Study of the influence of water reducing and setting retarder admixtures of polycarboxylate “s uperplasticizers ” on physical and mechanical properties of mortar and concrete

Production of bio‐based concrete water reducers from renewable resources: a review

“…36 Studies have thus shown that the mechanism of dispersion of these bio-based water reducers have potential impact on the final properties of concrete such as the setting time. 37 They are known to either retard or accelerate the setting time of concrete due to their effect on the rate of hydration product formation during concrete preparation. 38…”

“…Water reducing admixtures are known either to retard or accelerate the setting time of concrete. 37 Retarding water reducers increase the concrete setting time by reducing the rate of hydration of the cement while the accelerating-type water reducers have the opposite effect. To change the concrete retarding or accelerating properties of a given water reducer, some chemical materials can be dosed into the mix.…”

“…On the other hand, natural carbohydrate water reducers like cellulose, starch or their derivatives can disperse cement particles via the electrosteric effect because of their high molecular weights from repeating glucose units and the presence of charged ‐OH and carboxyl functional groups within their structures 36 . Studies have thus shown that the mechanism of dispersion of these bio‐based water reducers have potential impact on the final properties of concrete such as the setting time 37 . They are known to either retard or accelerate the setting time of concrete due to their effect on the rate of hydration product formation during concrete preparation 38 …”

“…The initial setting time is the time when the cement starts to lose its plasticity and the final setting time is the time when the cement completely loses its plasticity. Water reducing admixtures are known either to retard or accelerate the setting time of concrete 37 . Retarding water reducers increase the concrete setting time by reducing the rate of hydration of the cement while the accelerating‐type water reducers have the opposite effect.…”

Investigation of the Effect of Volumetric Hydrophobization on the Kinetics of Mass Transfer Processes Occurring in Cement Concretes during Corrosion

“…Hydrophobic additives introduced into concrete usually act on the basis of one or a combination of three mechanisms: reduction of capillarity by reducing the water–cement ratio, hydrophobization of capillaries, and physical or chemical blocking of pores. Reactive silicates [ 13 , 14 ], calcined clays [ 15 , 16 ], colloidal silicon dioxide [ 17 , 18 ], lignosulfonates [ 19 ], naphthalene sulfonate formaldehyde [ 20 , 21 , 22 ], sulfated melamine formaldehyde [ 22 , 23 ], and polycarboxylate ether [ 24 , 25 , 26 ] are used to reduce the capillarity of concrete. Hydrophobization of capillaries is achieved by introducing into concrete soap [ 27 ], bitumen [ 28 ], mineral oils [ 29 , 30 ], fatty acids [ 31 ], calcium and zinc stearates [ 32 , 33 , 34 , 35 ], butyl stearate [ 36 , 37 ], acrylic resins [ 38 , 39 ], thin wax emulsions [ 40 , 41 ], silicones [ 42 , 43 ], silane-siloxanes [ 44 , 45 ].…”