scholarly journals Effects of Modified Metakaolin Using Nano-Silica on the Mechanical Properties and Durability of Concrete

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2291 ◽  
Author(s):  
Nasir Shafiq ◽  
Rabinder Kumar ◽  
Muhammad Zahid ◽  
Rana Faisal Tufail
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Second Phase ◽  
Nano Silica ◽  
Chloride Permeability ◽  
Maximum Compressive Strength ◽  
Rapid Chloride Permeability ◽  
Anova Technique ◽  
Durability Of Concrete

This paper discussed the effects of modified metakaolin (MK) with nano-silica (NS) on the mechanical properties and durability of concrete. In the first phase, trial mixes of concrete were prepared for achieving the desired value of the 28 days compressive strength, and the charge passed in rapid chloride permeability test (RCPT). In the second phase, statistical analysis was performed on the experimental results using the response surface method (RSM). The RSM was applied for optimizing the mix proportions for the required performance by exploiting the relationship between the mix characteristics and the corresponding test results. A blend of 10% MK + 1% NS as part of cement replacement exhibited the highest mechanical properties and durability characteristics of concrete; concrete mix showed that the 28-days compressive strength (CS) was 103 MPa, which was 15% greater than the CS of the control mix without MK or NS. The same mix showed more than 40% higher flexural and split-tensile strength than the control mix; also it resulted in a reduction of 73% in the rapid chloride permeability value. ANOVA technique was used for optimizing the nano-silica and metakaolin content for achieving maximum compressive strength and minimum RCPT value. Statistical analysis using ANOVA technique showed that the maximum compressive strength and lowest RCPT value could be achieved with a blend of 10% MK and 1.55% NS.

Effect of Surface Penetrating Sealer on the Microstructure Properties of Cement-Based Composites

2013 ◽  
Vol 651 ◽  
pp. 245-250
Author(s):  
Tasi Lung Weng ◽  
Wei Ting Lin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Concrete Durability ◽  
Test Results ◽  
Chloride Permeability ◽  
Durability Test ◽  
Chloride Resistance ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Effect Of Surface

The effect of penetrating sealer on the structure of surface pore, mechanical properties, and durability of cement-based composites was studied. Concrete specimens with various water/cement ratios (w/c=0.35, 0.45, 0.55) were cast and treated surfaced with various amounts of penetrating sealer at different ages. The effect of penetrating sealer on the mechanical properties of concrete was assessed by compressive strength. And, the rapid chloride permeability was also explored to test concrete durability. Test results indicate that the application of penetrating sealer significantly improves concrete compressive strength and chloride resistance. By using scanning electron microscopes observation, the penetrating depth of penetrating sealer can be determined and is about 2 cm. The penetrating sealer in this study may be categorized as deep penetrating sealer.

Experimental Study on Compatibility between Alkali-Free Liquid Concrete Accelerators and Cement

2013 ◽  
Vol 438-439 ◽  
pp. 102-107 ◽  
Author(s):  
Wen Kang Guo ◽  
Li Wang ◽  
Shu Yin Wang ◽  
Dao Yin Lan ◽  
Sheng Ping Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Strength Ratio ◽  
Setting Times ◽  
Gypsum Content ◽  
Durability Of Concrete

This paper selected two kinds of alkali-free liquid concrete accelerators and tested their compatibility with ordinary Portland cement, Portland cement and moderate heat Portland cement by measuring the setting times, compressive strength and compressive strength ratio of samples. The results showed that the compatibility is good between alkali-free accelerators and two types of cement: ordinary Portland cement and moderate heat Portland cement. However, the compatibility of two accelerators and Portland cement are quite different, the compatibility of AFA-2 accelerator is excellent, but AFA-1 accelerator is very poor. The setting times of alkali-free accelerators is mainly influenced by the mixing materials content, gypsum content, C3A and C3S content. In order to ensure the mechanical properties and durability of concrete, the setting times of new concrete accelerator is not the shorter the better, the appropriate initial and final setting times are 1min30s~5min and 4min~ 12min respectively.

scholarly journals Development of Heavyweight Self-Compacting Concrete and Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1035 ◽  
Author(s):  
Afsaneh Valizadeh ◽  
Farhad Aslani ◽  
Zohaib Asif ◽  
Matt Roso
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Tensile Tests ◽  
Offshore Structures ◽  
Experimental Program ◽  
Geopolymer Concrete ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Maximum Compressive Strength ◽  
Heavyweight Concrete

Heavyweight self-compacting concrete (HWSCC) and heavyweight geopolymer concrete (HWGC) are new types of concrete that integrate the advantages of heavyweight concrete (HWC) with self-compacting concrete (SCC) and geopolymer concrete (GC), respectively. The replacement of natural coarse aggregates with magnetite aggregates in control SCC and control GC at volume ratios of 50%, 75%, and 100% was considered in this study to obtain heavyweight concrete classifications, according to British standards, which provide proper protection from sources that emit harmful radiations in medical and nuclear industries and may also be used in many offshore structures. The main aim of this study is to examine the fresh and mechanical properties of both types of mixes. The experimental program investigates the fresh properties of HWSCC and HWGC through the slump flow test. However, J-ring tests were only conducted for HWSCC mixes to ensure the flow requirements in order to achieve self-compacting properties. Moreover, the mechanical properties of both type of mixes were investigated after 7 and 28 days curing at an ambient temperature. The standard 100 × 200 mm cylinders were subjected to compressive and tensile tests. Furthermore, the flexural strength were examined by testing 450 × 100 × 100 mm prisms under four-point loading. The flexural load-displacement relationship for all mixes were also investigated. The results indicated that the maximum compressive strength of 53.54 MPa was achieved by using the control SCC mix after 28 days. However, in HWGC mixes, the maximum compressive strength of 31.31 MPa was achieved by 25% magnetite replacement samples. The overall result shows the strength of HWSCC decreases by increasing magnetite aggregate proportions, while, in HWGC mixes, the compressive strength increased with 50% magnetite replacement followed by a decrease in strength by 75% and 100% magnetite replacements. The maximum densities of 2901 and 2896 kg/m3 were obtained by 100% magnetite replacements in HWSCC and HWGC, respectively.

MECHANICAL PROPERTIES OF FLY ASH-BASED ALKALI-ACTIVATED CEMENT USING A STATISTICAL ANALYSIS TECHNIQUE

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Hyuk Lee ◽  
Vanissorn Vimonsatit
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Fly Ash ◽  
Silica Fume ◽  
Dry Density ◽  
Analysis Method ◽  
Solid Ratio ◽  
Alkali Activated ◽  
Alkali Activated Cement

This paper presents the mechanical properties of fly ash-based alkali-activated cement (AAC). A statistical analysis method was used to determine the effect of mix proportion parameters on the dry density and compressive strength of fly ash-based AAC pastes and mortars. For that purpose, sample mixtures were designed according to Taguchi’s experimental design method, i.e., in a L9 orthogonal array. Four factors were selected: “silica fume content” (SF), “sand to solid ratio” (s/c), “liquid to solid ratio” (l/s), and “superplasticiser content” (SP). The experimental results were analysed by using signal to noise for quality control of each mixture, and analysis of variance (ANOVA) was used to determine the significant effect on the compressive strength of fly ash-based AAC. Furthermore, a regression-analysis method was used to predict the compressive strength according to the variation of the four factors. Results indicated that silica fume is the most influencing parameter on compressive strength, which could be decreased by superplasticiser and l/s ratio. There is no significant effect of sand-to-cementitious ratio on compressive strength of fly ash-based AAC. The dry density decreases as the sand-to-cementitious ratio is decreased. The increasing l/s ratio and superplasticiser dosage could further decrease the dry density of fly ash-based AAC.

scholarly journals Mechanical Performance and Microscopic Mechanism of Coastal Cemented Soil Modified by Iron Tailings and Nano Silica

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1331
Author(s):  
Xinjiang Song ◽  
Haibo Xu ◽  
Deqin Zhou ◽  
Kai Yao ◽  
Feifei Tao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Mechanical Performance ◽  
Hydration Reaction ◽  
Unconfined Compression ◽  
Nano Silica ◽  
Microscopic Mechanism ◽  
Clay Particles ◽  
Soil Cement ◽  
Cement Soil

In order to explore the effect of composite materials on the mechanical properties of coastal cement soil, cement soil samples with different iron tailings and nano silica contents were prepared, and unconfined compression and scanning electron microscope tests were carried out. The results show that: (1) The compressive strength of cement soil containing a small amount of iron tailings is improved, and the optimum content of iron tailings is 20%. (2) Nano silica can significantly improve the mechanical properties of iron tailings and cement soil (TCS). When the content of nano silica is 0.5%, 1.5%, and 2.5%, the unconfined compressive strength of nano silica- and iron tailings-modified cement soil (STCS) is 24%, 137%, and 323% higher than TCS, respectively. (3) Nano silica can promote the hydration reaction of cement and promote the cement hydration products to adhere to clay particles to form a relatively stable structure. At the same time, nano silica can fill the pores in TCS and improve the compactness of STCS.

scholarly journals Effect of Alccofine and GGBS Addition on the Durability of Concrete

2019 ◽  
Vol 5 (6) ◽  
pp. 1273-1288 ◽  
Author(s):  
Balamuralikrishnan R ◽  
Saravanan J
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Large Scale ◽  
Scale Production ◽  
Acid Attack ◽  
Chloride Permeability ◽  
Fine Material ◽  
Large Scale Production ◽  
New Material ◽  
Durability Of Concrete

Portland cement is the most important ingredient of concrete.  A large scale production of cement plant consume large amount of energy and produce a number of undesirable products (  which negatively affect the environmental and depletion of natural resources. This treat to ecology has to lead to researchers to use industrial by-products as supplementary cementitious material in making concrete. In view this silica fume (SF), ground granulated blast furnace slag (GGBS), rice husk ash, fly ash (FL), metakolin, alccofine (AL), micro fine material, etc.; are tried out for replacing cement partially or fully in concrete, without compromising on its strength, also reduce greenhouse gases and sustainable way of management of waste. A new ultra-fine material emerged in market is called alccofine. This is available as a cementious material for replacing cement. Since this a new material, a study is tried out with the combination of Alccofine and GGBS. Ordinary Portland Cement 53 grade was used throughout the study and the grade of concrete is M20.  Totally 108 cubes and 27 cylinder were cast and tested in the laboratory with nine different percentage combination of alccofine (A), GGBS (G) and cement (C) (C100, C70A0G30, C90A10G0, C60A10G30, C30A10G30, C40A0G60, C85A15G0, C55A15G30, C25A15G60). Each case 3 nos. of specimen were used for repeatability. It is intended to study the compressive strength, and its durability properties like acid attack test, sulphate attack test and rapid chloride permeability test (RCPT). Among the nine different combination the maximum compressive strength of concrete is achieved by using AL10% and GGBS 30% is 38.08 N/mm2. C60A10G30 is 28.76% higher than the control mix. Result shows that concrete incorporating alccofine and GGBS have higher compressive strength and alccofine enhanced the durability of concrete also.

scholarly journals Effect of firing temperature on physico-mechanical properties of contemporary clay brick productions in Lalitpur, Nepal

2020 ◽  
Vol 55 (1) ◽  
pp. 43-52 ◽  
Author(s):  
NB Bohara ◽  
DB Ghale ◽  
YP Chapagain ◽  
N Duwal ◽  
J Bhattarai
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical Properties ◽  
Bulk Density ◽  
Firing Temperature ◽  
Apparent Porosity ◽  
Clay Brick ◽  
Mechanical And Physical Properties ◽  
Fired Bricks ◽  
Maximum Compressive Strength

Effect of firing temperature on some physico-mechanical properties of ten brick samples, those were composed by feldspars, quartz, alumina-rich spinel, primary mullite and hematite phases, was investigated in accordance with ASTM standards. The brick samples fired between 700° to 1100° C showed 11-23 % water adsorptivity (WA), 19-37 % apparent porosity (AP) and 1.50-1.65 g/cm3 bulk density (BD) indicate good physical properties. The maximum compressive strength (CS) of the fired-bricks at 950° to 1000° C was found to be between 15.6 and 17.1 MPa. At 700°-1000° C firing temperatures, the CS of these bricks is found to be increased exponentially with decreasing of both WA and AP, however it is found to be increased with increasing the BD. Consequently, it can be said that there is good correlation between mechanical and physical properties of the fired-brick samples up to the firing temperature of 1000° C. Bangladesh J. Sci. Ind. Res.55(1), 43-52, 2020

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