The Effect of Homogenization Procedure on Mechanical Properties of High-Performance Concrete with Partial Replacement of Cement by Supplementary Cementitious Materials

2019 ◽  
Vol 292 ◽  
pp. 102-107 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Karel Šeps ◽  
Roman Chylík ◽  
Vladimír Hrbek
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Water Content ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Depth Of Penetration ◽  
Cement Additive

High-performance concrete is a very specific type of concrete. Its production is sensitive to both the quality of compounds used and the order of addition of particular compounds during the homogenization process. The mechanical properties were observed for four dosing procedures of each of the three tested concrete mixtures. The four dosing procedures were identical for the three mixes. The three mixes varied only in the type of supplementary cementitious material used and in water content. The water content difference was caused by variable k-value of particular additives. The water-to-binder ratio was kept constant for all the concretes. The additives used were metakaolin, fly ash and microsilica. The comparison of particular dosing procedures was carried out on the values of basic mechanical properties of concrete. The paper compares compressive strength and depth of penetration of water under pressure. Besides the comparsion of macro-mechanical properties, the effect of microsilica and fly ash additives on micro-mechanical properties was observed with the use of scanning electron microscopy (SEM) and nanoindentation data analysis. Nanoindentation was used to determine the thickness and strength of interfacial transition zone (ITZ) for different sequence of addition of cement, additive and aggregate. The thickness obtained by nanoindentation was further investigated by SEM EDS line scanning.

Influence of Washing of Crushed Aggregate on Mechanical Properties of High-Performance Concrete Containing Supplementary Cementitious Materials

2020 ◽  
Vol 309 ◽  
pp. 26-30 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Tomáš Trtík ◽  
Roman Chylík ◽  
Vladimír Hrbek
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Positive Influence ◽  
Supplementary Cementitious Materials ◽  
Basic Material ◽  
Depth Of Penetration ◽  
Crushed Aggregate

The paper compares macromechanical and micromechanical properties of high-performance concrete containing supplementary cementitious materials and basalt aggregate. The aggregate was either a common unprocessed crushed basalt aggregate or crushed basalt aggregate the coarse fractions (4/8 and 8/16 mm) of which were washed by water and dried before use. The observed macro-mechanical properties were compressive strength, tensile strength, elastic modulus and depth of penetration of water under pressure; the paper is focused on the first observed property, which is the basic material characteristic. On the microscale, the thickness of the interfacial transition zone (ITZ) was determined by nanoindentation. The positive influence of supplementary cementitious materials and aggregate washing on compressive strength was confirmed and the correlation between macromechanical and micromechanical characteristics was proved.

Macroscopic and Microscopic Properties of High Performance Concrete with Partial Replacement of Cement by Fly Ash

2019 ◽  
Vol 292 ◽  
pp. 108-113 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Roman Chylík ◽  
Zdeněk Prošek
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Partial Replacement ◽  
Experimental Program ◽  
Second Phase ◽  
Depth Of Penetration ◽  
Cement Replacement

The paper describes an experimental program focused on the research of high performance concrete with partial replacement of cement by fly ash. Four mixtures were investigated: reference mixture and mixtures with 10 %, 20 % and 30 % cement weight replaced by fly ash. In the first stage, the effect of cement replacement was observed. The second phase aimed at the influence of homogenization process for the selected 30% replacement on concrete properties. The analysis of macroscopic properties followed compressive strength, elastic modulus and depth of penetration of water under pressure. Microscopic analysis concentrated on the study of elastic modulus, porosity and mineralogical composition of cement matrix using scanning electron microscopy, spectral analysis and nanoindentation. The macroscopic results showed that the replacement of cement by fly ash notably improved compressive strength of concrete and significantly decreased the depth of penetration of water under pressure, while the improvement rate increased with increasing cement replacement (strength improved by 18 %, depth of penetration by 95 % at 30% replacement). Static elastic modulus was practically unaffected. Microscopic investigation showed impact of fly ash on both structure and phase mechanical performance of the material.

scholarly journals Compressive and Flexural Strength Property Enhancement for Fibre Reinforced Standard Concrete (FRSC), High Strength Concrete (FRHSC) and High Performance Concrete (FRHPC) using Foundry Sand (FS) and Crushed Concrete Waste (CCW)

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Pruthviraj S R ◽  
Ravi Kumar C M ◽  
Yajnodbhavi H M ◽  
Maruthi T ◽  
Raghavendra S
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Research Work ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Specific Test ◽  
Foundry Sand ◽  
Crushed Concrete

Now days, many research works are carried for all grades of concrete to make the concrete most economical and durable there by adding the supplementary cementitious materials and alternative replacement aggregates. In this research work deals with the experimental investigation of mechanical properties of the M30, M50 and M80 grade concrete by replacing the fine and coarse aggregate by foundry sand and crushed concrete waste respectively. Mix design procedures were followed as per IRC44:2017 guidelines and recommendation. Proper dosage of super plasticizer (SP) was maintained in the concrete to make it better performed. In this present investigation, a Poly Propylene fibre (PPF) of 0.3% by weight of the cement is used. Mechanical properties such as Compressive strength and Flexural Strength were determined by preparing the respective mould sizes for specific test and are cured for 7, 14 and 28 days and result obtained for respective days were tabulated and discussed.  

scholarly journals Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1833 ◽  
Author(s):  
Dong Lu ◽  
Zhuo Tang ◽  
Liang Zhang ◽  
Jianwei Zhou ◽  
Yue Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Amorphous Phases ◽  
Micro Cracks

Concrete has low porosity and compact microstructure, and thus can be vulnerable to high temperature, and the increasing application of various types of supplementary cementitious materials (SCMs) in concrete makes its high-temperature resistant behavior more complex. In this study, we investigate the effects of four formulations with typical SCMs combinations of fly ash (FA), ultra-fine fly ash (UFFA) and metakaolin (MK), and study the effects of SCMs combinations on the thermal performance, microstructure, and the crystalline and amorphous phases evolution of concrete subjected to high temperatures. The experimental results showed that at 400 °C, with the addition of 20% FA (wt %), the thermal conductivity of the sample slightly increased to 1.5 W/(m·K). Replacing FA with UFFA can further increase the thermal conductivity to 1.7 W/(m·K). Thermal conductivity of concrete slightly increased at 400 °C and significantly reduced at 800 °C. Further, combined usage of SCMs delayed and reduced micro-cracks of concrete subjected to high temperatures. This study demonstrates the potential of combining the usage of SCMs to promote the high-temperature performance of concrete and explains the micro-mechanism of concrete containing SCMs at high temperatures.

Glass frit for concrete structures: a new, alternative cementitious material

2007 ◽  
Vol 34 (7) ◽  
pp. 793-802 ◽  
Author(s):  
Said Laldji ◽  
Arezki Tagnit-Hamou
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Drying Shrinkage ◽  
Chloride Ion ◽  
Glass Frit ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Concrete Durability

With today's requirements for high-performance concrete, mix proportions containing cementitious materials as partial replacement of, or in addition to, Portland cement, are being used more frequently. The most commonly used cementitious materials nowadays are fly ash, silica fume, and ground, granulated blast-furnace slag. However, alternative supplementary cementitious materials can successfully be used as long as they meet the acceptance criteria stated in various specifications. This paper provides data on properties of structural concrete containing glass frit. The performance of this type of concrete is highlighted by its rheological and mechanical behaviour, as well as its durability. Later-age compressive, splitting tensile, and flexural strengths are well above estimated values, and in many cases, are higher than those obtained with the control concrete. Durability aspects and characteristics expressed by drying shrinkage, surface scaling, and chloride-ion permeability have shown that concrete incorporating glass frit has a very good potential for long-term resistance.Key words: glass frit, cementitious material, workability, mechanical properties, durability.

scholarly journals Experimental Investigation and Prediction of Compressive Strength of Ultra-High Performance Concrete Containing Supplementary Cementitious Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Jisong Zhang ◽  
Yinghua Zhao ◽  
Haijiang Li
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Ann Model ◽  
Ultra High Performance Concrete ◽  
Superior Mechanical Properties ◽  
Normal Strength

Ultra-high performance concrete (UHPC) has superior mechanical properties and durability to normal strength concrete. However, the high amount of cement, high environmental impact, and initial cost are regarded as disadvantages, restricting its wider application. Incorporation of supplementary cementitious materials (SCMs) in UHPC is an effective way to reduce the amount of cement needed while contributing to the sustainability and cost. This paper investigates the mechanical properties and microstructure of UHPC containing fly ash (FA) and silica fume (SF) with the aim of contributing to this issue. The results indicate that, on the basis of 30% FA replacement, the incorporation of 10% and 20% SF showed equivalent or higher mechanical properties compared to the reference samples. The microstructure and pore volume of the UHPCs were also examined. Furthermore, to minimise the experimental workload of future studies, a prediction model is developed to predict the compressive strength of the UHPC using artificial neural networks (ANNs). The results indicate that the developed ANN model has high accuracy and can be used for the prediction of the compressive strength of UHPC with these SCMs.

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