Utilization of kimberlite tailings as aggregates in concrete – strength and selected durability properties

MRS Advances ◽  
2020 ◽  
Vol 5 (25) ◽  
pp. 1259-1266
Author(s):  
Mike Otieno ◽  
Esina Ndoro
Keyword(s):  
Compressive Strength ◽  
Water Demand ◽  
Concrete Strength ◽  
High Water ◽  
Negative Effects ◽  
Coarse Aggregates ◽  
Durability Properties ◽  
Mix Proportioning ◽  
Water Sorptivity ◽  
Strength And Durability

AbstractThe feasibility of using kimberlite tailings as aggregates in concrete was assessed. Compressive strength and selected durability tests were carried out on concretes made using various replacement levels (0, 40, 60 and 100%) fine and/or coarse blended crushed andesite and kimberlite tailings as aggregates. A w/b ratio of 0.50 and a CEM I 52.5R were used. The results show that the kimberlite tailings as aggregates have a relatively high water demand which was manifested as a reduction in workability of the fresh concretes with kimberlite tailings as a proportion of either fine and/or coarse aggregates. The results also showed that the use of the kimberlite tailings as a proportion of either fine or coarse aggregates in concrete resulted in a decrease in both compressive strength and durability properties viz water sorptivity and oxygen permeability. This was partly attributed to the low workability of the concretes which is known to limit the degree of compaction of fresh concrete. It is envisaged that careful concrete mix proportioning including the use of admixtures and pre-wetting of the aggregates can be used to offset the negative effects of high water demand of the kimberlite aggregates.

scholarly journals Influence of Rice Husk Ash Density on the Workability and Strength of Structural Concrete

2017 ◽  
Vol 2 (3) ◽  
pp. 36 ◽  
Author(s):  
John Kamau ◽  
Ash Ahmed ◽  
Fraser Hyndman ◽  
Paul Hirst ◽  
Joseph Kangwa
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
Water Demand ◽  
Rice Husk Ash ◽  
Concrete Strength ◽  
High Water ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Hardened Concrete ◽  
Structural Applications

Supplementary cementitious materials (SCMs) have been known to improve the properties of fresh and hardened concrete, and at the same time enhance the sustainability of concrete. Rice husk Ash (RHA), is one such material, but has neither been widely studied nor applied in practice. This work investigated the effect of the density of RHA on the workability and compressive strength of fresh and hardened RHA-replaced concrete respectively. Cement was replaced with RHA in concrete by weight (RHA-W) and by volume (RHA-V) at steps of 0%, 5%, 7.5%, 10%, 15%, 20%, 25% and 30%. The 0% replacement was used as the reference point from which performances were measured. Results showed that unlike the characteristic of other established pozzolans, RHA significantly reduced the workability of wet concrete and the rate of compressive strength gain over curing time due to a high water demand that is caused by the increased volume of replaced concrete, which results from its low density. Workability reduced with increased replacement for both RHA-W and RHA-V. Replacements of above 15% were not possible for the RHA-W due to the high water demand. However, replacements of up to 30% were achieved for the RHA-V. RHA-W specimens achieved lower compressive strengths and were observed to gain strength at a lower rate over the 28 to 91-days period of curing compared to RHA-V specimens. This behavior was attributed to the shortage of water that is necessary for the hydration of cement and subsequent pozzolanic reaction, which is the basis of the contribution that is made to the strength and performance of concrete by SCMs. However, the compressive strengths achieved were above the study’s target concrete strength of class C32/40 at 91 days, which is among those classes that are listed as being durable and suitable for structural applications. A conclusion that RHA should supplement cements by volumetric replacement rather than simple substitution by weight was drawn.

scholarly journals Effects of Nanosilica on Compressive Strength and Durability Properties of Concrete with Different Water to Binder Ratios

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Forood Torabian Isfahani ◽  
Elena Redaelli ◽  
Federica Lollini ◽  
Weiwen Li ◽  
Luca Bertolini
Keyword(s):  
Compressive Strength ◽  
Diffusion Coefficient ◽  
Reference Value ◽  
Chloride Diffusion ◽  
Gravimetric Analysis ◽  
Chloride Diffusion Coefficient ◽  
X Ray Diffraction ◽  
Durability Properties ◽  
Water Sorptivity ◽  
Strength And Durability

The effects of the addition of different nanosilica dosages (0.5%, 1%, and 1.5% with respect to cement) on compressive strength and durability properties of concrete with water/binder ratios 0.65, 0.55, and 0.5 were investigated. Water sorptivity, apparent chloride diffusion coefficient, electrical resistivity, and carbonation coefficient of concrete were measured. The results showed that compressive strength significantly improved in case of water/binder = 0.65, while for water/binder = 0.5 no change was found. Increasing nanosilica content, the water sorptivity decreased only for water/binder = 0.55. The addition of 0.5% nanosilica decreased the apparent chloride diffusion coefficient for water/binder = 0.65 and 0.55; however, higher nanosilica dosages did not decrease it with respect to reference value. The resistivity was elevated by 0.5% nanosilica for all water/binder ratios and by 1.5% nanosilica only for water/binder = 0.5. The carbonation coefficient was not notably affected by increasing nanosilica dosages and even adverse effect was observed for water/binder = 0.65. Further information of microstructure was also provided through characterization techniques such as X-ray diffraction, thermal gravimetric analysis, mercury intrusion porosimetry, and scanning electron microscopy. The effectiveness of a certain nanosilica dosage addition into lower strength mixes was more noticeable, while, for the higher strength mix, the effectiveness was less.

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.

Curing of slag concretes at low temperatures: effect on selected durability properties

MRS Advances ◽  
2020 ◽  
Vol 5 (25) ◽  
pp. 1267-1275
Author(s):  
Mike Otieno ◽  
Riccardo Opeka
Keyword(s):  
Oxygen Permeability ◽  
Gas Permeability ◽  
Curing Temperature ◽  
Durability Properties ◽  
Chloride Resistance ◽  
Blastfurnace Slag ◽  
Water Sorptivity ◽  
Chloride Conductivity ◽  
Strength And Durability ◽  
Durability Performance

AbstractThe influence of low curing temperatures (5, 10 and 15 ± 2 °C) on the strength and durability properties of ground granulated blastfurnace slag (GGBS) and ground granulated Corex slag (GGCS) concretes was studied. A standard curing temperature of 23 ± 2 °C) was also used for comparative purposes. Test specimens were cast using 100% CEM I 52.5N (PC), and three PC/Slag (GGBS or GGCS) replacement ratios of 50/50, 65/35 and 80/20, and a w/b ratio of 0.40. The specimens were cured for 28 days by submersion in water at the respective curing temperatures and then tested for durability. Durability was assessed using oxygen permeability, water sorptivity and chloride conductivity tests. The results showed that durability of the concretes decreased as the curing temperature decreased – gas permeability and water sorptivity increased while chloride resistance decreased. It was also observed that at a given curing temperature, the slag blended concretes showed superior durability performance than the plain PC concretes.

scholarly journals Compressive strength and durability properties of pozzolan obtained from co-fired clay and rice husk

2020 ◽  
Vol 7 (1) ◽  
pp. 1811453
Author(s):  
Mark Bediako ◽  
Albert A. Adjaottor ◽  
Simon K.Y Gawu ◽  
Eric Opoku Amankwah
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
Durability Properties ◽  
Strength And Durability

scholarly journals Experimental Studies on Rheological and Durability Properties of Self Compacting Concrete by Using Quatenary Blending

10.29007/81v5 ◽  
2018 ◽  
Author(s):  
Ashika Shah ◽  
Indrajit Patel ◽  
Jagruti Shah ◽  
Gaurav Gohil
Keyword(s):  
Compressive Strength ◽  
Experimental Studies ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Self Compacting Concrete ◽  
Durability Properties ◽  
Granulated Blast Furnace Slag ◽  
Strength And Durability ◽  
Primary Contribution ◽  
Furnace Slag

In the production of Self Compacting concrete (SCC), the use of quaternary blend of supplementary cementitious materials (SCM’s) has not found enough applications. For this purpose, an effort has been done to present a mix design for M60 grade and M80 grade SCC with quaternary blending of fly ash(FA), ground granulated blast furnace slag (GGBS), silica fume (SF) in accordance with EFNARC guidelines. Findings: In this study, cement has been replaced with SCM’s from 30% to 50%. Fresh properties of concrete were tested for slump flow, T50 test and U box. The hardened properties of concrete were tested for compressive strength and durability. The tests were performed for 7, 28, 56 and 91 days. The results indicate that the use of quaternary blend has improved the workability, compressive strength and durability properties of specimens than the control specimen. Application: The primary contribution is to fill the congestedreinforcement and increase the durability and life span of the structure.

scholarly journals Nano Silica and Metakaolin Effects on the Behavior of Concrete Containing Rubber Crumbs

CivilEng ◽  
2020 ◽  
Vol 1 (3) ◽  
pp. 264-274
Author(s):  
Navid Chalangaran ◽  
Alireza Farzampour ◽  
Nima Paslar
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Concrete Strength ◽  
Environmental Issues ◽  
Tensile Behavior ◽  
Concrete Mixture ◽  
Nano Silica ◽  
Negative Effects ◽  
Rubber Material ◽  
Concrete Aggregates

The excessive production of worn tires remaining from the transportation system and the lack of proper procedures to recycle or reuse these materials have caused critical environmental issues. Due to the rubber’s toughness, this material could be implemented to increase concrete toughness, and by crushing the tires concrete aggregates can be replaced proportionally with rubber crumbs and large quantities of scrapped rubber. However, this substitution decreases the concrete strength. In this study, crushed rubber with sizes from 1 to 3 mm and 3 to 6 mm were replaced by 5%, 10%, and 15% sand; the combination of two additives of nano silica and metakaolin additives with optimum values was used to compensate the degradation of the strength and improve the workability of the concrete. Moreover, the compressive strength, tensile behavior, and modulus of elasticity were measured and compared. The results indicate that the optimum use of nano silica and metakaolin additives could compensate the negative effects of the rubber material implementation in the concrete mixture while improving the overall workability and flowability of the concrete mixture.

Influences of Limestone Aggregates on Concrete Strength in Pipe Piles Production

2014 ◽  
Vol 584-586 ◽  
pp. 1370-1374
Author(s):  
Yuan Hai Jiang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Concrete Strength ◽  
Normal Pressure ◽  
Concrete Compressive Strength ◽  
Steam Curing ◽  
Coarse Aggregates ◽  
Siliceous Rocks ◽  
Pressure Steam ◽  
Autoclave Curing

Taking the limestone and siliceous rocks as coarse aggregates to mix concrete,through normal pressure steam curing and autoclave curing,the concrete compressive strength after demould and compressive strength after autoclave curing are tested.The results indicate that the concrete compressive strength increases obviously after normal pressure steam curing when taking the limestone and granite as coarse aggregates,and the strength increasing laws are basically in accordance.However,the concrete compressive strength is great different after autoclave curing when taking the limestone and granite as coarse aggregates,the concrete strength increases lower with limestone as coarse aggregate,but the concrete strength increases higher with siliceous rocks as coarse aggregate.

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