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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Análise da viabilidade técnica da utilização de resíduos de construção e demolição como agregado miúdo reciclado na confecção de blocos de concreto para pavimentação / Technical feasibility study of the use of construction and demolition waste as a fine aggregate in the manufacture of concrete block paving

Scott Hood, Rogério da Silva January 2006 (has links)
A questão ambiental é um tema muito discutido e pesquisado atualmente. Isto advém da constatação que os recursos naturais não são ilimitados e que o meio ambiente não tem a capacidade de absorver a quantidade atual de resíduos sem que haja um desequilíbrio ambiental. Neste contexto insere-se a indústria da construção civil, que apresenta importantes impactos ambientais em todas as etapas do seu processo produtivo, sendo um destes a geração de resíduos de construção e demolição (RCD) em centros urbanos, que resulta em efeitos deteriorantes do ambiente local onde estes são dispostos e, em virtude do seu desperdício, aumenta a extração de materiais minerais. Um dos meios de reduzir-se a quantidade de RCD disposto no meio ambiente e a extração de materiais minerais é a reciclagem do RCD e sua utilização na própria indústria que o gerou.Neste sentido, os blocos de concreto para pavimentação surgem como uma alternativa de pesquisa, já que estes têm ganhado espaço como solução para a pavimentação de áreas urbanas. Isto se deve ao aumento dos esforços de empresas e entidades representativas do setor em incentivar sua utilização e às vantagens técnicas inerentes ao sistema, como o fácil assentamento, a rápida liberação para o tráfego, a redução de iluminação pública e a permissão de acesso à rede subterrânea apenas com a retirada dos blocos, que podem ser recolocados após intervenção. Neste sentido, o presente trabalho estudou a utilização do RCD, proveniente de Porto Alegre – RS, como agregado miúdo reciclado em substituição ao agregado miúdo natural em blocos de concreto para pavimentação. Foi utilizado o intervalo de teores entre 0 % e 100%, com o objetivo de investigar-se um espectro grande de possibilidades de utilização do agregado miúdo reciclado de RCD, sendo que os ensaios escolhidos (resistência à compressão, resistência à abrasão e absorção de água) tiveram o intuito de dar subsídios ao entendimento do comportamento dos blocos produzidos perante as substituições. Após a realização dos ensaios, verificou-se que para o teor de 25% de substituição o material reciclado é passível de utilização, sendo que para os outros teores os resultados foram insatisfatórios. / Environmental issues are in the public eye and are the focus of extensive research nowadays as it becomes clear that natural resources are limited and that the large amounts of waste generated today will necessarily result in environmental imbalances. A considerable share of this waste is generated by the construction industry, whose activities hold a potential environmental impact throughout the stages of their production processes. Construction and demolition (C&D) waste generated in cities often produces detrimental effects in the sites where debris is dumped, a problem which is compounded by the fact that this waste could be used as a substitute for fresh materials that have to be extracted from mines, another activity with considerable environmental impact. A possible way to reduce the amount of C&D waste dumped in the environment and also the need for fresh mineral resources is the recycling of C&D waste by the same industry that generated it. Research on the use of concrete block paving provides an interesting alternative as this material has become more widely used in pavements of urban areas as a result of the efforts of construction companies and associations, which now endeavor to promote the use of concrete blocks. These have intrinsic technical advantages, such as their fast placement, the fast release of paved areas to traffic, the reduced need for street lighting and the ease of access to underground networks because blocks can be quickly opened up and reinstated. The present study investigated the use of C&D waste produced in Porto Alegre, RS, Brazil as a recycled substitute for conventional fine aggregate in concrete block paving. C&D waste was used as fine aggregate in concentrations ranging from 0% to 100% to provide a detailed picture of the possibilities of using recycled C&D waste as fine aggregate. The tests selected (compressive strength, abrasion resistance, water absorption) were used to provide information on the behavior of the blocks produced using different concentrations of C&D waste. These tests show that a concentration of 25% of recycled material as a substitution can be used with satisfactory results while all other concentrations yielded unsatisfactory results.
12

Evolução da resistência à compressão de prismas de blocos de concreto: análise experimental e modelagem matemática / Evolution of resistance to pressure compression of concrete blocks: experimental analysis and mathematical modeling

Oliveira, Afonso Henrique Lacerda Brito de 19 August 2016 (has links)
OLIVEIRA, A. H. L. B. Evolução da resistência à compressão de prismas de blocos de concreto: análise experimental e modelagem matemática. 2016. 128 f. Dissertação (Mestrado em Engenharia Civil)-Centro de Tecnologia, Programa de Pós-Graduação em Engenharia Civil: Estruturas e Construção Civil, Universidade Federal do Ceará, Fortaleza, 2016. / Submitted by Hohana Sanders (hohanasanders@hotmail.com) on 2017-10-27T11:03:50Z No. of bitstreams: 1 2016_dis_ahlboliveira.pdf: 2954070 bytes, checksum: a901b134d2b5e4a8ab5e2aeb1a390f93 (MD5) / Approved for entry into archive by Marlene Sousa (mmarlene@ufc.br) on 2017-10-30T18:59:53Z (GMT) No. of bitstreams: 1 2016_dis_ahlboliveira.pdf: 2954070 bytes, checksum: a901b134d2b5e4a8ab5e2aeb1a390f93 (MD5) / Made available in DSpace on 2017-10-30T18:59:53Z (GMT). No. of bitstreams: 1 2016_dis_ahlboliveira.pdf: 2954070 bytes, checksum: a901b134d2b5e4a8ab5e2aeb1a390f93 (MD5) Previous issue date: 2016-08-19 / This paper presents an experimental study in order to assess the evolution of the compressive strength of masonry, throughout the ages, through the materials resistance study consisting of two structural concrete blocks and propose a mathematical model able to estimate compressive strength of the prisms at different ages. For this purpose, the compressive strength tests were performed and prisms modulus of elasticity without grout and with grout, in ages of 7, 14 and 28 days, using three different resistances blocks, two types of mortar of industrialized and two lines of grout , totaling 12 different types of prisms. Moreover, in these ages, mortar and grout was evaluated for compressive strength and modulus of elasticity. It also evaluated the evolution of the mortar resistance, depending on the molding method and form of the specimens. It adds that the prisms were evaluated regarding the interference of their nominal and effective dimensions in the result of the compressive strength test. From the analysis of the test results, there is no significant interference of the dimensions of the prisms on the results of the compressive strength test, and no significant differences in relation to the body-of-proof mortar format and the respective result of resistance compression. It was also observed that the compressive strength results after 14 days is very close to the value obtained after 28 days (greater than 80%). It was concluded that also influence of components in the final strength of the prisms can be analyzed at seven days, so that if, at 7 days, a resistance increased in block causes increase in resistance in the prism, this same effect is observed after 28 days; Likewise, if, at 7 days, a resistance increase in the grout causes a decrease in resistance in the prism, this same effect is observed after 28 days. Finally, this study was able to provide three expressions for estimating prisms Compressive strength at different ages (7, 14 and 28 days), with grout or not, from the compressive strength of the units. / Este trabalho apresenta um estudo experimental com o objetivo de avaliar a evolução da resistência à compressão da alvenaria estrutural, ao longo das idades, através do estudo da resistência de primas, constituídos por dois blocos estruturais de concreto e propor um modelo matemático capaz de estimar a resistência à compressão dos prismas em diferentes idades. Para tanto, foram realizados ensaios de resistência à compressão e módulo de deformação de prismas não grauteados e grauteados, em idades de 7, 14 e 28 dias, utilizando blocos de três diferentes resistências, dois tipos de argamassa de assentamento industrializada e dois traços de graute, totalizando 12 diferentes tipos de prismas. Ademais, nas referidas idades, a argamassa e o graute foram avaliados quanto à resistência à compressão e ao módulo de deformação. Também foi avaliada a evolução da resistência da argamassa de assentamento, em função do método de moldagem e forma dos corpos de prova. Acrescenta-se que os prismas foram avaliados a respeito da interferência das suas dimensões nominais e efetivas no resultado do ensaio de resistência à compressão. A partir da análise dos resultados dos ensaios, não há interferência significativa das dimensões dos prismas nos resultados do ensaio de resistência à compressão, bem como não há diferenças significativas em relação ao formato do corpo-de-prova da argamassa e o respectivo resultado de resistência à compressão. Também observou-se que os resultados de resistência à compressão aos 14 dias é bem próximo do valor obtido aos 28 dias (superior a 80%). Concluíu-se também que a influência dos componentes na resistência final dos prismas pode ser analisada aos sete dias, de modo que, se, aos 7 dias, um aumento de resistência no bloco provoca aumento de resistência no prisma, esse mesmo efeito será observado aos 28 dias; da mesma forma, se, aos 7 dias, um aumento de resistência no graute provoca diminuição da resistência no prisma, esse mesmo efeito será observado aos 28 dias. Por fim, o presente trabalho foi capaz de fornecer três expressões para a estimativa de resistência à compressão de prismas, em diferentes idades (7, 14 e 28 dias), grauteados ou não, a partir das resistências à compressão das unidades.
13

Análise da viabilidade técnica da utilização de resíduos de construção e demolição como agregado miúdo reciclado na confecção de blocos de concreto para pavimentação / Technical feasibility study of the use of construction and demolition waste as a fine aggregate in the manufacture of concrete block paving

Scott Hood, Rogério da Silva January 2006 (has links)
A questão ambiental é um tema muito discutido e pesquisado atualmente. Isto advém da constatação que os recursos naturais não são ilimitados e que o meio ambiente não tem a capacidade de absorver a quantidade atual de resíduos sem que haja um desequilíbrio ambiental. Neste contexto insere-se a indústria da construção civil, que apresenta importantes impactos ambientais em todas as etapas do seu processo produtivo, sendo um destes a geração de resíduos de construção e demolição (RCD) em centros urbanos, que resulta em efeitos deteriorantes do ambiente local onde estes são dispostos e, em virtude do seu desperdício, aumenta a extração de materiais minerais. Um dos meios de reduzir-se a quantidade de RCD disposto no meio ambiente e a extração de materiais minerais é a reciclagem do RCD e sua utilização na própria indústria que o gerou.Neste sentido, os blocos de concreto para pavimentação surgem como uma alternativa de pesquisa, já que estes têm ganhado espaço como solução para a pavimentação de áreas urbanas. Isto se deve ao aumento dos esforços de empresas e entidades representativas do setor em incentivar sua utilização e às vantagens técnicas inerentes ao sistema, como o fácil assentamento, a rápida liberação para o tráfego, a redução de iluminação pública e a permissão de acesso à rede subterrânea apenas com a retirada dos blocos, que podem ser recolocados após intervenção. Neste sentido, o presente trabalho estudou a utilização do RCD, proveniente de Porto Alegre – RS, como agregado miúdo reciclado em substituição ao agregado miúdo natural em blocos de concreto para pavimentação. Foi utilizado o intervalo de teores entre 0 % e 100%, com o objetivo de investigar-se um espectro grande de possibilidades de utilização do agregado miúdo reciclado de RCD, sendo que os ensaios escolhidos (resistência à compressão, resistência à abrasão e absorção de água) tiveram o intuito de dar subsídios ao entendimento do comportamento dos blocos produzidos perante as substituições. Após a realização dos ensaios, verificou-se que para o teor de 25% de substituição o material reciclado é passível de utilização, sendo que para os outros teores os resultados foram insatisfatórios. / Environmental issues are in the public eye and are the focus of extensive research nowadays as it becomes clear that natural resources are limited and that the large amounts of waste generated today will necessarily result in environmental imbalances. A considerable share of this waste is generated by the construction industry, whose activities hold a potential environmental impact throughout the stages of their production processes. Construction and demolition (C&D) waste generated in cities often produces detrimental effects in the sites where debris is dumped, a problem which is compounded by the fact that this waste could be used as a substitute for fresh materials that have to be extracted from mines, another activity with considerable environmental impact. A possible way to reduce the amount of C&D waste dumped in the environment and also the need for fresh mineral resources is the recycling of C&D waste by the same industry that generated it. Research on the use of concrete block paving provides an interesting alternative as this material has become more widely used in pavements of urban areas as a result of the efforts of construction companies and associations, which now endeavor to promote the use of concrete blocks. These have intrinsic technical advantages, such as their fast placement, the fast release of paved areas to traffic, the reduced need for street lighting and the ease of access to underground networks because blocks can be quickly opened up and reinstated. The present study investigated the use of C&D waste produced in Porto Alegre, RS, Brazil as a recycled substitute for conventional fine aggregate in concrete block paving. C&D waste was used as fine aggregate in concentrations ranging from 0% to 100% to provide a detailed picture of the possibilities of using recycled C&D waste as fine aggregate. The tests selected (compressive strength, abrasion resistance, water absorption) were used to provide information on the behavior of the blocks produced using different concentrations of C&D waste. These tests show that a concentration of 25% of recycled material as a substitution can be used with satisfactory results while all other concentrations yielded unsatisfactory results.
14

Blocos de concreto sobre estacas posicionados nas divisas de terrenos: estudo analítico e análise numérica linear / Reinforced concrete blocks piles located on the limit of land: analitical study and numerical analyze linear

Danieli Colombo dos Santos Tanno 28 May 2012 (has links)
Este trabalho estuda o comportamento estrutural de blocos sobre estacas em concreto armado situados em divisas de terrenos. Foi feita revisão bibliográfica abordando os assuntos de blocos de coroamento, vigas de equilíbrio, modelo de bielas e tirantes e um breve comentário sobre o programa computacional Diana (2010). O trabalho apresenta um roteiro para análise estrutural e dimensionamento de vigas de equilíbrio sobre estacas com pilar excêntrico ao apoio. É apresentado um exemplo feito por Andrade (1989), comparado com o método proposto por Burke (1979) e com análise numérica. Além deste, foram analisados casos de projetos reais utilizando o método Burke (1979) adaptado neste trabalho. Alguns desses exemplos foram modelados em regime elástico e linear no programa computacional Diana (2010). São apresentadas comparações de resultados obtidos com o método Burke (1979) e análise numérica, comprovando a eficácia desse método. Em todos os exemplos estudados o método proposto por Burke (1979) indicou bons resultados quando comparados com os encontrados em análise computacional. A dissertação apresenta soluções para projetos de bloco sobre estacas, situados em divisas de terrenos e associados a vigas de equilíbrio. / This research investigates the structural behavior of reinforced concrete blocks piles located on the limit of land. Literature review was done about blocks piles, balance beams, strut and tie model and a short comment about the Diana computer program (2010). The dissertation presents a roadmap for structural analysis and sizing of balance beams on stakes with eccentric support pillar. An example, which was studied by Andrade (1989), is compared with the same example done using the method proposed by Burke (1979) and with numerical analysis. In addition to this, are analyzed real cases of projects using the method of Burke (1979). Some of these examples were modeled in linear and elastic characteristics using Diana program computer (2010). Here, it is presented comparisons between the method proposed by Burke (1979) and numerical analysis. It is presented comparisons between the method Burke (1979) and numerical analysis, proving the effectiveness of this method. In all examples studied the method proposed by Burke (1979) provided with good accuracy the results for computer analysis. The conclusion presents suggestions for projects of block piles located in limit of land associated with balance beams.
15

Análise da viabilidade técnica da utilização de resíduos de construção e demolição como agregado miúdo reciclado na confecção de blocos de concreto para pavimentação / Technical feasibility study of the use of construction and demolition waste as a fine aggregate in the manufacture of concrete block paving

Scott Hood, Rogério da Silva January 2006 (has links)
A questão ambiental é um tema muito discutido e pesquisado atualmente. Isto advém da constatação que os recursos naturais não são ilimitados e que o meio ambiente não tem a capacidade de absorver a quantidade atual de resíduos sem que haja um desequilíbrio ambiental. Neste contexto insere-se a indústria da construção civil, que apresenta importantes impactos ambientais em todas as etapas do seu processo produtivo, sendo um destes a geração de resíduos de construção e demolição (RCD) em centros urbanos, que resulta em efeitos deteriorantes do ambiente local onde estes são dispostos e, em virtude do seu desperdício, aumenta a extração de materiais minerais. Um dos meios de reduzir-se a quantidade de RCD disposto no meio ambiente e a extração de materiais minerais é a reciclagem do RCD e sua utilização na própria indústria que o gerou.Neste sentido, os blocos de concreto para pavimentação surgem como uma alternativa de pesquisa, já que estes têm ganhado espaço como solução para a pavimentação de áreas urbanas. Isto se deve ao aumento dos esforços de empresas e entidades representativas do setor em incentivar sua utilização e às vantagens técnicas inerentes ao sistema, como o fácil assentamento, a rápida liberação para o tráfego, a redução de iluminação pública e a permissão de acesso à rede subterrânea apenas com a retirada dos blocos, que podem ser recolocados após intervenção. Neste sentido, o presente trabalho estudou a utilização do RCD, proveniente de Porto Alegre – RS, como agregado miúdo reciclado em substituição ao agregado miúdo natural em blocos de concreto para pavimentação. Foi utilizado o intervalo de teores entre 0 % e 100%, com o objetivo de investigar-se um espectro grande de possibilidades de utilização do agregado miúdo reciclado de RCD, sendo que os ensaios escolhidos (resistência à compressão, resistência à abrasão e absorção de água) tiveram o intuito de dar subsídios ao entendimento do comportamento dos blocos produzidos perante as substituições. Após a realização dos ensaios, verificou-se que para o teor de 25% de substituição o material reciclado é passível de utilização, sendo que para os outros teores os resultados foram insatisfatórios. / Environmental issues are in the public eye and are the focus of extensive research nowadays as it becomes clear that natural resources are limited and that the large amounts of waste generated today will necessarily result in environmental imbalances. A considerable share of this waste is generated by the construction industry, whose activities hold a potential environmental impact throughout the stages of their production processes. Construction and demolition (C&D) waste generated in cities often produces detrimental effects in the sites where debris is dumped, a problem which is compounded by the fact that this waste could be used as a substitute for fresh materials that have to be extracted from mines, another activity with considerable environmental impact. A possible way to reduce the amount of C&D waste dumped in the environment and also the need for fresh mineral resources is the recycling of C&D waste by the same industry that generated it. Research on the use of concrete block paving provides an interesting alternative as this material has become more widely used in pavements of urban areas as a result of the efforts of construction companies and associations, which now endeavor to promote the use of concrete blocks. These have intrinsic technical advantages, such as their fast placement, the fast release of paved areas to traffic, the reduced need for street lighting and the ease of access to underground networks because blocks can be quickly opened up and reinstated. The present study investigated the use of C&D waste produced in Porto Alegre, RS, Brazil as a recycled substitute for conventional fine aggregate in concrete block paving. C&D waste was used as fine aggregate in concentrations ranging from 0% to 100% to provide a detailed picture of the possibilities of using recycled C&D waste as fine aggregate. The tests selected (compressive strength, abrasion resistance, water absorption) were used to provide information on the behavior of the blocks produced using different concentrations of C&D waste. These tests show that a concentration of 25% of recycled material as a substitution can be used with satisfactory results while all other concentrations yielded unsatisfactory results.
16

Mateřská škola / Kindergarden

Zlesáková, Aneta January 2019 (has links)
The aim of diploma thesis is a design project documentation of kindergarden in the construkction phase. The task was to design the most appropriate solution all of building structures in terms of construction and thermal engineering. The kindergarten will serve for education for children from 3 to 6 years old. In object are designes three departments. Individual departments are designes for total capacity 20 children. In the kindergarten there will lbe heating or preparation of only cold dishes. The kindergarten is designed single-storey with construct hight 4,25 m. Southern part of the building, where it is located ondividual departments, is designed breathable fasade. Zhe main entrance to the object is situated to the east side. Construction systém of the object is bricked from silicon-based porous concrete blocks. The roof is designed flat, vegetative. Filling of holes is made of wood-aluminum.
17

Enhanced Ductility of Masonry Shear Walls Using Laterally Confined (Self-Reinforced) Concrete Block

Joyal, Madeleine 04 1900 (has links)
<p>The aim of the study presented in this dissertation was to investigate a new method of improving the ductility of masonry shear walls by means of confinement. This proprietary method, referred to as Self-Reinforced Concrete Block (SR Block) employs a previously untried technique of molding lateral confining devices into concrete block. This internal reinforcement provides lateral confinement to the enclosed volume of block and grout material. The resulting triaxial state of compressive stress under axial load allows the confined material to maintain high compressive capacity while undergoing high axial compressive strains. The results from a proof-of-concept program indicated improved plasticity due to the presence of the confining devices within the block. Despite spalling of the unconfined portions of the block at high strains, the SR Block specimens retained load carrying capacities in excess of the peak capacity of similar unreinforced/unconfined block prisms at strains beyond 2% with no visible damage to the confining devices or to the confined material. Further to this proof-of-concept study, an experimental program was undertaken involving additional prism tests as well as testing of shear walls constructed with the SR Block. This program proved the efficacy of a second confining device design in enabling prisms to retain compressive load capacity to strains over six times larger than that of standard grouted masonry. Additionally, the results of the shear wall program indicated that these desirable characteristics were effective in a wall configuration and led to significant increases in the displacement ductility of the walls when compared to similar, unconfined walls. The data presented is expected to serve as a basis for future testing and acceptance of SR Block as a method of increasing the compressive strain capacity of reinforced masonry in order to improve the ductility of masonry shear walls as a lateral force resisting system.</p> / Master of Applied Science (MASc)
18

Finite Element Analysis of Unreinforced Concrete Block Walls Subject to Out-of-Plane Loading

He, Zhong 12 1900 (has links)
<p>Finite element modeling of the structural response of hollow concrete block walls subject to out-of-plane loading has become more common given the availability of computers and general-purpose finite element software packages. In order to develop appropriate models of full-scale walls with and without openings, a parametric study was conducted on simple wall elements to assess different modeling techniques. Two approaches were employed in the study, homogeneous models and heterogeneous models. The linear elastic analysis was carried out to quantify the effects of the modeling techniques for hollow blocks on the structural response of the assembly, specifically for out-of-plane bending. Three structural elements with varying span/thickness ratios were considered, a horizontal spanning strip, a vertical spanning strip and a rectangular wall panel supported on four edges. The values computed using homogeneous and heterogeneous finite element models were found to differ significantly depending on the configuration and span/thickness ratio of the wall.</p><p>Further study was carried out through discrete modeling approach to generate a three-dimensional heterogeneous model to investigate nonlinear behaviour of full-scale walls under out-of-plane loading. The Composite Interface Model, established based on multi-surface plasticity, which is capable of describing both tension and shear failure mechanisms, has been incorporated into the analysis to capture adequately the inelastic behaviour of unit-mortar interface.An effective solution procedure was achieved by implementing the Newton-Raphson method, constrained with the arc-length control method and enhanced by line search algorithm. The proposed model was evaluated using experimental results for ten full-size walls reported in the literature. The comparative analysis has indicated very good agreement between the numerical and experimental results in predicting the cracking and ultimate load values as well as the corresponding crack pattern. / Thesis / Master of Applied Science (MASc)
19

The Effect of Splice Length and Distance between Lapped Reinforcing Bars in Concrete Block Specimens

2014 April 1900 (has links)
The tensile resistance of No. 15 lap spliced reinforcing bars with varying transverse spacing and lap splice length was evaluated in full-scale concrete block wall splice specimens. The range of the transverse spacing between bars was limited to that which allowed the bars to remain within the same cell, and included the evaluation of tied spliced bars in contact. Two-and-a-half block wide by three course tall double pullout specimens reinforced with contact lap splices were initially used to determine the range of lap splice length values to be tested in the wall splice specimens such that bond failure of the reinforcement occurred. The double pullout specimens were tested in direct tension with six replicates per arrangement. Three values of lap splice length: 150, 200, and 250 mm, were selected from the testing of the double pullout specimens and tested in the wall splice specimens in combination with three values of transverse spacing: 0, 25, and 50 mm, with three replicates per configuration. A total of twenty-seven two-and-a-half block wide by thirteen course tall wall splice specimens reinforced with two lap splices were tested in four-point loading. Both the double pullout and the wall splice specimens were constructed in running bond with all cells fully grouted. The tensile resistance of the lap spliced bars in the double pullout specimens was measured directly. The contact lap splices with a 150, 200, and 250 mm lap splice length developed approximately 38, 35 and 29% of the theoretical yield load of the reinforcement, respectively. The difference between the mean tensile resistances of the three reinforcement configurations tested in the double pullout specimens was found to be statistically significant at the 95% confidence level. Different than expected, the tensile resistance of the lap spliced reinforcing bars in the double pullout specimens was inversely proportional to the lap splice length provided. For the short lap splice lengths used in this investigation, the linear but not proportional relationship between bond force and lap splice length known from reinforced concrete is believed to have caused this phenomenon. An iterative sectional analysis using moment-curvature response was used to calculate the tensile resistance of the lap spliced reinforcement in the wall splice specimens. The calculated mean tensile resistance of the reinforcement increased with increasing lap splice length, and was greater when the bars were in contact. Securing the bars in contact may have influenced the tensile capacity of the contact lap splices as higher stresses are likely to develop as a result of the bar ribs riding over each other with increasing slip. Results of the data analysis suggest that the tensile resistance of non-contact lap splices within the same cell is generally independent of the spacing between the bars. A comparison of the experimental results for the wall splice specimens with the development and splice length provisions in CSA S304.1-04 and TMS 402-11 indicate that both the Canadian and U.S. design standards are appropriate for both contact and non-contact lap splices located within the same cell given the limited test database included in this investigation.
20

A Study On Abrasion Resistance Of Concrete Paving Blocks

Aslantas, Onur 01 December 2004 (has links) (PDF)
Concrete block pavement (CBP) can be an alternative pavement to asphalt and concrete pavements. CBP is formed from individual concrete paving blocks (CPBs) that fit next to one another on a suitable sub base leaving a specific joint space among them to be filled with jointing sand. CBP differ from other pavements according to their mechanical behavior, manufacturing technique, structural design, installation technique and structural behavior. For a serviceable pavement all of these subjects have to be studied. The literature about the mechanical behavior of CPBs is not adequate. This study aims to determine the performance of CPBs formed from different mixes prepared with a white portland cement. For this purpose, 10 mixes with different cement contents and W/C ratios and 2 mixes from a commercial CPB manufacturer were tested. The compressive strength, tensile splitting strength, abrasion resistance, density and % water absorption tests were performed on each mix at 7, 14, 28 days. It was concluded that, the cement content in the mix, optimum water volume for a given cement content, the way the manufacturing equipment is operated and their interaction was effective on the mechanical properties of CPBs. It was also observed that there was no handicap to stop the abrasion resistance test at 8*22 revolutions instead of 16*22 revolutions given in TS 2824.

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