Effects of Water-Cement Ratio, Curing Age, Silica Fume, Polymer Admixtures, Steel Surface Treatments and Corrosion on the Bond between Concrete and Steel Reinforcing Bar

10.14359/417 ◽  
1998 ◽  
Vol 95 (6) ◽  
Keyword(s):  
Silica Fume ◽  
Steel Surface ◽  
Surface Treatments ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Reinforcing Bar ◽  
Curing Age

scholarly journals SUITABILITY OF BURNT AND CRUSHED COW BONES AS PARTIAL REPLACEMENT FOR FINE AGGREGATE IN CONCRETE

2017 ◽  
Vol 36 (3) ◽  
pp. 686-690
Author(s):  
NM Ogarekpe ◽  
JC Agunwamba ◽  
FO Idagu ◽  
ES Bejor ◽  
OE Eteng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Fine Aggregates ◽  
Concrete Mix ◽  
Average Compressive Strength ◽  
Curing Age

The suitability of burnt and crushed cow bones (BCCB) as partial replacement for fine aggregate in concrete was studied. The percentages of replacements of fine aggregates of 0, 10, 20, 30, 40 and 50%, respectively of BCCB were tested considering 1: 2: 4 and 1: 11/2 :3 concrete mix ratios. The cow bones were burnt for 50 minutes up to 92oC before being crushed. Ninety-six (96) concrete cubes of 1: 2: 4 mix ratio and ninety-six (96) concrete cubes of 1 : : 3 mix ratio measuring 150x150x150mm were tested for the compressive strength at 7, 14, 21 and 28 days respectively. The research revealed that the BCCB acted as a retarder in the concrete. Water-cement ratio increased with the increase in the percentage of the BCCB. The mixes of 1:2:4 and 1::3 at 28 days curing yielded average compressive strengths in N/mm2 ranging from 16.49 - 24.29 and 18.71 - 29.73, respectively. For the mix ratios of 1:2:4 and 1:: 3 at 28 days curing age,  it was observed that increase in the BCCB content beyond 40 and 50%, respectively resulted to the reduction of the average compressive strength below recommended minimum strength for use of concrete in structural works.http://dx.doi.org/10.4314/njt.v36i3.4

Etude de la résistance au gel de bétons contenant un fluidifiant

1991 ◽  
Vol 18 (4) ◽  
pp. 581-589 ◽  
Author(s):  
Michel Pigeon ◽  
Marcel Langlois
Keyword(s):  
Silica Fume ◽  
Plain Concrete ◽  
Freezing And Thawing ◽  
Freezing Resistance ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Spacing Factor ◽  
Thaw Cycle ◽  
Air Void

There is some controversy about freezing resistance of concrete containing superplasticizers. It has been quite convincingly demonstrated that, in some cases, such admixtures can significantly alter air-void systems in concrete. Some researchers believe, however, that concrete with superplasticizers can resist frost even when the air-void spacing factor is higher than the usual limit of 200 μm. The freeze–thaw cycle resistance tests described in this paper show that with the two types of concrete tested (a plain concrete with a water/cement ratio of 0.50 and a concrete with the same water/cement ratio but containing silica fume), the critical air-void spacing factor value is not significantly affected by the presence of a superplasticizer. When regular concrete is to be exposed to freeze–thaw conditions, the air-void system should meet the usual standards even when a superplasticizer is present. Key words: concrete, freezing and thawing, durability, superplasticizer, spacing factor, silica fume, water–cement ratio. [Journal translation]

La durabilité au gel des bétons à haute performance

1992 ◽  
Vol 19 (6) ◽  
pp. 975-980 ◽  
Author(s):  
Michel Pigeon ◽  
Richard Gagné ◽  
Pierre-Claude Aitcin ◽  
Marcel Langlois
Keyword(s):  
Silica Fume ◽  
Standard Procedure ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Spacing Factor ◽  
Thaw Cycle ◽  
Entrained Air ◽  
Air Void ◽  
Limiting Value

Frost resistance of high-strength concrete (80–100 MPa) was studied by subjecting 44 concrete mixes to freeze–thaw cycles in water (ASTM C666, standard procedure A) and to scaling tests in the presence of deicer salts (ASTM C672, standard). The test programme was designed to analyze the effects of the water/cement ratio, the type of cement, the type of coarse aggregate, the duration of curing, and the air-void spacing factor. Results demonstrate that the water/cement ratio limiting value, below which entrained air is no longer necessary to protect concrete against freeze–thaw cycles, is sometimes higher than 0.30 but is more often below 0.25. This limiting value is affected most by cement characteristics: type 30 cement yielded much more durable concretes. Laboratory scaling tests demonstrated that when water/cement ratios are less than 0.30, the resistance deicer salt is generally very good, no matter what are the type of cement, the silica fume content, or the air-void spacing factor of the concrete. Key words: durability, freeze–thaw cycle, silica fume, scaling, curing, spacing factor, water/cement ratio, compressive strength, cement type, entrained air, aggregate. [Journal translation]

Study of RPC Mechanical Properties and Anti-Freeze-Thaw Resistance

2010 ◽  
Vol 168-170 ◽  
pp. 1742-1748
Author(s):  
Yan Zhong Ju ◽  
Feng Wang ◽  
De Hong Wang
Keyword(s):  
Mechanical Properties ◽  
Silica Fume ◽  
Steel Fiber ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Early Strength ◽  
Reactive Powder

To study the mechanical properties of RPC performance and freeze-thaw resistance，through the experimental study discussed the water-cement ratio, silica fume cement ratio, steel fiber content, curing system and other factors on the mechanical properties of reactive powder concrete and anti-freezing properties. Research indicates that many factors in the RPC, the water cement ratio is the most important factor, followed by the silica fume cement ratio, finally the steel fiber content, and curing system for the growth of its early strength also have a greater role.

Effects of Temperature on Drying Shrinkage of Concrete

2014 ◽  
Vol 584-586 ◽  
pp. 1176-1181 ◽  
Author(s):  
Ying Zi Yang ◽  
Mao Guang Li ◽  
Hong Wei Deng ◽  
Qi Liu
Keyword(s):  
Fly Ash ◽  
Silica Fume ◽  
Drying Shrinkage ◽  
Shrinkage Strain ◽  
Mineral Admixture ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Granulated Blast Furnace Slag ◽  
Influence Of Water ◽  
Effects Of Temperature

The present study investigated experimentally effects of temperature on drying shrinkage of concrete in different water cement ratio and containing mineral admixture. Concrete was exposed to a controlled environment of 20±1oC, 35±1oC, 50±1oC, and 60% ± 5 RH, respectively. The drying shrinkage of concretes with water cement ratio of 0.3, 0.4 and 0.5 were evaluated. The resuluts showed that with the increase of temperature from 20 oC to 50 oC, the influence of water cement ratio on drying shrinkage of concrete was gradually weakened. The shrinkage strain of concretes with replacement of cement by 20% of ground granulated blast-furnace slag (GGBS), 10% of silica fume (SF), and 20% of fly ash (FA) were measured, respectively. Test results showed that GGBS had a little impact on drying shrinkage of concrete; Silica fume could increase the drying shrinkage of concrete significantly in the early and later ages, especially when concrete was subjected to high temperature; Fly ash reduced drying shrinkage in early ages and increased drying shrinkage of concrete in the later ages.

scholarly journals Chicken Feather Ash (CFA) as a Partial Replacement of Cement in Concrete

2021 ◽  
pp. 130-140
Author(s):  
Victor Emeka Amah ◽  
Ejikeme Ugwoha ◽  
Jahswill Macaulay
Keyword(s):  
Compressive Strength ◽  
Partial Replacement ◽  
Chicken Feather ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Chicken Feathers ◽  
Allowable Range ◽  
Full Factorial ◽  
Optimum Water ◽  
Curing Age

Every day, large quantities of chicken feathers are disposed of as waste at markets where birds are slaughtered and sold for meat. The possibility of using Chicken feather ash (CFA) as a partial replacement of cement in the concrete making was investigated. Water-cement ratio and percentage CFA used for replacement were chosen as variables in the design of the experiment. Compressive strength and workability were chosen as the required responses to observe and analyzed using response surface methodology. Full factorial design was used for the design of experiment, with CFA replacement and water-cement ratio ranging from 2 – 11% and 0.3 – 0.7 % by mass respectively. There were 27 trial mixes and the freshly made concrete mix was tested for workability. Concrete cubes were molded and cured for 7 and 14 days and were crushed to determine the compressive strength. It was found that as the CFA percentage increases, the workability of the concrete increases making it more fluid. The optimum water-cement ratio was observed to range from 0.49 to 0.51 % as the curing age increases. The optimum compressive strength was observed to range from 15.6 to 18.6 N/mm2 as the curing age increased. However, the allowable range of CFA to be used for concrete making is 3.8 to 6.34 % beyond which compressive strength reduces.

scholarly journals Fundamental Study on Low-Temperature Autoclaving Focused on the Water Cement Ratio and Silica Fume Content

2013 ◽  
Vol 62 (10) ◽  
pp. 615-620 ◽  
Author(s):  
Shin YAMAGUCHI ◽  
Masami UZAWA ◽  
Naofumi IWASAKI ◽  
Yoji OGAWA ◽  
Yoshinari ITOH ◽  
...  
Keyword(s):  
Low Temperature ◽  
Silica Fume ◽  
Fundamental Study ◽  
Cement Ratio ◽  
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.

The Effect of Water-Cement Ratio and Curing Age on the Strength of Recycled Concrete

2011 ◽  
Vol 217-218 ◽  
pp. 740-745
Author(s):  
Xue Bing Zhang ◽  
Chen Gang Kuang ◽  
Zhi Fang
Keyword(s):  
Growth Rate ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Empirical Formulas ◽  
Natural Sand ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Ordinary Concrete ◽  
Effect Of Water ◽  
Curing Age

The effect of water-cement ratio and curing age on the strength of recycled concrete was studied by experiment with the combination of the recycled coarse aggregate adding natural sand. The results showed that with the increase of curing age, the greater the water-cement ratio is, the smaller the strength growth rate is; the smaller the water-cement ratio is, the greater the strength growth rate is. There is a relatively larger increase in the growth rate of 90d strength than 28d’, which is significantly higher than that of the ordinary concrete. The linear relationship between water-cement ratio and strength of recycled concrete is worse than that of ordinary concrete. Under the same water-cement ratio and curing age, the strength of recycled concrete is lower than that of ordinary concrete, and the empirical formulas between the strength of 28d and 7d, 90d and 28d were obtained.

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