scholarly journals Experimental Study on the Vegetation Growing Recycled Concrete and Synergistic Effect with Plant Roots

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1855 ◽  
Author(s):  
Fengchi Wang ◽  
Chang Sun ◽  
Xiangqun Ding ◽  
Tianbei Kang ◽  
Xiaomei Nie
Keyword(s):  
Compressive Strength ◽  
Aggregate Size ◽  
Recycled Concrete ◽  
Plant Roots ◽  
X Ray Diffraction ◽  
Quick Freezing ◽  
Industrial Computed Tomography ◽  
Concrete Blocks ◽  
Cementing Material ◽  
Internal Pore

Vegetation growing recycled concrete (VGRC) is a relatively new building material that has both biocompatibility and engineering function. The basic performance of VGRC was investigated by experimental analysis, and the hydration products and pore structure of different VGRC mix proportions were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and industrial computed tomography (CT). The results show that ultrafine slag can reduce Ca(OH)2 content in cementing material and has a filling effect on micropores. VGRC has the best performance; the internal pore distribution is uniform when porosity is 20–25%, and the ultrafine slag content is 40%. The compressive strength of VGRC is greatly damaged by the quick-freezing method, while the degree of damage from natural freeze–thaw cycles is relatively small. Soaking in acid solution can effectively reduce the internal pore alkalinity of VGRC. Most plants can grow normally in vegetation concrete, and plant roots can penetrate 6-cm thick concrete blocks after being planted for 60 days. The compressive strength of VGRC decreased after turf planting of 30 days and then increased slowly. The permeability coefficient of VGRC increases with the increase in porosity and aggregate size and decreases after planting and covering. The frost resistance of VGRC is enhanced, and the influence of aggregate size and porosity is small after turf planting.

scholarly journals Study on the Deterioration of Concrete under Dry–Wet Cycle and Sulfate Attack

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4095
Author(s):  
Fang Liu ◽  
Tonghuan Zhang ◽  
Tao Luo ◽  
Mengzhen Zhou ◽  
Kunkun Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Sodium Sulfate ◽  
Distribution Curve ◽  
Early Stage ◽  
Sulfate Attack ◽  
Industrial Computed Tomography ◽  
Spectrum Distribution ◽  
Compressive Strength Of Concrete ◽  
Internal Pore Structure ◽  
Internal Pore

In order to study the deterioration and mechanism of dry–wet cycles and sulfate attack on the performance of concrete in seaside and saline areas, the deterioration of compressive strength of concrete with different water cement ratios under different erosion environments (sodium sulfate soaking at room temperature and coupling of dry–wet cycling and sodium sulfate) was studied here. At the same time, ICT (industrial computed tomography) and NMR (nuclear magnetic resonance) techniques were used to analyze the internal pore structure of concrete under different erosion environments. The results show that the compressive strength under different erosion environments increases first and then decreases, and the dry–wet cycle accelerates the sulfate erosion. With the increase of dry and wet cycles, larger pores are filled with erosion products and developed into small pores in the early stage of erosion; in the later stage of erosion, the proportion of larger pores increases, and cracks occur inside the sample. In the process of sulfate soaking and erosion, the smaller pores in the concrete account for the majority. As the sulfate erosion continues, the T2 spectrum distribution curve gradually moves right, and the signal intensity of the larger pores increases.

scholarly journals Mechanism of Alkali-Activated Copper-Nickel Slag Material

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Tingting Zhang ◽  
Haoliang Jin ◽  
Lijie Guo ◽  
Wenchen Li ◽  
Junan Han ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Testing Machine ◽  
Raw Material ◽  
Hydration Reaction ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
Copper Nickel ◽  
Activating Agent ◽  
Cementing Material ◽  
Alkali Activated

A copper-nickel slag-based alkali-activated cementing material (CNSCM) for backfilling was prepared using copper-nickel slag as a raw material and sodium silicate (SS) as an activating agent. The effects of SS content (6%, 8%, and 10%) and curing humidity on the compressive strength of CNSCM were investigated using an electronic universal testing machine. Types of hydration products and microstructures were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results indicated that by increasing the SS content, the compressive strength of the CNSCM exhibited an increasing trend, followed by a decreasing trend. The optimal content was 8%. Humidity was identified as another factor affecting compressive strength, which reached 17 MPa after curing for 28 d under standard conditions. A decrease in humidity could improve the compressive strength of the material. The main hydration reaction products of the CNSCM were C-S-H gel, Fe (OH)2 or Fe (OH)3 gel, and CaCO3.

scholarly journals Reusing of Construction Debris in Plain Concrete Elements

2021 ◽  
Vol 9 (3) ◽  
pp. 81-87
Author(s):  
A. Abdelrahman Abuserriya ◽  
B. Bashir H. Osman ◽  
C. Salma Y. Mahmoud
Keyword(s):  
Compressive Strength ◽  
Sea Water ◽  
Plain Concrete ◽  
Absorption Capacity ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Aggregate Content ◽  
Concrete Production ◽  
Concrete Blocks

Construction is a serious environmental problem and a challenge for people who concerned with sustainability in the construction field. Previous studies showed positive results for the use of recycled aggregates in the concrete production. This study portrays the results for utilizing construction debris for casting different types of concrete blocks. The recycled concrete debris was used in different ratios (0%, 50%, and 100%) in replacement for natural coarse aggregates for different targeted compressive strength (B250, B300, B350 and B400). Two types of water (pure and sea water) were used for curing the blocks. In addition, hollow block and paving block were casted with different ratios of recycled aggregate (0%, 20%, 45% and 100%) and cured with two types of water. The results showed a decrease in compressive strength with the increase recycled aggregate content. It was also noticed that the absorption capacity increases with high recycled aggregate content.  

Influence of Recycled Concrete Powder (RCP) and Recycled Brick Powder (RBP) on the Physical/Mechanical Properties and Durability of Raw Soil

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1475
Author(s):  
Li’an Zhou ◽  
Yang Liu ◽  
Jiacheng Lu ◽  
Wenjuan Zhou ◽  
Hui Wang
Keyword(s):  
Compressive Strength ◽  
Water Content ◽  
Recycled Concrete ◽  
Dry Density ◽  
X Ray Diffraction ◽  
X Ray ◽  
Freeze Thaw ◽  
Performance Change ◽  
Brick Powder ◽  
Research Findings

The influence of recycled concrete powder (RCP) and recycled brick powder (RBP) on the dry density, optimal water content, and compressive strength of raw soil materials was investigated in this study. Moreover, the following resistance of freeze–thaw cycles was also considered. Additionally, X-ray diffraction (XRD) and scanning electron microscope (SEM) were selected to detect its mineral composition and observe the microstructure, further revealing the mechanism of performance change. The mass ratios of recycled concrete powder and recycled brick powder were 2% ~ 14%. Results showed that the dry density decreased and the optimal water content increased with the increasing dosage of recycled concrete powder and recycled brick powder. When the dosage of RCP or RBP was lower than 14%, raw soil with RCP showed higher optimal water content and lower dry density. However, when the dosage was higher than 14%, the result was the opposite. The addition of recycled concrete powder and recycled brick powder was able to decrease the compressive strength of raw soil, except for 10% of recycled brick powder. Raw soil with recycled brick powder presented higher compressive strength than that of raw soil with recycled concrete powder. RBP could improve the freeze–thaw cycles’ resistance of specimens; however, RCP led to decreasing the resistance of freeze–thaw cycles. These research findings can provide reference to the recycling of construction waste.

scholarly journals Eksperimental Perbandingan Kekuatan Tekan Karakteristik Beton Self Compacting Menggunakan Agregat Kasar Alami Dan Agregat Kasar Daur Ulang

2020 ◽  
Vol 19 (1) ◽  
pp. 107-120
Author(s):  
Martinus Pramanata Sapeai ◽  
Johannes Adhijoso Tjondro
Keyword(s):  
Compressive Strength ◽  
Aggregate Size ◽  
Recycled Concrete ◽  
Mix Design ◽  
Sustainable Construction ◽  
Maximum Aggregate Size ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Coarse Aggregates ◽  
High Rise

Utilization of recycled concrete waste as an alternative to natural coarse aggregates in this experiment is in accordance with the concept of sustainable construction. Concrete is the main material of structural elements most commonly used in general construction and has properties that are difficult to recycle by themselves naturally. Nowdays concrete innovation with the concept of self compacting (SCC) is widely used especially in high rise building and buildings with special specification. SCC has high flowability properties so that it can flow and compact themselves, but in SCC with normal quality still need compactor. The concept of making test specimens is in accordance with real conditions in the field, where aggregates do not go through a cleaning process. There are four different mix design with the required specified compressive strength of 20 MPa. Mix design 1A (natural coarse) and 1B (recycled coarse aggregates) has a maximum aggregate size 12.50 mm, and mix design 2A (natural coarse) and 2B (recycled coarse aggregates) has a maximum aggregate size 19.00 mm. This experimental results in specified compressive strength concrete for mix design 1A, 1B, 2A, and 2B as follows: 30.93 MPa, 26.21 MPa, 30.82 MPa and 27.60 MPa. Therefore, recycled concrete aggregates can be alternative to natural coarse aggregates and can also be made into concrete with the SCC concept.

scholarly journals Study on Influence of Range of Data in Concrete Compressive Strength with Respect to the Accuracy of Machine Learning with Linear Regression

2021 ◽  
Vol 11 (9) ◽  
pp. 3866
Author(s):  
Jun-Ryeol Park ◽  
Hye-Jin Lee ◽  
Keun-Hyeok Yang ◽  
Jung-Keun Kook ◽  
Sanghee Kim
Keyword(s):  
Machine Learning ◽  
Compressive Strength ◽  
Linear Regression ◽  
Coarse Aggregate ◽  
Learning Algorithm ◽  
Linear Regression Analysis ◽  
Aggregate Size ◽  
Training Dataset ◽  
Machine Learning Algorithm ◽  
Concrete Compressive Strength

This study aims to predict the compressive strength of concrete using a machine-learning algorithm with linear regression analysis and to evaluate its accuracy. The open-source software library TensorFlow was used to develop the machine-learning algorithm. In the machine-earning algorithm, a total of seven variables were set: water, cement, fly ash, blast furnace slag, sand, coarse aggregate, and coarse aggregate size. A total of 4297 concrete mixtures with measured compressive strengths were employed to train and testing the machine-learning algorithm. Of these, 70% were used for training, and 30% were utilized for verification. For verification, the research was conducted by classifying the mixtures into three cases: the case where the machine-learning algorithm was trained using all the data (Case-1), the case where the machine-learning algorithm was trained while maintaining the same number of training dataset for each strength range (Case-2), and the case where the machine-learning algorithm was trained after making the subcase of each strength range (Case-3). The results indicated that the error percentages of Case-1 and Case-2 did not differ significantly. The error percentage of Case-3 was far smaller than those of Case-1 and Case-2. Therefore, it was concluded that the range of training dataset of the concrete compressive strength is as important as the amount of training dataset for accurately predicting the concrete compressive strength using the machine-learning algorithm.

scholarly journals Carbonization Durability of Two Generations of Recycled Coarse Aggregate Concrete with Effect of Chloride Ion Corrosion

2020 ◽  
Vol 12 (24) ◽  
pp. 10544
Author(s):  
Chunhong Chen ◽  
Ronggui Liu ◽  
Pinghua Zhu ◽  
Hui Liu ◽  
Xinjie Wang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Chloride Ion ◽  
Total Porosity ◽  
Recycled Concrete ◽  
Carbonation Depth ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Carbonation Resistance ◽  
Two Generations

Carbonation durability is an important subject for recycled coarse aggregate concrete (RAC) applied to structural concrete. Extensive studies were carried out on the carbonation resistance of RAC under general environmental conditions, but limited researches investigated carbonation resistance when exposed to chloride ion corrosion, which is an essential aspect for reinforced concrete materials to be adopted in real-world applications. This paper presents a study on the carbonation durability of two generations of 100% RAC with the effect of chloride ion corrosion. The quality evolution of recycled concrete coarse aggregate (RCA) with the increasing recycling cycles was analyzed, and carbonation depth, compressive strength and the porosity of RAC were measured before and after chloride ion corrosion. The results show that the effect of chloride ion corrosion negatively affected the carbonation resistance of RAC, and the negative effect was more severe with the increasing recycling cycles of RCA. Chloride ion corrosion led to a decrease in compressive strength, while an increase in carbonation depth and the porosity of RAC. The equation of concrete total porosity and carbonation depth was established, which could effectively judge the deterioration of carbonation resistance of RAC.

Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

2014 ◽  
Vol 894 ◽  
pp. 45-49 ◽  
Author(s):  
Luisa Pani ◽  
Lorena Francesconi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Ultrasonic Wave ◽  
Ultrasonic Test ◽  
Ultrasonic Waves ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Experimental Program ◽  
Static Modulus ◽  
Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

Study on the Mechanical Properties and Frost Resistance of Recycled Concrete Prepared by Village Construction Wastes

2011 ◽  
Vol 418-420 ◽  
pp. 406-410
Author(s):  
Jun Liu ◽  
Yao Li ◽  
Dan Dan Hong ◽  
Yu Liu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Frost Resistance ◽  
Cement Mortar ◽  
Strength Loss ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Replacement Rate ◽  
Concrete Mechanical Properties ◽  
Better Than

Abstract. Recycled aggregate—rural building material wastes pretreated by cement mortar—are applied into concrete with different replacement rates: 0, 25%, 50%, 75%, and 100%. Results from measurements of compressive strength, cleavage tensile strength, mass loss after fast freeze-thaw cycles, and compressive strength loss indicate that a different recycled aggregate replacement rate certainly influences concrete mechanical properties and frost resistance. Recycled aggregate replacement rates less than 75% performs better than common concrete. Data from the 100% replacement rate is worse than that of rates less than 75% but still satisfy the general demands of GB standard on C30 concrete.

Effect of P2O5 on the Properties of Alite-Calcium Strontium Sulphoaluminate Cement

2011 ◽  
Vol 306-307 ◽  
pp. 961-965
Author(s):  
Chao Nan Yin ◽  
Ling Chao Lu ◽  
Shou De Wang
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Heat Evolution ◽  
Petrographic Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulphoaluminate Cement ◽  
Suitable Amount ◽  
Acceleration Period ◽  
Scanning Electron

The influence of P2O5on the properties of alite-calcium strontium sulphoaluminate cement was researched by means of X-ray diffraction, scanning electron microscope-energy dispersive spectroscopy (SEM-EDS) and petrographic analysis. The results show that the optimal content of P2O5is 0.3% and the compressive strength of the cement at 1, 3, 28d are 27.0, 59.1, 110.9MPa when the calcining temperature is 1350°C. P2O5mainly exists in the belite and a suitable amount of P2O5can promote the formation of C1.5Sr2.5A3and alite. When the content of P2O5is higher than 0.3%, the formation of C1.5Sr2.5A3and alite can be hindered. P2O5can enhance the hydration heat evolution rate in the acceleration period and the hydrate heat of cement containing P2O5increases slightly.

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