Effect of admixtures on the setting times of high-strength concrete (original) (raw)
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The effect of mineral admixtures on the properties of high-performance concrete
Cement & Concrete Composites, 2000
The paper presents a laboratory study on the influence of two mineral admixtures, silica fume (SF) and fly ash (FA), on the properties of superplasticised high-performance concrete. Assessment of the concrete mixes was based on short- and long-term testing techniques used for the purpose of designing and controlling the quality of high-performance concrete. These include compressive strength, porosity, oxygen permeability, oxygen diffusion and chloride migration. Measurements were carried out after curing at 20% and 65% relative humidity up to the age of 1 yr. The results, in general, showed that mineral admixtures improved the properties of high-performance concretes, but at different rates depending on the binder type. While SF contributed to both short- and long-term properties of concrete, FA required a relatively longer time to get its beneficial effect. In the long term, both mineral admixtures slightly increased compressive strength by about 10%, but contributed more to the improvement of transport properties of concretes.
EFFECT OF MINERAL ADMIXTURES ON CHARACTERISTICS OF HIGH STRENGTH CONCRETE
There is great need to conserve all the natural resources. The various steps to be adopted in the direction that includes minimization of production of energy consuming materials and heavy utilization of industrial by-products. High strength concrete can be produce using such materials like fly ash, slag and silica fumes. In many countries, these materials are already used in manufacturing of concrete. Some of these material can be used as replacement for cement. Ultimately it results in the reduction of the cost manufacturing of concrete and reduces environmental pollution. To study the effect of mineral admixtures such as fly ash, slag and silica fume on mechanical properties of high strength concrete under the uniaxial compression and split tensile, experimental studies have been conducted. The cement was replaced by 5%, 10%, 15% and 20% with fly ash and slag respectively. The compressive strength and split tensile test were conducted on concrete specimen with different percentages of fly ash and slag at age of 7 days, 28 days and 56 days. This study shows that materials used in this experiment are suitable for HSC.
Effects of Different Mineral Admixtures on the Properties of Fresh Concrete
The Scientific World Journal, 2014
This paper presents a review of the properties of fresh concrete including workability, heat of hydration, setting time, bleeding, and reactivity by using mineral admixtures fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and rice husk ash (RHA). Comparison of normal and high-strength concrete in which cement has been partially supplemented by mineral admixture has been considered. It has been concluded that mineral admixtures may be categorized into two groups: chemically active mineral admixtures and microfiller mineral admixtures. Chemically active mineral admixtures decrease workability and setting time of concrete but increase the heat of hydration and reactivity. On the other hand, microfiller mineral admixtures increase workability and setting time of concrete but decrease the heat of hydration and reactivity. In general, small particle size and higher specific surface area of mineral admixture are favourable to produce highly dense and impermeable concrete; however, they cause low workability and demand more water which may be offset by adding effective superplasticizer.
The Effect of Different Mineral Admixtures on Characteristics of Concrete
This paper presents a review of the properties of fresh and hardened concrete by using mineral admixtures fly ash (FA), and silica fume (SF). In many countries, these materials are already used in manufacturing of concrete. However, these industrial by products is becoming popular throughout the world because of the minimization of their potential hazardous effects on environment. Some of these materials used as replacement for cement. Ultimately it results in the reduction of the cost manufacturing of concrete and reduces environmental pollution. In general, small particle size and higher specific surface area of mineral admixture are favorable to produce highly dense and impermeable concrete; however, they cause low workability and demand more water. To study the effect of mineral admixtures such as fly ash and silica fume on mechanical properties of concrete under the uniaxial compression experimental studies conducted. The cement was replaced by 10 %, 20 % and 30 % with fly ash and silica fume. The compressive strength test conducted on concrete specimen with different percentages of fly ash and silica fume at age of 7 days and 28 days.
The influence of mineral admixtures on the short and long-term performance of concrete
Building and Environment, 2007
This paper presents a laboratory study on the performance of concrete by adding mineral admixtures, silica fumes (SF) or/and fly ash (FA). Performance of the concrete mixes was determined with short and long-term tests, which include compressive strength, porosity, capillary absorption, wet-dry cycle and accelerated carbonation. The test results, in general, showed that mineral admixtures improved the performance of concretes. SF contributed to both short and long-term properties of concrete, whereas FA shows its beneficial effect in a relatively longer time. As far as the compressive strength is concerned, adding of both SF and FA slightly increased compressive strength, but contributed more to the improvement of transport properties of concretes.
Building and Environment, 2007
In this study, pulverized fly ash (FA), pulverized granulated blast furnace slag (PS) and silica fume (SF) were quantitatively studied with the incorporation of Portland cement (PC). PC was replaced with FA or PS at specified ratios. Basalt and quartz powder were used as an aggregate in the mixtures. Three different curing methods (standard, autoclave and steam curing) were applied to the specimens. Test results indicate that high strength concrete can be obtained with high volume mineral admixtures. Compressive strength of these mixtures is over 170 MPa. It seems that these mixtures can also be used for reactive powder concrete (RPC) production with some modifications.
Effect of retarding superplasticizers on the properties of cement paste, mortar and concrete
Asian Journal of Civil Engineering, 2019
Chemical admixtures are becoming increasingly popular as these could improve several properties of concrete, both in plastic and hardened condition. However, improper use of admixture may lead to the inferior performance of produced concrete. Effects of admixtures dosage on the properties of cement paste, mortar and concrete were studied in this research. The most recently developed polycarboxylic ether (PCE)-based admixtures from different manufacturers were used. The trial dosages were fixed considering their properties and suppliers' specifications. Firstly, the effect of retarding on cement setting times was evaluated using cement paste and then flow test was carried out on cement mortars to examine change in workability, i.e., superplasticizing effect with this. Compressive and tensile strength test on mortar cube and briquette samples was conducted to evaluate variation in strength with different dosage of admixture while keeping other materials' proportions same. Finally, the dosage effect on workability (slump retention) of fresh concrete was studied for every 15-min interval up to 1.5 h. Effect of slump retention using admixture on compressive strength was also evaluated. Experimental results show that a small variation in admixture dosage changes these properties significantly. It was concluded that properties of cement paste, mortar and concrete could be improved with an optimum dosage for each particular type of admixture; however, higher or lower dosage than this may put adverse effect. Within the usable time, there might be other chemical effects that enhance/ decrease the concrete performance while keeping all other quantity and parameters the same for all these concrete mixes.
Now a day's high performance concrete is globally used in the infrastructure industry for strong and durable structure, to produced high performance concrete various supplementary cementitious material are used as mineral admixture. This research involves the use of Fly ash, Alccofine and Silica fume at various proportions to enhance the compressive strength of high performance concrete. the investigation was carried out by replacing 10% fly ash along with 17% of alccofine and 10% fly ash along with 17% of silica fume by weight of cementitious material. To cover a wide range of compressive strength of concrete various water binder ratio (W/b) of 0.25, 0.3 and 0.35 were used. The effect of various parameters such as percentage replacement of mineral admixture, water to binder ratio and corresponding compressive strength is studied on fresh and hardened state of concrete. The study mainly consisted of establishing relation between these parameters graphically. Investigation demonstrates that alcofine performs batter than that of silica fume along with fly ash in fresh and harden state of concrete.
Data in brief, 2018
The aim of this work is to study the influence of the admixture of superplasticizers on the physical properties of cement paste to know the initial and final time, water content and mechanical performance of concrete. In this work we have incorporated an Advanced Superplasticité for Prolonged Slump Retention (ASPPSR402) in the formulation matrix of concrete at different percentages ranging from 0.5% to 5% by weight of cement with a step of 0.5%, while partially substituting the mixing water by the last one to reduce the amount of water used. The obtained results by different prospected formulations show that the admixture of ASPPSR402 in formulations matrix significantly reduces the (Water/Cement "W/C") ratio. Subsequently, we observed that the initial and final time increases in function of the percentage of ASPPSR402. Similarly, the compressive strength at the young age, median age and long-term has been improved.
Studies on High Performance Concrete Using Mineral Admixtures
International Journal for Research in Applied Science and Engineering Technology (IJRASET), 2022
High performance concrete is made using byproducts called cement replacement materials. Comparatively little information has been published regarding the results of different Effects of mineral admixtures on concrete's microstructural and team performance characteristics under various curing regimes. Additionally, it is unclear how concrete's strength relates to its conductivity and porous structure. Workability of the new concrete as well as engineering characteristics like cube and revised cube compressive strength and flexural strength were among the properties examined. The findings demonstrate that lanaba dry curing makes concretes weaker, more porous, with a increased pore size, and more permeable. It was discovered that tiny amounts of silica fume can make up for the reduction early in life compressive strength caused by the insertion of bagasse ash from sugar cane. With increasing concentrations of sugar cane bagasse ash or slag in the mixtures, the microstructural and engineering characteristics and concrete's capacity to breathe that contain them they seem to be more vulnerable to inadequate than concrete cubes for curing.