Deleterious Material
clay lumps, shale, soft,or laminated particles, vegetable matter, or other objectionable material
Or
The harmful material in any construction is called Deleterious material.
Main reactions of deleterious material:
Alkali aggregates reaction
Alkali silica reaction
Alkali carbonates reaction
Alkali–aggregate reaction is a term mainly referring to a reaction which occurs over time in concrete between the highly alkaline cement paste and non-crystalline silicon dioxide, which is found in many common aggregates
The alkali–silica reaction (ASR), more commonly known as "concrete cancer", is a reaction which occurs over time in concrete between the highly alkaline cement paste and the reactive non-crystalline (amorphous) silica found in many common aggregates, given sufficient moisture
Mechanism of concrete deterioration:
The mechanism of ASR causing the deterioration of concrete can be described in four steps as follows:
The alkaline solution attacks the siliceous aggregate, converting it to viscous alkali silicate gel.
Consumption of alkali by the reaction induces the dissolution of Ca2+ ions into the cement pore water.
The penetrated alkaline solution converts the remaining siliceous minerals into bulky alkali silicate gel. The resultant expansive pressure is stored in the aggregate.
The accumulated pressure cracks the aggregate and the surrounding cement paste when the pressure exceeds the tolerance of the aggregate
Alkali carbonate reaction:
The alkali–carbonate reaction is a process suspected for the degradation of concrete containing dolomite aggregate.
Alkali from the cement might react with the dolomite crystals present in the aggregate inducing the production of brucite, (MgOH)2, and calcite (CaCO3). This mechanism was tentatively proposed by Swenson and Gillott (1950) and may be written as follows:
CaMg(CO3)2 + 2 NaOH → CaCO3 + Na2CO3 + Mg(OH)2
Brucite (Mg(OH)2), could be responsible for the volumetric expansion after de-dolomitisation of the aggregate, due to absorption of water.
This section deals with potentially deleterious materials, including:
asbestos;
calcium silicate brickwork;
chlorides;
composite panels;
formaldehyde;
high alumina cement concrete;
2. Introduction:
Deleterious Material
clay lumps, shale, soft,or laminated particles, vegetable matter, or other
objectionable material
Or
The harmful material in any construction is called Deleterious material.
3. Deleterious Substances in Concrete
The substances that are harmful to concrete performance are:
a. Clay lumps and other friable particles
b. Materials that are finer than 75µm (No. 200 sieve)
c. coal
d. Soft particles
e. Lightweight chert
4. Main reactions of deleterious material:
Alkali aggregates reaction
Alkali silica reaction
Alkali carbonates reaction
5. alkali aggregate reactions (AAR)
Alkali–aggregate reaction is a term mainly referring to a reaction which
occurs over time in concrete between the highly alkaline cement paste and
non-crystalline silicon dioxide, which is found in many common aggregates
6. Alkali silica reaction:
The alkali–silica reaction (ASR), more commonly known as "concrete cancer",
is a reaction which occurs over time in concrete between the highly alkaline
cement paste and the reactive non-crystalline (amorphous) silica found in
many common aggregates, given sufficient moisture
7. Mechanism of concrete deterioration
The mechanism of ASR causing the deterioration of concrete can be described
in four steps as follows:
The alkaline solution attacks the siliceous aggregate, converting it to viscous
alkali silicate gel.
Consumption of alkali by the reaction induces the dissolution of Ca2+ ions into
the cement pore water.
The penetrated alkaline solution converts the remaining siliceous minerals
into bulky alkali silicate gel. The resultant expansive pressure is stored in the
aggregate.
The accumulated pressure cracks the aggregate and the surrounding cement
paste when the pressure exceeds the tolerance of the aggregate
8. Alkali carbonate reaction:
The alkali–carbonate reaction is a process suspected for the
degradation of concrete containing dolomite aggregate.
Alkali from the cement might react with the dolomite crystals
present in the aggregate inducing the production of brucite,
(MgOH)2, and calcite (CaCO3). This mechanism was tentatively
proposed by Swenson and Gillott (1950) and may be written as
follows:
CaMg(CO3)2 + 2 NaOH → CaCO3 + Na2CO3 + Mg(OH)2
Brucite (Mg(OH)2), could be responsible for the volumetric
expansion after de-dolomitisation of the aggregate, due to
absorption of water.
9.
10. This section deals with potentially
deleterious materials, including:
asbestos;
calcium silicate brickwork;
chlorides;
composite panels;
formaldehyde;
high alumina cement concrete;
11. Asbestos:
A highly heat-resistant fibrous silicate mineral that can be woven into fabrics,
and is used in brake linings and in fire-resistant and insulating materials
12. calcium silicate brickwork
Insulation brick based on Calcium Silicate is reacted Calcium Silicate
continuing reinforcing fibers (non-asbestos). It offers thermal efficiency of
flexible insulation like mineral wool and strength of conventional Insulation
Bricks.
Insulation pipe are ideal replacement for fibrous insulation and are un-
matched in places where insulation is exposed to water, floor traffic, impact
loads etc.
13.
14. chlorides
a compound of chlorine with another element or group, especially a salt of
the anion Cl
−
or an organic compound with chlorine bonded to an alkyl group.
The chloride ion is the anion (negatively charged ion) Cl
−
. It is formed when
the element chlorine (a halogen) gains an electron or when a compound such
as hydrogen chloride is dissolved in water or other polar
solvents. Chloride salts such as sodium chloride are often very soluble in
water.Chemical formula: Cl−
Molar mass: 35.45 g·mol−1
15. Composite panels
Composite panels are factory engineered panels used mainly for exterior
cladding, partitioning, load bearing walls and roofing elements in a wide
range of non-residential buildings.
17. High Alumina Cement
High Alumina Cement (HAC, sometimes known as calcium aluminate
cement(CAC) or aluminous cement) is composed of calcium aluminates,
unlike Portland cement which is composed of calcium silicates. It is
manufactured from limestone or chalk and bauxite.
18. most toxic building materials used in
residential construction today
PVC, lead and mercury would be top my list. Each of
these common building components have known health
and toxicity problems, and can become deadly under the
wrong conditions.
Pvc:
Lead:
Mercury:
19. PVC:
Polyvinyl Chloride has a tremendous upstream toxicity impact (chemical
manufacturing in “cancer alley”), releases phthalates during it’s use phase of
life, and releases dioxin when burned. Dioxin is one of the most toxic
substances known to exist. PVC and PVC-byproducts contain known
carcinogens, and developmental and reproductive toxicants.
20. LEAD:
We’re learning that lead exposure – at even lower rates than previously
known – has negative effects in the form of cancer, and developmental and
reproductive toxicity. Around the country you can still buy faucets and lead-
containing solder to be used for potable water. In fact, in the US, even “lead-
free” solder and flux is allowed to contain lead! So you have to specify “100%
lead-free” if you’re serious about eliminating lead.
21. MERCURY:
There is still mercury in some electronics and thermostats, but the most
significant source in the residential sector is in lighting. Since the massive
rollout of Compact Fluorescent Lights (CFLs), several states and the EPA have
published clean-up protocols for broken CFLs. Mercury is a known
developmental toxicant, and it’s suspected of many other health effects