Pengaruh Penambahan Serat Kawat Bendrat Terhadap Kuat Lentur Beton Geopolimer

Currently, innovation continues to be developed to replace cement with other materials so that the use of cement as a building material can be reduced. Utilization of coal waste (fly ash) is an alternative to subtitude cement. From previous studies, fly ash mixed with alkaline materials in the form of NaOH and Na2SiO3 in a ratio of 1:5 can produce geopolymer concrete. This geopolymer concrete research was continued by adding bendrat wire fibers into the geopolymer concrete mixture. The method used in testing the aggregate, testing the compressive strength of normal concrete K225, testing the flexural strength of normal concrete and geopolymer concrete refers to SNI. Another additional material that is mixed is bendrat wire fiber. The research was carried out in the form of making flexible beams of 10 cm x 10 cm x 50 cm with fiber variations of 0%, 0.5%, and 1,0% at the age of 14 and 28 days. The results of the flexural strength test of the BN beam at the age of 28 days can withstand loads than BG. The average flexural strength obtained with variations of BN, BN+SB 0.5% and BN+SB 1.0% respectively were 2.796 MPa, 3.113 MPa, and 3.879 MPa. The results of testing the average flexural strength of geopolymer concrete beams at 28 days, obtained variations of BG, BG+SB 0.5%, and BG+SB 1.0% respectively were 0 MPa, 0.055 MPa and 0.104 MPa. In addition, geopolymer concrete cannot be used as a beam and the addition of bendrat wire fiber to geopolymer concrete cannot withstand the tensile load on the concrete.

ANALISIS PENGARUH PENAMBAHAN IJUK 0,25% DAN 0,5% PADA CAMPURAN BETON fc’ 14,5 MPa (NON STRUKTUR)

Concrete is the majority of materials used in construction in Indonesia in general. Concrete mix innovations are needed so that concrete has better quality and quality. Innovation in concrete mixture one of them by using organic waste. In addition to improving quality, organic waste used is expected to reduce global warming. In Nagari IV Koto Palembayan ijuk from enau trees is not processed and left alone, so over time the ijuk can become waste. In this study discussed the effect of the addition of ijuk in the concrete mixture against the strong press of concrete. The targeted concrete press strong value is 14.5 MPa. The test object is made by varying the amount of ijuk addition in the concrete mixture by 0.25% and 0.5%. The test object used is a cylinder measuring 15cm in diameter and 30 cm high. Testing was conducted when the concrete was 7 days old, 14 days and 28 days old using 2 samples of test objects. The results showed a strong value of normal concrete press age of 28 days obtained at 15.57, while the strong value of additional concrete press ijuk 0.25% and 0.5% obtained by 19.82 MPa and 18.26 MPa. The results showed additional concrete ijuk 0.25% increased by 27.30% from the normal concrete press strength and the strong value of additional concrete press ijuk 0.5% also increased by 17.28% from the strong normal concrete press.

Effect of Using Ground Granulated Blast Furnace Slag in Rigid Pavement Overlays

Cement is replaced with Ground Granulated Blast Furnace Slag (GGBS), to produce a cost effective concrete and to gain effective compressive strength. It is produced in iron manufacturing industries. It has pozzolanic properties and has particle size less than 90μ. In this experimental study, cubes of size 150×150×150 mm and cylinders of 150 mm dia and 300 mm height were casted byreplacing GGBS from dosage of 8% up to 65% for curing period of 7days, 14days, 28days and 56days for M 40 grade concrete. Also, Alccofines were added in addition in varying percentage of 3%, 6%, 9% and 12% in order to gain high early strength and increase the workability. Hyper-Plasticizers were also added in order to reduce the water-content of the concrete. The results of GGBSCC were compared with that of normal concrete results.

POTENTIAL VOLUMIZING EFFECT OF THE POST-MORPH LIME FILLER IN ATTENUATING CONCRETE CARBONATION

A study on the crystallography of the lime that comes from mussel shell has been conducted to determine the packing density of the material. The experimental analysis encompasses of concrete samples preparation with lime replacement at 5%, 7.5% and 10% by cement weight. The samples were carbonised naturally over a period of six months and subjected to the phenolphthalein test at 60, 90, 120 and 180 days. It has been found that lime originating from the mussel shell is of both the aragonitic and calcitic crystal types. Both crystal polymorphs of aragonite and calcite are denser than the typical normal concrete by 27.8% and 18.3% respectively. This suggest a volumizing effect that is beneficial to reduce carbonation penetration into the capillarity of the concrete. Results from the carbonation test indicate that concrete containing mussel shell lime ash showed up to 51% lower carbonation coefficient and significantly lower intensity of capillarity as shown via FESEM. ABSTRAK: Kajian mengenai kristalografi kapur yang didapati daripada kulit kupang telah dijalankan bagi menentukan kepadatan bahan tersebut. Analisis eksperimen merangkumi penyediaan sampel-sampel konkrit yang mengandungi gantian kapur pada 5%, 7.5% dan 10% daripada berat simen. Sampel-sampel telah dikarbonatkan secara alami selama enam bulan dan menjalani ujian fenolftalin pada usia 60, 90, 120 dan 180 hari. Kajian telah mendapati bahawa kulit kupang terdiri daripada kapur-kapur berjenis aragonit dan kalsit. Kedua-dua polimorf kapur aragonit dan kalsit adalah 27.8% dan 18.3% lebih tumpat berbanding konkrit biasa. Hal ini berpotensi menjadi bahan penumpat yang bagus untuk mengurangkan serapan pengkarbonatan ke dalam kapilari konkrit. Keputusan ujian pengkarbonatan menunjukkan konkrit yang mengandungi abu kapur kulit kupang mempunyai pekali pengkarbonatan sehingga 51% lebih rendah dan mempunyai kerendahan kapilariti yang signifikan seperti yang ditunjukkan melalui FESEM.

Rehabilitation of Hybrid RC-I Beams with Openings Using CFRP Sheets

This research presents an experimental investigation of the rehabilitation efficiency of the damaged hybrid reinforced concrete beams with openings in the shear region. The study investigates the difference in retrofitting ability of hybrid beams compared to traditional beams and the effect of two openings compared with one opening equalized to two holes in the area. Five RC beams classified into two groups, A and B, were primarily tested to full-failure under two-point loads. The first group (A) contained beams with normal weight concrete. The second group (hybrid) included beams with lightweight concrete for web and bottom flange, whereas the top flange was made from normal concrete. Two types of openings were considered in this study, rectangular, with dimensions of 100×200 mm, and two square openings with a side dimension of 100 mm. A full wrapping configuration system for the shear region (failure zone) was adopted in this research. Based on the test results, the repaired beams managed to recover their load carrying capacity, stiffness, and structural performance in different degrees. The normal concrete beam regains its total capacity for all types of openings, while the hybrid beams gain 84% of their strength. The strength of hybrid concrete members compared with normal concrete is 81 and 88% for beams of one opening and two openings, respectively. Doi: 10.28991/CEJ-2022-08-01-012 Full Text: PDF

Mechanical and Impact Properties of Engineered Cementitious Composites Reinforced with PP Fibers at Elevated Temperatures

The repeated impact performance of engineered cementitious composites (ECCs) is not well explored yet, especially after exposure to severe conditions, such as accidental fires. An experimental study was conducted to evaluate the degradation of strength and repeated impact capacity of ECCs reinforced with Polypropylene fibers after high temperature exposure. Compressive strength and flexural strength were tested using cube and beam specimens, while disk specimens were used to conduct repeated impact tests according to the ACI 544-2R procedure. Reference specimens were tested at room temperature, while three other groups were tested after heating to 200, 400 and 600 °C and naturally cooled to room temperature. The test results indicated that the reference ECC specimens exhibited a much higher failure impact resistance compared to normal concrete specimens, which was associated with a ductile failure showing a central surface fracture zone and fine surface multi-cracking under repeated impacts. This behavior was also recorded for specimens subjected to 200 °C, while the exposure to 400 and 600 °C significantly deteriorated the impact resistance and ductility of ECCs. The recorded failure impact numbers decreased from 259 before heating to 257, 24 and 10 after exposure to 200, 400 and 600 °C, respectively. However, after exposure to all temperature levels, the failure impact records of ECCs kept at least four times higher than their corresponding normal concrete ones.

Analisis Karakteristik Serbuk Sabut Kelapa (Cocopeat) Sebagai Agregat Halus pada Campuran Beton

The advantages of coconut coir powder (cocopeat) are resistant to microorganisms, weathering and resistant to mechanical spelling, namely friction and blows. Based on these advantages, cocopeat can be used as a blend of fine aggregates in the manufacture of concrete. The sieve test was conducted on the cocopeat to determine the initial feasibility analysis of cocopeat as a blend of fine aggregates in the concrete manufacturing. The results of the cocopeat sieve test are that cocopeat is included in Region II which is classified as a fine module of slightly coarse grains with a fine module of fine aggregate grains of 2.37. This shows that cocopeat has a fairly good value in normal concrete mixtures but is not suitable for high resistance concrete mixtures that exceed 25 MPa. This was followed by a subsidence test that gave subsidence values for mixtures of concrete with a cocopeat composition of 25%, 50% and 75%, is 7.5 cm; 5.3 cm; and 2.2 cm. While a good subsidence ratio is used in the range of 6-18 cm. In addition, the concrete with a 25% blend of cocopeat has a stronger physical form and there are no fungus growing on the surface of the concrete. Meanwhile, concrete with a mixture of 50% and 75% cocopeat looks more fragile and forms molds on the surface of the concrete. Thus the concrete with a mixture of 25% cocopeat has better results.