scholarly journals Effects of Slag Addition and Mechanical Pre-Processing on the Properties of Recycled Concrete in Terms of Compressive Strength and Workability

2021 ◽  
Vol 64 (1) ◽  
pp. 11-29
Author(s):  
Madumita Sadagopan ◽  
Katarina Malaga ◽  
Magnus Lundin ◽  
Agnes Nagy
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Reference Value ◽  
Recycled Concrete ◽  
Quality Improvements ◽  
Concrete Compressive Strength ◽  
Concrete Aggregates ◽  
Crushed Concrete ◽  
Fine Aggregates ◽  
Furnace Slag

Abstract Concrete waste as crushed concrete aggregates (CCA) in structural concrete prolongs the technical life of the reference concrete accomplishing closed loop recycling. CCA concrete reaches the reference concrete compressive strength and workability by the densification of CCA and cement paste. Our previous study demonstrates CCA densification by mechanical pre-processing, aggregate quality improvements discerned by increased packing density giving reference concrete strength and workability. This study addresses paste densification with blast furnace slag (GGBS) to replace 30 (wt.%) of Portland cement at reference concrete w/b ratio 0.5 and a lower w/b 0.42. Two CCA replacements are investigated: fine aggregates, CCA50; overall aggregate replacement, CCA100. Compressive strength results show that both CCA50, CCA100 mixes achieve reference values at w/b 0.42, only CCA100 achieves reference value at w/b 0.5 as a climate-optimized concrete. The CCA50 mix-w/b 0.5 reaches reference strength when paste densification by GGBS is combined with CCA densification from mechanical pre-processing of aggregates. The 7-day strength of CCA100 with GGBS increases by 11% by mixing with pre-soaked GGBS. Statistical analysis of CCA100 strength results shows significant improvements with GGBS compared to mechanical pre-processing. Significant improvements are possible in CCA50 mix for a combination of mechanical pre-processed aggregates and GGBS replacement.

scholarly journals Natural aggregate totally replacement by mechanically treated concrete waste

2015 ◽  
Vol 10 (1) ◽  
pp. 83-90
Author(s):  
Jozef Junak ◽  
Nadezda Stevulova
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Reference Sample ◽  
Average Density ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Natural Aggregates ◽  
Recycled Material

Abstract This paper presents the results obtained from the research focused on the utilization of crushed concrete waste aggregates as a partial or full replacement of 4/8 and 8/16 mm natural aggregates fraction in concrete strength class C 16/20. Main concrete characteristics such as workability, density and compressive strength were studied. Compressive strength testing intervals for samples with recycled concrete aggregates were 2, 7, 14 and 28 days. The amount of water in the mixtures was indicative. For mixture resulting consistency required slump grade S3 was followed. Average density of all samples is in the range of 2250 kg/m3 to 2350 kg/m3. The highest compressive strength after 28 days of curing, 34.68 MPa, reached sample, which contained 100% of recycled material in 4/8 mm fraction and 60% of recycled aggregates in 8/16 mm fraction. This achieved value was only slightly different from the compressive strength 34.41 MPa of the reference sample.

scholarly journals Effect of Different Types of Recycled Concrete Aggregates on Equivalent Concrete Strength and Drying Shrinkage Properties

2018 ◽  
Vol 8 (11) ◽  
pp. 2190 ◽  
Author(s):  
Sungchul Yang
Keyword(s):  
Compressive Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Concrete Strength ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Test Results ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

Residual mortar attached to recycled concrete aggregate (RCA) always leads to a decrease in Young’s modulus and an increase in the drying shrinkage of RCA concrete, mainly due to an increase of total mortar volume. To overcome this inherent problem, the modified and equivalent mortar volume (EMV) methods were proposed by researchers. Despite the comparable test results, both models are still subject to the slump loss problem. Thus, under the same W/C (water to cement ratio) ratio and slump condition, this study assessed the influence of the modified EMV mix method on RCA concrete properties. A total of six mixes were proportioned using the modified EMV method with three different RCAs. Test results show that the concrete mixed with RCA produced from old PC concrete sleepers exhibited compressive strength, Young’s modulus, and flexural strength values within 2% variation, equivalent to those values of the companion natural aggregate concrete. In other mixes, compressive strength was found to decrease to 11–20%. It was observed that for 100% replacement of RCA mix, Young’s modulus increased to 10% and drying shrinkage increased to 8% only, while for 50% replacement of RCA mix, Young’s modulus decreased to 8% and drying shrinkage dropped to 4%.

scholarly journals Settlement Analysis of Recycled Concrete Fine Aggregate Blended Soils using Geostudio

2019 ◽  
Vol 9 (2) ◽  
pp. 3007-3010
Keyword(s):  
Recycled Concrete ◽  
Engineering Properties ◽  
Real Field ◽  
Fine Aggregate ◽  
Virgin Soil ◽  
Concrete Aggregates ◽  
Finite Element Software ◽  
Crushed Concrete ◽  
Fine Aggregates ◽  
Settlement Analysis

Crushed concrete (CC) is one of the most abundant waste materials generated from construction industry. This material is widely recycled and used in various applications like pavement, concrete aggregates and backfilling. Crushed concrete is mixed with any of virgin soil to increase the engineering properties of soil. In the present study, a sample of crushed concrete is collected from demolished buildings at Secunderabad and the material is segregated according to gradation for the present study. The index properties of crushed concrete like pH, specific gravity, water absorption, particle size distribution are obtained. Locally available soil is partially replaced i.e., 30%, 50%, and 70% with crushed concrete fine aggregates and its compaction characteristics and shear strength parameters are determined. In the continuation of the study, a numerical model is developed using a finite element software i.e GeoStudio Sigma/w. Mesh and boundary extent convergence studies are done for the model. The top 1m virgin soil is replaced with the mixture of CC and soils. Settlements for various percentages of CC and for different width of footing are obtained for a uniform stress of 200kPa. The stress is applied in 5 stages in order to simulate real field conditions. It was observed that 30% replacement of CC have given the least settlement for all widths of footing considered in the study

The Study of Washed Recycled Concrete Aggregates and Blast Furnace Slag Utilization in Concrete Production

2015 ◽  
Vol 1100 ◽  
pp. 197-201 ◽  
Author(s):  
Jozef Junak ◽  
Nadežda Števulová
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Recycled Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Concrete Production ◽  
Different Types ◽  
Range Of Variation ◽  
Furnace Slag

<p class="TTPAbstract">This contribution is focused on re-use of different types of industrial raw-wastes in concrete production. From examined wastes, blast-furnace slag and washed recycled concrete were prepared our tested concrete samples with dimension 150 mm. In these samples were fraction 0-4 mm replacement by blast-furnace slag with a range of variation from 0 to 100%. Fraction 4-8 mm and 8-16 mm were replacement by aggregate prepared from washed recycled concrete parts with a range of variation from 0 to 100% in both fractions. Concrete samples contained aggregate prepared form recycled concrete and blast-furnace slag, are tested after 14 and 28 days of hardening.</p> <p class="TTPAbstract">The highest value of compressive strength after 14 days (25.2 MPa) and 28 days of hardening (32.3 MPa) reached sample, which contained 20% of blast furnace slag as a substitute for natural aggregate in fraction 0/4 mm. Compressive strength of this sample is the same kind of reached a comparative sample. Lowest value of compressive strength after 14 and 28 days of hardening reached a sample, which contained 30% blast-furnace slag fraction 0-4 mm, and 100% aggregate prepared from recycled concrete fraction 4-8 and 8-16 mm. Before wider using of these selected wastes, another properties as a durability and corrosion are necessary to investigate.</p>

PENGKAJIAN KEKUATAN BETON STRUKTUR JEMBATAN PASCA KEBAKARAN

2013 ◽  
Vol 12 (3) ◽  
Author(s):  
Sudarmadi Sudarmadi
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Strength Assessment ◽  
Concrete Testing

In this paper a case study about concrete strength assessment of bridge structure experiencing fire is discussed. Assessment methods include activities of visual inspection, concrete testing by Hammer Test, Ultrasonic Pulse Velocity Test, and Core Test. Then, test results are compared with the requirement of RSNI T-12-2004. Test results show that surface concrete at the location of fire deteriorates so that its quality is decreased into the category of Very Poor with ultrasonic pulse velocity ranges between 1,14 – 1,74 km/s. From test results also it can be known that concrete compressive strength of inner part of bridge pier ranges about 267 – 274 kg/cm2 and concrete compressive strength of beam and plate experiencing fire directly is about 173 kg/cm2 and 159 kg/cm2. It can be concluded that surface concrete strength at the location of fire does not meet the requirement of RSNI T-12-2004. So, repair on surface concrete of pier, beam, and plate at the location of fire is required.

scholarly journals Evaluation of Self-Compacting Concrete Strength with Non-Destructive Tests for Concrete Structures

2019 ◽  
Vol 9 (23) ◽  
pp. 5109 ◽  
Author(s):  
Miguel C. S. Nepomuceno ◽  
Luís F. A. Bernardo
Keyword(s):  
Compressive Strength ◽  
Concrete Strength ◽  
Surface Hardness ◽  
Pulse Velocity ◽  
Concrete Compressive Strength ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Pull Out ◽  
Concrete Maturity ◽  
Non Destructive

Self-compacting concrete (SCC) shows to have some specificities when compared to normal vibrated concrete (NVC), namely higher cement paste dosage and smaller volume of coarse aggregates. In addition, the maximum size of coarse aggregates is also reduced in SCC to prevent blocking effect. Such specificities are likely to affect the results of non-destructive tests when compared to those obtained in NVC with similar compressive strength and materials. This study evaluates the applicability of some non-destructive tests to estimate the compressive strength of SCC. Selected tests included the ultrasonic pulse velocity test (PUNDIT), the surface hardness test (Schmidt rebound hammer type N), the pull-out test (Lok-test), and the concrete maturity test (COMA-meter). Seven sets of SCC specimens were produced in the laboratory from a single mixture and subjected to standard curing. The tests were applied at different ages, namely: 1, 2, 3, 7, 14, 28, and 94 days. The concrete compressive strength ranged from 45 MPa (at 24 h) to 97 MPa (at 94 days). Correlations were established between the non-destructive test results and the concrete compressive strength. A test variability analysis was performed and the 95% confidence limits for the obtained correlations were computed. The obtained results for SCC showed good correlations between the concrete compressive strength and the non-destructive tests results, although some differences exist when compared to the correlations obtained for NVC.

Utilization of Cockle Shell (Anadara Granosa) as Partial Replacement of Fine Aggregates in Concrete

2021 ◽  
Vol 6 (2) ◽  
pp. 96-103
Author(s):  
Ranno Marlany Rachman ◽  
Try Sugiyarto Soeparyanto ◽  
Edward Ngii
Keyword(s):  
Compressive Strength ◽  
National Standard ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Concrete Compressive Strength ◽  
Concrete Technology ◽  
Normal Concrete ◽  
Fine Aggregates ◽  
Blood Clam ◽  
Anadara Granosa

This research aimed to utilize Anadara Granosa (Blood clam shell) clamshell waste as a new innovation in concrete technology and to investigate the effect of Anadara Granosa clamshell powder utilization as an aggregate substitution on the concrete compressive strength. The sample size was made of cylinders with a size of 10 cm x 20 cm with variations of clamshell powder 10%, 20% and 30% from the fine aggregate volume then soaked for 28 days as per the method of the Indonesian National Standard. The evaluation results exhibited that the slump value exceeded the slump value of normal concrete with a slump value of 0% = 160 mm, 10% = 165 mm, 20% = 180 mm and 30% = 180 mm. Additionally, it was found that the concrete compressive strength obtained post 28 days were 20.78 Mpa, 21.95 Mpa, 21.17 Mpa and 24.28 Mpa for normal concrete (0%), substitution concrete (10%), substitution concrete (20%) and substitution concrete (30%), respectively. Leading on from these results, it was concluded that the increment of Anadara Granosa clamshell powder substitution led to the increase of concrete compressive strength test.

scholarly journals Effect of fine recycled aggregates on the properties of non-cement blended materials

2020 ◽  
Vol 323 ◽  
pp. 01018
Author(s):  
Wei-Ting Lin ◽  
Lukáš Fiala ◽  
An Cheng ◽  
Michaela Petříková
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Interface Structure ◽  
Strength Test ◽  
Recycled Aggregates ◽  
Test Results ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Compressive Strength Test ◽  
Furnace Slag

In this study, the different proportions of co-fired fly ash and ground granulated blast-furnace slag were used to fully replace the cement as non-cement blended materials in a fixed water-cement ratio. The recycled fine aggregates were replaced with natural fine aggregates as 10%, 20%, 30%, 40% and 50%. The flowability, compressive strength, water absorption and scanning electron microscope observations were used as the engineered indices by adding different proportions of recycled fine aggregates. The test results indicated that the fluidity cannot be measured normally due to the increase in the proportion of recycled fine aggregates due to its higher absorbability. In the compressive strength test, the compressive strength decreased accordingly as the recycled fine aggregates increased due to the interface structure and the performance of recycled aggregates. The fine aggregates and other blended materials had poor cementation properties, resulting in a tendency for their compressive strength to decrease. However, the compressive strength can be controlled above 35 MPa of the green non-cement blended materials containing 20% recycled aggregates.

scholarly journals Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

2021 ◽  
Vol 72 (4) ◽  
pp. 498-509
Author(s):  
Vuong Doan Dinh Thien ◽  
Hung Nguyen Thanh ◽  
Hung Nguyen Dinh
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Concrete Strength ◽  
Concrete Block ◽  
Bond Stress ◽  
Concrete Compressive Strength ◽  
Pull Out ◽  
Steel Bar ◽  
Stress Degradation ◽  
Slip Displacement

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

EFFECTS OF REPLACING CEMENT BY DATE PALM TREES WASTES ON CONCRETE PERFORMANCE

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ahmad Salah Edeen Nassef ◽  
Kalifa Hamed AlMuqbali ◽  
Sheikha Mahmood Al Naqabi
Keyword(s):  
Compressive Strength ◽  
Date Palm ◽  
Cement Content ◽  
Concrete Strength ◽  
Palm Tree ◽  
Compression Tests ◽  
Tree Leaves ◽  
Concrete Compressive Strength ◽  
Sustainable Environment ◽  
Palm Trees

This paper was studying the effects of palm tree wastes on the behavior of the concrete to reduce cement content in the concrete to ensure a sustainable environment. Both fibers of palm tree and the ash of palm tree leaves are used in this study considering different percentages of palm tree wastes, which are replaced the cement, to investigate both of workability and strength of the concrete. Also, the combination of palm tree leaves ash and fibers of palm trees is investigated. The slump and compression tests are carried out to evaluate both workability and concrete strength. The palm fibers were reducing the workability of concrete at both of different percentage of replacement and different fiber lengths. The slump is reduced by 26.667% at 2 cm fibers length and it is completely lost at 5 cm length fibers at the same percentage of replacement of 5% of the cement content. The palm fibers were weakening concrete compressive strength at different percentages and different fiber lengths. Palm leaves ash was enhancing concrete workability and concrete compressive strength.

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