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;