scholarly journals THE USE OF FRACTAL GEOMETRY FOR THE ASSESSMENT OF THE DIVERSIFICATION OF MACRO-PORES IN CONCRETE

2011 ◽  
Vol 30 (2) ◽  
pp. 89 ◽  
Author(s):  
Janusz Konkol ◽  
Grzegorz Prokopski
Keyword(s):  
Fractal Dimension ◽  
Cross Sections ◽  
Fractal Geometry ◽  
Relative Number ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Air Content ◽  
Box Method

The article presents the results of examination of the fractal dimension D of macro-pores in concrete. The concretes were made from coarse basalt aggregate. Fractal examinations showed that the fractal dimension D of macro-pores in concrete was different, depending on the water-cement ratio W/C. The performed examination of macro-pores in concretes has shown the existence of a statistically significant correlation between the fractal dimension DBC, as determined by the box method, the relative number of pore crosssections NA (or the number of pores N) and the total air content A, as well as between the fractal dimension DBC, the relative number of pore cross-sections NA and the water-cement ratio W/C.

scholarly journals Use of Nondestructive Testing of Ultrasound and Artificial Neural Networks to Estimate Compressive Strength of Concrete

Buildings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 44
Author(s):  
Fernando A. N. Silva ◽  
João M. P. Q. Delgado ◽  
Rosely S. Cavalcanti ◽  
António C. Azevedo ◽  
Ana S. Guimarães ◽  
...  
Keyword(s):  
Neural Networks ◽  
Compressive Strength ◽  
Artificial Neural Networks ◽  
Cross Sections ◽  
Influential Factors ◽  
Average Error ◽  
Ann Model ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Artificial Neural

The work presents the results of an experimental campaign carried out on concrete elements in order to investigate the potential of using artificial neural networks (ANNs) to estimate the compressive strength based on relevant parameters, such as the water–cement ratio, aggregate–cement ratio, age of testing, and percentage cement/metakaolin ratios (5% and 10%). We prepared 162 cylindrical concrete specimens with dimensions of 10 cm in diameter and 20 cm in height and 27 prismatic specimens with cross sections measuring 25 and 50 cm in length, with 9 different concrete mixture proportions. A longitudinal transducer with a frequency of 54 kHz was used to measure the ultrasonic velocities. An ANN model was developed, different ANN configurations were tested and compared to identify the best ANN model. Using this model, it was possible to assess the contribution of each input variable to the compressive strength of the tested concretes. The results indicate an excellent performance of the ANN model developed to predict compressive strength from the input parameters studied, with an average error less than 5%. Together, the water–cement ratio and the percentage of metakaolin were shown to be the most influential factors for the compressive strength value predicted by the developed ANN model.

Fractal geometry of ammonoid sutures

Paleobiology ◽  
1995 ◽  
Vol 21 (3) ◽  
pp. 329-342 ◽  
Author(s):  
Timothy M. Lutz ◽  
George E. Boyajian
Keyword(s):  
Fractal Dimension ◽  
Fractal Geometry ◽  
Two Dimensional ◽  
Evolutionary Time ◽  
Linear Features ◽  
Divider Method ◽  
Richardson Method ◽  
Components Analysis ◽  
Box Method ◽  
Range Of Variation

Interior chamber walls of ammonites range from smoothly undulating surfaces in some taxa to complex surfaces, corrugated on many scales, in others. The ammonite suture, which is the expression of the intersection of these walls on the exterior of the shell, has been used to assess anatomical complexity. We used the fractal dimension to measure sutural complexity and to investigate complexity over evolutionary time and showed that the range of variation in sutural complexity increased through time. In this paper we extend our analyses and consider two new parameters that measure the range of scales over which fractal geometry is a satisfactory metric of a suture. We use a principal components analysis of these parameters and the fractal dimension to establish a two-dimensional morphospace in which the shapes of sutures can be plotted and in which variations and evolution of suture morphology can be investigated. Our results show that morphospace coordinates of ammonitic sutures correspond to visually perceptible differences in suture shape. However, three main classes of sutures (goniatitic, ceratitic, and ammonitic) are not unambiguously discriminated in this morphospace. Interestingly, ammonitic sutures occupy a smaller morphospace than other suture types (roughly one-half of the morphospace of goniatitic and ceratitic sutures combined), and the space they occupied did not change dimensions from the Jurassic to the late Cretaceous.We also compare two methods commonly used to measure the fractal dimension of linear features: the Box method and the Richardson (or divider) method. Both methods yield comparable results for ammonitic sutures but the Richardson method yields more precise results for less complex sutures.

The Study of the Factors Effecting Bond Strength of Masonry

2014 ◽  
Vol 1065-1069 ◽  
pp. 2011-2016
Author(s):  
Tao Zhang ◽  
Qian Wang
Keyword(s):  
Bond Strength ◽  
Compression Strength ◽  
Hydration Products ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Air Content ◽  
The Impact ◽  
The Relationship

The results of this paper are being summarized in a series of articles categorized into the principal properties of the mortars, for example compression strength, admixtures, air-content and water cement ratio, and the impact of those properties on bond strength were analyzed. The second purpose of this article deals with the relationship between brick’s properties with bond strength. The results shown that those effecting factors mainly through make an influence on the amount of hydration products and the bonded area to determine bond strength.

scholarly journals Study on the Strength and Micro Characteristics of Grouted Specimens with Different Superfine Cement Contents

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6709
Author(s):  
Dongyue Zhang ◽  
Zhenqian Ma ◽  
Yihuai Zou ◽  
Hongfei Xie ◽  
Ruichong Guan
Keyword(s):  
Compressive Strength ◽  
Fractal Dimension ◽  
Cement Content ◽  
Uniaxial Compression Test ◽  
Injection Test ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Grouting Material ◽  
Comprehensive Performance ◽  
Scanning Electron

To provide the most effective comprehensive performance grouting material ratio, in this experimental investigation, a total of eight grouted specimens with two water-cement ratios (0.45:1, 0.55:1) and four different superfine cement contents (0%, 30%, 70%, 100%) were evaluated. Based on a uniaxial compression test, the fractal dimension of the fragments, a mercury injection test, and scanning electron microscopy, the effects of the superfine cement content on the strength characteristics and microscopic characteristics of the grouted specimens were studied. The results showed that increasing the superfine cement content could enhance the compressive and tensile strength of the grouted specimens and reduce the fractal dimension of the fragments and the porosity of the grouted specimens. The superfine cement content increased from 0% to 70% when the water-cement ratio was 0.45:1. The compressive strength of the grouted specimens increased from 16.7 MPa to 26.3 MPa, and the fractal dimension decreased from 1.8645 to 1.2301. When the water-cement ratio was 0.55:1, the compressive strength of the grouted specimens increased from 10.5 MPa to 20.6 MPa, and the fractal dimension value decreased from 2.2955 to 1.4458. When the superfine cement content increased from 0% to 100%, the water-cement ratio was 0.45:1. The porosity of the grouted specimens was reduced from 28.41% to 21.62%. When the water-cement ratio was 0.55:1, the porosity of the grouted specimens was reduced from 33.33% to 29.46%.

Study on the Influence of Three Factors on Mass Loss and Surface Fractal Dimension of Concrete in Sulfuric Acid Environments

2021 ◽  
Vol 5 (4) ◽  
pp. 146
Author(s):  
Jie Xiao ◽  
Xiang Long ◽  
Long Li ◽  
Haibo Jiang ◽  
Yaowen Zhang ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Sulfuric Acid ◽  
Mass Loss ◽  
Ph Value ◽  
Concrete Specimen ◽  
River Sand ◽  
Cement Ratio ◽  
Surface Fractal Dimension ◽  
Water Cement Ratio ◽  
Surface Fractal

When exposed to sulfuric acid environments, the service life of concrete structures would be reduced due to the high alkalinity of concrete. The influence of three factors including water/cement ratio, the pH value of the solution, and the chemical composition of the aggregate on the resistance of concrete subjected to sulfuric acid has been widely investigated by previous researchers. This paper aims to investigate the influence of these three factors on the durability evaluation indicators including mass loss and surface fractal dimension through orthogonal experiments, which has been reported rarely in previous research. Four combinations of coarse and fine aggregate including gravel and river sand, gravel and crushed marble sand, crushed marble stone and river sand, and crushed marble stone and marble sand were adopted, and three water/cement ratios including 0.35, 0.45, and 0.55 were selected, and the sulfuric acid solution pH values 0.95, 2, and 4 were chosen in this paper. The results showed that the larger the water/cement ratio, the smaller the mass loss and the surface fractal dimension of the specimens, and with the decrease of the pH value of the sulfuric acid solution, the mass loss and the surface fractal dimension of the specimens would be increased. The concrete specimen containing gravel and river sand had the greatest surface fractal dimension and greatest mass loss, while the concrete specimen containing crushed marble sand had a smaller surface fractal dimension and a smaller mass loss. The dominant and secondary order of three factors on mass loss and surface fractal dimension of concrete subjected to sulfuric acid was the pH value of the solution > the chemical composition of the aggregate > the water/cement ratio.

Coefficient of Linear Expansion of Air-Entraining Concrete with Silica Fume

2010 ◽  
Vol 168-170 ◽  
pp. 2116-2120
Author(s):  
Jian Chao Dou ◽  
Jian Sen Yang
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Linear Expansion ◽  
Content Increase ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Air Content ◽  
Effect Of Water ◽  
Compressive Strength Of Concrete ◽  
Coefficient Of Linear Expansion

The effect of water-cement ratio, air content, silica fume and sand ratio of concrete on the coefficient of linear expansion(CLE) was studied by orthogonal experiment. The results show that under a certain amount of cement material, CLE of concrete increase as the water-cement ratio increases and the effect of water-cement ratio on CLE of concrete is remarkable; with the increase of blending ratio of silica fume, the CLE of concrete increases; the CLE of concrete reduces with 3.5% air content in concrete, but rebound with 6% air content in concrete; with the sand rate increases, CLE of concrete increases; CLE per unit compressive strength of concrete with silica fume decreases with increase of silica fume content; CLE per unit compressive strength of concrete with air content increase when air content increase.

Experimental Study on Thermal Conductivity of Road Concrete

2012 ◽  
Vol 178-181 ◽  
pp. 1573-1576
Author(s):  
Yan Cong Zhang ◽  
Ling Ling Gao ◽  
Jun Min Shen
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Fly Ash ◽  
Coarse Aggregate ◽  
Gas Content ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Air Content ◽  
Main Factor

In order to analyses affection to thermal conductivity from various factors, such as: coarse aggregate, mortar ratio, sand ratio, water cement ratio, fly ash and air content, thermal conductivity of a series of concrete specimens were determined based on thermal conductivity meter. The results showed that: coarse aggregate, mortar ratio and gas content is the main factor affecting concrete thermal conductivity. Meanwhile, water-cement ratio, sand ratio and fly ash had few effects on the thermal conductivity. In addition, a certain formula to predict thermal conductivity of concrete was proposed.

Study on Frost Resistance of Nano SiO2 Cement Concrete

2012 ◽  
Vol 198-199 ◽  
pp. 48-51 ◽  
Author(s):  
Zheng Rong Zhao ◽  
Jie Kong ◽  
Hong Xia Yang
Keyword(s):  
Frost Resistance ◽  
Hardened Cement ◽  
Cement Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Ordinary Concrete ◽  
Air Content ◽  
Substantial Decline ◽  
The Relationship ◽  
Very High

According the test, this paper discussed the relationships among nano SiO2content of nano SiO2cement concrete ,air content, water-cement ratio and frost resistance property.Meanwhile, the relationship among the bubble parameter, structure of holes and the frost resistance is primarily discussed. The results show that the concrete mixed with some nano SiO2, with the increase of impervious holes in hardened cement paste, compared with ordinary concrete,both the ability of freezing-thawing resisting and compression strength will have an improvement. What’s more, when mixed with the air-entraining agent, freezing-thawing cycles number will have an obvious increase.When water-cement ratio is 0.35-0.39, the ability of frost resisting is very high but when water-cement ratio is larger than 0.39, freezing-thawing resisting performance is substantial decline.

scholarly journals Pore structure and strength of waste fiber recycled concrete

2019 ◽  
Vol 14 ◽  
pp. 155892501987470 ◽  
Author(s):  
Jinghai Zhou ◽  
Tianbei Kang ◽  
Fengchi Wang
Keyword(s):  
Mechanical Properties ◽  
Fractal Dimension ◽  
Pore Structure ◽  
Fiber Length ◽  
Volume Fraction ◽  
Fractal Theory ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio

The pore structure is one of the major factors affecting the mechanical properties of waste fiber recycled concrete. In this article, the pore structure and strength performance of waste fiber recycled concrete are experimentally studied. The design variables are water–cement ratio, recycled aggregate replacement rate, waste fiber length, and volume fraction of waste fibers. The pore structure characteristic parameters of waste fiber recycled concrete are investigated using mercury intrusion porosimetry test and fractal theory. The complex distribution of pore structure in space is quantitatively described by fractal dimension, and the pore structure is comprehensively evaluated. The results show that the water–cement ratio has the largest influence on the pore structure, and the fiber length has the least influence. The optimum volume fraction of waste fibers is 0.12%. There is an obvious linear relationship between the pore volume fractal dimension and strength. With the increase in the fractal dimensions, the compressive and splitting tensile strengths increase. Macroscopic mechanical properties of waste fiber recycled concrete can be predicted by the pore structure.

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