Experimental study on the basic phenomena of shrinkage and cracking of fresh mortar

Anna Kronlöf, Markku Leivo, Pekka Sipari

Research output: Contribution to journalArticleScientificpeer-review

46 Citations (Scopus)

Abstract

Evaporation, horizontal shrinkage, settlement, setting and capillary pressure of mortar mixes were measured during first hours with samples which were exposured to wind (velocity 4 m/s, T = 20 °C and RH 40%). The effects of different admixtures (super plasticizer, accelerating, retarding, air-entraining agent and one type of fibre) on the shrinking behaviour of the mortars were studied accordingly.
The well-known fact that proper long-term wet curing is vital for the crack-free surfaces of concrete or mortar was confirmed experimentally. The beginning of setting can be regarded as a critical moment. After that the mortar has capacity to resist the capillary forces and thus shrinkage. The mix modified by super plasticizer behaved unexpectedly, and the surface of the sample cracked. This cracking was indicated by zig-zag behaviour in the measured horizontal shrinkage and capillary pressure.
Air- entraining agent reduced horizontal shrinkage considerably. Use of fibre reduced shrinkage about 30% when compared to mix without fibre. Based on the results some conclusions are drawn concerning properly limed trowelling on horizontal shrinkage.
Original languageEnglish
Pages (from-to)1747-1754
JournalCement and Concrete Research
Volume25
Issue number8
DOIs
Publication statusPublished - 1995
MoE publication typeA1 Journal article-refereed

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Mortar
Plasticizers
Capillarity
Fibers
Air
Curing
Evaporation
Concretes
Cracks

Cite this

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title = "Experimental study on the basic phenomena of shrinkage and cracking of fresh mortar",
abstract = "Evaporation, horizontal shrinkage, settlement, setting and capillary pressure of mortar mixes were measured during first hours with samples which were exposured to wind (velocity 4 m/s, T = 20 °C and RH 40{\%}). The effects of different admixtures (super plasticizer, accelerating, retarding, air-entraining agent and one type of fibre) on the shrinking behaviour of the mortars were studied accordingly. The well-known fact that proper long-term wet curing is vital for the crack-free surfaces of concrete or mortar was confirmed experimentally. The beginning of setting can be regarded as a critical moment. After that the mortar has capacity to resist the capillary forces and thus shrinkage. The mix modified by super plasticizer behaved unexpectedly, and the surface of the sample cracked. This cracking was indicated by zig-zag behaviour in the measured horizontal shrinkage and capillary pressure. Air- entraining agent reduced horizontal shrinkage considerably. Use of fibre reduced shrinkage about 30{\%} when compared to mix without fibre. Based on the results some conclusions are drawn concerning properly limed trowelling on horizontal shrinkage.",
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Experimental study on the basic phenomena of shrinkage and cracking of fresh mortar. / Kronlöf, Anna; Leivo, Markku; Sipari, Pekka.

In: Cement and Concrete Research, Vol. 25, No. 8, 1995, p. 1747-1754.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Experimental study on the basic phenomena of shrinkage and cracking of fresh mortar

AU - Kronlöf, Anna

AU - Leivo, Markku

AU - Sipari, Pekka

PY - 1995

Y1 - 1995

N2 - Evaporation, horizontal shrinkage, settlement, setting and capillary pressure of mortar mixes were measured during first hours with samples which were exposured to wind (velocity 4 m/s, T = 20 °C and RH 40%). The effects of different admixtures (super plasticizer, accelerating, retarding, air-entraining agent and one type of fibre) on the shrinking behaviour of the mortars were studied accordingly. The well-known fact that proper long-term wet curing is vital for the crack-free surfaces of concrete or mortar was confirmed experimentally. The beginning of setting can be regarded as a critical moment. After that the mortar has capacity to resist the capillary forces and thus shrinkage. The mix modified by super plasticizer behaved unexpectedly, and the surface of the sample cracked. This cracking was indicated by zig-zag behaviour in the measured horizontal shrinkage and capillary pressure. Air- entraining agent reduced horizontal shrinkage considerably. Use of fibre reduced shrinkage about 30% when compared to mix without fibre. Based on the results some conclusions are drawn concerning properly limed trowelling on horizontal shrinkage.

AB - Evaporation, horizontal shrinkage, settlement, setting and capillary pressure of mortar mixes were measured during first hours with samples which were exposured to wind (velocity 4 m/s, T = 20 °C and RH 40%). The effects of different admixtures (super plasticizer, accelerating, retarding, air-entraining agent and one type of fibre) on the shrinking behaviour of the mortars were studied accordingly. The well-known fact that proper long-term wet curing is vital for the crack-free surfaces of concrete or mortar was confirmed experimentally. The beginning of setting can be regarded as a critical moment. After that the mortar has capacity to resist the capillary forces and thus shrinkage. The mix modified by super plasticizer behaved unexpectedly, and the surface of the sample cracked. This cracking was indicated by zig-zag behaviour in the measured horizontal shrinkage and capillary pressure. Air- entraining agent reduced horizontal shrinkage considerably. Use of fibre reduced shrinkage about 30% when compared to mix without fibre. Based on the results some conclusions are drawn concerning properly limed trowelling on horizontal shrinkage.

U2 - 10.1016/0008-8846(95)00170-0

DO - 10.1016/0008-8846(95)00170-0

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SN - 0008-8846

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ER -