Shrinkage reducing agent in concrete

Shrinkage reducing agent in concrete: The mechanism and its influences on the hydration process and mechanical properties

Feij, Jeroen (TU Delft Mechanical, Maritime and Materials Engineering)

Hermans, M.J.M. (mentor)
Richardson, I.M. (graduation committee)
Ye, G. (graduation committee)
Schlangen, E. (graduation committee)
Li, Z. (graduation committee)

Delft University of Technology

Materials Science and Engineering

2020-05-25

In floors without dilation joints drying shrinkage cracking can occur. Shrinkage reducing agents (SRAs) can reduce the amount of drying shrinkage and improve the durability of the concrete structure. The mechanism of shrinkage reduction and the influences on the hydration process and development of mechanical properties of the SRA Sika Control 40 were researched. Shrinkage reducing agents lower the surface tension of water which reduces the capillary tensile stresses and ultimately reducing the drying shrinkage. Experiments were performed on cement paste samples to investigate influences on the hydration process of cement (surface tension, rate of hydration, porosity, shrinkage, flexural and compressive strength). In addition experiments were performed on concrete samples to investigate the influences of applying shrinkage reducing agents on the mechanical properties of concrete (compressive strength, shrinkage, elastic modulus). Overall, the experimental results showed that applying Sika Control 40 is an effective method for reducing drying shrinkage when concentrations of 1.56 w% and 2.61 w% are used. The shrinkage reducing agent has positive effects on the surface tension, weight loss and drying shrinkage for concentrations of 1.56 w% and 2.61 w% of cement. It has negative effects on rate and degree of hydration, porosity, pore size distribution, compressive and flexural strength for concentrations of 1.56 w% and 2.61 w%. The elastic modulus lacks adequate data to observe a trend, however the results are within the range of expected values for concrete for mixtures 156 and 261. , An SRA concentration of 0.52 w% of cement resulted in unpredictable and contradicting results.

Shrinkage reducing agent
Drying shrinkage
Concrete
Sika Control 40
SRA

http://resolver.tudelft.nl/uuid:b0921d17-503f-495f-99bc-96f4f19b95df

Student theses

master thesis

© 2020 Jeroen Feij