Rheological Behavior of Self-Compacting Geopolymer Concrete Containing Recycled Aggregates: Effect of Na2SiO3/NaOH and Molarity of NAOH

2021 ◽  
Vol 872 ◽  
pp. 79-84
Author(s):  
Koran Salihi ◽  
Khaleel H. Younis
Keyword(s):  
Sodium Hydroxide ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Geopolymer Concrete ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Sustainable Concrete ◽  
Coarse Aggregates ◽  
Concrete Mixtures ◽  
Fresh State

To develop a sustainable concrete and to minimize the depletion of the natural resources, an attempt was made to develop sustainable concrete mixtures benefiting from the geopolymer technology and the use of recycled aggregate in self-compacting geopolymer concrete (SCGC). This study aim to examine the effects of sodium hydroxide (SH) molarity and sodium silicate (Na2SiO3)/ sodium hydroxide (SS/SH) ration the fresh properties of SCGC mixtures containing recycled coarse aggregates (RCA) Mixes were prepared with three different molarity (8M, 10M and 12M) of) and four SS/SH ratios (1.5, 2.0, 2.5 and 3.0). Six mixes were examined in this study. The results were compared with the EFNARC limits for self-compacting concrete (SCC). It was found that the SS/SH ratio and the molarity of SH affect the fresh properties of (SCGC). However, the results showed that, SCGC mixtures containing RCA can be developed and satisfy the requirements of EFNARC for fresh state of SCC.

scholarly journals Mechanical Properties of Geopolymer Concrete Made With Partial Replacement of Coarse Aggregate by Recycled Aggregate

2019 ◽  
Vol 9 (1) ◽  
pp. 2301-2304 ◽  
Keyword(s):  
Mechanical Properties ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Geopolymer Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Construction is the one the fast growing field in the worldwide. There are many environmental issues connected with the manufacture of OPC, at the same time availability of natural coarse aggregate is getting reduced. Geopolymer binder and recycled aggregates are promising alternatives for OPC and natural coarse aggregates. It is produced by the chemical action of inorganic molecules and made up of Fly Ash, GGBS, fine aggregate, coarse aggregate and an alkaline solution of sodium hydroxide and sodium silicate. 10 M sodium hydroxide and sodium silicate alkali activators are used to synthesis the geopolymer in this study. Recycled aggregates are obtained from the construction demolished waste. The main focus of this work is to find out the mechanical properties of geopolymer concrete of grade G40 when natural coarse aggregate(NCA) is replaced by recycled coarse aggregate in various proportions such as 0%, 10%, 20%, 30%,40% and 50% and also to compare the results of geopolymer concrete made with recycled coarse aggregates(RAGPC) with geopolymer concrete of natural coarse aggregate(GPC) and controlled concrete manufactured with recycled aggregates(RAC) and controlled concrete of natural coarse aggregates(CC) of respective grade. It has been observed that the mechanical properties are enhanced in geopolymer concrete, both in natural coarse aggregate and recycled coarse aggregate up to 30% replacement when it is compared with the same grade of controlled concrete.

scholarly journals Effect of Design Parameters on Compressive and Split Tensile Strength of Self-Compacting Concrete with Recycled Aggregate: An Overview

2021 ◽  
Vol 11 (13) ◽  
pp. 6028
Author(s):  
P. Jagadesh ◽  
Andrés Juan-Valdés ◽  
M. Ignacio Guerra-Romero ◽  
Julia M. Morán-del Morán-del Pozo ◽  
Julia García-González ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Design Parameters ◽  
Fine Aggregate ◽  
Self Compacting Concrete ◽  
Split Tensile Strength ◽  
Coarse Aggregates ◽  
Fine Aggregates

One of the prime objectives of this review is to understand the role of design parameters on the mechanical properties (Compressive and split tensile strength) of Self-Compacting Concrete (SCC) with recycled aggregates (Recycled Coarse Aggregates (RCA) and Recycled Fine Aggregates (RFA)). The design parameters considered for review are Water to Cement (W/C) ratio, Water to Binder (W/B) ratio, Total Aggregates to Cement (TA/C) ratio, Fine Aggregate to Coarse Aggregate (FA/CA) ratio, Water to Solid (W/S) ratio in percentage, superplasticizer (SP) content (kg/cu.m), replacement percentage of RCA, and replacement percentage of RFA. It is observed that with respect to different grades of SCC, designed parameters affect the mechanical properties of SCC with recycled aggregates.

Fresh Properties of Self-Compacting Concrete with Coarse Recycled Aggregate

2012 ◽  
Vol 602-604 ◽  
pp. 938-942 ◽  
Author(s):  
Wai Ching Tang
Keyword(s):  
Coarse Aggregate ◽  
Fresh Concrete ◽  
Cement Content ◽  
Recycled Aggregate ◽  
Test Results ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Filling Ability ◽  
Passing Ability

In this paper, the fresh properties of self-compacting concrete (SCC) using recycled coarse aggregate (RCA) were evaluated. Five types of SCC mixtures were made, where the percentage of substitution of natural coarse aggregate by RCA was 0, 25, 50, 75 and 100%. The cement content, water to binder (W/B) ratio and Superplasticizer dosage were kept the same for all mixes. The effects of RCA on the key fresh properties such as filling ability, passing ability, and segregation resistance of SCC were investigated by conducting several fresh concrete tests included slump-flow, L-box, and sieve stability tests. The overall test results suggest that RCA can be used to produce SCC substituting up to 100% natural coarse aggregates without affecting the key fresh properties of concrete.

scholarly journals A study of packing parameters that influence the fresh properties of self-compacting concrete

Cerâmica ◽  
2019 ◽  
Vol 65 (375) ◽  
pp. 432-442
Author(s):  
C. V. A. de Melo ◽  
P. C. C. Gomes ◽  
K. A. M. Moraes
Keyword(s):  
Distribution Coefficient ◽  
Fine Particles ◽  
The Self ◽  
Void Content ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Slump Flow ◽  
Fresh State

Abstract Some known self-compacting concrete (SCC) mix-designs are based on the lowest void content as a purpose of an ideal packing. However, a composition with a lower void content is not a guarantee of good synergy between the largest and smallest grain in the fresh state. The purpose of this study was to identify and evaluate different packing parameters in the aggregates gradations that influence on the self-compactability. Nine aggregates combinations (4 binaries, 4 ternaries and 1 quaternary) were used for determination of nine gradations. Tests as slump-flow, L-box and V-funnel were used. The distribution coefficient (q) was determined by the Alfred model. The results showed that not all values of q (between 0.201 and 0.253) attended the values given for SCC, and the gradations with the lowest difference among the coarse and fine particles, higher void content, continuous distributions and 50% of coarse aggregates had better performance.

scholarly journals Study on the Microstructure of the New Paste of Recycled Aggregate Self-Compacting Concrete

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2114
Author(s):  
Kheira Zitouni ◽  
Assia Djerbi ◽  
Abdelkader Mebrouki
Keyword(s):  
Mercury Intrusion Porosimetry ◽  
Strength Loss ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Self Compacting Concrete ◽  
Mercury Intrusion ◽  
Concrete Mixtures ◽  
Binder Ratio ◽  
Water To Binder Ratio ◽  
Different Levels

Previous literature indicates a decrease in the mechanical properties of various concrete types that contain recycled aggregates (RA), due to their porosity and to their interface of transition zone (ITZ). However, other components of the RA concrete microstructure have not yet been explored, such as the modification of the new paste (NP) with respect to a reference concrete. This paper deals with the microstructure of the new paste of self-compacting concrete (SCC) for different levels of RA. The water to binder ratio (w/b) was kept constant for all concrete mixtures, and equal to 0.5. The SCC mixtures were prepared with percentages of coarse RA of 0%, 30%, 50% and 100%. Mercury intrusion porosimetry test (MIP) and scanning electron microscope (SEM) observations were conducted on the new paste of each concrete. The results indicated that the porosity of the new paste presents a significant variation for replacement percentages of 50% and 100% with respect to NP0 and NP30. However, RA contributed to the refinement of the pore structure of the new paste. The amount of macrospores the diameter of which is in the 50–10,000 nm range was reduced to 20% for NP50 and NP100, while it was about 30% for NP0 and NP30, attributed to the water released by RA. Compressive strength loss for SCC50 and SCC100 concretes are both influenced by porosity of RA, and by the NP porosity. The latter is similar for these two concretes with the 26% increase compared to a reference concrete.

scholarly journals Performance of Self Compacting Concrete Replaced with Saturated Recycled Aggregate

2020 ◽  
Vol 9 (6) ◽  
pp. 505-510
Keyword(s):  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Recycled Aggregates ◽  
Self Compacting Concrete ◽  
Ordinary Concrete ◽  
Coarse Aggregates ◽  
Fine Aggregates ◽  
Hardened Properties ◽  
Concrete Concept

The use of recycled aggregate in any concrete saves the virgin coarse and fine aggregates to create for the production of concrete. This concept will deliver an ecofriendly, reduced eviction of natural resources and produce a green concrete concept. Coarse aggregate consists of more than 60% of total volume in ordinary concrete but only 40% is required for Self Compacting Concrete (SCC) by weight. Demolished concrete wastes which are crushed and sieved to the size are used as substitute for natural coarse aggregates. In this paper natural coarse aggregate in self-compacting concrete is replaced with 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% & 100% recycled aggregates in mix design. Furthermore, a detailed study on workability and hardened properties of specially proportioned mixes are also carried out and satisfactory results are obtained. Thus the derived SCC can come up with reduced CO2 emissions, economical and energy saving with all additional well-known advantages of fluid concrete.

scholarly journals Influence of Design Parameters on Fresh Properties of Self-Compacting Concrete with Recycled Aggregate—A Review

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5749
Author(s):  
Rebeca Martínez-García ◽  
P. Jagadesh ◽  
Fernando J. Fraile-Fernández ◽  
Julia M. Morán-del Pozo ◽  
Andrés Juan-Valdés
Keyword(s):  
Fresh Concrete ◽  
Recycled Aggregate ◽  
Mix Design ◽  
Recycled Aggregates ◽  
Design Parameters ◽  
Fresh Properties ◽  
Self Compacting Concrete ◽  
Concrete Properties ◽  
Mix Proportion ◽  
Negative Impacts

This article presents an overview of the bibliographic picture of the design parameter’s influence on the mix proportion of self-compacting concrete with recycled aggregate. Design parameters like water-cement ratio, water to paste ratio, and percentage of superplasticizers are considered in this review. Standardization and recent research on the usage of recycled aggregates in self-compacting concrete (SCC) exploit its significance in the construction sector. The usage of recycled aggregate not only resolves the negative impacts on the environment but also prevents the usage of natural resources. Furthermore, it is necessary to understand the recycled aggregate property’s role in a mixed design and SCC properties. Design parameters are not only influenced by a mix design but also play a key role in SCC’s fresh properties. Hence, in this overview, properties of SCC ingredients, calculation of design parameters in mix design, the effect of design parameters on fresh concrete properties, and the evolution of fresh concrete properties are studied.

scholarly journals Strength and Water Absorption of Sustainable Concrete Produced with Recycled Basaltic Concrete Aggregates and Powder

2021 ◽  
Vol 13 (11) ◽  
pp. 6277
Author(s):  
Ibrahim Sharaky ◽  
Usama Issa ◽  
Mamdooh Alwetaishi ◽  
Ahmed Abdelhafiz ◽  
Amal Shamseldin ◽  
...  
Keyword(s):  
Water Absorption ◽  
Edge Length ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Substitution ◽  
Small Reduction ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Sustainable Concrete

In this study, the recycled concrete aggregates and powder (RCA and RCP) prepared from basaltic concrete waste were used to replace the natural aggregate (NA) and cement, respectively. The NA (coarse and fine) was replaced by the recycled aggregates with five percentages (0%, 20%, 40%, 60% and 80%). Consequently, the cement was replaced by the RCP with four percentages (0%, 5%, 10% and 20%). Cubes with 100 mm edge length were prepared for all tests. The compressive and tensile strengths (fcu and ftu) and water absorption (WA) were investigated for all mixes at different ages. Partial substitution of NA with recycled aggregate reduced the compressive strength with different percentages depending on the type and source of recycled aggregate. After 28 days, the maximum reduction in fcu value was 9.8% and 9.4% for mixtures with coarse RCA and fine RCA (FRCA), respectively. After 56 days, the mixes with 40% FRCA reached almost the same fcu value as the control mix (M0, 99.5%). Consequently, the compressive strengths of the mixes with 10% RCA at 28 and 56 days were 99.3 and 95.2%, respectively, compared to those of M0. The mixes integrated FRCA and RCP showed higher tensile strengths than the M0 at 56 d with a very small reduction at 28 d (max = 3.4%). Moreover, the fcu and ftu values increased for the late test ages, while the WA decreased.

scholarly journals Effect of Recycled Coarse Aggregates in Properties of Concrete

2008 ◽  
Vol 3 (4) ◽  
pp. 130-137 ◽  
Author(s):  
R Kumutha ◽  
K Vijai
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Split Tensile Strength ◽  
Coarse Aggregates ◽  
The Cost

The properties of concrete containing coarse recycled aggregates were investigated. Laboratory trials were conducted to investigate the possibility of using recycled aggregates from the demolition wastes available locally as the replacement of natural coarse aggregates in concrete. A series of tests were carried out to determine the density, compressive strength, split tensile strength, flexural strength and modulus of elasticity of concrete with and without recycled aggregates. The water cement ratio was kept constant for all the mixes. The coarse aggregate in concrete was replaced with 0%, 20%, 40%, 60%, 80% and 100% recycled coarse aggregates. The test results indicated that the replacement of natural coarse aggregates by recycled aggregates up to 40% had little effect on the compressive strength, but higher levels of replacement reduced the compressive strength. A replacement level of 100% causes a reduction of 28% in compressive strength, 36% in split tensile strength and 50% in flexural strength. For strength characteristics, the results showed a gradual decrease in compressive strength, split tensile strength, flexural strength and modulus of elasticity as the percentage of recycled aggregate used in the specimens increased. 100% replacement of natural coarse aggregate by recycled aggregate resulted in 43% savings in the cost of coarse aggregates and 9% savings in the cost of concrete.

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