scholarly journals Behavior of blended cement pastes at elevated temperature

2006 ◽  
Vol 12 (2) ◽  
pp. 133-136
Author(s):  
G. Kakali ◽  
R. Leventi ◽  
V. Benekis ◽  
S. Tsivilis
Keyword(s):  
Portland Cement ◽  
Fire Resistance ◽  
Elevated Temperatures ◽  
Blended Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Building Structures ◽  
Cement Pastes ◽  
Blended Cements

Fire can cause severe damage to building structures. This fact has increased the importance of the fire resistance of concrete. The consideration of the fire resistance of concrete requires the complete knowledge of the behaviour of each concrete component under elevated temperatures. The resistance of blended cement pastes upon heating was studied in the present paper. Natural pozzolana, fly ash, ground granulated blast-furnace slag, metakaolin and limestone were used as the main cement constituents. Blended cements were prepared by replacing a part of Portland Cement (PC) with the minerals mentioned above (10% w/w in the case of metakaolin, 20% w/w in the case of the rest materials). The specimens were water-cured for 3 months and then they were thermally treated at 200, 400, 600 800 and 1000?C for 1h. Visual inspection, mass measurements and ultrasonic pulse velocity measurements were carried out after each thermal treatment. It was concluded that the cohesion of the pastes was strongly affected by the kind of the main constituent, added to the Portland cement. The use of pozzolanic materials and especially metakaolin improved the fire resistance of the pastes, while the samples with limestone show the worst behavior.

Evaluation of the Electrical Resistivity, Ultrasonic Pulse Velocity and Mechanical Properties in Portland Cement Pastes Type II

2020 ◽  
Vol 841 ◽  
pp. 198-202
Author(s):  
Judith Alejandra Velázquez Perez ◽  
Elia Mercedes Alonso Guzmán ◽  
Wilfrido Martínez Molina ◽  
Hugo Luis Chávez García ◽  
Ioscany Talingo Moreno ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Resistivity ◽  
Portland Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Type Ii ◽  
Cement Pastes ◽  
Cementing Material ◽  
Non Destructive

This research is focused on cement pastes with w/c ratio of 0.5. The cementing material is Portland cement type II. The main aim is to estimate the mechanical properties based on non-destructive tests such as ultrasonic pulse velocity, and electrical resistivity by a correlation with the destructive tests such as compressive strength, flexural strength, and tensile strength at ages of 3,7,14,21,28 and 45 days. The results suggest that there is a good correlation between evaluated properties.

scholarly journals PERFORMANCE EVALUATION OF COIR PITH ASH BLENDED CEMENT CONCRETE EXPOSED TO ELEVATED TEMPERATURE

2020 ◽  
Vol 82 (2) ◽  
Author(s):  
Balagopal V ◽  
Viswanathan Sambamurthy
Keyword(s):  
Elevated Temperature ◽  
Elevated Temperatures ◽  
Blended Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Visual Observation ◽  
Pulse Velocity ◽  
Air Cooling ◽  
Water Cooling ◽  
Coir Pith

The concrete characteristics exposed to elevated temperature are gaining importance in terms of structural stability and serviceability state assessment of the structure. This paper deals with the study on behavior of coir pith ash (CPA) blended concrete exposed to elevated temperatures. Concrete specimens were prepared by replacing cement with CPA by percentages ranging from 0% to 20%. The specimens were then subjected to thermal treatment by exposing to temperatures of 200 °C, 400 °C, 600 °C and 800 °C in an electric furnace for a duration of 1 hour after the attainment of peak temperature. After providing the exposure, the samples were cured by air cooling or water-cooling and were tested for visual observation, residual compressive strength and ultrasonic pulse velocity. It has been observed that thermal performance of CPA blended concrete was better than that of control mix sample. Also, out of the two different cooling regimes adopted, air cooling method showed better performance that water cooling.

scholarly journals Ultrasonic Pulse Velocity—Compressive Strength Relationship for Portland Cement Mortars Cured at Different Conditions

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 133 ◽  
Author(s):  
Esteban Estévez ◽  
Domingo Alfonso Martín ◽  
Cristina Argiz ◽  
Miguel Ángel Sanjuán
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Internal Quality ◽  
Curing Conditions ◽  
Linear Relationships ◽  
Cement Mortars ◽  
Strength Relationship

The purpose of this paper is to establish some correlations between the main technical parameter with regard to the cement-based materials technology, the 28-day compressive strength, and ultrasonic pulse velocity of standard mortar samples cured at three different conditions—(i) under water at 22 °C; (ii) climatic chamber at 95% RH and 22 °C; (iii) lab ambient, 50% RH, and 22 °C—and after five curing periods of 1, 2, 7, 14, and 28 days. Good correlations for each curing conditions were obtained. All the positive linear relationships showed better R2 than exponential ones. These findings may promote the use of ultrasonic pulse velocity for the estimation of the 28-day compressive strength of standard Portland cement samples within the factory internal quality control.

Soundness in Mortars of Portland Cement with Substitutions Using Cactus (Opuntia ficus-indica) and Corn Starch

2018 ◽  
Vol 789 ◽  
pp. 150-154
Author(s):  
Victor Hugo Blancas-Herrera ◽  
Jorge Alberto Pacheco-Segovia ◽  
Wilfrido Martínez-Molina ◽  
Hugo Luis Chávez García ◽  
Mauricio Arreola-Sanchez ◽  
...  
Keyword(s):  
Portland Cement ◽  
Corn Starch ◽  
Weight Ratio ◽  
Physical And Mechanical Properties ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Electric Resistivity ◽  
Cement Matrix ◽  
Opuntia Ficus Indica

The use of dehydrated fibres of cactus, Opuntia ficus-indica (FN), and starch (corn starch,Zea Mays (MZ)) as partial substitutes for the total mass of Portland Cement (CP) in the making ofmortar, aims at modifying its physical and mechanical properties, reducing the amount of cementand the CO2 emission. Four mixtures of CP mortar were designed incorporating a superplasticizeradditive with a water/cement weight ratio of 0.68. To compare the results, there was a controlmortar; two mixtures with partial substitutions using fibres of FN, 0.5 and 1.5% (in weight of CP)respectively; and a substituted mixture with 2% of corn starch plus 0.5% of cactus fibre (MZ - FN).The test age was 180 days. The specimens were subjected to an accelerated attack of sodiumsulphate, quantifying the electric resistivity (ER) and the ultrasonic pulse velocity (UPV). Theresults indicate that the substitution of the materials, remarkably densify the cement matrix, whichresults in the improvement of the physical properties and the durability.

Recycled Concrete Using Crushed Construction Waste Bricks Subject to Elevated Temperatures

2010 ◽  
Vol 152-153 ◽  
pp. 1-10
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai
Keyword(s):  
Compressive Strength ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Plain Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Recycled Concrete ◽  
Fine Aggregate ◽  
Term Performance

The objectives of this paper are to find the compressive strength and ultrasonic pulse velocity (UPV) of recycled concrete with various percentages of natural fine aggregate replaced by Recycled brick fine aggregate (RBFA) as well as the residual strength and residual UPV of recycled concrete subjected to elevated temperatures. Experiment results showed that the compressive strength and UPV decreased as amount of RBFA in concrete increased, the long-term performance of compressive strength and UPV development increased as the RBFA content increased. The residual strength of recycled concrete increased slightly after heating to 300°C and the residual UPV of recycled concrete decreased gradually as the exposed temperature increased beyond 300°C. In the range of 580 -800°C, recycled concrete lost most of its original compressive strength and UPV. After subjected to the temperature of 800°C, compared to plain concrete, recycled concrete with 100% RBFA had a greater discount rate of compressive strength and UPV of the order of 5-15% and 6-10%. Regression analysis results revealed that the residual strength and residual UPV of recycled concrete had a high relevance after elevated temperatures exposure.

scholarly journals Factors influencing ultrasonic pulse velocity in concrete

2020 ◽  
Vol 13 (2) ◽  
pp. 222-247 ◽  
Author(s):  
J. P. GODINHO ◽  
T. F. DE SOUZA JÚNIOR ◽  
M. H. F. MEDEIROS ◽  
M. S. A SILVA
Keyword(s):  
Portland Cement ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Hydrated Calcium Silicate ◽  
Degree Of Hydration ◽  
Mix Proportion ◽  
Non Destructive ◽  
Cylindrical Test

Abstract The hydration process of Portland cement triggers reactions of stabilization of minerals from the contact of the clinker with water, which is the Hydrated Calcium Silicate (C-S-H), the Etringite (3CaO.Al2O3.3CaSO4.32H2O) and the Portlandite (Ca(OH)2). In order to understand the effects of the evolution of hydration in cement, it is possible to apply non-destructive tests. In this context, the objective of this work is to evaluate the influence of the type of cement, the curing age, of the format and humidity of the test specimens of concrete in the ultrasonic pulse velocity (UPV). In order to do that, 36 cylindrical test specimens (10 x 20 cm) and 9 cubic ones with 25 cm of edges, with mix proportion of 1:2,7:3,2 (cement/sand/gravel), water/cement ratio of 0.58 and three types of Portland cement (CP II-Z-32, CP IV-32 RS and CP V-ARI) were molded. With data obtained it was possible to correlate the increase of concrete strength along time (at ages of 7, 14, 28, 70 and 91 days) with the increase of the ultrasonic pulse velocity. Besides, it was possible to prove the direct influence of the concrete moisture and of the degree of hydration in the UPV. The shape of the test specimen generally had no influence on the results, except in the case of cement CP V ARI.

scholarly journals Analisis Hubungan Kecepatan Gelombang Dengan Kuat Tekan Beton Menggunakan Metode UPV

2020 ◽  
Vol 10 (1) ◽  
pp. 11
Author(s):  
Anggia Eta Rizkiasari ◽  
Abdul Rouf
Keyword(s):  
Compressive Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Method ◽  
Average Error ◽  
Strength Testing ◽  
Building Structures ◽  
Concrete Compressive Strength ◽  
Strength Based

Until now the use of concrete as a building material is still widely used for building structures. It is important to do concrete compressive strength testing as one of the factors to know the quality of a concrete. NDT (Non-Destructive Testing) is a method of solid quality testing without damaging the object. Testing with the NDT method is considered more efficient than the destructive test method. One method for performing NDT testing is by utilizing UPV (Ultrasonic Pulse Velocity).UPV is a method for estimating concrete compressive strength based on the ultrasonic pulse velocity relationship through concrete with the concrete compressive strength itself. UPV testing works by emitting ultrasonic pulses of 40 kHz through concrete to obtain the travel time of the pulse. Then the resulting time will be calculated the value of its speed and then will be converted into concrete compressive strength.Concrete compressive strength measurement system for high-quality concrete using UPV method can be designed by utilizing relation between ultrasonic pulse velocity with concrete compressive strength. Based on the test results, the average error value of concrete compressive strength testing is 3.04% with a maximum error of 6.63%.

scholarly journals Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joseph Mwiti Marangu ◽  
Cyprian Muturia M’thiruaine ◽  
Mark Bediako
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Rice Husk ◽  
Elevated Temperatures ◽  
Rice Husk Ash ◽  
Blended Cement ◽  
Strength Development ◽  
Carbonation Depth ◽  
Blended Cements ◽  
Carbonation Resistance

In the presence of significant quantities of carbon dioxide (CO2) and elevated temperatures in the atmosphere due to climate change, cement-based materials are susceptible to carbonation. Blended cements are more prone to carbonation attack than Portland cement. There is a need to evaluate the carbonation resistance of blended cements in a carbonation-prone environment. This paper presents experimental findings obtained from an evaluation of carbonation resistance tests on Rice Husk Ash- (RHA-) blended cement. The blended cement was made by intergrinding of Portland Cement (PC) and RHA to make the test cement (PC-RHA). The RHA dosage in the PC-RHA was varied from 0 to 30% by mass of PC. Pozzolanicity, standard consistency, and setting time tests were conducted on PC-RHA. Mortar prisms measuring 160 mm × 40 mm x 40 mm were separately cast at a water/cement ratio ( w / c ) of 0.50 and 0.60 and cured in water for 2, 7, 14, 28, and 90 days. Compressive strength tests were conducted on the mortar prisms at each of the testing ages. The prepared mortars were also subjected to accelerated carbonation tests in two Relative Humidity (RH) curing regimes, one maintained at an RH greater than 90% and the other between 50–60%. Carbonation resistance of the mixtures was evaluated in terms of the changes in carbonation depth using a phenolphthalein test at the age of 7, 14, 28, and 56 days of curing in a continuous flow of CO2. Compressive strength measurements were also taken during each of the carbonation testing ages. For comparison, similar tests were conducted using commercial PC. The results showed that PC-RHA was pozzolanic while PC was nonpozzolanic. Higher water demand and longer setting times were observed in PC-RHA than in PC. Moreover, there was increased strength development in water-cured samples with increased curing duration. Carbonation results indicated that there was a marked increase in carbonation depth with increased dosage of RHA in PC-RHA binders, increased duration of exposure to CO2, and decreased RH (RH between 50–60%). PC-RHA binders exhibited lower carbonation resistance than PC. In conclusion, for mortars at any w / c ratio, carbonation resistance decreased with increase in RHA dosage and increased w / c ratio.

Effect of Elevated Temperature on the Strength and Ultrasonic Pulse Velocity of Glass Fiber and Nano-Clay Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 1532-1539 ◽  
Author(s):  
Chung Ming Ho ◽  
Wei Tsung Tsai
Keyword(s):  
Compressive Strength ◽  
Glass Fiber ◽  
Residual Strength ◽  
Elevated Temperatures ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Nano Clay ◽  
Compressive Strength Of Concrete ◽  
Temperature Exposure

The objectives of this paper are to find the strength and ultrasonic pulse velocity (UPV) of concrete adding admixtures by glass fiber and nano-clay. Residual strength and residual UPV of concrete specimens subjected to elevated temperatures are investigated. Experiment results showed that adding glass fiber and nano-clay would be beneficial for the later-age compressive strength of concrete. Adding nano-clay could considerably increase the flexural and split strength and the toughness of concrete. It is revealed that adding nano-clay could significantly maintain residual compressive and split strength of specimens after high temperature exposure. Regression analysis results revealed that the residual strength and residual UPV of concrete specimens had a high relevance after elevated temperatures exposure.

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