Study on Fire Resistance of Cement

2013 ◽  
Vol 320 ◽  
pp. 308-313
Author(s):  
Lian Wei Shan ◽  
Jun Li Zhang ◽  
Wei Li ◽  
Zhao Jing Liu ◽  
Ze Wu ◽  
...  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Chemical Composition ◽  
Theoretical Analysis ◽  
Internal Structure ◽  
Fire Resistance ◽  
Room Temperature ◽  
Strength Loss ◽  
Hydration Products

This work aims to study the effect of sintering temperatures on the compressive strength and weight of net cement. The compressive strength and quality variety of cement which undergo different sintering temperatures (400°C, 600°C, 800°C, 900°C) and sintered at different times (1h, 2h) are studied through experiments and theoretical analysis. By using XRD explore the inner of sample chemical composition and further obtain the mechanism about sample of weight loss and strength loss. The main internal components of cement are Ca (OH)2, C-S-H, Ca2SiO3 and CaCO3 at room temperature. When the temperature was up to 400°C, The internal structure of cement started to be destroyed due to its hydration products C-S-H, Ca (OH)2 and CaCO3 began to decompose slowly. Keywords: Cement, Fire resistance, Compressive strength

Durability of Sugar Cane Bagasse Ash (SCBA) Concrete towards Chloride Ion Penetration

2014 ◽  
Vol 567 ◽  
pp. 369-374 ◽  
Author(s):  
Nasir Shafiq ◽  
Asma Abd Elhsameed ◽  
Muhd Fadhil Nuruddin
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Penetration Depth ◽  
Sugar Cane ◽  
Fine Particles ◽  
Strength Loss ◽  
Sugar Cane Bagasse ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Sugar Cane Bagasse Ash

In this study, the effect of sugar cane bagasse ash (SCBA) on chloride penetration resistance of concrete was investigated. 100-mm side cubes were cast and cured in water for 28 days followed by six months curing in 4% NaCl solution. The resistance to chloride penetration was assessed by measuring the chloride penetration depth, weight loss, compressive strength loss and bond strength loss. Chloride penetration depth was measured using AgNO3–based method. It was obtained that inclusion of SCBA in concrete significantly reduced the chloride penetration depth, weight loss, compressive strength loss and bond loss that was attributed to the fine particles of SCBA that filled up the pores and prevented the chloride ingress in the concrete.

Modified Plasters for Restoration and Finishing Works

2014 ◽  
Vol 923 ◽  
pp. 42-47 ◽  
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Roman Kotiv
Keyword(s):  
Compressive Strength ◽  
Chemical Composition ◽  
Cementitious Materials ◽  
Quality Parameters ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Hydration Products ◽  
High Quality ◽  
Physico Chemical ◽  
White Portland Cement

The paper is devoted to the research and development of modified plasters for restoration and finishing works based on decorative multicomponent cements containing white Portland cement and supplementary cementitious materials (silica fume, metakaolin and fine ground limestone). This cements are similar to Roman cement by their chemical composition. The use of optimal granulometry of decorative multicomponent cements provide directed formation of microstructure of the cement matrix with the formation of stable hydration products. Compositions of modified plasters by the criterions of workability and compressive strength were designed. Physico-chemical modification of plaster by complex air-entraining admixture allows to obtain high-quality modified plasters with improved quality parameters.

scholarly journals Feasibility study of compost as a partial substitute for fine aggregate in concrete

2021 ◽  
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Fine Particles ◽  
Strength Loss ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
Control Specimen ◽  
Sem Image ◽  
Significant Difference

Abstract In this study, vermicompost is replaced for fine aggregate in geopolymer concrete (GPC). Initially mix design is made for GPC and mix proportion is proposed. The vermicompost is replaced at 5%, 10%, 15% and 20% with M sand in GPC. Result indicates the 5% replacement with vermicompost based geopolymer concrete (GPVC) has the compressive strength of 32 N mm−2 (M30 grade) whereas the compressive strength of control specimen made with GPC is 37 N mm−2. Other replacement shows 21 N mm−2, 14 N mm−2 and 11 N mm−2 respectively. The 5% replaced concrete cubes and control specimen are tested at an elevated temperature of 200°C, 400°C, 600°C and 800°C and compared with the control specimen. There is no significant difference observed in weight lost at control (GPC) and GPVC specimen. An elevated temperature, the weight loss is almost 4% at 200°C because of expulsion of water from the concrete. Afterwards only 2% weight loss is observed in remaining elevated temperature. The compressive strength loss is observed at an elevated temperature in GPC and GPVC specimen because of thermal incompatibility between aggregate and the binder. EDX results show M sand and compost contains Si, Al, C, Fe, Ca, Mg, Na and K and it is similar in the elemental composition and SEM image confirms vermicompost contains fine particles.

scholarly journals Damage Evolution of Concrete Exposed to Sulfate Attack Under Drying-Wetting Cycles

2014 ◽  
Vol 8 (1) ◽  
pp. 444-449
Author(s):  
Lei Jiang ◽  
Ditao Niu
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Layer Thickness ◽  
Damage Evolution ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Damage Mechanism ◽  
Sulfate Attack ◽  
Corrosion Products ◽  
Damage Layer

The damage evolution of concrete subjected to drying-wetting cycles in different concentration of sodium sulfate solution was investigated based on micro and macro-observations. Through the experiment, weight loss, compressive strength loss and the damage layer thickness of concrete were measured after different drying-wetting cycles. The mechanical properties degradation in the damage layer of concrete was also analyzed. Furthermore, the scanning electron microscopy and X-ray diffraction were used to investigate the corrosion products of concrete, and the damage mechanism was also investigated by the modern microanalysis techniques. The test results show that the deterioration degree of physical properties of concrete specimens increases with increasing concentration. Weight loss of specimens caused by sulfate attack is not obvious compared with the other evaluation index. When the damage layer thickness of concrete is thicker as well as the ultrasonic speed is lower, indicating that the deterioration degree of concrete increases, and the compressive strength loss in damage layer is serious. It was also found that the compressive loss of concrete is correspond with the observations for the damage layer thickness. Additionally, the main corrosion products of concrete in sulfate solutions subjected to drying-wetting cycles were confirmed to be ettringite and gypsum, and the quantity of corrosion products formed is proportional to the concentration of the solution.

scholarly journals Research of Curing Time and Temperature-Dependent Strengths and Fire Resistance of Geopolymer Foam Coated on an Aluminum Plate

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 87
Author(s):  
Van Su Le ◽  
Petr Louda
Keyword(s):  
Compressive Strength ◽  
Apparent Density ◽  
Fire Resistance ◽  
Room Temperature ◽  
Sandwich Panels ◽  
Aluminum Plate ◽  
Curing Time ◽  
Test Results ◽  
Mass Ratio ◽  
Temperature Dependent

Geopolymer foam (GF) uses a potassium activator and can be cured at high temperatures, which can improve its mechanical properties. In this study, we attempted to test this hypothesis by comparing the flexural and compressive strength, apparent density and fire resistance of GF. The composition of the GF used in the experiment included a potassium activator, basalt ground fiber and aluminum powder with a mass ratio to the binder of 0.45, 0.3 and 0.015, respectively. The samples were cured at room temperature and at 50, 70, 85 and 105 °C with a curing time of 2, 4, 6, 12 and 24 h. Then, the samples were kept until being tested on the third, seventh, 14th and 28th day. The results showed that the flexural and compressive strength and apparent density improved and stabilized after seven days at 85 °C. Furthermore, the GF exhibited a substantial increase after three days in its flexural strength by 111% and compressive strength by 122.9% at the optimal temperature of 85 °C for 2 h compared to the values at RT after 28 days. The GF had an apparent density of 0.558–0.623 g/cm3 on the 28th day. As a new alternative to aluminum materials, investigating the fire resistance of sandwich panels (an aluminum plate covered with a GF layer) is important for their safe impregnation. Sandwich panels with thicknesses of 10–20 mm were exposed to a gas fire. The test results showed that the sandwich panels had significantly improved fire resistance compared to unprotected panels. The longest fire resistance times for the aluminum plate coated with 20 mm of GF layer thickness was 7500 s. Thus, the GF coated on the aluminum plate exhibited superior fire resistance and a reduced heat transfer rate compared to uncoated panels.

High Temperature Properties of Geopolymeric Ceramic

2008 ◽  
Vol 368-372 ◽  
pp. 1529-1531
Author(s):  
Yi Hai Jia ◽  
Min Fang Han ◽  
Ze Sheng Xu ◽  
Yan Gao ◽  
Xian Xian Meng
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Thermal Properties ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Room Temperature ◽  
Raw Materials ◽  
High Temperature Properties ◽  
Alkaline Activator

With fly ash, metakaolin, slag and alkaline activator as raw materials, the geopolymeric ceramic was synthesized and the properties, such as the weight loss, compressive strength and the structures, at high temperatures of 400~1200°C were measured. The weight loss is in the range of 8~13% from 400°C to 800°C. Comparing with the strength at room temperature, the compressive strength of samples is mostly increased at 400°C and all of them increased at 800°C. 9.65~28.32% strength declines at 1200°C. The variation of the compressive strength with temperature is explained based on the analyses of the phases constitutes and the thermal properties of samples.

scholarly journals Geopolymer coating as a protection of concrete against chemical attack and corrosion

2018 ◽  
Vol 49 ◽  
pp. 00101 ◽  
Author(s):  
Szymon Sikora ◽  
Ewa Gapys ◽  
Bartosz Michalowski ◽  
Tomasz Horbanowicz ◽  
Mariusz Hynowski
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Organic Acids ◽  
Setting Time ◽  
Strength Loss ◽  
Corrosive Environment ◽  
Initial Value ◽  
Great Resistance ◽  
Chemical Attack ◽  
Inorganic Acids

In order to mitigate and prevent chemical attack and concrete corrosion one has to choose the right concrete to make it less permeable or isolate it from the corrosive environment by using a suitable coating. Here, we present the use of geopolymer mortar made of local waste materials and sodium silicate as a chemo-resistive coating for concrete. In this paper, the development of geopolymer mortar working parameters (e.g. setting time and adhesion to concrete) is described. Here, we investigated the resistance of concrete samples coated with geopolymer to 10% inorganic/organic acids and saturated solution of sodium chloride. During the soaking in corrosive environment, weight loss and compressive strength were measured. Geopolymer coating described in this work showed great resistance to organic and inorganic acids. Coating of concrete samples reduced their weight loss after exposure to organic acids from 15% to 2% with concomitant compressive strength loss from 49% to 9% of the initial value. The difference in chemical resistance for inorganic acids was even more visible. Coating of concrete samples reduced their weight loss after exposure to inorganic acids from 73% to 0.8% with adequate compressive strength loss from 96% to only 3.5% of the initial value.

Thermomechanical Treatment of a 4340 Ni-Cr-Mo Alloy Steel

1981 ◽  
Vol 39 ◽  
pp. 314-315 ◽  
Author(s):  
M.T. Jahn ◽  
J.C. Yang ◽  
C.M. Wan
Keyword(s):  
Mechanical Property ◽  
Chemical Composition ◽  
Alloy Steel ◽  
Thermomechanical Treatment ◽  
Room Temperature ◽  
Good Combination ◽  
Thermal Treatments ◽  
Low Carbon ◽  
4340 Steel ◽  
Good Improvement

4340 Ni-Cr-Mo alloy steel is widely used due to its good combination of strength and toughness. The mechanical property of 4340 steel can be improved by various thermal treatments. The influence of thermomechanical treatment (TMT) has been studied in a low carbon Ni-Cr-Mo steel having chemical composition closed to 4340 steel. TMT of 4340 steel is rarely examined up to now. In this study we obtain good improvement on the mechanical property of 4340 steel by TMT. The mechanism is explained in terms of TEM microstructures4340 (0.39C-1.81Ni-0.93Cr-0.26Mo) steel was austenitized at 950°C for 30 minutes. The TMTed specimen (T) was obtained by forging the specimen continuously as the temperature of the specimen was decreasing from 950°C to 600°C followed by oil quenching to room temperature. The thickness reduction ratio by forging is 40%. The conventional specimen (C) was obtained by quenching the specimen directly into room temperature oil after austenitized at 950°C for 30 minutes. All quenched specimens (T and C) were then tempered at 450, 500, 550, 600 or 650°C for four hours respectively.

HAYNES STELLITE ALLOY No. 98M2

Alloy Digest ◽  
1960 ◽  
Vol 9 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Physical Properties ◽  
Room Temperature ◽  
Base Alloy ◽  
Heat Treating ◽  
The Other ◽  
Stellite Alloy ◽  
Cobalt Base Alloy ◽  
Cobalt Base

Abstract HAYNES STELLITE 98M2 Alloy is a cobalt-base alloy having higher compressive strength and higher hardness than all the other cobalt-base alloys at room temperature and in the red heat range. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive strength as well as fracture toughness. It also includes information on heat treating, machining, and joining. Filing Code: Co-22. Producer or source: Haynes Stellite Company.

On the use of Ozawa/Flynn/Wall method to determine aging activation energy for elastomers

2021 ◽  
pp. 009524432110203
Author(s):  
Sudhir Bafna
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Dwell Time ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Degradation Mechanism ◽  
Kinetics Of ◽  
Wall Method

It is often necessary to assess the effect of aging at room temperature over years/decades for hardware containing elastomeric components such as oring seals or shock isolators. In order to determine this effect, accelerated oven aging at elevated temperatures is pursued. When doing so, it is vital that the degradation mechanism still be representative of that prevalent at room temperature. This places an upper limit on the elevated oven temperature, which in turn, increases the dwell time in the oven. As a result, the oven dwell time can run into months, if not years, something that is not realistically feasible due to resource/schedule constraints in industry. Measuring activation energy (Ea) of elastomer aging by test methods such as tensile strength or elongation, compression set, modulus, oxygen consumption, etc. is expensive and time consuming. Use of kinetics of weight loss by ThermoGravimetric Analysis (TGA) using the Ozawa/Flynn/Wall method per ASTM E1641 is an attractive option (especially due to the availability of commercial instrumentation with software to make the required measurements and calculations) and is widely used. There is no fundamental scientific reason why the kinetics of weight loss at elevated temperatures should correlate to the kinetics of loss of mechanical properties over years/decades at room temperature. Ea obtained by high temperature weight loss is almost always significantly higher than that obtained by measurements of mechanical properties or oxygen consumption over extended periods at much lower temperatures. In this paper, data on five different elastomer types (butyl, nitrile, EPDM, polychloroprene and fluorocarbon) are presented to prove that point. Thus, use of Ea determined by weight loss by TGA tends to give unrealistically high values, which in turn, will lead to incorrectly high predictions of storage life at room temperature.

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