Shrinkage of self-compacting concrete. A comparative analysis

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.

By means of concrete equivalent mortar (CEM) principle, concrete properties can be experimentally studied at mortar level. Based on this principle, this paper studies the influence of mix design parameters on autogenous and drying shrinkage of self-compacting concrete by means of experiments at mortar level. Mix design parameters of this study are W/C (water/cement) ratio and A/C (limestone filler /cement) ratio. The results show that autogenous shrinkage is increases with decreasing W/C and A/C ratios contrary to drying shrinkage which increases with higher ratios. Furthermore, based on mortar and paste results, it is shown that the model developed by Le Roy to predict the shrinkage of CEM and possibly of SCC, from shrinkage measured on cementing paste, is also valid for shrinkage of limestone filler based self-compacting cementitious materials. Furthermore, some known results on the influence of water/cement ratio and filler/cement ratio have been confirmed and can be explained by...

Materials and Structures, 2011

Shrinkage behavior of self-compacting concrete (SCC) can be different from that of traditional vibrated concrete, because of different paste and aggregate volumes. For traditional concrete, shrinkage can be estimated based on shrinkage results obtained on paste level. Based on homogenization techniques, Le Roy developed a model relating the shrinkage of concrete to the shrinkage of the representative cement paste, considering a granular coefficient taking into account the elastic properties and the concentration of the aggregates. By means of an extended experimental program, the applicability of this model to the case of SCC has been verified. Furthermore, some known results on the influence of water/cement ratio and filler/cement ratio have been confirmed and can be explained by porosity results.

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.

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).

2013

In the present paper, the results of an experimental campaign concerning the long-term behavior of hardened self-compacting concrete are presented. Five mixes of self-compacting concrete and one mix of conventional vibrated concrete have been employed, with different compressive strength. Strength levels have been selected to cover the range of application from cast-in-place to prestressed structures. For each mix, shrinkage and creep tests at two different ages at loading (7 and 28 days) have been performed for a period of about one year. Finally, experimental data both in terms of shrinkage and creep are compared with international code provisions. An apparent underestimation has been observed in all cases but MC2010 in predicting SCC creep behavior, where an over-prediction has been obtained. In general, the introduction inside models of the dependency from specific mix parameters seems to be advisable when considering SCCs.

2011

Proper estimate of autogenous shrinkage of self-consolidating concrete (SCC) can provide engineers with the information necessary for producing high quality products manufactured with SCC. An experimental program was undertaken to evaluate autogenous shrinkage of precast, prestressed SCC. Sixteen SCC with slump flow of 680 ± 20 mm were evaluated. These mixtures were made with 440 to 500 kg/m 3 of binder, Type MS cement or HE cement and 20% Class F fly ash, 0.34 to 0.40 w/cm, viscosity-modifying admixture content of 0 to 100 mL/100 kg of binder, and 0.46 to 0.54 sand-to-total aggregate volume ratio. Two high-performance concretes (HPC) with 0.34 and 0.38 w/cm and slump of 150 mm were also investigated. HPC developed similar autogenous shrinkage at 56 days compared to SCC made of a given binder type. Shrinkage was compared to prediction models proposed by Tawaza and Miyazawa 1997. The Tazawa and Miyazawa model was modified to provide adequate prediction of autogenous shrinkage for precast, prestressed SCC.

Structural Concrete, 2020

Self-compacting concrete (SCC) is a concrete that does not require vibration for casting and consolidation. It is able to flow under its own weight, completely filling the formwork and achieving full consolidation, even in the presence of congested reinforcement. SCC possesses special technical features and properties that recommend its application in a considerable amount of applications. Nevertheless, an inadequate behavior of the material at early ages has been observed in some situations, due to shrinkage. Shrinkage has a significant importance in the design, construction and in-service performance of concrete structures. The regulatory requirements were derived from experience with traditional concrete, which is not always suitable for SCC. In addition, the option of using new materials, such as binders with large amount of pozzolanic or latent hydraulic additions, strongly limits the validity of existing rules. In order to contribute for a better understanding of the major drawback of this material-its high potential shrinkage, experimental research was carried out using different commercial shrinkage-compensating products. This study focuses on the use of a shrinkage reducing admixture and an expansive agent. The results obtained demonstrate the efficiency of the individual or combined use of these products and allowed identifying three different strategies to control the shrinkage, with distinct levels of efficiency.

Journal of Advanced Concrete Technology, 2016

An extensive research was undertaken in order to determine the dependence of shrinkage of high and normal strength concrete on the compressive strength and concrete composition. The part of research concerning dependence of autogenous shrinkage on compressive strength is presented in this paper. Ten groups of concrete, with the total of twenty nine mixtures, were prepared. Concrete mixtures of each individual group were made using the same quantity of water, while the quantity of cement (CEM II/A-S 42,5R) and mineral admixture (silica fume) was varied in each group. Concrete groups differed according to the quantity of water. Autogenous shrinkage of concrete was monitored together with the influence of initial curing in water on concrete shrinkage. Initial autogenous expansion was noticed during testing autogenous shrinkage, especially on normal strength concrete. Based on the analysis of experimental results, the dependence of autogenous shrinkage at one day of concrete age on compressive strength was defined. The dependence of autogenous shrinkage at later ages on compressive strength of concrete was also presented. Finally, the autogenous shrinkage components of best-known theoretical shrinkage prediction models were compared with experimental data.

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.