Wyniki wyszukiwania - BazTech

1

Development of treated coarse recycled aggregate-based sustainable fibrous high-strength concrete with fine recycled aggregates

Dhaheer M. S. Abo, Nahhab Ali H., Nasr Mohammed Salah

Materials Science Poland

|

2024

|

Vol. 42, No. 2

1--15

EN

This research aims to develop sustainable high-strength concrete (SHSC) by replacing 100% fine and/or coarse aggregates with fine recycled aggregate (RA) and/or coarse RA. Due to the high surface water absorption of coarse RA, a surface treatment method was adopted, consisting of immersing it in a cement and silica fume slurry. Moreover, to improve the performance of the produced SHSC, steel fibers were employed at a relatively low volume fraction (0.5%). Eleven blends were cast and tested in this experimental study. A control SHSC mix (without RA) and ten other mixtures, including fine natural and RA, treated and untreated coarse RA, with and without steel fibers, were prepared. Compressive, splitting, and flexural strengths, water absorption, density, and ultrasonic pulse velocity (UPV) of the resulting SHSC were conducted. The results indicated that the use of RA in SHSC resulted in an average drop of 25% in its mechanical properties and an increase of about 30% in water absorption. However, using treated RA compensated the compressive and tensile strength reductions in SHSC by 9% and 7%, respectively, compared to mixes containing untreated RA. On the other hand, adding fibers helped improve compressive, flexural, and splitting tensile strengths by about 8%, 23%, and 31%, respectively, compared to the corresponding control mix. Consequently, the results showed that it is possible to produce durable SHSC made from 100% RA and 0.5% steel fibers with a reduced density and improved mechanical performance to a comparable level or even superior to high-strength concrete (HSC) with only natural aggregates (NAs).

2

The properties and application of composite materials on the example of concrete with addition of steel and synthetic fibres

Mazewska Marta

Modern Engineering

|

2023

|

1

1--5

EN

The properties of fibre reinforced concretes are currently the subject of many studies due to the possibility of using that type of material in various fields of building engineering. The fibre reinforced concretes are composite materials, that consist of a concrete matrix and fibers. There are applied many kinds of fibres, for example made of steel, polypropylene or glass. The addition of fibers to the concrete has a beneficial effect on many of its features, including increased impact strength, reduced shrinkage and it also improves concrete strength. The paper presents the possibilities of using reinforced concretes with the addition of steel and propylene fibres.

3

Mechanical properties of concretes modified with steel fibers and polypropylene

Helbrych Paweł

Zeszyty Naukowe Akademii Morskiej w Szczecinie

|

2022

|

nr 71 (143)

56--63

EN

This paper presents the effect of the addition of steel and propylene fibers on the mechanical properties of floor concretes (compressive and tensile strengths in the bending test). The polypropylene fibers used in the tests (fibrillated and single fibers) are dosed in the amount of 0.5 kg/m3 to 2 kg/m3 , and the straight and hooked steel is dosed from 10 kg/m3 to 25 kg/m3 . It is shown that, after 28 days of maturation, the highest compressive strength is achieved by concretes containing the addition of 25 kg/m3 of hook-like steel fiber. In addition, the influence of the fiber content on the consistency of the concrete mix and workability is investigated. It was shown that the amount of steel fibers dosed in the tests, regardless of their shape, did not adversely affect the consistency and workability of the concrete mix. On the other hand, the addition of polypropylene fibers has a significant impact on the characteristics of the concrete mix. The addition of 2 kg/m3 of polypropylene fibers caused the change of consistency from S4 to S1/S2 and worsened the workability of the mixture. All of the tested series of the concrete are created using the same technology. The concrete production technology reflects the concrete production technology for flooring concretes.

4

To determine the performance of metakaolin‑based fiber‑reinforced geopolymer concrete with recycled aggregates

Zaid Osama, Martínez-García Rebeca, Abadel Aref A., Fraile-Fernández Fernando J., Alshaikh Ibrahim M. H., Palencia-Coto Covadonga

Archives of Civil and Mechanical Engineering

|

2022

|

Vol. 22, no. 3

art. no. e114

EN

In the present research, geopolymer concrete for construction applications comprising metakaolin was evaluated by partial addition of recycled coarse aggregates and steel fibers to develop eco-friendly cementitious composites. Mechanical and durability characteristics of geopolymer composites were then assessed such as compression, splitting tensile and flexural strength, water absorption, and drying shrinkage. It was observed that with the inclusion of steel fibers, no significant change in compressive strength occurred. Mixtures were prepared with a binder amount of 440 kg/m3 in total. The recycled coarse aggregates were substituted with natural coarse aggregates at a rate of 15, 25, and 35% by their weight. The inclusion of steel fibers in the mixes was 1.0, 2.0, and 3.0% of metakaolin content. Because of the addition of steel fibers, the split tensile strength, flexural strength, and drying shrinkage were improved significantly. The load-displacement graph showed that the fracture toughness of geopolymer composites was enhanced due to the inclusion of steel fibers which leads to maximum loads capacity. From the stress-strain curve, it was observed that the geopolymer paste and the steel fibers had a strong bond, which will help in restraining the propagation of cracks. From XRD analysis, it was shown that a mix having 25% recycled coarse aggregates and 3.0% steel fibers in metakaolin-based geopolymer concrete results in environment-friendly composite with suitable strength and durability that will help in bringing sustainability to the construction industry.

5

Assessment of the influence of the shape of steel fibers on the properties of concrete composites

Helbrych Paweł

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

|

2021

|

Z. 27 (177)

63-68

PL

Poruszono zagadnienie przydatności włókien stalowych w mieszankach betonowych oraz poddano pod ocenę wpływ kształtu włókien stalowych. Analizowano dwa rodzaje włókien stalowych - proste oraz haczykowate. Włókna do badań były wykonane z tej samej stali oraz miały dokładnie tę samą smukłość, średnicę oraz długość. Próbki badano po upływie 28 dni dojrzewania, a właściwości mechaniczne, jakie sprawdzono, to wytrzymałość na ściskanie, wytrzymałość betonu na rozciąganie w próbie zginania oraz wytrzymałość betonu na rozciąganie przy rozłupywaniu. Wyniki poddano analizie statystycznej.

EN

The article deals with the issue of the suitability of steel fibers in concrete mixtures. The influence of the shape of steel fibers was also assessed. Two types of steel fibers were analyzed, straight and hooked. The test fibers were made of the same steel and had exactly the same slenderness, diameter and length. The samples were tested after 28 days of maturation, and the mechanical properties that were checked were compressive strength, concrete tensile strength in a bend test and concrete tensile strength when splitting. The results were statistically analyzed and presented in the article.