Combined Use of Shrinkage Reducing Admixture and CaO in Cement Based Materials

World Multidisciplinary Civil Engineering-Architecture-Urban Planning Symposium - WMCAUS

土木建筑工程

Tittarelli, Francesca^1,2 ; Giosuè, Chiara^1 ; Monosi, Saveria^1

Department of Materials, Environmental Sciences and Urban Planning - SIMAU, Università Politecnica Delle Marche-UdR INSTM, Via Brecce Bianche 12, Ancona

60131, Italy^1

Institute of Atmospheric Sciences and Climate (CNR-ISAC), Via Piero Gobetti 101, Bologna

40129, Italy^2

关键词: Cement based material;    Drying shrinkages;    Hydration products;    Microstructure development;    Retarding effect;    Shrinkage reducing admixture (SRA);    Shrinkage reducing admixtures;    Synergistic effect;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/245/2/022093/pdf
DOI  :  10.1088/1757-899X/245/2/022093

学科分类：土木及结构工程学

来源: IOP

【 摘 要 】

The combined addition of a Shrinkage-Reducing Admixture (SRA) with a CaO-based expansive agent (CaO) has been found to have a synergistic effect to improve the dimensional stability of cement based materials. In this work, aimed to further investigate the effect, mortar and self-compacting concrete specimens were prepared either without admixtures, as reference, or with SRA alone and/or CaO. Their performance was compared in terms of compressive strength and free shrinkage measurements. Results showed that the synergistic effect in reducing shrinkage is confirmed in the specimens manufactured with SRA and CaO. In order to clarify this phenomenon, the effect of SRA on the hydration of CaO as well as cement was evaluated through different techniques. The obtained results show that SRA induces a finer microstructure of the CaO hydration products and a retarding effect on the microstructure development of cement based materials. A more deformable mortar or concrete, due to the delay in microstructure development by SRA, coupled with a finer microstructure of CaO hydration products could allow higher early expansion, which might contribute in contrasting better the successive drying shrinkage.