAC) Processed by Decompression and Rapid Release 高质量再生骨料混凝土(HiRAC)的减压快速释放处理

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10597

H. Tamura, A. Nishio, J. Ohashi, K. Imamoto

{"title":"High Quality Recycled Aggregate Concrete (HiRAC) Processed by Decompression and Rapid Release","authors":"H. Tamura, A. Nishio, J. Ohashi, K. Imamoto","doi":"10.14359/10597","DOIUrl":"https://doi.org/10.14359/10597","url":null,"abstract":"Quality of concrete with recycled aggregate is generally lower than that of virgin aggregate. The main reason is that, recycled aggregate with its higher water absorption property has more porous mortar matrix around than that of the virgin aggregate and hence develops an inferior bond. In order to improve the quality of recycled aggregate concrete, an innovative method is proposed in this paper. High quality recycled aggregate concrete (HiRAC) can be obtained through a decompression and rapid release (DC-RR) procedure applied after normal mixing of concrete with recycled aggregate. Through the DC-RR procedure, the quality of transition zone between aggregate and cement matrix can be dramatically improved. In this paper, experimental studies are described on the effectiveness of DC-RR procedure on some of the mechanical and physical properties of recycled aggregate concrete. It was found that, by applying the DC-RR procedure, compressive strength of recycled aggregate concrete can be increased by about 20%; creep and carbonation depth can be reduced by about 20% and 30%, respectively.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123856541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 19

High-Strength Concrete Columns Under Biaxial Bending 双轴弯曲作用下高强混凝土柱

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10581

P. Sarker, S. Adolphus, S. Patterson, B. Rangan

引用次数: 7

Influence of the Nature and the Grading Curve of the Powder on the Rheology of Self-Compacting Concrete 粉料性质及级配曲线对自密实混凝土流变学的影响

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10591

A. Poppe, G. Schutter

引用次数: 7

Ettringite Formation and Sulfate Attack on Concrete 钙矾石的形成及硫酸盐对混凝土的侵蚀

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10569

M. Collepardi

{"title":"Ettringite Formation and Sulfate Attack on Concrete","authors":"M. Collepardi","doi":"10.14359/10569","DOIUrl":"https://doi.org/10.14359/10569","url":null,"abstract":"The paper presents a critical review of the relationship between ettringite formation and sulfate attack. Ettringite formation is associated with expansion. However, any ettringite-related expansion is not necessarily related to sulfate attack. Early ettringite formation (EEF) which occurs immediately (within hours) in a plastic fresh mixture does not produce any damaging expansion and is associated with the regulation of setting time of portland cement paste. Expansion after the hardening of cement paste can be advantageously used for development of chemical prestress in expansive cements. Delayed ettringite formation (DEF) occurs at late ages and the related heterogeneous expansion in a very rigid hardened concrete can produce cracking and spalling. Two different types of DEF are examined depending on the sulfate source: DEF caused by external sulfate attack (ESA) or internal sulfate attack (ISA). ESA, related to the interaction of environmental sulfate with the cement matrix, can be precluded by the use of impermeable concrete. On the other hand, ISA occurs in a sulfate-free environment due to the interaction of internal sulfate (from cement or gypsum contaminated aggregate) with calcium-aluminate hydrates of the cement paste. Two different mechanisms of DEF caused by ISA are examined. The first one is based on the thermal decomposition of ettringite in high-temperature cured concrete elements and the subsequent re-formation of ettringite at ambient temperature in a saturated atmosphere. According to the second mechanism ISA is based on a chain of three essential events (microcracking, late sulfate release, and exposure to water) and DEF could occur even at room temperature.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"56 9","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120892901","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 37

Innovative Methods for Water Content Control of Recycled Aggregate Concrete: Rapid Absorption Test for Aggregate and Continuous Monitoring of Freshly-Mixed Concrete at Site 再生骨料混凝土含水率控制的创新方法:骨料快速吸收试验和现场新拌混凝土的连续监测

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10614

H. Tamura, M. Arai, K. Imamoto

{"title":"Innovative Methods for Water Content Control of Recycled Aggregate Concrete: Rapid Absorption Test for Aggregate and Continuous Monitoring of Freshly-Mixed Concrete at Site","authors":"H. Tamura, M. Arai, K. Imamoto","doi":"10.14359/10614","DOIUrl":"https://doi.org/10.14359/10614","url":null,"abstract":"Recycled aggregate concrete was used as structural concrete at site under the strict quality control system especially on water content in concrete. Two innovative methods were applied for this project: one is the rapid test method for water absorption of aggregate, and the other is the continuous real-time monitoring of water content of freshly mixed concrete at site using a radio isotope (RI) moisture meter. With regard to the rapid test method for water absorption of aggregate, hot water and pressure were applied for the test. By the rapid method, test results could be obtained within two hours. This method is very useful in water content control of concrete produced at mixing plants, especially for concrete with recycled aggregate, water absorption of which generally fluctuates more than that of normal aggregate. As for the water content control using RI moisture meter, water content of freshly mixed concrete transported to the site was being continuously monitored during pumping by a meter attached to the transporting pipe of the concrete pump. Neutron radiation intensity measured varies with the water content of concrete. Every 120 seconds, measurements were used for running mean of water content. According to some experimental studies on this method, standard deviation of the water content of concrete is about 3 kg/m3. In this paper, outline of above-mentioned methods and their application at site are described.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123993076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Concentration Profile of Water-Soluble Chloride in 32 Year-Old Marine Concrete Piles 32年海工混凝土桩中水溶性氯离子浓度分布

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10573

C. Lim, K. Ong, K. H. Law, P. Paramasivam

{"title":"Concentration Profile of Water-Soluble Chloride in 32 Year-Old Marine Concrete Piles","authors":"C. Lim, K. Ong, K. H. Law, P. Paramasivam","doi":"10.14359/10573","DOIUrl":"https://doi.org/10.14359/10573","url":null,"abstract":"The alkaline nature of concrete made from normal portland cements provides a natural protection against corrosion of steel bars embedded as reinforcement. Presence of chloride in small quantities, depending on the Cl/OH ratio tends to destroy this passivity of steel reinforcement even at a pH considerably above 11.5. The present paper compares numerical predictions, using Fick's second law of diffusion, against concentration profile of water-soluble chloride obtained from the atmospheric, tidal and submerged zones of six 32 year-old marine piles extracted from a wharf in the Port of Singapore. Concentrations of water-soluble chloride at the level of steel reinforcement were compared with the loss in mass of the reinforcing bars. The concrete was sampled using the drill and suction method at locations spaced approximately 1m along the entire length of the extracted piles. The results show that the numerical estimates were in good agreement with the actual values of water-soluble chloride concentrations obtained under Singapore conditions. Diffusion parameters calculated were within the expected range for the grade of concrete used, 30 MPa cube strength. Locations where reinforcement corrosion were found corresponded to those that showed presence of water-soluble chloride in concentrations as low as 0.025% by mass of concrete occurring mainly in the atmospheric zone.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132160398","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Properties of Self-leveling Concrete: Influence of a Viscosity Agent and Cement Content 自流平混凝土性能:粘滞剂和水泥掺量的影响

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10589

J. Ambroise, J. Pera

引用次数: 2

Study on Durability of Anti-Washout Concrete Under Marine Environment 海洋环境下抗冲混凝土耐久性研究

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10603

S. Sakoda, Nobufumi Takeda, S. Sogo

{"title":"Study on Durability of Anti-Washout Concrete Under Marine Environment","authors":"S. Sakoda, Nobufumi Takeda, S. Sogo","doi":"10.14359/10603","DOIUrl":"https://doi.org/10.14359/10603","url":null,"abstract":"In recent years, structures made with anti-washout concrete under marine environment have been increasing. However, the durability of such structures is not yet clarified. Therefore, in order to understand the durability of reinforced concrete made with anti-washout concrete, exposure tests were carried out under a marine environment for ten years. The reinforced concrete specimens prepared with anti-washout concrete containing either silica fume or ternary low heat cement were exposed to marine atmosphere and underwater. Investigations were focused on the variation of concrete quality, concentration chloride ion and corrosion of reinforcement. From test results, the compressive strength of anti-washout concrete is similar to reference concrete in ordinary structures. The carbonation depth of the anti-washout concrete made without silica fume admixture is lower than that of reference concrete. At the distance of 2 cm from the surface of underwater cast concrete of the chloride ion concentration is sufficient to corrode the reinforcement of any concrete. After 10 years of exposure to marine environment, that of reference concrete is from 5 to 10 times that of anti-washout concrete. Therefore, the anti-washout concrete is durable under marine environment and it is possible to design for durability in the same way as for normal concrete.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131467240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Long-Term Deformations of High-Strength Concrete Containing Silica Fume and Metakaolin 含硅灰和偏高岭土高强混凝土的长期变形

"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference" Pub Date : 2001-06-01 DOI: 10.14359/10574

J. Brooks, M. Johari

引用次数: 3