Individual and combined effects of modified starch, bentonite and their composite powder with HPMC on the performance of cement mortars

2013 ◽  
Vol 33 (6) ◽  
pp. 551-555 ◽  
Author(s):  
Ke Yuan ◽  
Libing Liao ◽  
Yunhua Wang ◽  
Zepeng Zhang ◽  
Daimei Chen ◽  
...  
Keyword(s):  
Water Retention ◽  
Composite Powder ◽  
Cement Mortar ◽  
Methyl Cellulose ◽  
High Water ◽  
Cellulose Ether ◽  
Modified Starch ◽  
Water Retention Value ◽  
Combined Use ◽  
Cement Mortars

Abstract A series of acetate starch was synthesized and mixed with bentonite to prepare acetate starch/bentonite composite as a novel additive in order to improve the thixotropic property of cement mortar. The thixotropic index and water retention value of the fresh cement mortar containing acetate starch, bentonite, and acetate starch/bentonite composite, respectively, were measured with and without hydroxypropyl methyl cellulose ether (HPMC). Acetate starch with the degree of substitution (DS) of about 0.5 provided the largest increase in the thixotropic index of the cement mortar. Application of HPMC gave high water retention ability and viscosity to the mortar, but the thixotropic property was not improved. Adding acetate starch or starch/bentonite composite to the mortar can increase its thixotropic index, whereas no significant improvements on the water retention ability and viscosity of mortars were observed. By the combined use of acetate starch/bentonite composite with HPMC, the water retention value (WRV) of the mortar was as high as 98%, and its thixotropic index increased from 4.06 to 5.30, with a high value of viscosity.

scholarly journals Water Retention Mechanism of HPMC in Cement Mortar

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2918 ◽  
Author(s):  
Ning Chen ◽  
Peiming Wang ◽  
Liqun Zhao ◽  
Guofang Zhang
Keyword(s):  
Network Structure ◽  
Water Retention ◽  
Fine Particles ◽  
Cement Mortar ◽  
Methyl Cellulose ◽  
Retention Mechanism ◽  
Plastic Viscosity ◽  
Cellulose Ether ◽  
3D Network ◽  
Migration Capacity

In this paper, the effect of HPMC (hydroxypropyl methyl cellulose ether) on the cement mortar water retention (WR) and composition was studied. The relationship between the plastic viscosity and water retention of cement mortar was revealed. The results showed that HPMC formed a colloidal film with a 3D network structure in water, which changed the ability of water to migrate. The HPMC colloid adsorbed on the surface of cement and sand particles and played a bridging role due to the influence of the spatial network structure of the thin film. Fine particles formed a grid-like distribution, and the hydration products formed a unique fibrous tree-like structure. A positive correlation was observed between the plastic viscosity and the water holding capacity of cement mortar. Finally, the mechanism responsible for the improved water retention of cement mortar by HPMC was analyzed using the changing water migration capacity, migration channels, and mortar cohesion.

scholarly journals Effects of Chemical Admixtures on the Working and Mechanical Properties of Ordinary Dry-Mixed Mortar

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Shu-Chun Zhou ◽  
Heng-Lin Lv ◽  
Ning Li ◽  
Jie Zhang
Keyword(s):  
Mechanical Properties ◽  
Water Retention ◽  
Cement Mortar ◽  
Setting Time ◽  
Methyl Cellulose ◽  
Cellulose Ether ◽  
Hydroxypropyl Methyl Cellulose ◽  
Chemical Admixtures ◽  
Retarding Effect ◽  
Mixed Mortar

The effects of hydroxypropyl methyl cellulose ether, starch ether, bentonite, and redispersion emulsoid powder on the working and mechanical properties of fresh dry-mixed mortar were studied. The results show that hydroxypropyl methyl cellulose ether has the greatest impact on the consistency and water retention of ordinary dry-mixed mortar and that redispersion emulsoid powder reduces the water action and starch ether has essentially no effect on water retention. It also shows that the time of mortar condensation when mixed with hydroxypropyl methyl cellulose ether is the longest, followed by redispersion emulsoid powder and bentonite. Starch ether can slightly, but not obviously, extend the setting time of cement mortar. Hydroxypropyl methyl cellulose ether has the greatest impact on the mechanical properties of ordinary dry-mixed mortar, followed by redispersion emulsoid powder, starch ether, and bentonite. As the water retention increases, the setting time of the mortar also increases. The use of water as a thickening material has a retarding effect on the mortar, increases the water-retention rate, and increases the retarding effect. Moreover, increasing the content of the chemical admixtures decreases the strength of cement mortar.

scholarly journals The Influence of Cement Type on the Properties of Plastering Mortars Modified with Cellulose Ether Admixture

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7634
Author(s):  
Edyta Spychał ◽  
Przemysław Czapik
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Portland Cement ◽  
Bulk Density ◽  
Water Retention ◽  
High Water ◽  
Cellulose Ether ◽  
Cement Type ◽  
Water Retention Value ◽  
Mineral Additives

In this article, the effect of cement type on selected properties of plastering mortars containing a cellulose ether admixture was studied. In the research, commercial CEM I Portland cement, CEM II and CEM III, differing in the type and amount of mineral additives, and cement class, were used as binders. Tests of consistency, bulk density, water retention value (WRV), mechanical properties and calorimetric tests were performed. It was proved that the type of cement had no effect on water retention, which is regulated by the cellulose ether. All mortars modified with the admixture were characterized by WRV of about 99%. High water retention is closely related to the action of the cellulose ether admixture. As a result of the research, the possibility of using cement with additives as components of plasters was confirmed. However, attention should be paid to the consistency, mechanical properties of the tested mortars and changes in the pastes during the hydration process. Different effects of additives resulted from increasing or decreasing the consistency of mortars; the flow was in the range from 155 mm to 169 mm. Considering the compressive strength, all plasters can be classified as category III or IV, because the mortars attained the strength required by the standard, of at least 3.5 MPa. The processes of hydration of pastes were carried out with different intensity. In conclusion, the obtained results indicate the possibility of using CEM II and CEM III cements to produce plastering mortars, without changing the effect of water retention.

scholarly journals Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2136
Author(s):  
Shaokang Zhang ◽  
Ru Wang ◽  
Linglin Xu ◽  
Andreas Hecker ◽  
Horst-Michael Ludwig ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Bond Strength ◽  
Cement Mortar ◽  
Retention Rate ◽  
Methyl Cellulose ◽  
Tensile Bond Strength ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Cement Mortars

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

Preparation of Coal Gangue Cement Mortar

2013 ◽  
Vol 684 ◽  
pp. 159-162
Author(s):  
Wen Xia Li ◽  
Dong Li Wang ◽  
Ji Shou Niu ◽  
Xian Wei Ma
Keyword(s):  
Cement Mortar ◽  
Methyl Cellulose ◽  
Coal Gangue ◽  
Cellulose Ether ◽  
Low Strength

Many researches on coal gangue are aimed at increasing its activity by many methods together such as thermal, mechanical and chemical. The methods are so complex that they are difficult to be adopted by some companies. In this paper, considering the low-strength requirement of cement mortar, the activity of coal gangue is more evidently shown by Ca(OH)2 activator. The 28-days strength of coal gangue cement mortar can reach 18MPa and the hydrated mortar shows and keeps an expansive behavior by adding methyl cellulose ether and CaSO4•2H2O at all the ages.

Use of Spongilites as Pozzolanic Additives in Cement Mortars

2021 ◽  
Vol 325 ◽  
pp. 65-70
Author(s):  
Martin Vyšvařil ◽  
Patrik Bayer ◽  
Tomáš Žižlavský
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
Frost Resistance ◽  
Water Retention ◽  
Cement Mortar ◽  
Partial Replacement ◽  
Fine Grained ◽  
Natural Pozzolans ◽  
Cement Mortars ◽  
Pozzolanic Additives

In this study, the utilization of two types of spongilites in various addition in cement mortars has been investigated with the purpose of exploring a new application of this natural pozzolans as cement mortar additives. The influence of the addition of spongilites on the physico-mechanical properties, frost-resistance, and microstructure of cement mortars as a function of time was studied. The results revealed that the rising proportion of spongilites in cement mortars causes increase in water retention of mortars, reduction of their bulk density, increase in porosity of mortars due to the growing predominance of capillary pores maintaining sufficient mortars strengths, and slightly increase in the frost-resistance of mortars. After initial tests, partial replacement of cement in fine-grained cement mortars with hitherto unexploited spongilites seems to be very promising. Based on the achieved results, a 20% cement replacement can be recommended as optimal.

scholarly journals UV polymerization and property analysis of maleacylated methyl cellulose acrylic acid absorbent resin

2020 ◽  
Vol 22 (2) ◽  
pp. 34-41
Author(s):  
Ying Li ◽  
Amatjan Sawut ◽  
Gongbo Hou ◽  
Mingyu He ◽  
Mamatjan Yimit
Keyword(s):  
Acrylic Acid ◽  
Water Absorption ◽  
Water Retention ◽  
Methyl Cellulose ◽  
High Water ◽  
Optimal Conditions ◽  
Synthetic Resin ◽  
Reaction Conditions ◽  
High Water Absorption ◽  
Maximum Water

AbstractIn this paper, maleic anhydride (MA) was grafted onto methyl cellulose (MC) and then reacted with acrylic acid to synthesize a high gel strength and fast water absorption resin (AA-co-MC-g-MA) by UV polymerization. The reaction conditions of maleylated methylcellulose (MC-g-MA) were investigated, including the ratio of MC to MA, reaction time and catalyst amount. In addition, the reaction conditions for the synthesis of super absorbent resin were as follows: the amount of MC-g-MA, the degree of substitution of MC-g-MA, polymerization time, and the amount of initiator. Under optimal conditions, the maximum water absorption volume of synthetic resin was 2116 g/g, and the maximum salt absorption rate was 139 g/g. The water absorption resin prepared this time had high water absorption, water retention, excellent pH sensitivity, etc. It was hoped that it will have a good application prospect in the field of industrial production and agriculture in the future.

scholarly journals The Influence of Hydrated Lime and Cellulose Ether Admixture on Water Retention, Rheology and Application Properties of Cement Plastering Mortars

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5487
Author(s):  
Edyta Spychał ◽  
Ryszard Dachowski
Keyword(s):  
Rheological Properties ◽  
Water Retention ◽  
Hydrated Lime ◽  
Plastic Viscosity ◽  
Subjective Rating ◽  
Cellulose Ether ◽  
Technological Properties ◽  
Water Retention Value ◽  
Rheological Measurements ◽  
Standard Tests

In this article, the effect of hydrated lime and cellulose ether on the water retention, rheology, and application properties of plasters was studied. For mortars, the consistency, bulk density, and water retention were tested. Rheological measurements of pastes included yield stress and plastic viscosity. In addition to standard tests of mortars and examining the rheological properties of the pastes, a proprietary method for testing the application properties was proposed. The obtained research results made it possible to evaluate the performance of the tested plasters. An attempt was also made to correlate the rheological properties of pastes (plastic viscosity) to the water retention value. The influence of hydrated lime and cellulose ether on selected properties of pastes and plasters was also presented using the statistical Box–Behnken method. The subjective rating of an expert plasterer confirmed the necessity of the modification of plastering mortars with hydrated lime and cellulose ether. As shown, modification of cement plastering mortar with hydrated lime and cellulose ether at the same time allows obtaining a material with favorable technical and technological properties, especially mortars applied by machine.

Incorporation of Iraqi Rocks in the Production of Eco-Friendly Cement Mortar

2020 ◽  
Vol 38 (10A) ◽  
pp. 1522-1530
Author(s):  
Rawnaq S. Mahdi ◽  
Aseel B. AL-Zubidi ◽  
Hassan N. Hashim
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Water Absorption ◽  
Structural Properties ◽  
Mechanical Milling ◽  
Cement Mortar ◽  
Cement Mortars

This work reports on the incorporation of Flint and Kaolin rocks powders in the cement mortar in an attempt to improve its mechanical properties and produce an eco-friendly mortar. Flint and Kaolin powders are prepared by dry mechanical milling. The two powders are added separately to the mortars substituting cement partially. The two powders are found to improve the mechanical properties of the mortars. Hardness and compressive strength are found to increase with the increase of powders constituents in the cement mortars. In addition, the two powders affect water absorption and thermal conductivity of the mortar specimens which are desirable for construction applications. Kaolin is found to have a greater effect on the mechanical properties, water absorption, and thermal conductivity of the mortars than Flint. This behavior is discussed and analyzed based on the compositional and structural properties of the rocks powders.

The Influence of the Ash Addition from Thermal Power Plant on the Mechanical, Thermal and Dielectric Characteristics of Mortars

2018 ◽  
Vol 69 (8) ◽  
pp. 2040-2044
Author(s):  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Adriana Moanta ◽  
Ladislau Radermacher ◽  
Adriana Mariana Bors
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Power Plant ◽  
Cement Mortar ◽  
Thermal Power ◽  
Total Content ◽  
Ash Content ◽  
Dielectric Losses ◽  
Dielectric Characteristics ◽  
Cement Mortars

The influence of fly ash adittion (90 % fraction [ 100 mm) on the cement mortar characteristics was studied. The XRD, XRF, SEM and FTIR determinations indicated that fly ash used has a hollow microstructure of microsphere and cenosphere whose total content in SiO2, Al2O3 and Fe2O3 is 88.63 % and that of CaO and MgO of 8.55 %. The mechanical, thermal and dielectric determinations made on mortar samples with content of fly ash in the 0-40 % range have highlighted fact that the mechanical strength of cement mortars is maximal at 20 %, the increase in fly ash content leads to a decrease in relative density and thermal conductivity as well as and to increased dielectric losses tgd.

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