scholarly journals INFLUENCE OF WATER-CEMENT RATIO AND WATER REDUCING ADMIXTURES ON THE REBOUND NUMBER OF HARDENED CONCRETE

2020 ◽  
Vol 32 (3) ◽  
Author(s):  
Kolawole Adisa Olonade
Keyword(s):  
Coefficient Of Determination ◽  
Hardened Concrete ◽  
Schmidt Hammer ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
New Correlation ◽  
Correlation Graph ◽  
Influence Of Water ◽  
Rebound Number ◽  
Schmidt Hammer Rebound Number

In this paper, effect of water-cement ratio (w/c) and type of water reducing admixtures (WRA) on the Schmidt hammer rebound number (RN) were investigated. Concrete of mix ratio 1:2:4 was prepared at the w/c of 0.45, 0.50, 0.55 and 0.60 and with each of the three WRA at the w/c of 0.45. Concrete cubes of size 150 mm were cast and cured in water for 3, 7 and 28 days. RNs of the cubes were determined and the compressive strengths (fc) corresponding to the RNs obtained from the conversion graph supplied by the manufacturer were compared with the compressive strengths obtained from crushing machine (CM). The results showed that as the w/c increased, the RN increased up to when w/c was 0.5 and began to drop, while there was no significant effect of all the WRA on the RN. It was also found that fc obtained from CM and those obtained using the conversion graph differed considerably. A new correlation graph was therefore proposed, which showed a correlation coefficient of 0.96, while coefficient of determination obtained for the regression equation between RN and fc, was as high as 0.92. The study concluded that w/c had effect on RN and that the equation developed could be used to determine fc, once RN is known.

Experimental Investigation on the Influence of Water-Cement Ratio on Air-Void Parameters of Cement Concrete

2013 ◽  
Vol 771 ◽  
pp. 29-33
Author(s):  
Jin Xi Zhang ◽  
Chao Wang ◽  
Ming Yang Guo ◽  
Mao Cheng Ma
Keyword(s):  
Experimental Investigation ◽  
Hardened Concrete ◽  
Cement Concrete ◽  
Marked Rise ◽  
Air Voids ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Influence Of Water ◽  
Air Void ◽  
The Impact

This paper studies the effect of water-cement ratio [w/ on the air-void parameters of cement concrete, which has a significant influence on the durability of concrete. Based on the experimental investigation, it is found that the impact on the air content of hardened concrete due to different water-cement ratio is not great. Test results also indicate that with the increase of water-cement ratio, the spacing factors also experienced a marked rise, and the mean diameters as well as the specific areas of air voids evidently increased or declined, respectively, which may lead to an adverse effect on the frost resistance of concrete.

scholarly journals Effect of Water Cement Ratios on Compressive Strength of Palm Kernel Shell Concrete

2019 ◽  
Vol 2 (Issue 1) ◽  
Author(s):  
A.O Adeyemi ◽  
M.A Anifowose ◽  
I.O Amototo ◽  
S.A Adebara ◽  
M.Y Olawuyi
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Fresh Concrete ◽  
Palm Kernel ◽  
Hardened Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Palm Kernel Shell ◽  
Compressive Strength Of Concrete ◽  
Palm Kernel Shells

This study examined the effect of varying water cement ratio on the compressive strength of concrete produced using palm kernel shell (PKS) as coarse aggregate at different replacement levels. The replacement levels of coarse aggregate with palm kernel shells (PKS) were 0%, 25%, 50%, and 100% respectively. PKS concrete cubes (144 specimens) of sizes 150mm x 150mm x 150mm were cast and cured in water for 7, 14, 21 and 28 days respectively. A mix ratio of 1:2:4 was adopted with water-cement ratio of 0.45, 0.5, and 0.6 respectively while the batching was done by weight. Slump test was conducted on fresh concrete while compressive strength test was carried out on the hardened concrete cubes using a compression testing machine of 2000kN capacity. The result of tests on fresh concrete shows that the slump height of 0.45 water cement ratio (w/c) increases with an increase in PKS%. This trend was similar to 0.50 and 0.60 w/c. However, the compressive strength of concrete cube decreases with an increase in w/c (from 0.45 to 0.60) but increases with respect to curing age and also decreases with increase in PKS%. Concrete with 0.45 water-cement ratio possess the highest compressive strength. It was observed that PKS is not a good substitute for coarse aggregate in mix ratio 1:2:4 for concrete productions. Hence, the study suggest the use of chemical admixture such as superplasticizer or calcium chloride in order to improve the strength of palm kernel shells-concrete.

scholarly journals تأثير إستخدام خبث أفران مجموعة جياد الصناعية على جودة الخرسانة

2021 ◽  
Vol 9 (2) ◽  
pp. 1-6
Author(s):  
علي حسين محمد علي ◽  
الطيب عبداللطيف أحمد حبيب
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Hardened Concrete ◽  
Gradual Reduction ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Artificial Materials ◽  
Percent Increase ◽  
And Performance ◽  
Furnace Slag

The need to produce high performance concrete led the researchers to try to exploit the potentialities of natural or artificial materials so as to improve the properties and performance of concrete. Slag is an industrial disposal which considered as a secondary product of pig-iron, these disposal will cause a severe harm to the environment in case of not get rid of it. In this investigation iron furnace slag which is produced at Giad Group - Iron Factory has been used as an alternative of proportion on cement after being processed, since its main oxides are similar to those of cement. In the practical part of our research slag has been added to the concrete mix in two ways, first by using it to replace as cement by weight as a substitutions of cement in different percent [10, 20, 30]% without changing in water-cement ratio [W/C], second by using the slag with the same previous percentage in addition to [15, 25]% to replace cement with reducing in water-cement ratio [W/C], and in addition superplasticizer [SP 901] has been added as percent from cement used in the mixture. The effect of slag was studied on the properties of fresh and hardened concrete including slump test and compressive strength in [7, 14, 28] days were investigated. The results show improvement in all concrete specimens for the added percentage of the slag as replacement materials and the addition of superplasticizer in the production of concrete and improvement in its properties. However, there is a gradual reduction in slump measurements due to slag percent increase in case of the two methods.  

Kansas Water-Cement Ratio Meter: Preliminary Results

1996 ◽  
Vol 1532 (1) ◽  
pp. 73-79
Author(s):  
Mustaque Hossain ◽  
James Koelliker ◽  
Hisham Ibrahim ◽  
John Wojakowski
Keyword(s):  
Fresh Concrete ◽  
Accurate Determination ◽  
Hardened Concrete ◽  
Cement Slurry ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Concrete Mix ◽  
Predominant Factor ◽  
The One ◽  
Strength And Durability

The water-cement ratio of fresh concrete is recognized as the one factor that affects the strength and durability of an adequately compacted concrete mix. Although water-cement ratio is the predominant factor affecting strength of hardened concrete, currently no widely used, reliable method is available for measuring water-cement ratio in the field. A prototype device has been developed to measure the water-cement ratio of a plastic concrete mix. The method is based on the measurement of turbidity of water-cement slurry separated out of a concrete mixture by pressure sieving. Consistent results were obtained for air-entrained and non-air-entrained concrete. Statistical analyses of the test results have shown that this meter can measure the water-cement ratio of fresh concrete with an accuracy of ±0.01 on the water-cement ratio scale for a single test at a 90 percent confidence interval. The equipment will cost less than $10,000. If the method works as well in the field as it does in the laboratory, accurate determination of water-cement ratio could dramatically improve the ability of the concrete industry to ensure the quality of concrete construction.

Research Based on Scanning Electron Microscopy to Determine Original Water-Cement Ratio of Hardened Concrete

2014 ◽  
Vol 936 ◽  
pp. 1485-1489 ◽  
Author(s):  
Yue Li ◽  
Huan Tong ◽  
Jin Bo Yang ◽  
Wan Guo Dong
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Experimental Results ◽  
Hardened Concrete ◽  
Capillary Porosity ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
The Relationship ◽  
Original Water ◽  
Scanning Electron

In order to detect the influence of age on the experiment that use scanning electron microscopy (SEM) to determinate the original water-cement ratio (w/c) of hardened concrete, a series of concrete mixes are tested. Experimental results show that early ages do have an effect on the water-cement ratio of hardened concrete that determined from scanning electron microscopy, this effect will decrease while age increases. The relationship between capillary porosity, w/c and age is analyzed and a calculation equation is given.

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