UNIVERSITY OF AZAD JAMMU AND KASHMIR MUZAFFARABAD

The Institute of GeologyDELETERIOUS MATERIAL

Prepared by :

Zeeshan Afzal Roll No 66

Submitted To:Prof. Sohail Mustafa

Introduction:

Deleterious Materialclay lumps, shale, soft,or laminated particles, vegetable matter, or other objectionable material Or The harmful material in any construction is called Deleterious material.

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

Main reactions of deleterious material: Alkali aggregates reaction Alkali silica reaction Alkali carbonates reaction

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

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

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;

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

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.

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

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.

formaldehyde

a colourless pungent gas in solution made by oxidizing methanol

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.

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:

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.

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.

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

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