01478662

Component

Expansive cements were developed to mitigate shrinkage cracking by means of providing early-age expansion. The increase in volume during the hydration of expansive cement plays a crucial role in development of residual compressive stress which can compensate the tensile stresses induced due to drying shrinkage. This paper reports the early-age deformation (restrained and unrestrained) of cement paste and concrete incorporating two different expansive components: calcium sulfoaluminate-based that forms ettringite, and CaO-based that forms calcium hydroxide crystals. A noticeable difference in the rate of expansion of the two different expansive systems is observed. Most of the expansion in CaO-based system occurs within 24 hours compared to several days in calcium sulfoaluminate-based system. The effect of mineral admixtures on early-age deformation of expansive cements is also investigated. The class ‘C’ fly ash appears to have increased the expansion whereas silica fume decreased the extent of expansion. The rate at which material gains strength and develops resistance against the deformation was identified as a potential factor influencing the expansion. Additionally, the importance of set time is discussed in correctly estimating the “effective” expansion.

This paper was sponsored by TRB committee AFN40 Concrete Materials and Placement Techniques.

01470560

13-3748

English

18p

2013

Transportation Research Board 92nd Annual Meeting

Digital/other

Figures; Photos; References; Tables

Bridge decks; Cracking of concrete pavements; Expansive cement; Shrinkage; Volume changes

Bridges and other structures; Highways; Materials; I32: Concrete

Transportation Research Board Annual Meeting 2013 Paper #13-3748

TRIS, TRB, ATRI

Feb 5 2013 12:44PM