scholarly journals An An Analysis of Crystalline Admixtures in Terms of Their Influence on the Resistance of Cementitious Composites to Aggressive Environments

2020 ◽  
Author(s):  
Ámos Dufka ◽  
Nikol Žižková ◽  
Jiří Brožovský
Keyword(s):  
Computed Tomography ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Reference Laboratory ◽  
Chemical Analyses ◽  
X Ray ◽  
Physical Chemical

This paper describes the influence of crystalline admixtures on the chemical resistance of cement composites exposed to aggressive environments. The effect of the crystalline admixtures was determined by a series of physical-mechanical and innovative physical-chemical methods. Specifically, this concerned the measurement of flexural strength, compressive strength, determination of the dynamic modulus of elasticity by the ultrasonic pulse velocity test, and an analysis of the internal structure by mercury intrusion porosimetry and x-ray computed tomography. Physical-chemical analyses were also performed; namely an x-ray diffraction analysis to determine the mineralogical composition and electron microscopy to examine the microstructure. The use of non-destructive testing methods (ultrasonic pulse velocity test and computed tomography) made it possible to compare the properties of the same specimens for 16 months. The specimens were stored in reference laboratory conditions, a sodium sulphate solution and an ammonium chloride solution. The physical-mechanical tests and physical-chemical analyses clearly showed the benefit that crystalline admixtures have for the resistance of cementitious composites attacked by chemically aggressive solutions without affecting the fresh-mixture rheology or decreasing the strength of the composites.

scholarly journals Ultrasonic, Molecular and Mechanical Testing Diagnostics in Natural Fibre Reinforced, Polymer-Stabilized Earth Blocks

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
C. Galán-Marín ◽  
C. Rivera-Gómez ◽  
F. Bradley
Keyword(s):  
Soil Stabilization ◽  
Ultrasonic Pulse Velocity ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Mechanical Resistance ◽  
Chemical Compositions ◽  
Natural Polymer ◽  
Natural Polymers ◽  
X Ray ◽  
Earth Blocks

The aim of this research study was to evaluate the influence of utilising natural polymers as a form of soil stabilization, in order to assess their potential for use in building applications. Mixtures were stabilized with a natural polymer (alginate) and reinforced with wool fibres in order to improve the overall compressive and flexural strength of a series of composite materials. Ultrasonic pulse velocity (UPV) and mechanical strength testing techniques were then used to measure the porous properties of the manufactured natural polymer-soil composites, which were formed into earth blocks. Mechanical tests were carried out for three different clays which showed that the polymer increased the mechanical resistance of the samples to varying degrees, depending on the plasticity index of each soil. Variation in soil grain size distributions and Atterberg limits were assessed and chemical compositions were studied and compared. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), and energy dispersive X-ray fluorescence (EDXRF) techniques were all used in conjunction with qualitative identification of the aggregates. Ultrasonic wave propagation was found to be a useful technique for assisting in the determination of soil shrinkage characteristics and fibre-soil adherence capacity and UPV results correlated well with the measured mechanical properties.

scholarly journals Attempts to Improve the Subsurface Properties of Horizontally-Formed Cementitious Composites Using Tin(II) Fluoride Nanoparticles

Coatings ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 83 ◽  
Author(s):  
Kamil Krzywiński ◽  
Łukasz Sadowski ◽  
Jacek Szymanowski ◽  
Andrzej Żak ◽  
Magdalena Piechówka-Mielnik
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Abrasion Resistance ◽  
Mechanical Performance ◽  
Reference Sample ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Fluoride Nanoparticles

This article presents studies that were performed in order to improve the subsurface properties of horizontally-formed cementitious composites using tin(II) fluoride nanoparticles. The main aim of the study was to solve the problem of the decrease in subsurface properties caused by mortar bleeding and the segregation of the aggregate along the height of the overlay. The article also aims to highlight the patch grabbing difficulties that occur during the process of forming horizontally-formed cementitious composites. Four specimens were analyzed: one reference sample and three samples modified with the addition of 0.5, 1.0, and 1.5% of tin(II) fluoride nanoparticles in relation to the cement mass. To analyze the mechanical properties of the specimens, non-destructive (ultrasonic pulse velocity) and destructive tests (flexural tensile strength, compressive strength, abrasion resistance, pull-off strength) were performed. It was indicated that due to the addition of the tin(II) fluoride, it was possible to enhance the subsurface tensile strength and abrasion resistance of the tested cementitious composites. To confirm the obtained macroscopic results, the porosity of the subsurface was measured using SEM. It was also shown that the addition of the tin(II) fluoride nanoparticles did not reduce its flexural and compressive strength. The results show that horizontally-formed cementitious composites with the addition of 1.0% of tin(II) fluoride nanoparticles in relation to the cement mass obtained the most effective mechanical performance, especially with regard to subsurface properties.

scholarly journals Non Destructive Studies on Engineered Cementitious Composites using Microsilica & Polypropylene Fibre

2019 ◽  
Vol 8 (2S5) ◽  
pp. 18-21
Keyword(s):  
Compressive Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Mineral Admixture ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Polypropylene Fibres ◽  
Curing Regimes ◽  
Non Destructive

This study focuses on assessing the durability property of engineered cementitious composites using Ultrasonic pulse velocity method (direct and semi direct) to compute the compressive strength. Even the effect of mineral admixture on the mortar properties for different curing regimes shall be determined using this method. Mortar specimens containing microsilica in different percentages ranging from 5% to 25%, replacing portland cement by weight and adding polypropylene fibres ranging from 0.5% to 2% are chosen for evaluation. 20% of microsilica and 2% of polypropylene fibres induced to increase the range of UPV from 3463 m/s to 3505 m/s for 7 and 28 day curing regimes and also the compressive strength significantly improved for the above constituent. However there was a marginal decrease in the compressive strength and UPV outcomes when cement is replaced by microsilica greater than 20%. A relationship had been framed between ultrasound pulse velocity and compressive strength.

scholarly journals Multi-Analysis Characterisation of a Vernacular House in Doha (Qatar): Petrography and Petrophysics of its Construction Materials

Minerals ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 241
Author(s):  
Freire-Lista ◽  
Kahraman ◽  
Carter
Keyword(s):  
Analytical Data ◽  
Construction Materials ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Effective Porosity ◽  
City Centre ◽  
X Ray ◽  
Aesthetic Characteristics ◽  
Original Construction

This study characterises the original construction materials (building stones and mortars) of a collapsed two-storey colonnaded structure in the Ismail Mandani house, located in the old city centre of Doha (Qatar). Results were drawn based on interpretation and integration of historical, in situ observations and analytical data. The mortars and stones were characterised following a multidisciplinary approach, combining macroscopic observation with petrographic microscopy, mineralogical analysis (X-ray diffraction) and elemental analysis (handheld X-ray fluorescence) of samples. Moreover, hydric properties, ultrasonic pulse velocity and colour of representative samples of the house were studied. The results revealed the use of two types of stones and three different types of gypsum mortars. The original construction materials came from nearby coastal stones. Gypsum of the most used mortar had a calcination temperature between 120 and 160 °C and its colour was produced by lumps with higher Fe content. The materials’ effective porosity and water absorption were high, and their ultrasonic pulse velocity was low. These petrophysical results indicated they had low quality for construction purposes. The composition and colour of the original construction materials were quantified, which will allow the reproduction of their aesthetic characteristics and improvement of their quality in future reconstruction works.

scholarly journals Performance Evaluation of Cementitious Composites Incorporating Nano Graphite Platelets as Additive Carbon Material

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 290
Author(s):  
Farhan Ahmad ◽  
Arshad Jamal ◽  
Mudassir Iqbal ◽  
Muwaffaq Alqurashi ◽  
Meshal Almoshaogeh ◽  
...  
Keyword(s):  
Flexural Strength ◽  
Water Absorption ◽  
Microstructural Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Cementitious Composites ◽  
Air Content ◽  
Mechanical Durability ◽  
Huge Impact

Nano graphite platelets (NGPs) belong to the carbon family and have a huge impact on the construction industry. NGPs are used as multi-functional fillers and have the potential to develop reinforcing within cementitious composites. In this paper, NGPs were incorporated in cementitious composites to investigate the effects of NGPs on the fresh, mechanical, durability, and microstructural properties of concrete. Five mixes were prepared with intrusion of NGPs (0%, 0.5%, 1.5%, 3%, and 5% by weight of cement). The properties studied involved workability, air content, hardened density, compressive strength, tensile strength, flexural strength, sorptivity, ultrasonic pulse velocity (UPV), water absorption, and external sulfate attack. The workability and percent air content decrease by 22.5% and 33.8%, respectively, for concrete with 5% NGPs compared to the control mix. The specimens containing 5% of NGPs revealed the hardened density, compressive, tensile, and flexural strength to increase by 11.4%, 38.5%, 31.6%, and 44.34%, respectively, compared to the control mix. The results revealed that the incorporation of 5%NGPs in cementitious composites reduces the sorptivity and water absorption by 32.2% and 73.9%, respectively, whereas, it increases the UPV value by 7.5% compared to the control mix. Furthermore, the incorporation of NGPs provided better resistance against external sulfate attacks. SEM–EDX spectroscopy was carried out to investigate its microstructural analysis.

scholarly journals Quality Control and Evaluation Methods of Concrete Engineering and Its Reliability Analysis

2015 ◽  
Vol 9 (1) ◽  
pp. 639-643
Author(s):  
Xiaojian Wang ◽  
Kaiyu Jiang
Keyword(s):  
Compressive Strength ◽  
Reliability Analysis ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Reinforced Concrete Beams ◽  
Nondestructive Tests ◽  
Reliability Method ◽  
Analysis Models

Ultrasonic pulse velocity (UPV) and rebound hammer (RH) tests are often used for assessing the quality of concrete and estimation of its compressive strength. Several parameters influence the property of concrete, such as the type and size of aggregates, cement content and the implementation of concrete. To account for these factors, both of the two tests are combined and their measurements are calibrated with the results of mechanical tests on cylindrical specimens cast on site. In this study, the two tests cited above have been used to determine the concrete quality by applying regression analysis models between compressive strength of in situ concrete on existing structure and the nondestructive tests values. With the combined method, equations are derived using statistical analysis (simple and multiple regression) to estimate compressive strength of concrete on site. Besides, this paper presents the reliability analysis to nonlinear reinforced concrete beams. A First Order Reliability Method (FORM) is used, and the results are compared to the ones given by Monte Carlo simulation.

Effect of All-Component Recycled GFRP on Physical-Mechanical Properties and Microstructures of Concrete

2021 ◽  
Vol 1036 ◽  
pp. 402-418
Author(s):  
Bo Yu Zhou ◽  
Mo Zhang ◽  
Guo Wei Ma
Keyword(s):  
Setting Time ◽  
Ultrasonic Pulse Velocity ◽  
Cementitious Materials ◽  
Ultrasonic Pulse ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
Depth Of Field ◽  
Fine Aggregate ◽  
Reinforced Plastics ◽  
Splitting Strength

Large inventory and non-degradability made waste glass fiber reinforced plastics (GFRP) a heavy burden to environment. They are increasingly reclaimed through mechanical crushing and used as aggregate replacement in concrete. However, reuse of all-component recycled GFRP (rGFRP) was still limited due to the inconsistent influences of powder and fiber on cementitious materials. In this study, mortar and concrete with two different gradations of all-component rGFRP at 10 wt%, 20 wt% and 30 wt% were investigated with mechanical tests, ultrasonic pulse velocity inspection, Depth-of-Field optical microscopy, Scanning Electron Microscopy (SEM) and micro-CT. It revealed that the splitting strength of cement mortar was significantly increased while 10 wt% of rGFRP was added, whereas the compressive and flexural strength were barely affected. For concrete, the initial and final setting time were prolonged by the addition of 30 wt% rGFRP up to 93.8% and 124.3%, respectively. The mechanical strength of concrete increased with rGFRP content firstly, and then decreased, due to the reduced dispersity of rGFRP and compactness of mortar. When 10 wt% of rGFRP was added, the 28-day compressive, flexural and splitting strength of concrete were optimized to 25.8 MPa, 4.25 MPa and 3.02 MPa, respectively. The failure pattern analysis indicated that rGFRP can restrain crack propagation, reduce crack width and improve the integrity of fractured concrete. The results suggested the potential feasibility of rGFRP as fine aggregate replacement, and provided solid experimental references for practically reusing rGFRP in cementitious materials.

scholarly journals Effects of plasticizer and antifreeze on concrete at elevated temperatures and different cooling regimes

2020 ◽  
Vol 19 (3) ◽  
pp. 347-357
Author(s):  
İlknur Bekem Kara ◽  
◽  
Metin Arslan ◽  
Keyword(s):  
Elevated Temperatures ◽  
Strength Loss ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Concrete Mixtures ◽  
Main Components

In recent years, chemical admixtures have become one of the main components of concrete alongside aggregate, cement and water. In this study, the plasticizer and the antifreeze were used. The concrete specimens (the reference concrete without an admixture, concrete with plasticizer, concrete with antifreeze and concrete with plasticizer+antifreeze) were exposed to elevated temperatures (200, 400, 550 and 700 ºC) and cooling via air and water. Water absorption, ultrasonic pulse velocity and compressive strength tests were performed on the specimens. The concrete specimens were also analyzed using X-ray diffraction. The test results indicated that at the temperatures of 550 and 700 ºC and against both of the cooling regimes the plasticizer+antifreeze concrete showed a maximum strength loss. When the air cooled specimens were examined, the lowest strength loss was this obtained for reference concrete at 550 and 700 ºC. The lowest strength loss at these temperatures for the water cooled specimens was observed in the concrete with antifreeze. After being exposed to 700 ºC and the cooling regimes, no portlandite peaks were observed in the concrete mixtures was when they were compared at with the control specimen exposed to 20 ºC in the X-ray diffraction analysis.

Investigation of pozzolanic activity of volcanic rocks from the northeast of the Black Sea

2016 ◽  
Vol 23 (3) ◽  
pp. 315-323
Author(s):  
Mustafa Çullu ◽  
Hakan Bolat ◽  
Alaaddin Vural ◽  
Ertan Tuncer
Keyword(s):  
Black Sea ◽  
Early Stage ◽  
Volcanic Rocks ◽  
Chemical Properties ◽  
Blended Cement ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Mechanical Tests ◽  
Pulse Velocity ◽  
The Black Sea

AbstractMineralogical and chemical properties, as well as the pozzolanic activities, of the volcanic rocks in the northeast of the Black Sea were examined. Physical and mechanical tests were conducted on samples collected from the study area and the feasibility of using volcanic rocks as pozzolanic admixture in the concrete industry was investigated. Mortar samples containing admixture in the ratios of 0%, 10%, 20%, 30%, 40%, and 50% were prepared by keeping fineness of pozzolanic admixtures fixed. By using these mortar samples, prismatic mortar samples of 4×4×16 cm were prepared and the samples were cured in water. Their 7-, 28-, and 90-day tensile strengths, compressive strengths, and ultrasonic pulse velocity were determined. As a result, it was determined that volcanic rocks can be used to produce blended cement by considering their specific gravity, pozzolanic activities, and compressive strengths. It was noted that increase in trass rate significantly reduced tensile and compressive strength of cement in the early stage as expected.

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

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