Optimization and modeling the impact of a green cementless binder and biogenic nanosilica on cement setting time

2021 ◽  
Author(s):  
Ibtisam Kamal ◽  
Ammar Ali ◽  
Aryan Far Sherwani
Keyword(s):  
Setting Time ◽  
Cementless Binder ◽  
The Impact ◽  
Cement Setting

Influence of Aluminous Cement on the Hardening Rate of Cement-Based Stucco Mortars

2016 ◽  
Vol 865 ◽  
pp. 57-61 ◽  
Author(s):  
Wojciech Siemiński ◽  
Marcin Kaczmarczyk
Keyword(s):  
Portland Cement ◽  
Setting Time ◽  
Experimental Studies ◽  
Cellulose Ether ◽  
Hydrophobic Properties ◽  
Content Ratio ◽  
Flow Table ◽  
Aluminous Cement ◽  
Hydrophobic Nature ◽  
The Impact

Renovation mortars used to restore damaged stucco elements are materials with special physical properties due to the nature of the work and environment in which they are applied. They must be characterized by low shrinkage, relatively short setting time, appropriate working properties and hydrophobic nature of hardened mortar. This paper analyzes the impact of mortar stucco ingredients on these parameters. The analysis was performed by experimental studies. The effect of the content ratio of aluminate cement to Portland cement on the change in mortar setting time was studied. Suitable workability of fresh mortar is achieved by the use of consistence-modifying additives. To assess this parameter, flow table method was applied in accordance with PN-EN 1015-3: 2000. The additives used were a system of thickeners, which included: cellulose ether in the form of hydroxyethylmethylcellulose and modified starch ether (starch 2-hydroxypropyl ether). Hydrophobic properties were obtained by the addition of triethoxyoctylsilane. The results were presented as graphs and tables. It was found that the ratio of aluminous cement to Portland cement most beneficial in terms of the setting rate of the resulting stucco mortar is 25% (m/m). This amount accelerates the end of setting time to 2 hours, the beginning of the setting time being 20 minutes. Suitable working characteristics were obtained by the addition of 0.080% of hydroxyethylmethylcellulose and 0.025% (m/m in dry mix) of starch 2-hydroxypropyl ether. Best hydrophobic properties of the hardened mortar was obtained by the addition of 0.075% (m/m in dry mix) of triethoxyoctylsilane.

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

2018 ◽  
Vol 149 ◽  
pp. 01012 ◽  
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.

scholarly journals Reduce the Influence of Horizontal and Vertical Cold Joints on the Behavior of High Strength Concrete Beam Casting in Hot Weather by Using Sugar Molasses

2018 ◽  
Vol 7 (4.19) ◽  
pp. 794
Author(s):  
Fatimah Hameed Naser Al-Mamoori ◽  
Ali Hameed Naser Al-Mamoori
Keyword(s):  
High Strength Concrete ◽  
Concrete Beam ◽  
Setting Time ◽  
Weather Condition ◽  
High Strength ◽  
Point Load ◽  
Concrete Element ◽  
Strength Concrete ◽  
Hot Weather ◽  
The Impact

The current research studies the effect of cold joints on the behavior shear and flexure of High Strength Concrete (HSC) beams caused by delayed casting sequence during the hot weather in summer of Iraq.Fresh concrete should be kept alive during the various casting batches for concrete element by re-vibration. However, the over vibration caused loss in homogeneity and it is difficult to keep the workability of concrete during hot weather due to the effect of setting time.To deal with this problem of improper casting sequence, which eventually leads to the formation of cold joints, it will be used sugar waste (named as Sugar Molasses (SM)) is a by-product resulted from refining process of sugar as a delayed agent to increase the setting time in order to prevent early set of concrete due to adverse effects in construction joint of hot weather.In the current study, the first objective aims to investigate some of fresh and hardened mechanical properties of HSC (with high cement content) using SM at percentages of (0, 0.05, 0.1, 0.2, 0.3) % from the weight of cement under the concept of sustainable development. The second objective aims to investigate the location and surface texture effect of horizontal and vertical cold joints on the flexural and shear behavior of beam with/without SM. This objective includes testing of twenty four plain concrete beam of (110×110×650 mm) under two point load; half of them casting without roughing (smooth) the old layer and the other casted after roughed it.SM content of 0.2% of cement weight can improve compressive strength by about 11.2% at 28 days and delay initial setting time by about 4.617 hours (277 minutes). No adverse effect on concrete have been observed at this dosage of SM concentration for the ages of concrete cylinders studied. Delays in the setting of concrete at this dosage of SM content help in reducing the early setting of concrete and therefore reduced the impact of the cold joints formation in concrete beams under Iraqi hot weather condition. The failure load for the beams with SM of smooth and rough vertical joints is in the range between (1.95 - 2.12) and (1.46-1.37); respectively times that of the case of beam without SM. 

scholarly journals Effect of boron-containing aggregates on setting and hardening of Portland cement mortars

2018 ◽  
Vol 163 ◽  
pp. 04003 ◽  
Author(s):  
Aneta Antolik ◽  
Michał A. Glinicki ◽  
Marek Gawlicki
Keyword(s):  
Isothermal Calorimetry ◽  
Setting Time ◽  
Radiation Shielding ◽  
Boron Compounds ◽  
Concrete Technology ◽  
Neutron Shielding ◽  
Mortar Strength ◽  
Cement Mortars ◽  
Isothermal Calorimeter ◽  
Cement Setting

Multicomponent cement-based composites are known as versatile structural materials for enhanced radiation shielding. The use of selected elements, like boron, cadmium, or rare earth elements, provides an increased neutron shielding capacity. Because of profusion, reasonable costs and large cross-section for neutron capture, boron containing minerals are suggested as aggregates for radiation shielding concrete. Despite many advantages, boron additives may act as cement setting retarders. Uncontrolled setting and hardening is not acceptable in radiation shielding concrete technology. In this work we present results from isothermal calorimetry measurements on cement mortars with boron-containing aggregates. Four types of boron aggregates were used in the studies: colemanite, ulexite, borax and boron carbide. Based on calorimetric curves, the beginning of setting time was determined. Additionally early mortar strength was investigated and linear relationship between the heat generated in the isothermal calorimeter and the early compressive strength has been observed. The use of isothermal calorimetry allowed us to estimate the limits for the content of boron compounds to be used cement mortar.

scholarly journals Influence of Lithium Carbonate on C3A Hydration

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Weiwei Han ◽  
Tao Sun ◽  
Xinping Li ◽  
Zhonghe Shui ◽  
Youzhi Chen ◽  
...  
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Setting Time ◽  
Lithium Ion ◽  
Mineralogical Composition ◽  
Lithium Carbonate ◽  
Initial Setting Time ◽  
Initial Setting ◽  
High Alkalinity ◽  
Cement Setting

Lithium salts, known to ameliorate the effects of alkali-silica reaction, can make significant effects on cement setting. However, the mechanism of effects on cement hydration, especially the hydration of C3A which is critical for initial setting time of cement, is rarely reported. In this study, the development of pH value of pore solution, conductivity, thermodynamics, and mineralogical composition during hydration of C3A with or without Li2CO3 are investigated. The results demonstrate that Li2CO3 promotes C3A hydration through high alkalinity, due to higher activity of lithium ion than that of calcium ion in the solution and carbonation of C3A hydration products resulted from Li2CO3. Li2CO3 favors the C3A hydration in C3A-CaSO4·2H2O-Ca(OH)2-H2O hydration system and affects the mineralogical variation of the ettringite phase(s).

scholarly journals An Experimental Investigation on Concrete by Partially Replacing Cement Using Bagasse Ash Powder

2021 ◽  
pp. 414-426
Author(s):  
Manish Ram E ◽  
Sindhu Vaardhini U
Keyword(s):  
Experimental Investigation ◽  
Compressive Strength ◽  
Sugarcane Bagasse ◽  
Setting Time ◽  
Mineral Admixtures ◽  
Partial Replacement ◽  
Waste Products ◽  
Agricultural Industry ◽  
Sugarcane Bagasse Ash ◽  
The Impact

Utilization of the waste products in the agricultural industry has been the focus of Research for economic, environmental, and technical reasons. Sugarcane Bagasse Ash (SCBA) is one of the promising material, with its potential proved to be used as a partial replacement of cement as well as mineral admixtures for producing concrete; properties of such concrete depend on the chemical composition, fineness, specific surface area of SCBA. An experimental investigation will be carried out to examine the impact of replacing cement by bagasse ash to the mechanical and physical properties of pastes and mortars, fresh and harden concrete such as consistency, setting time and workability, compressive strength. Sugarcane Bagasse Ash powder used by replacing fly ash at 40%, 50%, and 60%. Compressive strength and water absorption test will be carried out for evaluating the performance of the material.

scholarly journals Unicondylar knee arthroplasty in the inpatient vs. outpatient setting: Impact on process time

2018 ◽  
Vol 7 (3) ◽  
pp. 17
Author(s):  
Ibrahim Mamdouh Zeini ◽  
Meghan Hufstader Gabriel ◽  
Xinliang Liu ◽  
Alice Noblin ◽  
Bernardo Ramirez ◽  
...  
Keyword(s):  
Knee Arthroplasty ◽  
Setting Time ◽  
Ordinary Least Squares ◽  
Outpatient Setting ◽  
Unicondylar Knee Arthroplasty ◽  
Process Time ◽  
Inpatient Setting ◽  
Least Squares Regression ◽  
Time Savings ◽  
The Impact

Objective: There is a lack of research on the impact of transitioning inpatient procedures to the outpatient setting, specifically on process time. Unicondylar knee arthroplasty (UKA) presents an opportunity for further investigation as it is already in the early stages of transitioning to the outpatient setting.Methods: This study analyzed the medical records of 1,075 patients who received UKA from a single surgeon (400 in the outpatient setting and 675 in the inpatient setting). Time in Pre-Op, surgery time, and time in post-anesthesia care unit (PACU) were recorded and compared between inpatient and outpatient settings using Ordinary Least Squares Regression models.Results: Outpatient UKAs outperformed inpatient UKAs across two out of three process time variables even after controlling for comorbidities, social history, demographics, and surgery related characteristics. Actual surgery time was no different between the two settings.Conclusions: This study demonstrated that UKA performed in the outpatient setting is associated substantial time savings preoperatively and postoperatively compared with cases performed in the inpatient setting. More research is needed to compare other outcome measures such as patient outcomes of UKA between the two settings. Implications beyond time savings should consider supply and human resources costs.

scholarly journals Modification of early strength parameters of concrete by the addition of fly ash and admixture of nano C-S-H for application in 3D printing

2020 ◽  
Vol 323 ◽  
pp. 01016
Author(s):  
Bartosz Szostak ◽  
Grzegorz L. Golewski
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Hydraulic Press ◽  
Cement Matrix ◽  
Strength Parameters ◽  
Early Maturation ◽  
Cement Mortars ◽  
Compressive Strength Test ◽  
The Impact ◽  
Positive Effect

In the paper, the authors present the results of tests concerning traditional cement mortars with the addition of silica fly ash and the C-S-H nano-admixture. The use of fly ash results in improved plasticity of the mixture. The use of the C-S-H nano-admixture has a positive effect on shortening the setting time and a rapid increase in the strength of mixtures without losing their subsequent properties, which is presented in the research described in the paper. On this basis, the impact of fly ash and the nano-admixture on the selected parameters of the cement paste in the early maturation periods was determined – after 4, 8, 12, 24, 72h and also 7 and 28 days. The following tests were carried out on previously prepared samples: the compressive strength test on a hydraulic press, the test of setting time and the test of cement matrix shrinkage.

scholarly journals The Influence of Rice Husk on the Physical Properties of Portland Pozzoland Cement at the Cement Industry Scale

2019 ◽  
Vol 258 ◽  
pp. 01005
Author(s):  
Agus Maryoto ◽  
Gathot Heri Sudibyo
Keyword(s):  
Physical Properties ◽  
Rice Husk ◽  
Setting Time ◽  
Cement Industry ◽  
Good Effect ◽  
Type I ◽  
Test Results ◽  
Rice Husks ◽  
False Set ◽  
Cement Setting

This study aims to determine the effect of rice husk as a source of substitute fuel on the manufacture of cement at the industry scale. The parameters tested include the physical properties of the cement consisting of the Blain fineness test, false set, cement setting time, and mortar compressive strength at 3, 7, and 28 days. The average values for the results of these tests on cement produced using rice husks as a substitute fuel were 380 m2/kg, 81%, 132 minutes, 253 minutes, and 225, 298, and 379 kg/cm2, respectively. Based on the test results, we have shown that rice husk ash has a good effect on the characteristics of cement type I which still meet the standards of SNI-2049-2015.

Improving the Reliability of Cement-Setting-Time Tests by Taking Into Account the Influence of Shear

1993 ◽  
Vol 8 (01) ◽  
pp. 51-56 ◽  
Author(s):  
R.P.A.R. van Kleef ◽  
J.P.M. van Vliet
Keyword(s):  
Setting Time ◽  
Cement Setting
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