scholarly journals Behavior of Cementitious Materials under the Effect of an Eco-Cement Based on Dredged Sludge

2021 ◽  
Vol 45 (6) ◽  
pp. 455-465
Author(s):  
Riad Ali Halassa ◽  
Mekki Bibi ◽  
Mohamed-Aziz Chikouche
Keyword(s):  
Ecological Impact ◽  
High Strength ◽  
Weather Conditions ◽  
Cementitious Materials ◽  
Technical Innovation ◽  
Test Results ◽  
Ordinary Concrete ◽  
Optimal Exploitation ◽  
Green Materials ◽  
Dredged Sludge

This paper attempts to simulate the use of green materials from the silt in a dam, and reduce the harmful impacts of siltation on Algerian dams affected by frequent droughts and irregular rainfalls, which are resulted from climate change. These harsh weather conditions are the main cause of water erosion in Algeria, leading to a high silting level in many dams across the country. Therefore, it is necessary to dredge the considerable volumes of sludge in the dam areas. This paper treats the sludge dredged from the K’sob dam, and adds the treated sludge into cement, creating a hybrid binder that can be used in composition of cementitious materials. Specifically, the sludge extracted from the K’sob dam was characterized chemically, physically, mineralogically, and mechanically, and introduced both as a substitute of cement and a component in the mixture of ordinary concrete/mortar. The sludge was firstly activated through calcination, and added to cement at the mass dosages of 10%, 15%, and 20% separately. The mechanical behavior, especially that under compression, of cementitious materials (concrete/mortar) based on the treated sludge was studied through lab tests. The test results show that this technical innovation gives the finished product three major properties, namely, high strength, economy, and a beneficial ecological impact. The results obtained are encouraging and promise an optimal exploitation of the sludge from similar dam areas.

scholarly journals Preparation and Mechanical Properties of Cemented Uranium Tailing Backfill Based on Alkali-Activated Slag

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Fulin Wang ◽  
Guoliang Chen ◽  
Lu Ji ◽  
Zhengping Yuan
Keyword(s):  
Preparation Method ◽  
High Strength ◽  
Cementitious Materials ◽  
Test Results ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Cementing Material ◽  
Uranium Tailings ◽  
Cement Solidification ◽  
Alkali Activated

Backfilling disposal based on cement solidification is one of the ways to solve the environmental and safe problems of uranium tailing surface stacking. Alkali-activated slag, especially sodium silicate activated geopolymer, has become the preferred cementing material for the uranium tailing backfilling system because of its advantages of corrosion resistance and high strength. In this paper, uranium tailings and slag are taken as research objects, and the unconfined compressive strength (UCS) is taken as the main quality index. The preparation method of the cemented uranium tailing backfill based on alkali-activated slag was studied, hereinafter referred to as CUTB. The effects of additive amount, activator amount and activator modulus on the strength of CUTB were investigated. The results show that alkali-activated slag is an effective cementing material for the backfilling system of uranium tailing aggregate. The maximum UCS of 28 d age in the test groups is 16.45 MPa. Quicklime is an important additive for preparing CUTB. When the amount of quicklime is 0%, the early and late strengths of the filling body cannot be measured or at a very low level. At the age of 7 d, the order of each factor is additive amount > activator modulus > activator amount, but at the age of 28 d, the order of each factor is additive amount > activator amount > activator modulus. The test results can provide a basis for choosing cementitious materials for backfilling disposal of uranium tailings.

Evaluation of strength of concrete on different initial exposure condition

2020 ◽  
Vol 13 ◽  
Author(s):  
Sri Ram Krishna Mishra ◽  
Pradeep Kumar Ghosh ◽  
Manoj Kulshreshtha
Keyword(s):  
Portland Cement ◽  
High Strength ◽  
Cementitious Materials ◽  
General Purpose ◽  
Supplementary Cementitious Materials ◽  
Exposure Condition ◽  
Portland Cement Concrete ◽  
Initial Exposure ◽  
Skilled Manpower ◽  
Standard Practices

Background: The previous studies have focused curing effect of mainly on high strength concrete, where strict supervision is maintained. This study is based upon general purpose concreting work for commercial and residential construction in absence of skilled manpower and supervision. Objective: The objective of this study is to establish a thumb rule to provide 7 days initial curing for maintaining quality for unsupervised concreting irrelevant to type of cement and grading. Methods: In this study concrete samples made with locally available commercial cements were cured for various initial exposure. Results: The results shows that concrete cured after a gap of 4 days from the time of de-moulding have given lowest strength as compared to concrete cured in standard practices i.e. where proper curing protocol had been followed. Conclusion: Initial curing is most important aspect of gaining desired strength. The findings after this study shows that curing affects the strength of concrete in variable grading. Initial curing has great importance for concrete with all types of Portland cement. Concrete with supplementary cementitious materials gives lowest strength initially but results higher strength after 28 days as compared to Portland cement.

Effects of Nano-CaCO3 on the Compressive Strength and Microstructure of High Strength Concrete in Different Curing Temperature

2011 ◽  
Vol 121-126 ◽  
pp. 126-131 ◽  
Author(s):  
Qing Lei Xu ◽  
Tao Meng ◽  
Miao Zhou Huang
Keyword(s):  
Compressive Strength ◽  
Low Temperature ◽  
High Strength Concrete ◽  
High Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Strength Concrete ◽  
Calcium Nitrite ◽  
Orientation Index ◽  
Early Strength

In this paper, effects of nano-CaCO3 on compressive strength and Microstructure of high strength concrete in standard curing temperature(21±1°C) and low curing temperature(6.5±1°C) was studied. In order to improve the early strength of the concrete in low temperature, the early strength agent calcium nitrite was added into. Test results indicated that 0.5% dosage of nano-CaCO3 could inhibit the effect of calcium nitrite as early strength agent, but 1% and 2% dosage of nano-CaCO3 could improve the strength of the concrete by 13% and 18% in standard curing temperature and by 17% and 14% in low curing temperature at the age of 3days. According to the XRD spectrum, with the dosage up to 1% to 2%, nano-CaCO3 can change the orientation index significantly, leading to the improvement of strength of concrete both in standard curing temperature and low curing temperature.

scholarly journals Properties of High-Strength Flowable Mortar Reinforced with Palm Fibers

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Eethar Thanon Dawood ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Test Results ◽  
Palm Fiber ◽  
Toughness Index ◽  
Strength And Toughness

This study was conducted to determine some physical and mechanical properties of high-strength flowable mortar reinforced with different percentages of palm fiber (0, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, and 1.6% as volumetric fractions). The density, compressive strength, flexural strength, and toughness index were tested to determine the mechanical properties of this mortar. Test results illustrate that the inclusion of this fiber reduces the density of mortar. The use of 0.6% of palm fiber increases the compressive strength and flexural strength by about 15.1%, and 16%, respectively; besides, the toughness index (I5) of the high-strength flowable mortar has been significantly enhanced by the use of 1% and more of palm fiber.

Effect of Chopped Basalt Fiber on the Fresh and Hardened Properties of Fly Ash High Strength Concrete

2014 ◽  
Vol 567 ◽  
pp. 381-386 ◽  
Author(s):  
Nasir Shafiq ◽  
Muhd Fadhil Nuruddin ◽  
Ali Elheber Ahmed Elshekh ◽  
Ahmed Fathi Mohamed Salih
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength Concrete ◽  
Basalt Fiber ◽  
High Strength ◽  
Progressive Increase ◽  
Test Results ◽  
Strength Concrete ◽  
Hardened Properties ◽  
Chopped Basalt Fiber

In order to improve the mechanical properties of high strength concrete, HSC, several studies have been conducted using fly ash, FA. Researchers have made it possible to achieve 100-150MPa high strength concrete. Despite the popularity of this FAHSC, there is a major shortcoming in that it becomes more brittle, resulting in less than 0.1% tensile strain. The main objective of this work was to evaluate the fresh and hardened properties of FAHSC utilizing chopped basalt fiber stands, CBFS, as an internal strengthening addition material. This was achieved through a series of experimental works using a 20% replacement of cement by FA together with various contents of CBFS. Test results of concrete mixes in the fresh state showed no segregation, homogeneousness during the mixing period and workability ranging from 60 to 110 mm. Early and long terms of compressive strength did not show any improvement by using CBFS; in fact, it decreased. This was partially substituted by the effect of FA. Whereas, the split and flexural strengths of FASHC were significantly improved with increasing the content of CBFS as well as the percentage of the split and flexural tensile strength to the compressive strength. Also, test results showed a progressive increase in the areas under the stress-strain curves of the FAHSC strains after the CBFS addition. Therefore, the brittleness and toughness of the FAHSC were enhanced and the pattern of failure moved from brittle failure to ductile collapse using CBFS. It can be considered that the CBFS is a suitable strengthening material to produce ductile FAHSC.

Deterioration of Mechanical Properties of High-Strength Pumpcrete after Exposure to High Temperatures

2010 ◽  
Vol 168-170 ◽  
pp. 564-569
Author(s):  
Guang Lin Yuan ◽  
Jing Wei Zhang ◽  
Jian Wen Chen ◽  
Dan Yu Zhu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Heating Rate ◽  
High Strength Concrete ◽  
Heating Temperature ◽  
High Strength ◽  
Air Cooling ◽  
Test Results ◽  
Strength Deterioration ◽  
Residual Compressive Strength

This paper makes an experimental study of mechanical properties of high-strength pumpcrete under fire, and the effects of heating rate, heating temperature and cooling mode on the residual compressive strength(RCS) of high-strength pumpcrete are investigated. The results show that under air cooling, the strength deterioration speed of high-strength concrete after high temperature increases with the increase of concrete strength grade. Also, the higher heating temperature is, the lower residual compressive strength value is. At the same heating rate (10°C/min), the residual compressive strength of C45 concrete after water cooling is a little higher than that after air cooling; but the test results are just the opposite for C55 and C65 concrete. The strength deterioration speed of high-strength concrete after high temperature increases with the increase of heating rate, but not in proportion. And when the heating temperature rises up between 200°C and 500°C, heating rate has the most remarkable effect on the residual compressive strength of concrete. These test results provide scientific proofs for further evaluation and analysis of mechanical properties of reinforced-concrete after exposure to high temperatures.

High Strength Combined Support Technology in Deep High Stress Soft Rock Roadway

2012 ◽  
Vol 524-527 ◽  
pp. 598-603
Author(s):  
Nian Jie Ma ◽  
Zhi Qiang Zhao ◽  
Hua Zhao ◽  
Li Shuai Jiang
Keyword(s):  
High Stress ◽  
Soft Rock ◽  
High Strength ◽  
Parameter Determination ◽  
Test Results ◽  
Actual Measurement ◽  
Computer Numerical Simulation ◽  
Soft Rock Roadway ◽  
Rock Roadway

In order to solve the serious damage and repeat revision problem of high stress soft rock roadway in deep -950 level of Tangshan coal mine, based on the theory of the maximum stress level, together with the actual measurement of geostress and the laboratory mechanical parameters of rock-core and computer numerical simulation, the high strength combined support technology and supporting parameters are determined and the engineering test has been done. The engineering test results show that the parameter determination of high strength combined support technology, which based on the actual measurement of geostress, can effective solve the support issue of high stress soft rock roadway and provide useful experience for similar engineering problems.

scholarly journals Experimental Investigation into Corrosion Effect on Mechanical Properties of High Strength Steel Bars under Dynamic Loadings

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hui Chen ◽  
Jinjin Zhang ◽  
Jin Yang ◽  
Feilong Ye
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Dynamic Loading ◽  
High Strength Steel ◽  
High Strength ◽  
Tensile Tests ◽  
Reinforcing Steel ◽  
Test Results ◽  
Cross Sectional ◽  
Steel Bars

The tensile behaviors of corroded steel bars are important in the capacity evaluation of corroded reinforced concrete structures. The present paper studies the mechanical behavior of the corroded high strength reinforcing steel bars under static and dynamic loading. High strength reinforcing steel bars were corroded by using accelerated corrosion methods and the tensile tests were carried out under different strain rates. The results showed that the mechanical properties of corroded high strength steel bars were strain rate dependent, and the strain rate effect decreased with the increase of corrosion degree. The decreased nominal yield and ultimate strengths were mainly caused by the reduction of cross-sectional areas, and the decreased ultimate deformation and the shortened yield plateau resulted from the intensified stress concentration at the nonuniform reduction. Based on the test results, reduction factors were proposed to relate the tensile behaviors with the corrosion degree and strain rate for corroded bars. A modified Johnson-Cook strength model of corroded high strength steel bars under dynamic loading was proposed by taking into account the influence of corrosion degree. Comparison between the model and test results showed that proposed model properly describes the dynamic response of the corroded high strength rebars.

Properties of High Strength Fibre Reinforced Concrete Using Ultra Fine Slag

2016 ◽  
Vol 857 ◽  
pp. 183-188
Author(s):  
C. Mohan Lal ◽  
Vontary Sai Srujan Reddy
Keyword(s):  
High Strength Concrete ◽  
Steel Fibre ◽  
High Strength ◽  
Target Strength ◽  
Partial Replacement ◽  
Fibre Reinforced Concrete ◽  
Test Results ◽  
Design Requirement ◽  
Split Tensile Strength ◽  
Strength Concrete

High strength concrete has become a design requirement in recent years due to increase in number of infrastructure projects. This paper presents the effect of incorporating Ultra Fine Slag (UFS) and steel fibre to obtain high strength concrete. To achieve target strength of about 80 MPa, it is proposed to the replacement of cement of 10%, 20% and 30% with UFS and incorporating 0.5% and 1.0% fibre in concrete. An experimental investigation is carried out to find the mechanical properties of the concrete. From the test results, it was observed that a compressive strength of 95 MPa was achieved at 30% replacement of cement with UFS and 1.0% fibre content. In addition, there was a significant improvement in split tensile strength and flexural strength of the concrete. This study demonstrates that a high strength concrete can be obtained from partial replacement of cement with UFS and addition of steel fibre.

The Study on the Impact of Recycled Fine Aggregate and Powder on the Mechanics and Thermal Performance of Recycled Concrete Hollow Blocks

2012 ◽  
Vol 509 ◽  
pp. 119-122
Author(s):  
Wei Zhou ◽  
Ling Huan Lu ◽  
Zhen Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Thermal Performance ◽  
High Strength ◽  
Recycled Concrete ◽  
Fine Aggregate ◽  
Ordinary Concrete ◽  
Recycled Fine Aggregate ◽  
The Impact ◽  
The Heat Transfer Coefficient

The impact of recycled fine aggregate and powder on the mechanics and thermal performance of recycled concrete hollow blocks was discussed in this paper. The results showed that 30% recycled fine aggregate and powder have slight affect on the strength of recycled concrete hollow blocks. But the strength reduced significantly when the replacement is above 50%. The impact of recycled fine aggregate and powder on the performance of concrete hollow blocks with high strength grade is notable . The heat transfer coefficient of recycled concrete hollow blocks with 30% recycled fine aggregate and powder was equivalently to ordinary concrete hollow blocks.

Sign in / Sign up

Export Citation Format

Share Document