Effectiveness of Thermal Stimulation of Superplasticizers on Fresh Properties of Cement Mortar

AbstractPolycarboxylic acid-based superplasticizers are used in various types of concrete work. Wide variations in environmental temperatures are known to affect how well chemical admixtures perform as superplasticizers, influencing the properties of the concrete. However, little has been reported on changes in performance caused by thermal variations. Previous studies have reported that heating superplasticizers change the polymer structure, improving and sustaining cement particles' dispersibility. Moreover, the improved fluidity from thermal stimulation is not temporary. The effect has been observed to remain for about seven days, with the residual characteristics differing depending on the superplasticizers used. Therefore this study evaluates mortar stiffness when using thermally stimulated superplasticizers and evaluates how the stimulation affects construction performance using measures such as the flow and rheological properties (plastic viscosity) of fresh mortar, vane shear tests, blade viscometer tests, and mortar vibration box tests. Mortar's fluidity was found to improve by about 25% when using thermally stimulated additives, with plastic viscosity dropping by up to 45% and the stress likely to be needed for pumping also being reduced by about 16%. Filling speed was also found to increase by about 26%. Thus, thermal stimulation improves mortar and concrete construction performance, and it may be possible in the future to carry out the construction with fewer workers utilizing this technology’s benefits. The study indicates a need for further investigation of how thermal stimulation affects polymer molecules’ adsorption efficiency with cement to elucidate the mechanism at full scale and propose ways to adopt thermal stimulation at actual construction sites.

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Effect of Delaying Addition of Heat Stimulated Superplasticizer on Fresh Properties of Mortar

Materials Science Forum ◽

10.4028/www.scientific.net/msf.890.396 ◽

2017 ◽

Vol 890 ◽

pp. 396-400 ◽

Cited By ~ 1

Author(s):

Zabihollah Tahery ◽

Faraidoon Rahmanzai ◽

Shigeyuki Date

Keyword(s):

Portland Cement ◽

Ordinary Portland Cement ◽

Cement Mortar ◽

Polycarboxylic Acid ◽

Fresh Properties ◽

External Temperature ◽

Factors Affecting ◽

Air Content ◽

Heat Stimulation ◽

Stimulation Of

To assure the quality and required workability of mortar or concrete, various types of superplasticizers are used. There are many factors affecting the performance of superplasticizers explicitly, type and dosage of the superplasticizers, type of cement, temperature and mixing procedure, as well as the addition times of the superplasticizers. Some researchers investigated the effect of delaying the addition time of superplasticizer to mortar or concrete, but there is not enough data about the effect of external temperature on performance of superplasticizers and consequent influences on fresh properties of mortar or concrete. In this research the effect of delaying the addition time of superplasticizers and influence of external temperature, namely, heat stimulation of superplasticizers, on fluidity, fresh density and air content of fresh cement mortar was investigated. Two types of Precast and Ready-Mix of Polycarboxylic acid-based ether superplasticizers with Ordinary Portland Cement was used. Delaying the addition time of superplasticizers enhanced the fluidity, slightly decreased the fresh density and increased the air content of mortar in comparison with simultaneous addition time with both heated and non-heated Superplasticizers.

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Basic Research of Improving the Mortar Flow by Thermal Stimulation to Superplasticizer

MATEC Web of Conferences ◽

10.1051/matecconf/201927801003 ◽

2019 ◽

Vol 278 ◽

pp. 01003

Author(s):

Mizuki Takigawa ◽

Fraidoon Rahmanzai ◽

Rio Kita ◽

Shigeyuki Date

Keyword(s):

Thermal Fluctuation ◽

Basic Research ◽

Thermal Stimulation ◽

Polycarboxylic Acid ◽

Heat Temperature ◽

Basic Performance ◽

Long Time ◽

Stimulation Of

Polycarboxylic acid-based superplasticizers are being used for various fields of concrete work, however little has reported on changing basic performance by thermal fluctuation. In this study, heating superplasticizers itself is hereinafter as referred to as “thermal stimulation”, the effect of thermal stimulation and heat retention of superplasticizer on the fresh mortar, moreover the influence of molecular structural changed of superplasticizer by thermal stimulation were investigated. As the result, it was confirmed that improving fluidity of the mortar flow on this condition the highly heat temperature and heat over a long time by thermal stimulation of superplasticizer. In addition, it turned out that this phenomenon was caused molecular structural changed by thermal stimulation, and the result was revealed that the effect of thermal stimulation varies according to the type of polymer.

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Preparation of Electric- and Magnetic-Activated Water and Its Influence on the Workability and Mechanical Properties of Cement Mortar

Sustainability ◽

10.3390/su13084546 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4546

Author(s):

Kaiyue Zhao ◽

Peng Zhang ◽

Bing Wang ◽

Yupeng Tian ◽

Shanbin Xue ◽

...

Keyword(s):

Magnetic Field ◽

Mechanical Properties ◽

Compressive Strength ◽

Flexural Strength ◽

Cement Paste ◽

Cement Mortar ◽

Environmental Issues ◽

Chemical Admixtures ◽

Untreated Water ◽

Alternating Voltage

Cement-based materials prepared with activated water induced by a magnetic field or electric field represent a possible solution to environmental issues caused by the worldwide utilization of chemical admixtures. In this contribution, electric- and magnetic-activated water have been produced. The workability and mechanical properties of cement mortar prepared with this activated water have been investigated. The results indicate that the pH and absorbance (Abs) values of the water varied as the electric and magnetic field changed, and their values increased significantly, exhibiting improved activity compared with that of the untreated water. In addition, activated water still retains activity within 30 min of the resting time. The fluidity of the cement paste prepared with electric-activated water was significantly larger than that of the untreated paste. However, the level of improvement differed with the worst performance resulting from cement paste prepared with alternating voltage activated water. In terms of mechanical properties, both compressive strength and flexural strength obtained its maximum values at 280 mT with two processing cycles. The compressive strength increased 26% as the curing time increased from 7 days to 28 days and flexural strength increased by 31%. In addition, through the introduction of magnetic-activated water into cement mortar, the mechanical strength can be maintained without losing its workability when the amount of cement is reduced.

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