Microstructural Study of Aggregate/Hydrated Paste Interface in Very High Strength River Gravel Concretes

1987 ◽  
Vol 114 ◽  
Author(s):  
Shondeep L. Sarkar ◽  
Yaya Diatta ◽  
Pierre-Claude Aïtcin
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Strength ◽  
Hydrated Lime ◽  
Excellent Correlation ◽  
Correlation Index ◽  
Microstructural Study ◽  
Weakest Link ◽  
Very High ◽  
Microstructural Examination

ABSTRACTThe aggregate/hydrated paste interface represents the weakest link in very high strength river gravel concrete, due to the surface smoothness of these aggregates.Microstructural examination of the aggregate/hydrated paste interface in four different (very low W/C ratio) very high strength concretes with and without silica fume shows major differences in the nature of the transition zone at the interface level. In the non-silica fume concretes, hydrated lime and ettringite are found quite exclusively at the interface, while in silica fume concretes, only C-S-H is observed.The modulus of elasticity can be correlated to the compressive strength by the equation, , with a low correlation index (78%) for non-silica fume concrete, whereas in silica fume concrete it becomes MPa, with excellent correlation in ex of 95%.These results can be explained by the nature of the aggregate/hydrated paste interface, which is stronger in silica fume concrete.

Microstructural Study of Different Types of Very High Strength Concretes

1986 ◽  
Vol 85 ◽  
Author(s):  
Pierre-Claude Aitcin ◽  
Shondeep L. Sarkar ◽  
Yaya Diatta
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Strength ◽  
Surface Cracks ◽  
Cement Type ◽  
Normal Concrete ◽  
Microstructural Study ◽  
Different Types ◽  
Early Strength ◽  
Very High

ABSTRACTVery high strength concretes with water-cement ratios ranging from 0.21 to 0.27, having compressive strengths varying between 73 and 118 MPa, were prepared. One series was made with only high early strength cement (Type III), and the other series contained 6% to 11% silica fume.In general, the microstructure of very high strength concrete is very dense and is composed mainly of C-S-H in the gel and crystalline phases. Mg, Al, S, Cl, K and Fe were detected in a number of C-S-H locales. The Ca/Si ratio was variable. In concretes without silica fume, the CH content is much lower than in normal concrete, and in the silica fume concretes it is still lower and not well crystallized. A few large, partly reacted and unreacted silica fume particles with surface cracks were present.Strong cement-aggregate bonding is seen in concretes with silica fume containing limestone aggregates, whereas the gravel concretes show microcracks and a weaker bonding.

Cropped Steel Fiber Reinforced Chemically Bonded Ceramic (CBC) Composites

1987 ◽  
Vol 114 ◽  
Author(s):  
Sean Wise ◽  
Kevan Jones ◽  
Claudio Herzfeld ◽  
David D. Double
Keyword(s):  
Silica Fume ◽  
Steel Fiber ◽  
High Strength ◽  
Cement Matrix ◽  
Metal Fiber ◽  
Morphological Form ◽  
The Matrix ◽  
Compressive And Flexural Strengths ◽  
Equivalent Properties ◽  
Very High

ABSTRACTVery high strength castable chemically bonded ceramic (CBC) materials have been prepared which consist of finely chopped steel fibers and steel aggregate in a silica modified portland cement matrix. This paper examines the effect of metal fiber addition on compressive and flexural strengths. The overall chemistry of the matrix is held constant but the morphological form of silica used and the cure conditions are altered to examine their effect. Compressive strengths in excess of 500 MPa and flexural strengths in excess of 80 MPa can be obtained.It is found that flexural strength increases proportionally with fiber content over the range of 0 to 10% by volume. Compressive strengths are not affected. Use of silica fume in the mixes produces higher strengths at low temperatures than mixes which contain only crystalline silica. High temperature curing/drying (400°C), which produces the highest strengths, produces equivalent properties for formulations with and without silica fume. Higher water/cement ratios are found to reduce compressive strengths but have relatively little effect on the flexural properties.

scholarly journals Strength Characteristics of High Strength Concrete (HSC) with and without Coarse Aggregate

2019 ◽  
Vol 9 (2) ◽  
pp. 4701-4704
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Flexural Strength ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Mechanical Characteristics ◽  
Coarse Aggregate ◽  
High Strength ◽  
Set Up

This paper aimed to investigate the mechanical characteristics of HSC of M60 concrete adding 25% of fly ash to cement and sand and percentage variations of silica fumes 0%,5% and 10% to cement with varying sizes of 10mm,6mm,2mm and powder of granite aggregate with w/c of 0.32. Specimens are tested for compressive strength using 10cm X 10cmX10cm cubes for 7,14,28 days flexural strength was determined by using 10cmX10cmX50cm beam specimens at 28 days and 15cm diameter and 30cm height cylinder specimens at 28 days using super plasticizers of conplast 430 as a water reducing agent. In this paper the experimental set up is made to study the mechanical properties of HSC with and without coarse aggregate with varying sizes as 10mm, 6mm, 2mm and powder. Similarly, the effect of silica fume on HSC by varying its percentages as 0%, 5% and 10% in the mix studied. For all mixes 25% extra fly ash has been added for cement and sand.

scholarly journals Properties of Reactive Powder Concrete Using Local Materials and Various Curing Conditions

2019 ◽  
Vol 4 (6) ◽  
pp. 74-83 ◽  
Author(s):  
Gamal I. K. ◽  
K. M. Elsayed ◽  
Mohamed Hussein Makhlouf ◽  
M. Alaa
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Strength Concrete ◽  
Steel Fiber ◽  
High Strength ◽  
Hot Water ◽  
Reactive Powder Concrete ◽  
Normal Water ◽  
Reactive Powder ◽  
Local Materials

Reactive Powder Concrete RPC is comprise of (cement, quartz powder, sand, and superplasticizer) mixture with low water/cement ratio. It has not coarse aggregates and characterized by highly dense matrix, high strength concrete, excellent durability, and economic. This study aims to investigate fresh and hardened properties of locally cast RPC with several available economical materials such as silica fume (SF), fly ash (FA), steel fiber (STF), and glass fiber (GF). Experimental investigation were performed to study the effectiveness of partial replacement of cement by SF or FA to reach ultra-high strength concrete, effect of additional materials STF or GF in order to improve the fracture properties of the RPC mixes, and influence of the treated with normal water as well as with hot water. Fifteen different RPC mixes were cast with 20, 25, 30, and 35% cement replacement by SF, 25% cement replacement by FA, and another proportions taken combination between SF and FA with percentages 15, 20, 25% FA and constant 10% SF. Varying fiber types (steel fiber or glass fiber) added to concrete by different percentages 1, 2, and 3%. Specimens were treated with normal water 25ᵒC and hot water at 60ᵒC and 90ᵒC by 2 mixes with silica fume content 25% of binder and steel fiber content 2% by total volume. Performance of the various mixes is tested by the slump flow, compressive strength, flexure strength, splitting tensile strength, and density. The production of RPC using local materials is successfully get compressive strength of 121 MPa at the age of 28 days at standard conditions and normal water curing 25°C with Silica fume content 25% of binder and steel fiber content 2% by total volume of RPC and water/binder ratio of 0.25.  The results also showed the effect of curing by hot water 60 and 90°C, it is observed that compressive strength increases proportionally with curing temperatures and a compressive strength of 149.1 MPa at 90°C for 1days was obtained.

L'utilisation des bétons à très haute résistance au Canada

1989 ◽  
Vol 16 (5) ◽  
pp. 661-668
Author(s):  
Pierre Laplante ◽  
Pierre-Claude Aïtcin
Keyword(s):  
Compressive Strength ◽  
North America ◽  
High Strength Concrete ◽  
High Strength ◽  
Cement Ratio ◽  
Strength Concrete ◽  
Chicago Area ◽  
New Type ◽  
Ready Mixed Concrete ◽  
Very High

In the late sixties, several concrete producers in the Chicago area developed very high strength concrete. The compressive strength of this new type of concrete was increased gradually, and it is now possible to buy 100 MPa ready-mixed concrete in several places in North America. Of significant technological importance, very high strength concrete is becoming popular all over North America due to its profitability. As to why and how very high strength concrete is made, the readily available answers to the first question contrast with the predominately empirical approach that has characterized research into producing very high strength concrete up to now. In fact, there are no miracle mixes that will universally guarantee the availability of 100 MPa ready-to-use concretes. Nonetheless, some guidelines have been established that should be followed in order to avoid various pitfalls. In Canada, very high strength concrete is beginning to be used in the Toronto and Montreal areas. This paper summarizes the principal results obtained on two specific projects: the construction of an experimental column in Montreal in 1984, and the construction of Nova Scotia Plaza in Toronto in 1986. Key words: high-strength concrete, water/cement ratio, superplasticizer, silica fume, slag.

Analysis of Post-Combustion High-Strength Concrete Compressive Strength Using Polypropylene Fibers

2020 ◽  
Vol 26 (1) ◽  
pp. 118-127
Author(s):  
Teuku Budi Aulia ◽  
Muttaqin Muttaqin ◽  
Mochammad Afifuddin ◽  
Zahra Amalia
Keyword(s):  
Compressive Strength ◽  
Thermal Stress ◽  
Silica Fume ◽  
High Temperatures ◽  
High Strength Concrete ◽  
High Strength ◽  
Polypropylene Fibers ◽  
Concrete Compressive Strength ◽  
Strength Concrete ◽  
Maximum Value

High-strength concrete is vulnerable to high temperatures due to its high density. The use of polypropylene fibers could prevent structure explosion by forming canals due to melted fibers during fire, thus release its thermal stress. This study aims to determine the effect of polypropylene fibers on compressive strength of high-strength concrete after combustion at 400ºC for five hours. High-strength concrete was made by w/c-ratio 0.3 with cement amount 550 kg/m3 and added with silica fume 8% and superplasticizer 4% by cement weight. The variations of polypropylene fibers were 0%, 0.2% and 0.4% of concrete volume. The compression test was carried out on standard cylinders Ø15/30 cm of combustion and without combustion specimens at 7 and 28 days. The results showed that compressive strength of high-strength concretes without using polypropylene fibers decreased in post-combustion compared with specimens without combustion, i.e., 0.81% at 7 days and 23.42% at 28 days. Conversely, the use of polypropylene fibers can increase post-combustion compressive strength with a maximum value resulted in adding 0.2% which are 25.52% and 10.44% at 7 and 28 days respectively. It can be concluded that the use of polypropylene fibers is effective to prevent reduction of high-strength concrete compressive strength that are burned at high temperatures.

Dosage of Silica Fume in High Performance Concrete

2016 ◽  
Vol 677 ◽  
pp. 98-102 ◽  
Author(s):  
Michal Ženíšek ◽  
Tomáš Vlach ◽  
Lenka Laiblová
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
High Performance ◽  
High Performance Concrete ◽  
Rheological Behaviour ◽  
High Strength ◽  
Economic Benefits ◽  
Effective Dosage ◽  
Material Structure ◽  
Economic Point

Durability and high strength of concrete are closely associated with low porosity and generally denser material structure. This is achieved using the addition, which include also silica fume. This article deal with an effective dosage of silica fume in high performance concrete, in a proportion of 0-25 % by the weight of cement. Compressive strength, rheological behaviour and economic benefits were the main questions in this work. The expected increase in compressive strength showed itself in lower doses of silica fume, while higher doses did not produce a further increase in strength. In the case of rheological behaviour, we can confirm lower bleeding and segregation, but also faster drying of the surface layer. From the economic point of view, a small doses of silica fume are better, because then we have observed the highest increase in strength.

scholarly journals Effect of Silica fume on Ordinary Portland Cement and Polymer Concrete Made out of M Sand

2019 ◽  
Vol 9 (2S2) ◽  
pp. 42-46
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Silica Fume ◽  
Unsaturated Polyester ◽  
High Strength ◽  
Pozzolanic Reaction ◽  
Maximum Strength ◽  
Polymer Concrete ◽  
Split Tensile Strength ◽  
Conventional Concrete

In this investigation, conventional concrete was made with replacing the sand by 80 % of M-sand and the cement by fillet material silica fume in varying percentages say 5%, 10 % , and 15%, to study the compressive strength, split tensile strength and flexural strength. In order to the maximum strength was attained at 10% of silica fume. The result showed that by increasing the silica fume content, the strength of the M-sand concrete was decreased because higher fineness of silica fume content decreases the strength of the M-sand concrete. Secondly polymer concrete with unsaturated polyester resin with hardener MEKP, Cobalt as the accelerator and silica fume in varying percentages say 0%, 5% and 10% was made to study the compressive strength and split tensile strength of polymer concrete. In improved silica fume content the strength was high. Polymer concrete improved the mechanical properties. Polymer concrete system was mainly useful to fill the micro voids. In this research, the maximum strength was attained at 5% of silica fume filler added with polymer concrete. Thus the high strength of the concrete was obtained due to the pozzolanic reaction with the silica fume.

Sign in / Sign up

Export Citation Format

Share Document