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.

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.

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.

scholarly journals The effect of Vietnam’s nano-silica on mechanical properties of high-performance concrete

2021 ◽  
Vol 72 (1) ◽  
pp. 76-83
Author(s):  
Lam Le Hong ◽  
Lam Dao Duy ◽  
Huu Pham Duy
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Nano Silica ◽  
Nano Sio2 ◽  
Curing Period ◽  
Compressive Strength Test

The demand for High Performance Concrete (HPC) is steadily increasing with massive developments. Conventionally, it is possible to use industrial products such as silica fume (SF), fly ash, as supplementary cementitious materials (SCM), to enhance the attributes of HPC. In recent years, nano-silica (NS) is used as an additive in added mainly to fill up the deviation arises with the addition of SF for HPC. This study aims to optimize the proportion of NS (produced in Vietnam) in the mixture used for fabricating 70 MPa high-performance concrete. SiO2 powder with particle size from 10 to 15 nm were used for mixing. A series of compressive strength test of HPC with nano-SiO2 varied from 0 to 2.8 percent of total of all binders (0%, 1.2%, 2%, 2.8%), and the fixed percentage of silica fume at 8% were proposed. Results show compressive strength increases with the increase of nano-SiO2, but this increase stops after reaching 2%. And at day 28 of the curing period, only concrete mixture containing of 8% silica fume and 2% nano-SiO2, had the highest compressive strength.

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 Mechanical Properties of Ultra-High Performance Concrete before and after Exposure to High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 770 ◽  
Author(s):  
How-Ji Chen ◽  
Yi-Lin Yu ◽  
Chao-Wei Tang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperatures ◽  
High Performance ◽  
High Performance Concrete ◽  
Silicon Powder ◽  
Supplementary Cementitious Materials ◽  
Ultra High Performance Concrete ◽  
Splitting Strength ◽  
Experimental Group

Compared with ordinary concrete, ultra-high performance concrete (UHPC) has excellent toughness and better impact resistance. Under high temperatures, the microstructure and mechanical properties of UHPC may seriously deteriorate. As such, we first explored the properties of UHPC with a designed 28-day compressive strength of 120 MPa or higher in the fresh mix phase, and measured its hardened mechanical properties at seven days. The test variables included: the type of cementing material and the mixing ratio (silica ash, ultra-fine silicon powder), the type of fiber (steel fiber, polypropylene fiber), and the fiber content (volume percentage). In addition to the UHPC of the experimental group, pure concrete was used as the control group in the experiment; no fiber or supplementary cementitious materials (silica ash, ultra-fine silicon powder) were added to enable comparison and discussion and analysis. Then, the UHPC-1 specimens of the experimental group were selected for further compressive, flexural, and splitting strength tests and SEM observations after exposure to different target temperatures in an electric furnace. The test results show that at room temperature, the 56-day compressive strength of the UHPC-1 mix was 155.8 MPa, which is higher than the >150 MPa general compressive strength requirement for ultra-high-performance concrete. The residual compressive strength, flexural strength, and splitting strength of the UHPC-1 specimen after exposure to 300, 400, and 500 °C did not decrease significantly, and even increased due to the drying effect of heating. However, when the temperature was 600 °C, spalling occurred, so the residual mechanical strength rapidly declined. SEM observations confirmed that polypropylene fibers melted at high temperatures, thereby forming other channels that helped to reduce the internal vapor pressure of the UHPC and maintain a certain residual strength.

Effects of corrosion inhibiting admixtures and supplementary cementitious materials combinations on the strength and certain durability properties of HPC

2017 ◽  
Vol 44 (11) ◽  
pp. 918-926 ◽  
Author(s):  
H.Z. Lopez-Calvo ◽  
P. Montes-Garcia ◽  
E.M. Alonso-Guzmán ◽  
W. Martinez-Molina ◽  
T.W. Bremner ◽  
...  
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Durability Properties ◽  
Corrosion Evaluation ◽  
Chloride Profiles ◽  
Calcium Nitrite ◽  
Strength And Durability

This paper reports a study carried out to evaluate the effects of corrosion inhibiting admixtures, calcium nitrite and disodium tetrapropenyl succinate, in combination with supplementary cementitious materials, fly ash and silica fume Portland cement, on the compressive strength and certain durability properties of high performance concrete. Mixture formulations, including binary and ternary combinations of these admixtures were evaluated. Chloride profiles after 91 and 365 days of exposure and the compressive strength and electrical resistivity at 1, 7, 14, 28, 180, and 365 days of age were estimated. Also, results of corrosion evaluation after five-year exposure to a natural marine environment at Treat Island Maine, USA are presented and discussed. Results indicate that the use of corrosion inhibitors in combination with supplementary cementitious materials was beneficial, albeit to various degrees, in enhancing the strength and durability properties of high performance concrete with no noticeable adverse effects.

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