A Rule-Breaking Approach to a Better Understanding of the Method of Tests for Slump, Air Content and Compressive Strength

2019 ◽  
Vol 57 (6) ◽  
pp. 433-440
Author(s):  
S. Komatsu ◽  
Y. Kondo ◽  
N. Ikawa ◽  
C. Hashimoto
Keyword(s):  
Compressive Strength ◽  
Air Content ◽  
Rule Breaking

scholarly journals PROPERTIES OF MORTARS CONTAINING TIRE RUBBER WASTE AND EXPANDED POLYSTYRENE (EPS)

2018 ◽  
pp. 219-225 ◽  
Author(s):  
Adriane Pczieczek ◽  
Adilson Schackow ◽  
Carmeane Effting ◽  
Itamar Ribeiro Gomes ◽  
Talita Flores Dias
Keyword(s):  
Compressive Strength ◽  
Specific Gravity ◽  
Water Absorption ◽  
Expanded Polystyrene ◽  
Fine Aggregate ◽  
Tire Rubber ◽  
Air Content ◽  
Rubber Waste ◽  
Hardened State ◽  
Entrained Air

This study aims to evaluate the application of discarded tire rubber waste and Expanded Polystyrene (EPS) in mortar. For mortars fine aggregate was replaced by 10%, 20% and 30% of rubber and, 7.5% and 15% of EPS. We have verified the consistency, density, amount of air and water retentitivity in fresh state. The compressive strength, water absorption, voids ratio and specific gravity have been also tested in hardened state. The application of rubber powder contributed to the increase in entrained air content and in reducing specific gravity, as well as reducing compressive strength at 28 days. The addition of EPS also contributed to the increase of workability, water absorption and voids ratio, and decreased density and compressive strength when compared to the reference mortar. The use of rubber waste and EPS in mortar made the material more lightweight and workable. The mortars mixtures containing 10% rubber and 7.5% EPS showed better results.

scholarly journals Effect of the Initial Air Content in Fresh Slurry on the Compressive Strength of Hardened Cemented Paste Backfill

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Youzhi Zhang ◽  
Deqing Gan ◽  
Zhenlin Xue ◽  
Xun Chen ◽  
Sheng Hu
Keyword(s):  
Compressive Strength ◽  
Sodium Dodecyl ◽  
Contact Structures ◽  
Cemented Paste Backfill ◽  
Mining Method ◽  
Force Analysis ◽  
Air Content ◽  
Ground Pressure ◽  
Paste Backfill ◽  
The Mathematical Model

Filling mining method can dispose of the tailings into filling slurry, which can be transported to the stope through pipelines to manage the ground pressure and protect the environment. To improve the flowability of filling slurry, additives are used more and more widely. However, some additives can increase the air content in the slurry. The air in the slurry will become pores in the hardened cemented paste backfill (CPB). Therefore, it is necessary to explore the influence of initial air content in fresh slurry on the compressive strength of CPB. In this paper, sodium dodecyl sulfate (SDS) was used to regulate the air content in the fresh slurry. After measuring the initial air content, the slurry was made into test blocks. Then, the uniaxial compressive strength (UCS) of CPB at 28 d age was tested, and the distribution of CPB microscopic pores was observed by scanning electron microscope (SEM). The results show that as the initial air content in fresh slurry increases, the UCS of CPB first increases and then decreases. Before the initial air content in fresh slurry is 6.03%, the CPB pores distribution is relatively uniform. However, after exceeding this value, “discontinuous contact” structures, pore groups, and macropores occur in CPB. Through the CPB microscopic force analysis, the mathematical model describing the effect of initial air content on UCS of CPB should be a combination of logarithmic function and quadratic polynomial. This work can provide a supplement to the theory of CPB strength.

Effect on the Flow Properties of the Mortar Using Micro-Nano Bubbles

2015 ◽  
Vol 1110 ◽  
pp. 249-252
Author(s):  
Takayoshi Maruyama ◽  
Naoya Takahashi ◽  
Shinchiro Hashimoto ◽  
Shigeyuki Date
Keyword(s):  
Compressive Strength ◽  
Tap Water ◽  
Flow Speed ◽  
The Other ◽  
Filling Material ◽  
Typical Characteristic ◽  
Construction Sector ◽  
Flow Properties ◽  
Agricultural Industry ◽  
Air Content

Bubble of which diameter ranges 50μm to nanometer-order is called micro-nanobubble (here in after “MNB”), it has properties different from the millimeter-order and centimeter-order naturally generated. In general, the bubble rises rapidly in water and burst at the surface. However, the MNB tends to stay in the water as the diameter of itself becomes small. In addition, MNB has various characteristics unlike general water. A typical characteristic includes water purification effect, and is utilized such as water treatment, agricultural industry and chemical industry. However, there is not much report that was utilized in the construction sector so far. In this study, it paid attention to the feature of MNB that the resistance when flowing in the tube decreases, and the possibility of the workability improvement of the grout material and the filling material by the use of MNB was investigated by the experiment of the cement paste. As the results, when it compared properties of the paste that used both MNB and tap water, no difference was observed in the air content and the flow value. However, plastic viscosity of the paste that used MNB was smaller than control paste. In consequence it was confirmed that the flow speed of the paste when it flows in the pipe was improved. On the other hand there is no difference in the compressive strength.

scholarly journals INVESTIGATIONS ON THE RELATIONSHIP BETWEEN POROSITY AND STRENGTH OF ADMIXTURES MODIFIED HIGH PERFORMANCE SELF-COMPACTING CONCRETE

2016 ◽  
Vol 22 (4) ◽  
pp. 520-528 ◽  
Author(s):  
Beata ŁAŹNIEWSKA-PIEKARCZYK
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Total Porosity ◽  
Self Compacting Concrete ◽  
Research Results ◽  
Air Content ◽  
New Generation ◽  
The Relationship ◽  
Viscosity Modifying Admixture

The influence of a type of new generation: superplasticizer (SP), anti-foaming admixture (AFA) and viscosity modifying admixture (VMA) on the air-content, workability of high performance self-compacting concrete (HPSCC) is analyzed in the paper. The purpose of this study was to examine the influence of type of the admixtures on porosity of HPSCC in the aspect of the compressive strength. The research results indicated that type of admixtures and its combina­tions result in different strengths of HPSCC, regardless of the total porosity characteristics of HPSCC.

scholarly journals Towards Innovative and Sustainable Construction of Architectural Structures by Employing Self-Consolidating Concrete Reinforced with Polypropylene Fibers

2020 ◽  
Author(s):  
Wael Zatar ◽  
Hai Nguyen
Keyword(s):  
Compressive Strength ◽  
Reinforced Concrete ◽  
Fiber Reinforced Concrete ◽  
Sustainable Construction ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Self Consolidating Concrete ◽  
Air Content ◽  
Slump Flow ◽  
Architectural Structures

Self-consolidating concrete (SCC) has been successfully employed to reduce construction time and enhance the quality, performance, and esthetic appearance of concrete structures. This research aimed at developing environmentally friendly fiber-reinforced concrete (FRC) consisting of SCC and recycled polypropylene (PP) fibers for sustainable construction of city buildings and transportation infrastructure. The addition of the PP fibers to SCC helps reducing shrinkage cracks and providing enhanced mechanical properties, durability, and ductility of the concrete materials. Several mix designs of self-consolidating fiber-reinforced concrete (SCFRC) were experimentally examined. Material and esthetic properties of the SCFRC mixtures that include micro silica, fly ash, and PP fibers were evaluated. Trial-and-adjustment method was employed to obtain practically optimum SCFRC mixtures, mixtures that are affordable and easy to make possessing enhanced compressive strength and esthetic properties. Slump flow and air content testing methods were used to determine the fresh properties of the SCFRC mixtures, and the esthetic properties of the mixtures were also evaluated. The hardened properties of the SCFRC mixtures were examined using three- and seven-day compression tests. The amount of fine/coarse aggregate, water, and other admixtures were varied while the Portland cement content in all mixtures was maintained unchanged. The maximum three-day compressive strength was 43.17 MPa and the largest slump flow was 736.6 mm. Test results showed enhanced material properties such as slump flow, air content and compressive strength values of the SCFRC mixtures and their excellent esthetic appearance. The favorable seven-day compressive strength of the SCFRC mixture, with 4.8 percent air content and 660.4 mm slump flow, is 39.26 MPa. The mixtures’ in this study are proven to be advantageous for potential SCFRC applications in architectural structures including building façades and esthetically-pleasing bridges.

scholarly journals Evaluation of Physical Characteristics and Sorption of Cement Mortars with Recycled Ceramic Aggregate

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7852
Author(s):  
Agata Stolarska ◽  
Teresa Rucińska
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Thermal Conductivity Coefficient ◽  
Sorption Isotherms ◽  
Sorption Kinetics ◽  
Fine Aggregate ◽  
Air Content ◽  
Nonstationary Method ◽  
Moisture Conditions

The subjects of this study were mortars with varying amounts of recycled ceramic aggregate (RCA). As part of the fine aggregate, the RCA volume share is 10%, 20%, 30%, 50% and 100%. First, fresh mixture parameters were evaluated, such as consistency and air content measurement by pressure method. Next, specimens were molded for compressive strength and flexural strength tests after 7, 28 and 56 days of curing. The thermo-humidity parameters of the composites, i.e., coefficient of capillary action and thermal conductivity coefficient were also investigated using nonstationary method. Sorption kinetics of the mortars at different moisture conditions at 20 °C were also evaluated. Sorption tests were carried out using two methods: TM and DVS. The sorption isotherms were plotted on the basis of equilibrium moisture content for the materials tested. The isotherms obtained by the two methods were evaluated. The results allowed us to draw conclusions on the physical and mechanical parameters of the composites with different amounts of RCA and to evaluate the ability to absorb moisture from the environment by these types of materials. A clear decrease in the compressive strength after 28 days of curing compared to the reference mortar was recorded after using 30% to 100% of RCA (approx. 26% to approx. 39%). Changes in flexural strength were significantly smaller, reaching no more than approx. 7.5%. It was shown that the amount of RCA translates into the ability to sorb moisture, which may affect the application of this type of composites. The amount of RCA translates also into the thermal conductivity coefficient, which decreased with increasing amount of RCA.

scholarly journals Experimental Study on Mechanical Properties and Fractal Dimension of Pore Structure of Basalt–Polypropylene Fiber-Reinforced Concrete

2019 ◽  
Vol 9 (8) ◽  
pp. 1602 ◽  
Author(s):  
Ditao Niu ◽  
Daguan Huang ◽  
Hao Zheng ◽  
Li Su ◽  
Qiang Fu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fractal Dimension ◽  
Pore Structure ◽  
Polypropylene Fiber ◽  
Splitting Tensile Strength ◽  
Fiber Reinforced Concrete ◽  
Hybrid Fibers ◽  
Air Content

This study investigates the effects of basalt–polypropylene fibers on the compressive strength and splitting tensile strength of concrete and calculates the fractal dimension of the pore structure of concrete by using a fractal model based on the optical method. Test results reveal that hybrid fibers can improve the compressive strength and splitting tensile strength of concrete, and the synergistic effect of the hybrid fibers is strongest when the contents of basalt fiber (BF) and polypropylene fiber (PF) are 0.05% each, and that the maximum increments in compressive strength and splitting tensile strength are 5.06% and 9.56%, respectively. The effect of hybrid fibers on splitting tensile strength is greater than on compressive strength. However, hybrid fibers have adverse effects on mechanical properties when the fiber content is too high. The pore structure of basalt–polypropylene fiber-reinforced concrete (BPFRC) exhibits obvious fractal characteristics, and the fractal dimension is calculated to be in the range of 2.297–2.482. The fractal dimension has a strong correlation with the air content and spacing factor: the air content decreases significantly whereas the spacing factor increases with increasing fractal dimension. In addition, the fractal dimension also has a strong positive correlation with compressive strength and splitting tensile strength. Therefore, the fractal dimension of the pore structure can be used to evaluate the microscopic pore structure of concrete and can also reflect the influence of the complexity of the pore structure on the macroscopic mechanical properties of concrete.

Effect of concrete specifications and inspection practices on freeze–thaw resistance: a field study

1990 ◽  
Vol 17 (2) ◽  
pp. 271-276
Author(s):  
M. A. Ward ◽  
B. W. Langan
Keyword(s):  
Compressive Strength ◽  
Statistical Analysis ◽  
Field Study ◽  
Key Words ◽  
Freeze Thaw ◽  
Air Content ◽  
Rigorous Statistical Analysis ◽  
Metropolitan Center ◽  
Concrete Materials ◽  
Job Site

In the late sixties significant durability problems were encountered in a major metropolitan center in Canada. A review of prevailing construction practices was undertaken, together with a rigorous statistical analysis of the air content and compressive strength results. The main outcome of that study was a conclusion that a significant amount of the concrete placed on the job site had an unacceptably low air content. It is understood that these results, coupled with a review of specifications used in other metropolitan centers, provided the basis for revising the concrete materials specification in 1970. A similar review of strength and air content results was carried out at the end of that year. It was evident that an increase of approximately 1% had occurred in the average measured air content together with a small increase in compressive strength as the result of the specification changes. To assess the effect of this specification and further changes that have occurred since 1970, a third review was carried out in 1987. It was noted that during the intervening period a further increase in air content had taken place. Reasons for these changes are reviewed with respect to current construction practices. Also included is a review of the current specifications for this class of concrete in use in Canada. Key words: air content, compressive strength, specifications, inspection, statistics, durability.

A laboratory investigation for potential durability of ready-mixed concrete retempered for air content and workability

1976 ◽  
Vol 3 (4) ◽  
pp. 570-577 ◽  
Author(s):  
B. W. Langan ◽  
M. A. Ward
Keyword(s):  
Compressive Strength ◽  
Laboratory Investigation ◽  
Hardened Concrete ◽  
Air Content ◽  
Spacing Factor ◽  
Void System ◽  
Air Void ◽  
Ready Mixed Concrete ◽  
Mixed Concrete

The effects of agitation and retempering on some properties of fresh and hardened concrete are considered.Data are presented on the influence of agitation and retempering with an air-entraining agent on the workability, compressive strength, and air void system in hardened concrete.The results indicate that although agitation reduces air content and increases the spacing factor, the original parameters can be regained by proper retempering. It is shown that any loss in compressive strength due to retempering is accompanied by an increase in potential durability due to the improvement of the air void system.

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