scholarly journals Analysis of compressive strength of concrete prepared by triplemixing technology depending on both the discharge and curing time

2018 ◽  
Vol 13 (1) ◽  
pp. 113-121
Author(s):  
Karol Urban ◽  
Alena Sicakova
Keyword(s):  
Compressive Strength ◽  
Fine Fraction ◽  
Coating Material ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Curing Time ◽  
Discharge Time ◽  
Compressive Strength Of Concrete ◽  
Prolonged Discharge

Abstract Compressive strength of concrete having recycled concrete aggregate is influenced by the properties and amount of those aggregate. The worse quality of RCA can be eliminated by specific mixing approach. Practical mixing and delivery of concrete could affect the properties of ready concrete due to prolonged time. In this paper, both the fly ash and fine fraction of recycled concrete were used to improve the quality of concrete due to coating of RCA, while the triple mixing technology was applied for this purpose. The compressive strength is evaluated from two aspects: the curing time (2, 28 and 90 days) and discharge time (0, 45 and 90 minutes after mixing) with attention being paid to the type of aggregate and the type of coating material. When using triple mixing technology, prolonged discharge time brings only small effect on the compressive strength (up to 12%) both in positive and negative way, depending on kind of coating material.

scholarly journals The Influence of Discharge Time, Kind of Additive, and Kind of Aggregate on the Properties of Three-Stage Mixed Concrete

2018 ◽  
Vol 10 (11) ◽  
pp. 3862 ◽  
Author(s):  
Alena Sicakova ◽  
Karol Urban
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Discharge Time ◽  
Concrete Mixtures ◽  
Concrete Properties ◽  
Concrete Production ◽  
The Impact

Application of recycled aggregates (RA) for concrete production is limited due to their poor quality. While the environmental benefits of using the RA are well accepted, some unsolved problems prevent this type of material from wide application in structural concrete. The research and development of techniques which can minimize the adverse effect of RA on the concrete properties are highly requested. A specific mixing approach can also be helpful; here, mineral additives play a significant role for improvement of RA performance within the mixing process. However, delivery process can influence the homogeneity and uniformity of the concrete mixtures, resulting in negative effect on technical parameters. In this study, the impact of delivery time (0 min, 45 min, and 90 min) on the set of hardened concrete properties is presented while the three-stage mixing is used. Two kinds of additives—fly ash (FA) and recycled concrete powder (RCP)—were tested to coat the coarse fraction of recycled concrete aggregate (RCA) in the first step of mixing. For comparison, cement as coating material and natural aggregate instead the RCA were also used. The following parameters were tested after 28 days of setting and hardening: density, compressive strength, splitting tensile strength, water absorption capacity, and depth of penetration of water under pressure. Generally, 90 min of working with concrete mixtures left no significantly negative influence on tested characteristics. Based on ANOVA results, with prolonged discharge time, the changes in composition of the mixtures become less important for compressive strength, density, and water absorption.

A Study on the Effect of Surface-Treated Coarse Recycled Concrete Aggregate (RCA) on the Compressive Strength of Concrete

2014 ◽  
Vol 935 ◽  
pp. 184-187 ◽  
Author(s):  
Sallehan Ismail ◽  
Ramli Mahyuddin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Experimental Works ◽  
Compressive Strength Of Concrete ◽  
Coarse Recycled Concrete Aggregate ◽  
Effect Of Surface

This paper reports the experimental works performed to improve the properties of recycled concrete aggregate (RCA) by using different acid molarities at low concentration as agent for surface treatment. The effects of using RCA after treatment on the improvement in the strength of concrete were evaluated and compared. The findings reveal that this treatment can enhance the physical and mechanical properties of RCA. Moreover, treated RCA particles can significantly promote surface contact between the new cement paste and the aggregate, thereby improving the strength of concrete.

scholarly journals Testing of Nutmeg Shell as a Normal Concrete Material in Terms of Volume Weight and Compressive Strength Value

2021 ◽  
Vol 21 (3) ◽  
pp. 129-138
Author(s):  
Keyword(s):  
Compressive Strength ◽  
Specific Gravity ◽  
Concrete Aggregate ◽  
Fine Aggregate ◽  
Normal Concrete ◽  
Concrete Material ◽  
Average Value ◽  
Volume Weight ◽  
Compressive Strength Of Concrete

Normal concrete uses fine aggregate and coarse aggregate with concrete density 2200 kg/m3-2400 kg/m3 with a compressive strength of about 15-40 MPa [1]. The purpose of this study is to determine characteristics of the concrete aggregate and the compressive strength of the concrete design based on the DOE (Department of Environment) method and the SNI Standard. In this research, the use of nugmet shell was varied as follows: 0%, 0,25%, 0,50%, 0,75% and 1% of the cement weight. The results showed that the use of nutmeg shells as a normal concrete affected the specific gravity and the value compressive strength of concrete. The higher the percentage of nutmeg shells, the lower the specific gravity and compressive strength of the concrete. The average value of density to nutmeg shell concrete (NSC) 2254.72 (kg/m3) and normal concrete 2304.32 (kg/m3). The compressive strength of normal concrete is 224.2 kg/cm2 and the nutmeg shell concrete (NSC) the composition of 0.25% and 0.5% obtained by 129.6 kg/cm2 and 140.0 kg/cm2 increases the use of nutmeg shell 0.75% and 1% obtained value ​​of 117.6 kg/cm2 and 118.1 kg/cm2 decreased at the age of 28 days. The compressive strength of normal concrete 22 MPa while the maximum nutmeg shell concrete (NSC) 14 MPa, so it does not meet the quality of normal concrete in general.

Effect of CO2 Curing on the Strength of High Strength Pervious Concrete

2020 ◽  
Vol 846 ◽  
pp. 207-212
Author(s):  
Ming Gin Lee ◽  
Yung Chih Wang ◽  
Wan Xuan Xiao ◽  
Ming Ju Lee ◽  
Tuz Yuan Huang
Keyword(s):  
Carbon Dioxide ◽  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
High Strength ◽  
Pervious Concrete ◽  
Control Group ◽  
Curing Time ◽  
Compressive Strength Of Concrete ◽  
Curing Pressure

This study was conducted to assess the effect of CO2 curing on the compressive strength of high strength pervious concrete. The factors studied to evaluate compressive strength of concrete on CO2 curing pressure, curing time, and age of specimen at testing. Three Aggregate sizes, three CO2 curing pressures, three CO2 curing time, and three testing ages were used in this investigation. The research tried to produce a high strength pervious concrete and use carbon dioxide for curing to find out whether it could enhance the compressive strength. The results show that the compressive strength of the control group increases rapidly and its 90-day compressive strength closed to 60 MPa. The 1-day compressive strength has a major impact after CO2 curing and their strength decreased by about 0% to 50% as compared to the control group. However, it is observed that there is only slight difference in relationship between modulus of elasticity and compressive strength obtained from 100 by 200mm cylinders with CO2 curing.

scholarly journals Effect of River Indus Sand and Recycled Concrete Aggregates as Fine and Coarse Replacement on Properties of Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 3832-3835 ◽  
Author(s):  
A. R. Sandhu ◽  
M. T. Lakhiar ◽  
A. A. Jhatial ◽  
H. Karira ◽  
Q. B. Jamali
Keyword(s):  
Tensile Strength ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Compressive Strength Of Concrete ◽  
River Indus ◽  
Concrete Materials

As the demand for concrete rises, the concrete materials demand increases. Aggregates occupy 75% of concrete. A vast amount of aggregates is utilized in concrete while aggregate natural resources are reducing. To overcome this problem, River Indus sand (RIS) and recycled concrete aggregate (RCA) were utilized as fine and coarse aggregate respectively. The aim of this experimental investigation is to evaluate the workability, and compressive and tensile strength of concrete utilizing RIS and RCA. Concrete samples of 1:2:4 proportions were cast, water cured for 7, 14, 21 and 28 days, and tested for compressive and tensile strength. The outcomes demonstrate that concrete possessed less workability when RIS and RCA were utilized. It was predicted that compressive strength of concrete would reduce up to 1.5% when 50% RIS and 50% RCA were utilized in concrete and 11.5% when natural aggregate was fully replaced by RIS and RCA, whereas the tensile strength decreased up to 1.60% when 50% by 12% respectively.

Fuzzy application in the prediction of axial compressive strength of Portland concrete based on traces and curing time

2021 ◽  
Author(s):  
DENNIS SANTOS TAVARES ◽  
BRUNA CAMPOS AMARAL ◽  
DAVID AUGUSTO RIBEIRO ◽  
TADAYUKI YANAGI JUNIOR ◽  
FRANCISCO CARLOS GOMES ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Fuzzy Systems ◽  
Main Property ◽  
Membership Functions ◽  
Curing Time ◽  
Axial Compressive Strength ◽  
Compressive Strength Of Concrete ◽  
Input Variables ◽  
Main Material

Concrete is the main material used in the construction industry and its main property is the axial compressive strength. Usually the prediction of compressive strength is restricted to limited empirical equations and / or laboratory dosages. The objective of this study is to develop fuzzy systems capable of obtaining the axial compressive strength of concrete, from the mixtures and curing time. Several fuzzy systems were developed with Mamdani inference and different defuzzification methods. Triangular membership functions were adopted for the input variables in all systems and triangular functions for the output variables. The developed models were simulated and evaluated using three statistical indexes. The systems with Mamdani inference and centroid, bisector and mom defuzzification proved to be reliable and highly effective. The best performance was obtained by the fuzzy centroid defuzzification system according to the analyses.,

scholarly journals Effect of basalt aggregates and plasticizer on the compressive strength of concrete

2015 ◽  
Vol 4 (4) ◽  
pp. 520 ◽  
Author(s):  
Mohammad Al-Rawashdeh ◽  
Ashraf Shaqadan
Keyword(s):  
Compressive Strength ◽  
Laboratory Investigation ◽  
Concrete Strength ◽  
Experimental Program ◽  
Sieve Analysis ◽  
Curing Time ◽  
Compressive Test ◽  
Slump Test ◽  
Compressive Strength Of Concrete

The purpose of this research is to investigate the feasibility of using basalt aggregates and plasticizers in concrete mixes. An elaborate experimental program that included a variation of plasticizer and basalt in concrete mixes. The laboratory investigation included measurements of sieve analysis, compressive strength, and slump test. The compressive test was evaluated at 7, 14, 28 days of curing time. The results show significant improvement in concrete strength up to 2% of additive plasticizer after that concrete strength was reduced.

scholarly journals Mechanical and Durability Properties of Cement-Stabilized Recycled Concrete Aggregate

2020 ◽  
Vol 12 (18) ◽  
pp. 7380
Author(s):  
Qingfu Li ◽  
Jing Hu
Keyword(s):  
Cement Content ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Partial Replacement ◽  
Concrete Aggregate ◽  
Curing Time ◽  
Recycled Concrete Aggregate ◽  
Replacement Ratio ◽  
Obvious Effect ◽  
Study Test

This research investigates the effect of using recycled concrete aggregate (RCA) as a partial replacement of natural aggregate (NA) on the mechanical and durability-related properties of a cement-stabilized recycled concrete aggregate (CSR) mixture. In this case, mixtures were prepared with 0%, 40%, 70%, and 100% (by weight) RCA to replace NA, and cement contents of 4%, 5%, and 6% were used in this study. Test parameters included the replacement ratio, cement content, and curing time. Tests were carried out to establish the unconfined compressive strength (UCS), indirect tensile strength (ITS), drying shrinkage, and water loss ratio of each mix proportion. The preliminary results of UCS and ITS tests indicated that the incorporation of RCA resulted in a decrease of strength compared with a cement-stabilized macadam (CSM) mixture, but the seven-day strength of the CSR mixture met the related requirements of road bases. The increase in cement content and curing time had an obvious effect on strength improvement. The drying shrinkage test showed that the drying shrinkage properties of the CSR mixture were obviously reduced with a high replacement ratio. It is evident that the CSM mixture presented a better drying shrinkage performance than that of the CSR mixture.

scholarly journals The effect of coarse aggregate hardness on the fracture toughness and compressive strength of concrete

2019 ◽  
Vol 258 ◽  
pp. 04011
Author(s):  
Atur P. N. Siregar ◽  
Emma L. Pasaribu ◽  
I Wayan Suarnita
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Los Angeles ◽  
Coarse Aggregate ◽  
Concrete Aggregate ◽  
Beam Size ◽  
Intensity Factors ◽  
Coarse Aggregates ◽  
Los Angeles Abrasion ◽  
Compressive Strength Of Concrete

Coarse aggregate is the dominant constituent in concrete. Aggregate hardness is a variable needed to investigate in determining its effect on the critical stress intensity factors (KIC), dissipated fracture energy (Gf) and compressive strength (fc’) of the concrete. The hardness of coarse aggregate based on Los Angeles abrasion values of 16.7%., 22.6%, and 23.1% was used incorporated with Portland Composite Cement (PCC), and superplasticizer to create specimens. Cubes of 150x150x150 mm were employed to determine the fc’, and four beam sizes: 50x100x350 mm, 50x150x500 mm, 50x300x950 mm and 50x450x1250 mm were engaged to determine KIC and Gf. The fc’ and Gf of specimens manufactured by three different hardness of coarse aggregates were 45, 43, 40 MPa and 89.4, 54.0, 56.3 N/m respectively. KIC of specimens was 138.9, 119.4 and 114.1 MPa.mm1/2 for beam size of 50x100x350 mm; 148.2, 115.8 and 108.8 MPa.mm1/2 for beam size of 50x150x500 mm; 230.9, 183.1 and 157.9 MPa.mm1/2 for beam size of 50x300x950 mm; and 293.2, 248.1 and 244.3 MPa.mm1/2 for beam size of 50x450x1250 mm. Experimental results showed that decreasing hardness of coarse aggregate was found to have significant effect on the fracture toughness rather than on the compressive strength of concrete.

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