scholarly journals Quantitative Analysis of Surface Attached Mortar for Recycled Coarse Aggregate

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 257
Author(s):  
Guoying Liu ◽  
Qiuyi Li ◽  
Jialin Song ◽  
Liang Wang ◽  
Haibao Liu ◽  
...  
Keyword(s):  
Water Absorption ◽  
Apparent Density ◽  
Coarse Aggregate ◽  
Mechanical Action ◽  
Hardened Cement ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates ◽  
Before And After ◽  
Strengthening Technique

Due to the large amount of old hardened cement mortar attached to the surface of aggregate and the internal micro-cracks formed by the crushing process, the water absorption, apparent density, and crushing index of recycled coarse aggregate are still far behind those of natural coarse aggregate. Based on the performance requirements of different qualities of recycled coarse aggregate, the performance differences of recycled coarse aggregate before and after physical strengthening were observed. The results showed that the physical strengthening technique can remove old hardened mortar and micro powder attached to the surface of recycled coarse aggregate by mechanical action, which can effectively improve the quality of recycled coarse aggregate. The optimum calcination temperature of the recycled coarse aggregate was 400 °C and the grinding time was 20 min. The contents of the attached mortar in recycled coarse aggregates of Class I, II, and III were 7.9%, 22.8%, and 39.7%, respectively. The quality of recycled coarse aggregate was closely related to the amount of mortar attached to the surface. The higher the mortar content, the higher the water absorption, lower apparent density, and higher crushing index of the recycled coarse aggregate.

Influence of Physical Strengthening Technology on the Properties of Recycled Coarse Aggregate

2017 ◽  
Vol 727 ◽  
pp. 1074-1078
Author(s):  
Gong Bing Yue ◽  
Qiu Yi Li ◽  
Gao Song
Keyword(s):  
Water Absorption ◽  
Bulk Density ◽  
Apparent Density ◽  
Void Ratio ◽  
Coarse Aggregate ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates ◽  
Absorption Ratio ◽  
Index Value

This paper studied the properties improvement of recycled coarse aggregate by the physical strengthening technology (particle-shaping method). Through the analysis for obtained properties which consist of density, crush index, bulk density and water absorption. etc of recycled coarse aggregates in different strengthening technologies, the categories of recycled coarse aggregate could be assessed and determined. The results showed that ordinary recycled coarse aggregates that was handled twice by using particle shaping equipment can achieve the standard of class Iaggregates and its water absorption ratio at 24h was 1.2%, the apparent density reached 2575kg/m3, crush index value was 9%, the void ratio was 45%, all property parameters were close to those of natural coarse aggregate.

Effects of Adhered Mortar Content on Quality of Recycled Coarse Aggregate of Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1059-1062 ◽  
Author(s):  
Hong Zhu Quan
Keyword(s):  
Specific Gravity ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Stream ◽  
Manufacturing Method ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates ◽  
Mechanical Crushing

Although the adhered mortar content affects the properties of recycled aggregate concrete, there are few papers describing those effects. This paper presents the results of a series of experimental study on the effects of adhered mortar content on the quality of recycled coarse aggregate of concrete. 5 kinds recycled coarse aggregates made with heating and rubbing method, mechanical crashing method and separating lightweight particle with water stream method were tested for specific gravity, absorption and adhered mortar content. Specific gravity in oven-dried condition ranged from 2.35g/cm3 to 2.59 g/cm3, absorption ranged from 1.58% to 5.83% and adhered mortar content ranged from 8.0% to 68.4%, depending on manufacturing method of recycled aggregate. Absorption decreased linearly with the increase of specific gravity. Specific gravity decreased and absorption increased with the increase of adhered mortar content. Recycled aggregate made by heating and rubbing method showed lower adhered mortar content corresponding to lower absorption and higher specific gravity, while those made by mechanical crushing method showed higher adhered mortar content corresponding to higher absorption and lower specific gravity. In conclusion, the upper limit of adhered mortar content of recycled coarse aggregate is considered to be 15%, in order to keep up the quality of coarse aggregate and properties equal to natural coarse aggregate.

Organic Pretreatment of Recycled Aggregates of Rural Construction Waste

2012 ◽  
Vol 161 ◽  
pp. 1-5
Author(s):  
Jun Liu ◽  
Yao Li ◽  
Xu Ming Wang ◽  
Run Qing Liu
Keyword(s):  
Acetic Acid ◽  
Water Absorption ◽  
Absorption Rate ◽  
Coarse Aggregate ◽  
Construction Waste ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates ◽  
Water Absorption Rate ◽  
Pretreatment Technology ◽  
Rural Construction

Through using acetic acid resin, asphalt and urea resin organic pretreatment methods to pretreat the surface of rural construction waste, and testing of crush index and water absorption rate of recycled coarse aggregate after pretreatment, the research for the influence of organic pretreatment technology on physical and mechanical performance of recycled coarse aggregate. The results prove that organic infiltrating pretreatment technology can effectively enhance the density of the coarse aggregate and decrease the crush of recycled coarse aggregate index, in a certain extent. The crush index of recycled coarse aggregates after organic pretreatment decreases at almost 17.63%, what’s more, organic pretreatment technology can decrease the water absorption rate of coarse aggregate by a large margin. The water absorption rate of coarse aggregate can be reduced to a minimum of 2.03% which closes to the level of natural aggregates. Because of urea resin solidified into film at fast speed, high integrity and high wear resistance, and relatively cheap, urea resin’s pretreatment effects on recycled coarse aggregates is better than acetic acid resin and asphalt.

Research on Properties of Recycled Coarse Aggregate

2013 ◽  
Vol 779-780 ◽  
pp. 144-150
Author(s):  
Yong Jun Qin ◽  
Rui Liang ◽  
Aihemaiti Yibulayin ◽  
Jiang Yu ◽  
Lei Li
Keyword(s):  
Water Absorption ◽  
Apparent Density ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Test Results ◽  
Particle Content ◽  
National Regulation ◽  
Recycled Coarse Aggregate ◽  
Powder Content

The performance of recycled coarse aggregate has significant effects on recycled concrete. The performance of recycled coarse aggregate were tested according to Recycled coarse aggregate for concrete (GB/T 25177-2010). The Result showed that the recycled coarse aggregate grading in accordance with regulation requirements, and compared with the natural coarse aggregate: high powder content and water absorption, low needle and plate particle content, low apparent density, compression capability as low as soundness. And the property of recycled coarse aggregate after cleaning has the performance of guaranteeing the quality by using. Through the test results and consult the national regulation, the recycled coarse aggregate in Xinjiang can be preliminary division to the categories of I and II.

Coarse Aggregates Obtained from Red Mud via Pelletizing Process

2014 ◽  
Vol 798-799 ◽  
pp. 492-497
Author(s):  
Luiz Franscisco Isaias ◽  
Luana Spricigo Furlan ◽  
Fernando Pelisser ◽  
Michael Peterson ◽  
Oscar Rubem Klegues Montedo ◽  
...  
Keyword(s):  
Water Absorption ◽  
Clay Mineral ◽  
Apparent Density ◽  
Red Mud ◽  
Mineral Content ◽  
Coarse Aggregate ◽  
Mineral Contents ◽  
Coarse Aggregates ◽  
Test Pieces ◽  
Processing Properties

The aim of this work was the obtaining coarse aggregate from red mud (RM) focused on the processing properties. RM and two clays (A and B) were selected from Pará state (Brazil) and characterized by XRD, XRF and HSM. Six compositions were planned by mixture design. RM amount varied from 80 to 100wt%. Compositions were pelletized in a pelletizer disc, resulting test pieces of 4 to 19 mm (diameter). Firing temperatures ranged from 1150 to 1190 oC and holding time from 15 to 90 min. Pelletizing humidity, dry friability, water absorption, and apparent density were determined. Clays A and B presented clay mineral content about 67 and 12 wt%, quartz 25 and 82wt%, respectively. The higher clay mineral contents the smaller dry friability and water absorption. Appropriated clay mineral contents and firing parameters is needed in order to satisfy processing and final properties requirements, being possible to obtain aggregates from pelletizing process.

scholarly journals Effect of Recycled Coarse Aggregate and Bagasse Ash on Two-Stage Concrete

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 556
Author(s):  
Muhammad Faisal Javed ◽  
Afaq Ahmad Durrani ◽  
Sardar Kashif Ur Rehman ◽  
Fahid Aslam ◽  
Hisham Alabduljabbar ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Construction Material ◽  
Strength Reduction ◽  
Recycled Aggregate ◽  
Two Stage ◽  
Conventional Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Numerous research studies have been conducted to improve the weak properties of recycled aggregate as a construction material over the last few decades. In two-stage concrete (TSC), coarse aggregates are placed in formwork, and then grout is injected with high pressure to fill up the voids between the coarse aggregates. In this experimental research, TSC was made with 100% recycled coarse aggregate (RCA). Ten percent and twenty percent bagasse ash was used as a fractional substitution of cement along with the RCA. Conventional concrete with 100% natural coarse aggregate (NCA) and 100% RCA was made to determine compressive strength only. Compressive strength reduction in the TSC was 14.36% when 100% RCA was used. Tensile strength in the TSC decreased when 100% RCA was used. The increase in compressive strength was 8.47% when 20% bagasse ash was used compared to the TSC mix that had 100% RCA. The compressive strength of the TSC at 250 °C was also determined to find the reduction in strength at high temperature. Moreover, the compressive and tensile strength of the TSC that had RCA was improved by the addition of bagasse ash.

scholarly journals Study on the Effect of Recycled Coarse Aggregate on the Shrinkage Performance of Green Recycled Concrete

2021 ◽  
Vol 13 (23) ◽  
pp. 13200
Author(s):  
Yang Yu ◽  
Peihan Wang ◽  
Zexin Yu ◽  
Gongbing Yue ◽  
Liang Wang ◽  
...  
Keyword(s):  
Primary Particle ◽  
Coarse Aggregate ◽  
Cementitious Material ◽  
Recycled Concrete ◽  
Low Carbon ◽  
Replacement Ratio ◽  
Recycled Coarse Aggregate ◽  
Shrinkage Property ◽  
Low Carbon Emission

Shrinkage property is a significant indicator of the durability of concrete, and the shrinkage of green recycled concrete is particularly problematic. In this paper, construction waste was crushed and screened to generate simple-crushed recycled coarse aggregate (SCRCA). The SCRCA was then subjected to particle shaping to create primary particle-shaped recycled coarse aggregate (PPRCA). On this basis, the PPRCA was particle-shaped again to obtain the secondary particle-shaped recycled coarse aggregate (SPRCA). Under conditions where the dosage of cementitious material is 300 kg/m3 and the sand rate is 38%, a new high-belite sulphoaluminate cement (HBSAC) with low carbon emission and superior efficiency was used as the basic cementitious material. Taking the quality of recycled coarse aggregate (SCRCA, PPRCA, and SPRCA) and the replacement ratio (25%, 50%, 75%, and 100%) as the influencing factors to prepare the green recycled concrete, the workability and shrinkage property of the prepared concrete were analyzed. The results show that the water consumption of green recycled concrete decreases as the quality of the recycled coarse aggregate (RCA) increases and the replacement ratio decreases, provided that the green recycled concrete achieves the same workability. With the improvement of RCA quality and the decrease of replacement ratio, the shrinkage of recycled concrete decreases. The shrinkage performance of green recycled concrete configured with the SPRCA completely replacing the natural coarse aggregate (NCA) is basically the same as that of the natural aggregate concrete (NAC).

Characterization, Modification and Rheology of Green Clay

2015 ◽  
Vol 820 ◽  
pp. 60-64
Author(s):  
Leila Verônica da Rocha-Gomes ◽  
Antônio José Santana ◽  
Camila Martini Matos ◽  
Valquíria de Fátima Justo ◽  
Maria Das Graças Silva-Valenzuela ◽  
...  
Keyword(s):  
Water Absorption ◽  
Rheological Properties ◽  
Apparent Density ◽  
Industrial Applications ◽  
Clay Sample ◽  
Oil Drilling ◽  
Smectite Clays ◽  
Swelling Capacity ◽  
Before And After ◽  
Green Clay

Smectite clays or bentonites are used in several industrial applications. The aim of this study was to describe the characterization and organophilization of a green clay sample coming from the State of Paraíba, Brazil. The clay was characterized by XRD, XRF, CEC, SEM, stereoscopic microscopy, Fann viscosity (before and after the organophilization process), swelling capacity in water and some organic solvents. Prismatic specimens were conformed by pressing, for which were conformed the mechanical sthegth after drying at 110°C and after burning at 950°C. The burned specimens were analyzed to evaluate dimensional variations, water absorption, apparent porosity and apparent density. XRD showed that the sample was constituted mainly for montmorillonite claymineral. Analysis of rheological properties of the modified clay indicates its potential to meet the specifications of the standard N-2604 of Petrobras, concerning clays used to oil drilling.

scholarly journals Evaluation of the Effects of Coarse Aggregate Sizes on Concrete Quality

2017 ◽  
Vol 2 (10) ◽  
pp. 1 ◽  
Author(s):  
Lawrence Echefulechukwu Obi
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Aggregate Size ◽  
Test Results ◽  
Construction Sites ◽  
Coarse Aggregates ◽  
Appreciable Increase ◽  
Concrete Production ◽  
Concrete Quality

This work was necessitated by the observations made at construction sites where artisans and craftsmen were left alone in concrete production. It was discovered that they used inadequate quantity and size of coarse aggregates due to difficulty associated in the mixing as if the coarse aggregates were not needed in concrete production. The research has established that the coarse aggregates and their sizes play critical roles in the development of adequate strength in concrete. It was observed that with proper mixing, the slump test results did not witness shear or collapse type of slump rather there were true slump in all cases of the test. The workability decreased with slight differences when the coarse aggregate size was increased. The increase in the coarse aggregates yielded appreciable increase in the compressive strength. It can therefore be inferred that the quality of concrete in terms of strength can be enhanced through an increase in the coarse aggregate size when proper mix ratio, batching, mixing, transporting, placing and finishings are employed in concrete productions.

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.

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