This paper deals with trial testing on concrete reinforced by different combinations of carbon-steel, polypropylene-steel or steel-hybrid fibers in the low volume content range to ensure high electrical resistivity of the fiber concrete. Optimum reinforcement composition is obtained for (compression, splitting tension, and flexural) strength testing conditions and for post-peak behavior. The effect of various measures adopted to promote uniform fiber distribution are assessed by impedance measurements. During the testing program, fiber distribution is checked by microscopy and SEM.
{"title":"Properties of Carbon-Steel and Polypropylene-Steel Hybrid Fiber Concrete in Low-Volume Fraction Range","authors":"P. Stroeven, Z. Shui, C. Qian, Y. Cheng","doi":"10.14359/10611","DOIUrl":"https://doi.org/10.14359/10611","url":null,"abstract":"This paper deals with trial testing on concrete reinforced by different combinations of carbon-steel, polypropylene-steel or steel-hybrid fibers in the low volume content range to ensure high electrical resistivity of the fiber concrete. Optimum reinforcement composition is obtained for (compression, splitting tension, and flexural) strength testing conditions and for post-peak behavior. The effect of various measures adopted to promote uniform fiber distribution are assessed by impedance measurements. During the testing program, fiber distribution is checked by microscopy and SEM.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"72 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":"130519019","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}
Unlike circular columns, jacketing of oblong or wall-type columns produces only marginal improvement in strength and ductility because of inadequate confinement and premature debonding of the wrap. Some possible ways to overcome this problem, at least partially, are to round the corners, to add a semi-circular segment at each of its shorter sides or to produce an elliptical shape enclosing the oblong columns. A total of 13 specimens of these cross sectional shapes were tested in direct compression to assess the enhancement afforded by external fiber wraps. It has been found that the modification of a rectangular section by including a semi-circular segment on each of its shorter sides or transforming the section to an ellipse before applying fiber wrap leads to a substantial improvement in strength as well as ductility. Of the two fibers used, the glass fiber composite proved to be more cost effective in terms of strength and ductility enhancement.
{"title":"Strength and Ductility of Concrete Confined by External Wrap","authors":"S. Mandal, M. A. Mansur","doi":"10.14359/10609","DOIUrl":"https://doi.org/10.14359/10609","url":null,"abstract":"Unlike circular columns, jacketing of oblong or wall-type columns produces only marginal improvement in strength and ductility because of inadequate confinement and premature debonding of the wrap. Some possible ways to overcome this problem, at least partially, are to round the corners, to add a semi-circular segment at each of its shorter sides or to produce an elliptical shape enclosing the oblong columns. A total of 13 specimens of these cross sectional shapes were tested in direct compression to assess the enhancement afforded by external fiber wraps. It has been found that the modification of a rectangular section by including a semi-circular segment on each of its shorter sides or transforming the section to an ellipse before applying fiber wrap leads to a substantial improvement in strength as well as ductility. Of the two fibers used, the glass fiber composite proved to be more cost effective in terms of strength and ductility enhancement.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"26 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":"127853218","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}
This paper compares the structural performance of full-scale (300 x 300 x 3000 mm) columns cast using ordinary concrete and self-compacting (SCC) concretes with stirrup configurations representing different degrees of confinement. SCC and ordinary concretes having compressive strengths of 35 MPa (housing) and 60 MPa (civil engineering) were used to cast a total of eight columns. Two pairs of columns were cast using ordinary concrete and SCC. For each pair of the reinforced columns, one column was tested in uniaxial compression to determine its load carrying capacity, while the other one was used to take core samples to determine the distribution of in-situ compressive strengths along its height. The core results were compared to strengths determined on control cubes cured in standard conditions (water) and in air. In general, the in-situ compressive strengths or SCC were closer to standard cube strength than those of ordinary concrete. The distribution of in-situ properties was found to be more uniform in the case of SCC than that of the ordinary concrete. The compressive strength and the ductility of SCC and the ordinary concrete obtained from the 3-m column tests are also compared in this paper.
本文比较了采用普通混凝土和自密实(SCC)混凝土浇筑的全尺寸(300 x 300 x 3000 mm)柱的结构性能，箍筋配置代表不同程度的约束。采用抗压强度分别为35mpa(房屋)和60mpa(土木工程)的SCC混凝土和普通混凝土共浇筑8根柱。两对柱采用普通混凝土和SCC浇筑。对每一对配筋柱，一根柱进行单轴压缩试验，确定其承载能力，另一根柱进行岩心取样，确定原位抗压强度沿高度的分布。将核心结果与在标准条件下(水)和空气中固化的对照立方体的强度进行了比较。一般情况下，混凝土的原位抗压强度或SCC比普通混凝土更接近标准立方体强度。结果表明，与普通混凝土相比，SCC混凝土的原位性能分布更为均匀。本文还比较了混凝土的抗压强度和延性与普通混凝土的3米柱试验结果。
{"title":"Performance of Reinforced Columns Cast with Self-Compacting Concrete","authors":"M. Sonebi, P. Bartos","doi":"10.14359/10592","DOIUrl":"https://doi.org/10.14359/10592","url":null,"abstract":"This paper compares the structural performance of full-scale (300 x 300 x 3000 mm) columns cast using ordinary concrete and self-compacting (SCC) concretes with stirrup configurations representing different degrees of confinement. SCC and ordinary concretes having compressive strengths of 35 MPa (housing) and 60 MPa (civil engineering) were used to cast a total of eight columns. Two pairs of columns were cast using ordinary concrete and SCC. For each pair of the reinforced columns, one column was tested in uniaxial compression to determine its load carrying capacity, while the other one was used to take core samples to determine the distribution of in-situ compressive strengths along its height. The core results were compared to strengths determined on control cubes cured in standard conditions (water) and in air. In general, the in-situ compressive strengths or SCC were closer to standard cube strength than those of ordinary concrete. The distribution of in-situ properties was found to be more uniform in the case of SCC than that of the ordinary concrete. The compressive strength and the ductility of SCC and the ordinary concrete obtained from the 3-m column tests are also compared in this paper.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"26 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":"128866552","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}
Lightweight concrete with lower water absorption for thin structural elements was the goal of this investigation. Polypropylene fibers contributed to concrete ductility. For lower bulk density the authors used polystyrene grains. They used polymer modified concrete for realization of better adhesion between concrete and fiber. Polymer membranes cover the micro-fissures which may appear due to shrinkage, so polymer modified concrete has smaller water absorption. The influence of polypropylene fiber and cement quantity on concrete properties is investigated in this paper. Experimental work included several kinds of concrete, made with different cement contents, consistency, quantity of polypropylene fibers and with polymer latex, styrenebutadiene rubber modifier. River aggregate with grain size of up to 8 mm was used. The polymer portland cement concrete properties depend, not only on composition but also on the way of preparation, compacting and curing. Curing includes: 1 day in wet conditions, 6 days in the water followed by 21 days in the air. Compressive and splitting tensile strength and water absorption values are reported. It can be concluded that using polypropylene fibers has a better effect on splitting to compressive strength ratio for concrete with bulk density lower than 1800 kg/m3.
{"title":"Polymer Modified Concrete with Expanded Polystyrene Grains Reinforced with Polypropylene Fibers","authors":"K. Jankovic, L. Lončar","doi":"10.14359/10596","DOIUrl":"https://doi.org/10.14359/10596","url":null,"abstract":"Lightweight concrete with lower water absorption for thin structural elements was the goal of this investigation. Polypropylene fibers contributed to concrete ductility. For lower bulk density the authors used polystyrene grains. They used polymer modified concrete for realization of better adhesion between concrete and fiber. Polymer membranes cover the micro-fissures which may appear due to shrinkage, so polymer modified concrete has smaller water absorption. The influence of polypropylene fiber and cement quantity on concrete properties is investigated in this paper. Experimental work included several kinds of concrete, made with different cement contents, consistency, quantity of polypropylene fibers and with polymer latex, styrenebutadiene rubber modifier. River aggregate with grain size of up to 8 mm was used. The polymer portland cement concrete properties depend, not only on composition but also on the way of preparation, compacting and curing. Curing includes: 1 day in wet conditions, 6 days in the water followed by 21 days in the air. Compressive and splitting tensile strength and water absorption values are reported. It can be concluded that using polypropylene fibers has a better effect on splitting to compressive strength ratio for concrete with bulk density lower than 1800 kg/m3.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127093531","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}
Because of their low water/cement ratio, high-performance concretes have not only a high density but also a great tendency to chemical shrinkage deformation (autogenous shrinkage) as a result of "self desiccation". The autogenous shrinkage increases if silica fume is added. Theoretical calculations show that the usual addition of silica fume leads to an increase in total porosity, and hence to a deterioration of the packing density of the binder mixture, while at the same time raising the specific surface area of the dry powder. On the other hand, replacement of cement by optimized fine cements improves the theoretical packing density in the binder, even though with a lower increase in the specific surface area. Investigations carried out on hardened cement paste made from fine cements have shown that this leads not only to higher density but also to lower autogenous shrinkage values.
{"title":"High-Performance Binders with Reduced Autogenous Shrinkage on the Basis of Fine Cement","authors":"Martschuk","doi":"10.14359/10579","DOIUrl":"https://doi.org/10.14359/10579","url":null,"abstract":"Because of their low water/cement ratio, high-performance concretes have not only a high density but also a great tendency to chemical shrinkage deformation (autogenous shrinkage) as a result of \"self desiccation\". The autogenous shrinkage increases if silica fume is added. Theoretical calculations show that the usual addition of silica fume leads to an increase in total porosity, and hence to a deterioration of the packing density of the binder mixture, while at the same time raising the specific surface area of the dry powder. On the other hand, replacement of cement by optimized fine cements improves the theoretical packing density in the binder, even though with a lower increase in the specific surface area. Investigations carried out on hardened cement paste made from fine cements have shown that this leads not only to higher density but also to lower autogenous shrinkage values.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132813991","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}
H. Park, C.-Y. Kim, In-Chul Choi, Sang-Woon Bae, J. Ryu
This study discusses application of expansive additives for concrete to improve the serviceability of precast box culvert by inducing chemical stress. For this purpose, both expansive concrete slabs and normal concrete slabs are tested to verify the effect of expansive additives. Then the failure tests of the full-scale precast box culverts are carried out and the critical aspects of the structural behavior are investigated. The result of the material tests shows that the optimal proportion of expansive additives is 13% of cement weight, and the properties of expansive concrete are the same as those of normal concrete in that proportion. Both the experimental cracking load and service load of the expansive concrete members are increased in comparison with those of the normal concrete. In addition to the above results, the deformation of expansive concrete member is less than that of normal concrete member, and permanent strain result from cyclic load is decreased. It can be concluded that the use of expansive additives to induce chemical prestress in precast box culvert greatly improves the serviceability.
{"title":"Chemically Prestressed Precast Concrete Box Culvert with Expansive Additives","authors":"H. Park, C.-Y. Kim, In-Chul Choi, Sang-Woon Bae, J. Ryu","doi":"10.14359/10577","DOIUrl":"https://doi.org/10.14359/10577","url":null,"abstract":"This study discusses application of expansive additives for concrete to improve the serviceability of precast box culvert by inducing chemical stress. For this purpose, both expansive concrete slabs and normal concrete slabs are tested to verify the effect of expansive additives. Then the failure tests of the full-scale precast box culverts are carried out and the critical aspects of the structural behavior are investigated. The result of the material tests shows that the optimal proportion of expansive additives is 13% of cement weight, and the properties of expansive concrete are the same as those of normal concrete in that proportion. Both the experimental cracking load and service load of the expansive concrete members are increased in comparison with those of the normal concrete. In addition to the above results, the deformation of expansive concrete member is less than that of normal concrete member, and permanent strain result from cyclic load is decreased. It can be concluded that the use of expansive additives to induce chemical prestress in precast box culvert greatly improves the serviceability.","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":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129201797","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}
In early 1996, the Singapore Government announced its decision to expand the country's mass rapid transit system by building the North-East Line from the World Trade Center in the south of the island to the new towns of Hougang, Sengkang and Punggol in northeastern Singapore. The S$5 b Northeast MRT Line will be approximately 20 km long and it will be built primary underground using precast tunnel-lining segments. The specifications for the precast tunnel lining segments include the use of high-performance concrete with a maximum water-cementitious material ratio of 0.45, a minimum 28-day compressive strength of 60 MPa, and a maximum "rapid chloride permeability" value of 1000 coulombs. In addition, the specification included the use of high yield bars with a fused epoxy coating to mitigate corrosion of the reinforcing steel due to chlorides in the groundwater. At the request of the contractor, the specifying agency accepted the use of silica fume and a corrosion inhibitor as an alternate. Thousands of precast, high-performance concrete tunnel-lining segments are currently being produced for the construction of the underground tunnels. In this paper, information on the development of the high-performance concrete mixtures for the tunnel-lining segments, production issues, QA/QC measures that have been implemented to ensure compliance with the specification, and the impact of the high-performance concrete on the construction schedule are presented and discussed. An overview of the northeast MRT Line project is also presented.
{"title":"Application of High-Performance Concrete in Singapore’s North-East and Changi MRT lines","authors":"C. Nmai, K. Seow, E. L. Khor, P. Robery","doi":"10.14359/10580","DOIUrl":"https://doi.org/10.14359/10580","url":null,"abstract":"In early 1996, the Singapore Government announced its decision to expand the country's mass rapid transit system by building the North-East Line from the World Trade Center in the south of the island to the new towns of Hougang, Sengkang and Punggol in northeastern Singapore. The S$5 b Northeast MRT Line will be approximately 20 km long and it will be built primary underground using precast tunnel-lining segments. The specifications for the precast tunnel lining segments include the use of high-performance concrete with a maximum water-cementitious material ratio of 0.45, a minimum 28-day compressive strength of 60 MPa, and a maximum \"rapid chloride permeability\" value of 1000 coulombs. In addition, the specification included the use of high yield bars with a fused epoxy coating to mitigate corrosion of the reinforcing steel due to chlorides in the groundwater. At the request of the contractor, the specifying agency accepted the use of silica fume and a corrosion inhibitor as an alternate. Thousands of precast, high-performance concrete tunnel-lining segments are currently being produced for the construction of the underground tunnels. In this paper, information on the development of the high-performance concrete mixtures for the tunnel-lining segments, production issues, QA/QC measures that have been implemented to ensure compliance with the specification, and the impact of the high-performance concrete on the construction schedule are presented and discussed. An overview of the northeast MRT Line project is also presented.","PeriodicalId":184301,"journal":{"name":"\"SP-200: Fifth CANMET/ACI Conference on Recent Advances in Concrete Technology-Proceeding, Fifth International Conference\"","volume":"102 12","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113985099","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}
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