Should Minimum Cementitious Contents for Concrete Be Specified?

2017 ◽  
Vol 2629 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Karthik H. Obla ◽  
Rongjin Hong ◽  
Colin L. Lobo ◽  
Haejin Kim
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Laboratory Tests ◽  
Cementitious Materials ◽  
Slag Cement ◽  
Fly Ash Concrete ◽  
Primary Focus ◽  
Strength And Durability

Minimum cementitious contents are commonly specified in project specifications. The primary focus of this study was to examine the influence of the cementitious content on concrete performance at specific water-to-cementitious materials ratios. The experimental variables included water-to-cementitious materials ratios ranging from 0.40 to 0.55, mixtures containing portland cement only, and mixtures containing 40% slag cement or 25% fly ash. Concrete performance was evaluated through laboratory tests on workability, strength, and durability. The results showed that at a given water-to-cementitious ratio a higher cementitious content results in higher paste volumes and poorer concrete performance. On the basis of these results the value of maintaining minimum cementitious content requirements in project specifications is questioned.

scholarly journals Sustainable cementitious materials: The effect of fly ash percentage as a part replacement of portland cement composite (PCC) and curing temperature on the early age strength of fly ash concrete

2019 ◽  
Vol 258 ◽  
pp. 01001
Author(s):  
Gidion Turuallo ◽  
Harun Mallisa
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Cement Composite ◽  
Cementitious Materials ◽  
Curing Temperature ◽  
Early Age ◽  
Water Tank ◽  
Lower Strength ◽  
Fly Ash Concrete ◽  
Lower Temperature

This research aims to determine the effect of fly ash percentage as a part replacement of Portland cement and curing temperatures to the early age strength of concrete. The percentages of fly ash used were 0, 10 and 15% by cement weight. The cured temperatures were 25, 30 dan 50°C. The concrete specimens were cubes of 150 x 150 x 150 mm3. The cubes, which were cured at 25°C, placed in water tank, while those cured at 30 and 50°C cured in oven until 7 days and then continued in water. The testing was conducted at ages 3, 7, 14 dan 28 days. The results showed that at early ages, the strength of concrete without fly ash cured at 25°C were higher than that of fly ash concrete. The higher level replacement of cement with fly ash, the lower strength of concrete obtained. The higher the curing temperature at earlier age resulted the higher the strength of concrete. The strength of concretes with 10% of fly ash cured at 25, 30 and 50°C at age three days were 15.111, 15.481 and 16.296 MPa respectively. Conversely, the strength of concrete that of cured at higher temperatures at ages 28 days, were lower than that of concretes cured at lower temperature. The results of this research also showed that fly ash could improve the workability of concrete.

scholarly journals Study of Effect of Nano-Silica on Strength and Durability Characteristics of High Volume Fly Ash Concrete for Pavement Construction

2019 ◽  
Vol 5 (6) ◽  
pp. 1341-1352 ◽  
Author(s):  
Bimal Kumar ◽  
Sanjeev Sinha ◽  
Hillol Chakravarty
Keyword(s):  
Fly Ash ◽  
High Volume ◽  
Cementitious Materials ◽  
Nano Silica ◽  
Split Tensile Strength ◽  
Fly Ash Concrete ◽  
Rigid Pavements ◽  
High Volume Fly Ash ◽  
Pavement Construction ◽  
Strength And Durability

Increasing demands of cement concrete for construction of rigid pavements motivates for the utilization of other sustainable waste cementitious materials. High volume fly-ash concrete (HVFAC) which is composed of more than 50% fly-ash fulfils the aspiration of large volume of fly-ash which are produced world over. The disadvantage which the HVFAC has is its delayed gain of strength. Contemporary literature identifies nano-silica as the material which when added in small percentages in HVFAC has the potential to improve its strength and durability characteristics at an early age. The objective of the study is to investigate the strength and durability characteristics of HVFAC modified with addition of different percentages of nano-silica so that it can be used for construction of rigid pavements. The methodology of the study involves mix proportioning of HVFAC and introducing nano-silica powder in aqueous medium after mixing it thoroughly at 2500 rpm. Various tests related to strength and durability was carried out after 28, 56 and 90 days age of concrete. The tests related to strength namely flexural strength, compressive strength and split tensile strength tests were carried out. Durability characteristics were evaluated by permeability, sorptivity and rapid chloride penetration tests and were confirmed by density and ultrasonic pulse velocity test.  The test results show that the utilization of 2% nano-silica in HVFAC enhances the strength and durability characteristics to a level that are comparable to that of normal concrete after 28 days and thus, can be sustainably utilized for rigid pavement construction.

scholarly journals Performance of Recycled Concrete Aggregate in Self Compacting Concrete

2018 ◽  
Vol 7 (3.35) ◽  
pp. 1
Author(s):  
T. V. Arul Prakash ◽  
Dr. M. Natarajan ◽  
Dr. T. Senthil Vadivel ◽  
K. Vivek
Keyword(s):  
Fly Ash ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Self Compacting Concrete ◽  
Fly Ash Concrete ◽  
Local Construction ◽  
Class F Fly Ash ◽  
Strength And Durability

This article presents the influence of the Recycled Concrete Aggregate (RCA) on the mechanical properties of self-compacting fly ash concrete (M30 Grade). The RCA from local construction demolition site were employed as a replacement for natural coarse aggregate (0% - 30%) in self-compacting concrete (SCC). The Viscosity modifying material used in this study was Class F fly ash. The results indicate that recycled concrete aggregate can be replaced by an optimal 25% replacement percentage in the manufacture of SCC without significantly affecting strength and durability.  

Research on Durability of High Volume Fly Ash Concrete

2012 ◽  
Vol 174-177 ◽  
pp. 380-383 ◽  
Author(s):  
Hong Zhu Quan
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Experimental Studies ◽  
High Volume ◽  
Portland Cement Concrete ◽  
Freezing And Thawing ◽  
Replacement Ratio ◽  
Rapid Reduction ◽  
Fly Ash Concrete

The paper presents the results of series of experimental studies on effects of the type and replacement ratio of fly ash to portland cement on durability of concrete. Specimens made from 28 mixes of fly ash concrete with water binder ratio of 38% to 60% and with replacement ratio of fly ash of 25% to 70% and 5 mixes of portland cement concrete with water cement ratio of 38% to 75% were tested for compressive strengths, drying shrinkage, carbonation and resistance to freezing and thawing. As a results, drying shringkage decreased with fly ash addition regardless of type and replacement ratio of fly ash. Carbonation increased with fly ash replacement ratio, and type 1 fly ash showed higher carbonation. Type 1 and tpye 2 fly ashes showed practically no change in durability factor after 300 cycles of freezing and thawing up to 55% replacement, while type 4 fly ash showed rapid reduction in durability factor up to 40% replacement ratio.

Water Penetration Resistance of Fly Ash Concrete Incorporating with Quarry Wastes

2017 ◽  
Vol 886 ◽  
pp. 159-163 ◽  
Author(s):  
Suppachai Sinthaworn
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
High Strength ◽  
Cementitious Materials ◽  
Fine Aggregate ◽  
Water Penetration ◽  
Strength Concrete ◽  
Fly Ash Concrete ◽  
Suitable Amount ◽  
Normal Strength

Slump of fresh concrete, compressive strength and water penetration depth under pressure of fly ash concrete incorporate with quarry waste as fine aggregate were investigated. The cementitious materials of the concrete includes ordinary Portland cement 80% and fly ash 20% by weight of cementitious. The mix proportions of the concrete were set into two classes of compressive strength. The results show that fly ash enhances workability of both concretes (normal concrete and concrete incorporate with quarry waste). Increasing the percentage of quarry dusts as fine aggregate in concrete seem negligible effect on the compressive strength whereas adding fly ash shows a slightly improve the compressive strength in the case of cohesive concrete mixture. Besides, adding the suitable amount of fly ash could improve the permeability of concrete. Therefore, fly ash could be a good admixture to improve the water resistant of normal strength concrete and also could be a supplemental material to improve the compressive strength of normal high strength concrete.

Mechanical Properties of Class C High Volume Fly Ash Concrete with Lime Water as Mixing Water

2014 ◽  
Vol 660 ◽  
pp. 312-316
Author(s):  
Mochamad Solikin ◽  
Budi Setiawan
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Flexural Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
High Volume ◽  
Fly Ash Concrete ◽  
Lime Water ◽  
High Volume Fly Ash ◽  
Mixing Water

This paper reports an investigation on mechanical properties of high volume fly ash (HVFA) concrete produced using different types of mixing water i.e. tap water and saturated lime water. The mechanical properties of ordinary Portland cement concrete are also investigated as control tests. The concrete were tested for their compressive strength, flexural strength and splitting tensile strength at the curing ages of 56 days. The results showed that strength development of high volume fly ash concrete up to 56 days is lower than ordinary portal cement. In addition, the flexural strength and splitting strength of concrete are lower than ordinary Portland cement. Moreover, the use of saturated lime water as mixing water reduces the mechanical properties of class C high volume fly ash concrete.

scholarly journals Comparison of strength and durability characteristics of a geopolymer produced from fly ash, ground glass fiber and glass powder

2017 ◽  
Vol 67 (328) ◽  
pp. 136 ◽  
Author(s):  
H. Rashidian-Dezfouli ◽  
P. R. Rangaraju
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Glass Fiber ◽  
Glass Powder ◽  
Silica Content ◽  
Ground Glass ◽  
Alkali Silica Reaction ◽  
Strength And Durability ◽  
Cement Mixtures

Strength and durability characteristics of geopolymers produced using three precursors, consisting of fly ash, Ground Glass Fiber (GGF), and glass-powder were studied. Combinations of sodium hydroxide and sodium silicate were used as the activator solutions, and the effect of different sodium and silica content of the activators on the workability and compressive strength of geopolymers was investigated. The parameters used in this study were the mass ratio of Na2O-to-binder (for sodium content), and SiO2-to-Na2O of the activator (for silica content). Geopolymer mixtures that achieved the highest compressive strength from each precursor were assessed for their resistance to alkali-silica reaction and compared against the performance of portland cement mixtures. Test results revealed that GGF and fly ash-based geopolymers performed better than glass-powder-based geopolymer mixtures. The resistance of GGF-based and fly ash-based geopolymers to alkali-silica reaction was superior to that of portland cement mixtures, while glass-powder-based geopolymer showed inferior performance.

scholarly journals STRENGTH AND DURABILITY PERFORMANCE OF FLY ASH BASED GEOPOLYMER CONCRETE USING NANO SILICA

2020 ◽  
Vol 4 (2) ◽  
pp. 1-12
Author(s):  
SAMEER VYAS ◽  
Sameer Mohammad ◽  
Shilpa Pal ◽  
Neetu Singh
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Geopolymer Concrete ◽  
Infrastructure Development ◽  
X Ray Diffraction ◽  
Nano Silica ◽  
Adverse Conditions ◽  
Concrete Production ◽  
Class F Fly Ash ◽  
Strength And Durability

With the increasing infrastructure development across the globe, the demand of cement  production increases day by day. However, the production of cement is associated with the emission of large amount of CO2 causing global warming. Scientist and engineers are in search of a green eco friendly alternative  for concrete production. Geopolymers are rapidly emerging as an alternative to Portland cement as the binder of structural concrete. In this respect, the fly ash based geopolymers  shows considerable prospect for application in concrete industry as an alternative binder to the Portland cement. Development of geopolymer concrete using class F fly ash brings many advantages like; enhancing workability, durability, better strength as well as lowering the price. There is not only a reduction in the greenhouse footprint but, also considerable increase in strength and resistivity to adverse conditions. In order to enhance the performance of Geopolymer concrete, the use of  Nano-silica is  found to be suitable and practiced by researchers.  Use of Nano materials as fillers in the concrete matrix has proven effective in increasing mechanical and durability properties. This research is based on performance evaluation of geopolymer concrete using different percentage of Nano-silica.. It was observed that Geopolymer concrete  with Nano-silica ( GPC-N)  shows good compressive strength as well as  durability under aggressive conditions. The materials performance were also investigated using X-Ray Diffraction technique. (XRD). Results show that the presence of nano silica  enhanced the performance of Geopolymer concrete with respect to strength and durability purposes.  

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