This document discusses the use of micro silica in concrete. Micro silica is a very fine mineral admixture that is spherical and less than 1 micron in diameter. When added to concrete at around 30kg/m3, it improves the concrete's strength, durability, and impermeability. The document outlines how preliminary and experimental investigations were conducted to study micro silica's effects as a partial cement replacement. Micro silica works by reducing calcium hydroxide through a pozzolanic reaction and filling pores as a micro filler to enhance properties. Applications include high strength, waterproof, heat resistant, sulfate resistant, corrosion resistant, and abrasion resistant concrete. The conclusions indicate that a 10% micro silica replacement

1. Advance Construction Material –
Micro Silica In Concrete

2. 1.0 Introduction
1.1 General
• Micro silica is a mineral admixture
composes of very fine solid glassy
spheres of silicon dioxide (SiO2).
• Most micro silica particles are less
than 1 micron (0.00004 inch) in
diameter,
• generally 50 to 100 times finer than
average cement or fly ash particles.
• Added to concrete at around
30kg/m3 it improve concrete
strengths, durability and
impermeability.
Fig.1 Micro silica is 100 x finer
than cement and the particles
are spherical

3. 2.0 Methodology
The methodology adopted comprised of both preliminary and
experimental investigations carried out using the study material and these are
presented as follows:
• Preliminary Investigations
• For the preliminary investigations, micro silica and cement was
subjected to physical and chemical analyses to determine
whether they are in compliance with the standard used.
• experimental investigations
• The experimental program was designed to investigate silica
fume as partial cement replacement in concrete.
• The replacement levels of cement by silica fume are selected as
5%, 10%, 15%, 20%, and 25% for standard size of cubes for the
M30 grade of concrete.

4. Figure 2. Micro Silica in a sample Pan.
3.0 Concrete color effects
• Micro silica is essentially
non crystalline.
• Freshly mixed concrete
containing micro silica can
be almost black, dark gray,
or depending on the
dosage of micro silica and
its carbon content.
• The more carbon and
iron in the admixture, the
darker the resulting
concrete.

5. 4.0 How Micro silica Works in Concrete ?
Micro silica in concrete contributes to strength and durability two ways:
4.1 Pozzolanic effect:
• When water is added to
OPC(Ordinary Portland cement) ,
hydration occurs forming two
products, as shown below:
• OPC+ H2O CSH (Calcium
silicate hydrate) + Ca(OH)2
• In the presence of micro silica, the
silicon dioxide from the micro silica
will react with the calcium hydroxide
to produce more aggregate binding
CSH as follows:-
• Ca(OH)2 + SiO2 + H20 CSH
• The reaction reduces the amount of
calcium hydroxide in the concrete.
The weaker calcium hydroxide does
not contribute to strength.
4.2 Micro filler effect :
• This micro filler effect will greatly
reduced permeability and improves
the paste-to-aggregate bond of silica
fume concrete compared to
conventional concrete.
• The silica reacts rapidly providing
high early age strengths and
durability.
• The efficiency of micro silica is 3-5
times that of OPC and consequently
vastly improved concrete
performance can be obtained.
• a filler, micro silica decreases the
average size of pores in the cement
paste.

6. 5.0 How micro silica improves concrete
Figure 3.Flowchart of Micro silica (improving concrete)

7. 6.0 Micro silica Concrete Applications
• Because of the pozzolanic and micro filler effect of micro silica, its
use in concrete can improve many of its properties opening up a
wide range of applications including.
• 6.1 High Strength Concrete:
• 6.2 Silica Fume Waterproof Concrete
• 6.3 Heat Reduction
• 6.4 Sulphate Resistance
• 6.5 Corrosion Resistance
• 6.6 Abrasion Resistance
• 6.7 hemical Resistance:

8. 7.0 Conclusions
• Cement replacement up to 10% with silica fume
leads to increase in compressive strength.
• The maximum replacement level of silica fume is
10% for M30 grade of concrete.
• Due to use of the micro silica in a OPC concrete
the life of that concrete is increase 4-5 times than
the OPC concrete.
• The use of micro silica in high strength concrete
leads to economical and faster construction.

9. Presented by-Mukul panchal
(14/9/27)