Hinderance of C-S-H sheet piling during first drying using a shrinkage reducing agent: A SAXS study

This research is part of the mortar’s plastic shrinkage study. Contents in this article is related to how the Expansive Additive (EX), Shrinkage Reducing Agent (SRA), and Fly Ash (FA) help to reduce and control the shrinkage and to compare the effectiveness of these substances used in the normal curing, i.e., at 30 °C and in the steam curing process by using the factorial design with 3 factors and to be divided into 2 levels. Factors to be studied are the amount of EX, SRA and FA replacement. The test of plastic shrinkage was conducted in accordance with the ASTM C1579-06 standard, placing the strain gauge 0.5 centimeters beneath the surface in the middle of the mold, recording the shrinkage rate starting from the initial setting time for 24 hours. The results showed that, in normal curing, the EX influences the expansion while, in steam curing, the EX and SRA significantly influences the expansion. To add the FA in high volume along with the EX significantly effects the expansion for both the normal and steam curing. Furthermore, the study model and equation for plastic shrinkage of mortar are presented in the form of factor proportion to be considered from the factorial design study basis.

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Effects of Shrinkage Reducing Agent and Expansive Additive on Plastic Shrinkage of Mortar at Different Temperatures

MATEC Web of Conferences ◽

10.1051/matecconf/201820602002 ◽

2018 ◽

Vol 206 ◽

pp. 02002

Author(s):

Sarapon Treesuwan ◽

Komsan Maleesee ◽

Shigeyuki Date

Keyword(s):

High Temperature ◽

Setting Time ◽

Reducing Agent ◽

Early Age ◽

Initial Setting Time ◽

Plastic Shrinkage ◽

Different Temperatures ◽

Expansive Additive ◽

Hot Weather ◽

Shrinkage Reducing Agent

In the construction, it is inevitable to perform plaster work in hot weather which causes the dehydration and rapid shrinkage on the paste during the early age. This research shows the studies of reducing the plastic shrinkage of mortar during the early age with such additives as the Shrinkage Reducing Agent (SRA), the Expansive Additive (EX), and the Fly Ash (FA) in controlled temperatures at 30°C and 40°C, with relative humidity between 60% and 70% according to the ASTM C1579-06 standard, with the strain gauge installed at 0.5 cm.from the surface. The shrinkage rate was measured starting from the Initial Setting Time and every 10 minutes afterwards for 24 hours. The results show that high temperature effects the cracking and how to use different formulas of additive under different circumstances is considerably important. To use only one additive is not sufficient in high temperature. To use the SRA in addition to the EX enhances better expansion than to use only the EX. Moreover, it is recommended to pay close attention in adding large amount of the FA into mortar with the EX and SRA added which extremely enhances the expansion and potential cracking.

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Drying Shrinkage of Concrete Combining Expansive Additives and Shrinkage Reducing Agent

Journal of the Korea Concrete Institute ◽

10.4334/jkci.2006.18.3.397 ◽

2006 ◽

Vol 18 (3) ◽

pp. 397-404 ◽

Cited By ~ 6

Keyword(s):

Drying Shrinkage ◽

Reducing Agent ◽

Shrinkage Reducing Agent

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Tensile and Cracking Behaviors of Strain-Hardening Cement Composite (SHCC) with Fluosilicate Based Shrinkage-Reducing Agent (SRA)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.525.473 ◽

2014 ◽

Vol 525 ◽

pp. 473-477 ◽

Cited By ~ 1

Author(s):

Seung Ju Han ◽

Seok Joon Jang ◽

Zhong Jie Yu ◽

Hyun Do Yun

Keyword(s):

Strain Hardening ◽

Volume Fraction ◽

Cement Composite ◽

Tensile Tests ◽

Reducing Agent ◽

Direct Tension ◽

Direct Tension Test ◽

Rich Mixture ◽

Direct Tensile ◽

Shrinkage Reducing Agent

This paper provides the results of direct tensile tests for strain-hardening cement composite (SHCC) to investigate the influence of fluosilicate based shrinkage-reducing agent (SRA) on the tensile and cracking behaviors of SHCC material under direct tension. The specified compressive strength of the SHCC material is 50MPa. The adding ratio of fluosilicate based SRA for SHCC material is 2.5 and 5.0%. Two mixitures of SHCC with 2.2% polyvinyl alcohol (PVA) fibers at the volume fraction were mixed; two mixtures with SRA and one mixture of conventional SHCC material. To evaluate the tensile and cracking behaviors of SHCC materials, two dumbbell-shaped tensile specimens for each mixture were manufactured and tested in direct tension. Test results show that the addition of fluosilicate based SRA improved direct tensile and cracking behaviors of SHCC materials with rich mixture. This phenomenon is noticeable for SHCC with higher volume of SRA.

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