Influence of superplasticizers on early age drying shrinkage of cement paste with the same consistency

Abstract

The influence of superplasticizer (SP) on the early age drying shrinkage of cement paste with the same consistency was investigated. To conduct the test, which lasted for 72 hours, three paste mixtures were used for comparison. The 72 hours early age drying shrinkage staring from the initial setting time was measured by a clock gauge. The pore size distribution was measured by Mercury Intrusion Method. The surface tension of capillary simulation liquid and mass loss of paste were also measured. The experimental results showed that the addition of SP increased the early drying shrinkage greatly. The ratios of water evaporation and the total free water in mixtures added with SPs showed great differences. SPs fined the capillary pores of paste, and the volume of pore with diameter within 50 nm was well consistent with shrinkage rate. The addition of SPs did not raise the capillary liquid surface tension. It showed that with the volume of pore with diameter within 50 nm and the ratio of water evaporation and the total free water a tolerable shrinkage result of paste added with SP could be predicted, and the elastic modulus could have an influence on the early shrinkage. These results have never been proposed before.

Keywords

superplasticizer / early age drying shrinkage / paste / water evaporation / pore size distribution

References

[1] Collepardi M Admixtures Used to Enhance Placing Characteristics of Concrete [J]. Cem. Concr. Compos., 1998, 20: 103-112.

[2] Tazawa E, Miyazawa S Influence of Cement and Admixture on Autogenous Shrinkage of Cement Paste [J]. Cem. Concr. Res., 1995, 25(2): 281-287.

[3] Al-Amoudi OSB, Abiola TO, Maslehuddin M Effect of Superplasticizer on Plastic Shrinkage of Slain and Silica Fume Cement Concretes [J]. Constr. Build. Mater., 2006, 20: 642-647.

[4] Brooks JJ Influence of Mix Proportions, Plasticizers and Superplasticizers on Creep and Drying Shrinkage of Concrete [J]. Mag. Concrete Res., 1989, 41(148): 145-153.

[5] Ma B-g, Wang X-g, Liang W-q, . Study on Early-age Cracking of Cement-based Materials with Superplasticizers [J]. Constr. Build. Mater., 2007, 21: 2 017-2 022.

[6] Holt E Contribution of Mixture Design to Chemical and Autogenous Shrinkage of Concrete at Early Ages [J]. Cem. Concr. Res., 2005, 35: 464-472.

[7] Yang Y, Wen Z Influence of Different Superplasticizers on Drying Shrinkage of Mortar [J]. Journal of Building Material, 2002, 5(4): 336-341.

[8] Chen M, Zhou M, Li B Investigation on Appraisal Methods for Application Effect of Superplasticizer in Cement-based Materials [J]. Journal of Wuhan University of Technology, 2007, 29(4): 1-4.

[9] Neville A Properties of Concrete [M], 1995 Essex Pearson Education Limited

[10] Lea FM The Chemistry of Cement and Concrete [M], 1970 3rd ed London Edward Arnold

[11] Vanbreugel K Numerical Simulation of Hydration and Microstructural Development in Hardening Cement-based Materials.2. Applications [J]. Cem. Concr. Res., 1995, 25(3): 522-530.

[12] Sakai E, Kasuga T, Sugiyama T, . Influence of Superplasticizers on the Hydration of Cement and the Pore Structure of Hardened Cement [J]. Cem. Concr. Res., 2006, 36: 2 049-2 053.

[13] Hua C, Acker P, Ehrlacher A Analyses and Models of the Autogenous Shrinkage of Hardening Cement Paste: I. Modelling at Macroscopic Scale [J]. Cem. Concr. Res., 1995, 25: 1 457-1 468.

[14] Escalante-Garcia JI Nonevaporable Water from Neat OPC and Replacement Materials in Composite Cements Hydrated at Different Temperatures [J]. Cem. Concr. Res., 2003, 33: 1 883-1 888.

[15] Wittmann FH On the Action of Capillary Pressure in Fresh Concrete [J]. Cem. Concr. Res., 1976, 6: 49-56.

[16] Zhu Y Experimental Investigation and Theoretical Modeling on Early-age Shrinkage Cracking in Concrete [D], 2005 Hangzhou Zhejiang University

[17] Zhu Y Effect Mechanism Research of Water Reducers on Dry Shrinkage of Cement Concrete [D], 2006 Beijing China Building Materials Academy

[18] Mehta PK, Monteiro PJM Concrete: Structure, Properties, and Materials [M], 1993 2nd ed. New Jersey Prentice Hall