Study of the addition of a chemical mix additive and curing temperature on the setting time and mechanical properties of no‐cement castable

Steel fibers and their aspect ratios are important parameters that have significant influence on the mechanical properties of ultrahigh-performance fiber-reinforced concrete (UHPFRC). Steel fiber dosage also significantly contributes to the initial manufacturing cost of UHPFRC. This study presents a comprehensive literature review of the effects of steel fiber percentages and aspect ratios on the setting time, workability, and mechanical properties of UHPFRC. It was evident that (1) an increase in steel fiber dosage and aspect ratio negatively impacted workability, owing to the interlocking between fibers; (2) compressive strength was positively influenced by the steel fiber dosage and aspect ratio; and (3) a faster loading rate significantly improved the mechanical properties. There were also some shortcomings in the measurement method for setting time. Lastly, this research highlights current issues for future research. The findings of the study are useful for practicing engineers to understand the distinctive characteristics of UHPFRC.

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Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

Materials ◽

10.3390/ma14071611 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1611

Author(s):

Gintautas Skripkiūnas ◽

Asta Kičaitė ◽

Harald Justnes ◽

Ina Pundienė

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Setting Time ◽

Calcium Nitrate ◽

Curing Temperature ◽

Hardened Concrete ◽

Cement Pastes ◽

Initial Setting Time ◽

Initial Setting ◽

Early Strength

The effect of calcium nitrate (CN) dosages from 0 to 3% (of cement mass) on the properties of fresh cement paste rheology and hardening processes and on the strength of hardened concrete with two types of limestone-blended composite cements (CEM II A-LL 42.5 R and 42.5 N) at different initial (two-day) curing temperatures (−10 °C to +20 °C) is presented. The rheology results showed that a CN dosage up to 1.5% works as a plasticizing admixture, while higher amounts demonstrate the effect of increasing viscosity. At higher CN content, the viscosity growth in normal early strength (N type) cement pastes is much slower than in high early strength (R type) cement pastes. For both cement-type pastes, shortening the initial and final setting times is more effective when using 3% at +5 °C and 0 °C. At these temperatures, the use of 3% CN reduces the initial setting time for high early strength paste by 7.4 and 5.4 times and for normal early strength cement paste by 3.5 and 3.4 times when compared to a CN-free cement paste. The most efficient use of CN is achieved at −5 °C for compressive strength enlargement; a 1% CN dosage ensures the compressive strength of samples at a −5 °C initial curing temperature, with high early strength cement exceeding 3.5 MPa but being less than the required 3.5 MPa in samples with normal early strength cement.

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Utilization of Solid Waste from Brick Industry and Hydrated Lime in Self-Compacting Cement Pastes

Materials ◽

10.3390/ma14051109 ◽

2021 ◽

Vol 14 (5) ◽

pp. 1109

Author(s):

Mati Ullah Shah ◽

Muhammad Usman ◽

Muhammad Usman Hanif ◽

Iqra Naseem ◽

Sara Farooq

Keyword(s):

Mechanical Properties ◽

Solid Waste ◽

Manufacturing Industry ◽

Setting Time ◽

Hydrated Lime ◽

Pozzolanic Reaction ◽

Early Age ◽

Cement Pastes ◽

Brick Powder ◽

High Degree

The huge amount of solid waste from the brick manufacturing industry can be used as a cement replacement. However, replacement exceeding 10% causes a reduction in strength due to the slowing of the pozzolanic reaction. Therefore, in this study, the pozzolanic potential of brick waste is enhanced using ultrafine brick powder with hydrated lime (HL). A total of six self-compacting paste mixes were studied. HL 2.5% by weight of binder was added in two formulations: 10% and 20% of waste burnt brick powder (WBBP), to activate the pozzolanic reaction. An increase in the water demand and setting time was observed by increasing the replacement percentage of WBBP. It was found that the mechanical properties of mixes containing 5% and 10% WBBP performed better than the control mix, while the mechanical properties of the mixes containing 20% WBBP were found to be almost equal to the control mix at 90 days. The addition of HL enhanced the early-age strength. Furthermore, WBBP formulations endorsed improvements in both durability and rheological properties, complemented by reduced early-age shrinkage. Overall, it was found that brick waste in ultrafine size has a very high degree of pozzolanic potential and can be effectively utilized as a supplementary cementitious material.

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Enhancing the mechanical properties and cytocompatibility of magnesium potassium phosphate cement by incorporating oxygen-carboxymethyl chitosan

Regenerative Biomaterials ◽

10.1093/rb/rbaa048 ◽

2020 ◽

Author(s):

Changtian Gong ◽

Shuo Fang ◽

Kezhou Xia ◽

Jingteng Chen ◽

Liangyu Guo ◽

...

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Physicochemical Properties ◽

Bone Cement ◽

Ph Value ◽

Setting Time ◽

Potassium Phosphate ◽

Carboxymethyl Chitosan ◽

Bioactive Substances ◽

Magnesium Potassium Phosphate Cement

Abstract Incorporating bioactive substances into synthetic bioceramic scaffolds is challenging. In this work, oxygen-carboxymethyl chitosan (O-CMC), a natural biopolymer that is nontoxic, biodegradable and biocompatible, was introduced into magnesium potassium phosphate cement (K-struvite) to enhance its mechanical properties and cytocompatibility. This study aimed to develop O-CMC/magnesium potassium phosphate composite bone cement (OMPC), thereby combining the optimum bioactivity of O-CMC with the extraordinary self-setting properties and mechanical intensity of the K-struvite. Our results indicated that O-CMC incorporation increased the compressive strength and setting time of K-struvite and decreased its porosity and pH value. Furthermore, OMPC scaffolds remarkably improved the proliferation, adhesion and osteogenesis related differentiation of MC3T3-E1 cells. Therefore, O-CMC introduced suitable physicochemical properties to K-struvite and enhanced its cytocompatibility for use in bone regeneration.

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Effect of Heat Setting Methods on Structures and Properties of High Strength Polyvinyl Alcohol Fibre

Materials Science Forum ◽

10.4028/www.scientific.net/msf.815.643 ◽

2015 ◽

Vol 815 ◽

pp. 643-648

Author(s):

Yin Zhu ◽

Jiong Xin Zhao

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Polyvinyl Alcohol ◽

Setting Time ◽

High Strength ◽

Single Fibre ◽

X Ray Diffraction ◽

Heat Setting ◽

Heat Treated ◽

Setting Process

The effect of heat setting methods on the structures and mechanical properties of high strength polyvinyl alcohol (PVA) fibre is studied in this article. The microstructure and mechanical properties of heat treated PVA fibre is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fibre electronic tensile strength tester. Results show that the heat setting method with constant tension is a good heat setting method which can largely enhance the tensile strength of PVA fibre. During the heat setting process, the mechanical properties of PVA fibre are greatly affected by the temperature, tension and setting time. When the temperature is 220°C, tension is 5cN/dtex and setting time is 90sec, the tensile strength of PVA fibre increases from 12.0cN/dtex to 16.4cN/dtex in compare with the PVA fibre without heat setting

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Physical-Mechanical Properties of Cupola Slag Cement Paste

Applied Sciences ◽

10.3390/app11157029 ◽

2021 ◽

Vol 11 (15) ◽

pp. 7029

Author(s):

Carlos Thomas ◽

José Sainz-Aja ◽

Israel Sosa ◽

Jesús Setién ◽

Juan A. Polanco ◽

...

Keyword(s):

Mechanical Properties ◽

Circular Economy ◽

Setting Time ◽

Casting Process ◽

Industrial Sector ◽

Sulphate Attack ◽

Experimental Campaign ◽

High Consumption ◽

Superior Mechanical Properties ◽

Environmental Savings

The high consumption of natural resources in the industrial sector makes it necessary to implement measures that enable the reuse of the waste generated, seeking to achieve circular economy. This work assesses the viability of an alternative to the use of CEM III B 32.5 R cement in mortars for the internal coating of centrifugally spun cast iron pipes for water piping. The proposal is to reuse the slag generated in the casting process after being finely ground, as an addition mixed with CEM I 52.5 R cement, which is basically Portland clinker. In order to analyse this possibility, an extensive experimental campaign was carried out, including the analysis of the cupola slag (micro-structural and chemical composition, leachates, setting time, vitrification, puzzolanicity and resistance to sulphate) and regarding the mortars (workability and mechanical properties). The experimental programme has shown that the optimum substitution is achieved with a replacement percentage of 20% of the cement, with which similar workability, superior mechanical properties and guaranteed resistance to sulphate attack are obtained. In addition, both economic and environmental savings are achieved by not having to transport or landfill the waste. In addition, the new cement is cheaper than the cement currently used.

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Effect of Tartaric Acid on the Printable, Rheological and Mechanical Properties of 3D Printing Sulphoaluminate Cement Paste

Materials ◽

10.3390/ma11122417 ◽

2018 ◽

Vol 11 (12) ◽

pp. 2417 ◽

Cited By ~ 8

Author(s):

Mingxu Chen ◽

Xiangyang Guo ◽

Yan Zheng ◽

Laibo Li ◽

Zhen Yan ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Property ◽

3D Printing ◽

Tartaric Acid ◽

Apparent Viscosity ◽

Setting Time ◽

Sulphoaluminate Cement ◽

Low Viscosity ◽

Ultimate Deformation ◽

Rapid Setting

Rapid setting and low viscosity of sulphoaluminate cement (SAC) make it difficult to be extruded by 3D printing (3DP) technique. In this study, the effect of tartaric acid (TA) on printability, rheology and mechanical property of 3DP SAC paste is investigated. The experimental results indicate that the setting time, hydration evolution and apparent viscosity of SAC paste can be well controlled by adding a proper amount of TA to satisfy the requirements of 3DP. An excellent structure of SAC paste with the ultimate deformation rate less than 10% can be printed without compromising mechanical strength.

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Effect of TiO2 Nanoparticles on Physical and Mechanical Properties of Cement at Low Temperatures

Advances in Materials Science and Engineering ◽

10.1155/2018/8934689 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 8

Author(s):

Li Wang ◽

Hongliang Zhang ◽

Yang Gao

Keyword(s):

Mechanical Properties ◽

Low Temperatures ◽

Cement Hydration ◽

Setting Time ◽

Physical And Mechanical Properties ◽

Xrd Analysis ◽

Cementitious Materials ◽

Strength Test ◽

Hydration Degree ◽

Time Test

Low temperature negatively affects the engineering performance of cementitious materials and hinders the construction productivity. Previous studies have already demonstrated that TiO2 nanoparticles can accelerate cement hydration and enhance the strength development of cementitious materials at room temperature. However, the performance of cementitious materials containing TiO2 nanoparticles at low temperatures is still unknown. In this study, specimens were prepared through the replacement of cement with 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.%, and 5 wt.% TiO2 nanoparticles and cured under temperatures of 0°C, 5°C, 10°C, and 20°C for specific ages. Physical and mechanical properties of the specimens were evaluated through the setting time test, compressive strength test, flexural strength test, hydration degree test, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD) analysis, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM) in order to examine the performance of cementitious materials with and without TiO2 nanoparticles at various curing temperatures. It was found that low temperature delayed the process of cement hydration while TiO2 nanoparticles had a positive effect on accelerating the cement hydration and reducing the setting time in terms of the results of the setting time test, hydration degree test, and strength test, and the specimen with the addition of 2 wt.% TiO2 nanoparticles showed the superior performance. Refined pore structure in the MIP tests, more mass loss of CH in TGA, intense peak appearance associated with the hydration products in XRD analysis, and denser microstructure in SEM demonstrated that the specimen with 2 wt.% TiO2 nanoparticles exhibited preferable physical and mechanical properties compared with that without TiO2 nanoparticles under various curing temperatures.

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Application areas of phosphogypsum in production of mineral binders and composites based on them: a review of research results

MATEC Web of Conferences ◽

10.1051/matecconf/201814901012 ◽

2018 ◽

Vol 149 ◽

pp. 01012 ◽

Cited By ~ 1

Author(s):

Leonid Dvorkin ◽

Nataliya Lushnikova ◽

Mohammed Sonebi

Keyword(s):

Mechanical Properties ◽

Blast Furnace ◽

Blast Furnace Slag ◽

Setting Time ◽

Industrial Wastes ◽

Cement Clinker ◽

Complete Replacement ◽

Slaked Lime ◽

The Impact ◽

Furnace Slag

The increase of the consumption of gypsum products in construction industry with a limited amount of natural gypsum deposits requires alternative sources of gypsum-containing raw materials. In some countries which have fertilizers industry plants, the problem can be solved using industrial wastes, e.g. phosphorgypsum – a byproduct of fertilizers’ production. Kept in dumps over decades, phosphorgypsum is subjected to the chemical changes due to washing out impurities with rain and other natural factors. However, there are observed deviations of harmful impurities in dumped PG depending on its age., Phosphorgypsum of any age requires chemical treatment to neutralize remains of phosphorus and sulfuric acids, fluorine compounds. According to our researches one of the most simple and effective method of neutralization the impurities is using lime-containing admixtures. The paper presents results of laboratory tests of phosphorgypsum as a component of clinker and non-clinker binders. There were investigated the impact of phosphorgypsum as admixture for clinker binders to substitute natural gypsum. Neutralized phosphorgypsum can be applied as mineralizing admixture in calcination of Portland cement clinker. Adding 2 to 2.5% of phosphorgypsum as setting time regulator resulted in a similar physical and mechanical properties compared to mix made with natural gypsum. Another important area of phosphorgypsum application is sulphate activatoion of low-clinker blast-furnace slag cement (clinker content is less than 19%). According to results, the incorporation of phosphorgypsum as sulphate activator in cement has the better effect as natural gypsum. Other development has been carried out to modify the phosphorgypsum binder properties. Complex additive consisted of polycarboxylate-based superplasticizer and slaked lime permitted an increase mechanical properties of hardened phosphorgypsum binder due to significant a reduction of water consumption. Such modified binder can be used as partial or complete replacement of gypsum binder for filling cements and finishing plasters. It can substitute gypsum in non-clinker binders like supersulphated cements. There were also developed compositions of supersulphated cements based on low-alumina blast furnace slag and phosphorgypsum. Supersulphated cements were tested in normal-weight and light-weight concrete.

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Mechanical properties of bulk Sylgard 184 and its extension with silicone oil

Scientific Reports ◽

10.1038/s41598-021-98694-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

R. Moučka ◽

M. Sedlačík ◽

J. Osička ◽

V. Pata

Keyword(s):

Mechanical Properties ◽

Tensile Test ◽

Ambient Temperature ◽

Oil Content ◽

Silicone Oil ◽

Polymer System ◽

Industrial Applications ◽

Curing Temperature ◽

Rotational Rheometer ◽

Oil Concentration

AbstractDue to its simple curing and very good mechanical properties, Sylgard 184 belongs to the most widely and frequently used silicones in many industrial applications such as microfluidics and microengineering. On top of that its mechanical properties are further controllable through the curing temperature, which may vary from ambient temperature up to 200 °C; the lower the curing temperature the lower the mechanical properties (Johnston et al. in J Micromech Microeng 24:7, 2014. 10.1088/0960-1317/24/3/035017). However, certain specialised application may require even a softer binder than the low curing temperature allows for. In this study we show that this softening can be achieved with the addition of silicone oil into the Sylgard 184 system. To this end a series of Sylgard 184 samples with varying silicone oil concentrations were prepared and tested (tensile test, rotational rheometer) in order to determine how curing temperature and silicone oil content affect mechanical properties. Curing reaction of the polymer system was found to observe 2nd order kinetics in all cases, regardless the oil concentration used. The results suggest that within the tested concentration range the silicone oil addition can be used to soften commercial silicone Sylgard 184.

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