Experimental Investigation of Shrinkage Strains for Elements of Self- Compacted Concrete (SCC (original) (raw)
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Development trends for high rise constructions, modern skyscrapers are indicating that building of such constructions with normal concretes and low consistency is impossible, therefore there is a need for concrete with high processes because of great amount of reinforcement in cross section of concrete elements. Solution for such construction is self-compacted concrete because of ability to fill good formworks without compaction and vibration. In this line, we conducted an experimental research to determine the mechanical characteristics of concrete, cracks, strains, deflections, strains on long term process and strains at failure test. The experimentally-obtained results will be presented for both types of concrete for: compression strength, splitting tensile strength, strains on concrete and strains on reinforcement for duration failure testing time t = 40 days. .
Shrinkage behavior of self-compacting concrete
Journal of Zhejiang University SCIENCE A, 2012
In the structures where long-term behavior should be monitored and controlled, creep and shrinkage effects have to be included precisely in the analysis and design procedures. Shrinkage varies with the constituent and mixture proportions, and depends on the curing conditions and the work environment as well. Self-compacting concrete (SCC) contains combinations of various components, such as aggregate, cement, superplasticizer, water-reducing agent and other ingredients which affect the properties of the SCC including shrinkage. Hence, the realistic prediction shrinkage strains of SCC are an important requirement of the design process for this type of concrete structures. This study reviews the accuracy of the conventional concrete (CC) shrinkage prediction models proposed by the international codes of practice, including CEB-. Also, SCC shrinkage prediction models proposed by , Larson , Cordoba (2007) and are reviewed. Further, a new shrinkage prediction model based on the comprehensive analysis on both of the available models, i.e., the CC and the SCC is proposed. The predicted shrinkage strains are compared with the actual measured shrinkage strains in 165 mixtures of SCC and 21 mixtures of CC.
Shrinkage of self-compacting concrete. A comparative analysis
Journal of Building Engineering, 2017
Self-compacting concrete (SCC) is a concrete type that does not require vibration for placing and compacting. SCC possesses special technical features and properties that recommend its application in many jobs. Nevertheless, in some situations, it has been observed an inadequate behavior of the material at early ages due to shrinkage. The existing shrinkage prediction models were developed for standard concrete. In this paper three SCC mixtures, with different compressive strength, are studied in terms of autogenous and total shrinkage. The results are compared with the Eurocode 2 model. For the studied mixtures it was found that this model underestimates the autogenous shrinkage, while the total shrinkage is generally overestimated.
A Review Oncreep And Shrinkage Behavior Of High Strength Self-Compacting Concrete
In the present paper reviewon creep and shrinkage of high-strength self-compacting concrete and experimental measurement of creep and shrinkage of HSC and HSSCC gets affected by local construction material and under Indian environmental conditions. To Studies, time-dependent deformations are very important because of the volatility of the creep and shrinkage properties and the need for better-developed models that can account for concretes containing mineral additives. These phenomena are very important in concrete design and cannot be ignored. This is especially true for typical concretes since very limited creep and Shrinkage tests were performed and therefore empirical data is scarce for the Indian Scenario.
2006
This paper presents a study on cracking risk due to shrinkage of self-compacting concrete ͑SCC͒. Cracking of SCC was investigated through a comparison of material properties, such as shrinkage, modulus of elasticity, creep, and fracture parameters, between SCC mixtures and ordinary concrete ͑OC͒ mixtures. Restrained shrinkage tests ͑ring tests͒ were also performed on the same mixtures. Numerical simulations were then used to assess the correlation between material properties and results of restrained shrinkage tests. SCC and OC were found to have equivalent shrinkage cracking tendency, provided that compressive strength is kept the same and that SCC has adequate segregation resistance.
DEFLECTIONS IN BEAMS OF SELF-COMPACTING CONCRETE AND CONVENTIONAL CONCRETE FOR ALONG-TERM PROCESS
The developmental trends of high-rise construction require high-quality concrete because of the large amount of reinforcement in the cross sections of concrete elements. A potential solution for such construction is self-compacting concrete because of its ability to provide support without compaction and vibration. Therefore, studies of concrete deflection, cracking, mechanical characteristics and strain have been conducted worldwide. In this study, we conducted experimental research to determine the strains, deflections and cracks in beams of self-compacting concrete and compared these results to those of conventional concrete over short-and long-term processes. In this paper, we present the experimentally obtained results for both types of concrete, including the deflections, module of elasticity values and compression strength sover a long-term process.
Evaluation of the shrinkage and creep of medium strength self compacting concrete
IOP Conference Series: Materials Science and Engineering, 2017
The difference between self compacting concrete (SCC) and conventional concrete (CC) is in fresh state, is the high fluidity at first and the need for vibration at second, but in hardened state, both concretes must comply with the resistance specified, in addition to securing the safety and functionality for which it was designed. This article describes the tests and results for shrinkage and creep at some medium strength Self Compacting Concrete with added sand (SCC-MSs) and two types of cement. The research was conducted at the Laboratorio de Tecnología de Estructuras (LTE) of the Universitat Politécnica de Catalunya (UPC), in dosages of 200 liters; with the idea of evaluating the effectiveness of implementation of these new concretes at elements designed with conventional concrete (CCs).
Materials and Structures, 2009
Self-compacting concrete (SCC) used in Switzerland contains about 80 l/m 3 more volume of paste than conventionally vibrated concrete (CVC). Consequently, there are some systematic differences in the properties of the hardened concrete. Normally, shrinkage of SCC is higher than shrinkage of CVC. Therefore, risk of cracking in case of restrained deformations can be increased for SCC. In this study shrinkage of thirteen different SCC mixtures using volume of paste, water content, type of binder, grain size distribution or content of shrinkage reducing admixture (SRA) as variables was compared with shrinkage of three different CVC mixtures with constant volume of paste but variable w/b. Furthermore, the risk of cracking of the different SCC-and CVC-mixtures in restrained conditions was studied under constant and varying curing conditions. The results show that shrinkage is mainly depending on volume of paste. Due to the higher volume of paste, SCC displayed higher shrinkage than CVC. Adding an SRA was the only measure to reduce shrinkage of SCC to values of CVC. Restrained shrinkage cracking is depending on shrinkage rate, mechanical properties and drying velocity. For slow shrinkage stress development, cracking risk of SCC can be lower compared to CVC despite the higher shrinkage rate.
Cement and Concrete Research, 2001
An experimental and numerical study on mechanical properties, such as strength, elastic modulus, creep and shrinkage, of selfcompacting concrete (SCC) and the corresponding properties of normal compacting concrete (NC) is outlined in this article. The study included eight mix proportions of sealed or air-cured specimens with water ± binder ratio (w/b) varying between 0.24 and 0.80. Half of the mixes studied were based on NC. The age at loading of the concretes in the creep studies varied between 2 and 90 days. Four different stress to strength levels were studied. Parallel studies were performed on strength (f c) and relative humidity (RH). The results show that elastic modulus, creep and shrinkage of SCC did not differ significantly from the corresponding properties of NC. The ongoing study was started in 1997.
Effect of shrinkage restraint on deflections of reinforced self-compacting concrete beams
KSCE Journal of Civil Engineering, 2013
This paper presents the results of a study aimed at investigating the effects of restrained shrinkage on the in-plane deflection behavior of reinforced beams cast with self-compacting concrete. The load-deflection data from the tests on two sets of heavilyreinforced concrete beams were analyzed. The first set of beams was made with self-compacting concrete while conventionally vibrated concrete with shrinkage reducing admixture was used in the second set. It was found out that the first set underwent shrinkage cracking at early ages and this cracking caused the member responses of the beams to be closer to the fully-cracked response at the initial stages of loading. The second set of beams was found to have initial responses approximate to the uncracked response and the maximum shrinkage restraint stresses were calculated to be in the order of 20-40% of the modulus of rupture of concrete. The maximum shrinkage-induced restraint stress expressions of the AS 3600-2001, AS 3600-2009, EC2, and CSA A23.3-04 codes were found to underestimate the restraint stresses developed in the first set, yet the estimates from code solutions were in closer agreement with the experimental values in the second set.