Description : (3) preventing rapid setting of cement Explanation: Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates, the remainder consisting of ... mixed with water by way of a complex series of chemical reactions still only partly understood.
Last Answer : Milk is a colloidal system in which: (1) Water is dispersed in fat (2) Fat is dispersed in water (3) Fat and water are dispersed in each other (4) Fat is dissolved
Description : The setting and hardening of cement after addition of water is due to a) Binding action of water b) Evaporation of water c) Hydration and hydrolysis of some constituent compounds of cement* d) Additional hardening compounds added to cement
Last Answer : c) Hydration and hydrolysis of some constituent compounds of cement*
Description : Main constituents of Portland cement are calcium aluminate and (A) Gypsum (B) Silicates (C) Sodium silicate (D) Carbonates
Last Answer : (B) Silicates
Description : Cement setting under water employs a/an __________ process. (A) Hydration (B) Decomposition (C) Oxidation (D) Reduction
Last Answer : (A) Hydration
Description : Tricalcium aluminate (C3A) (A) Reacts fast with water (B) Generates less heat of hydration (C) Causes initial setting and early strength of cement (D) Does not contribute to develop ultimate strength
Last Answer : Answer: Option B
Description : Pick up the incorrect statement from the following: (A) The degree of grinding of cement, is called fineness (B) The process of changing cement paste into hard mass, is known as setting of ... (D) The heat generated during chemical reaction of cement with water, is known as heat of hydration
Last Answer : Answer: Option C
Description : The deleterious materials present in the aggregate (a) Prevent normal hydration of cement (b) Reduce the strength and durability of concrete. (c) Modify the setting action and cause efloresecence. (d) All of the above
Last Answer : (d) All of the above
Description : Di-calcium silicate (C2S) (A) Hydrates rapidly (B) Generates less heat of hydration (C) Hardens rapidly (D) Provides less ultimate strength to cement
Description : Initial setting of cement is caused due to (A) Tri-calcium silicate (B) Di-calcium silicate (C) Tri-calcium aluminate (D) Tetra calcium alumino ferrite
Description : Ceramics are produced from silicates or clayish materials: Which of the following is not a ceramic material? (A) Slag cement (B) Glasses (C) Porcelain/Potteries (D) Teflon
Last Answer : (D) Teflon
Description : Kidney stones are mainly formed by which of the following compound - (1) Sodium chloride (2) Silicates (3) Calcium bicarbonate (4) Calcium oxalate
Last Answer : (4) Calcium oxalate Explanation: Kidney stones form when your urine contains more crystal-forming substances — such as calcium, oxalate and uric acid — than the fluid in your urine can dilute.
Description : Asbestos (A) Is a natural fibrous mineral substance (B) Is composed of hydrous silicates of calcium and magnesium (CaSiO3, 3MgSiO3) (C) Contains iron oxide and alumina (D) All the above
Last Answer : Answer: Option D
Description : Hydration of cement is due to chemical action of water with (A) Tricalcium silicate and dicalcium silicate (B) Dicalcium silicate and tricalcium aluminate (C) Tricalcium aluminate and tricalcium alumino ferrite (D) All the above
Description : Pick up the correct statement from the following: (A) The concrete gains strength due to hydration of cement (B) The concrete does not set at freezing point (C) The strength of concrete increases with its age (D) All the above
Description : Pick up the correct statement from the following: (A) Water cement paste hardens due to hydration (B) During hardening cement binds the aggregates together (C) Cement provides strength, durability and water tightness to the concrete (D) All the above
Description : Concrete gains strength due to (A) Chemical reaction of cement with sand and coarse aggregates (B) Evaporation of water from concrete (C) Hydration of cement (D) All the above
Description : Hydration of cement is due to the chemical action of water with. (a) Tricalcium silicate (b) Dicalcium silicate (c) Tricalcium aluminate (d) All of these
Last Answer : (d) All of these
Description : Concrete gains strength due to [ A ] Chemical reaction of cement with sand and coarse aggregates [ B ] Evaporation of water from concrete [ C ] Hydration of cement [ D ] All the above
Last Answer : [ C ] Hydration of cement
Description : Setting time of cement increases by adding (A) Gypsum (B) Hydrogen peroxide (C) Calcium chloride (D) Sodium oxide
Last Answer : Answer: Option A
Description : The main constituent of cement which is responsible for initial setting of cement is (A) Di-calcium silicate (B) Tri-calcium silicate (C) Tri-calcium aluminate (D) All of the above
Description : To retard the initial setting time of cement, the compound responsible, is (A) Tri-calcium silicate (B) Gypsum (C) Di-calcium silicate (D) Tri-calcium aluminate
Description : Setting time of cement increases by adding (i)gypsum (ii)sodium oxide (iii)calcium chloride [ A ] i [ B ] i and ii [ C ] i and iii [ D ] i, ii and iii
Last Answer : [ A ] i
Description : Setting of plaster of paris involves – (1) dehydration process (2) hydration to form other hydrates (3) oxidation process (4) reduction process
Last Answer : (2) hydration to form other hydrates Explanation: The setting of plaster of Paris takes place by hydration due to the formation of a solid crystalline hydrate and hardening of Plaster of Paris is ... . A slight expansion takes place in the process and heat is evolved. This process is exothermic.
Description : Setting of plaster of Paris is accompanied with (A) Hydration (B) Dehydration (C) Hydrolysis (D) Loss of CO2
Description : The process of conversion of plastic concrete to solid stage is called [ A ] Hydration [ B ] Hardening [ C ] Setting [ D ] Curing
Last Answer : [ C ] Setting
Description : Setting of plaster of paris involves (1) dehydration process (2) hydration to form other hydrates (3) oxidation process (4) reduction process
Last Answer : hydration to form other hydrates
Description : Differentiate between retarding and accelerating admixtures with following points. i) Hydration process ii) Setting time iii) Weather condition iv) Use
Last Answer : The accelerating and retarding admixtures can be compared as follows. Accelerating Admixture Retarding Admixture Hydration process Due to accelerating admixture, hydration process completes ... where slow hardening of concrete is necessary i.e. in mass concrete structures.
Description : What is the first stage of hydration in cement?
Last Answer : Need answer
Description : When each particle of aggregates is thinly coated with cement paste, a heterogeneous solid is formed, which is known as (A) Hydration (B) Gel (C) Concrete (D) None of these
Description : The condition not applicable to water cement ratio law, is (A) Internal moisture conditions on hydration continue till complete strength is gained (B) Concrete specimens may be tested at any temperature (C) Concrete specimens need be of same age (D) Concrete specimens need be of same size
Description : Addition of pozzolana to cement (A) Decreases workability (B) Increases strength (C) Increases heat of hydration (D) None of these
Description : Addition of pozzolana to cement causes (A) Reduction in permeability (B) Loss of heat of hydration (C) Reduction in bleeding (D) All the above
Description : Portland pozzolana cement possesses (A) Higher resistance to chemical attack (B) Lower heat of hydration (C) Lower shrinkage on drying (D) All the above
Description : Addition of pozzolana to ordinary Portland cement increases (A) Bleeding (B) Shrinkage (C) Permeability (D) Heat of hydration
Description : The presence of dicalcium silicate in cement. (a) Hydrates the cement slowly. (b) Generates less heat of hydration. (c) Has more resistance to sulphate attack. (d) All of these
Description : The presence of tricalcium silicate in cement (a) Hydrates the cement rapidly (b) Generates less heat of hydration. (c) Offer high resistance to sulphate attack (d) All of these
Last Answer : (a) Hydrates the cement rapidly
Description : The heat of hydration for low heat cement at the age of 7 days shall not exceed [ A ] 80 cal / gm [ B ] 75 cal / gm [ C ] 70 cal / gm [ D ] 65 cal / gm
Last Answer : [ D ] 65 cal / gm
Description : During the process of hardening of cement, _______ will takes place [ A ] Bleeding [ B ] Segregation [ C ] Hydration [ D ] All the above
Last Answer : [ C ] Hydration
Description : Cement is made hard with (1) dehydration (2) hydration and dissociation of water (3) Dissociation of water (4) Polymerisation
Last Answer : hydration and dissociation of water
Description : Write the significance of water-cement ratio and its effect on hydration of cement.
Last Answer : Significance of water-cement ratio: The W/C ratio plays very vital role in concrete mixture. The improper or random selection of W/C ratio leads in various defects in fresh and hardened concrete ... of water for sufficient hydration. But such large water may not give proper binding of aggregates.
Description : Define hydration of cement
Last Answer : Hydration of cement: It is exothermic chemical reaction takes place when water is added to cement, which gives rise cement paste and large amount heat is evolved. About 120 cal/gm, heat is evolved. This is called as hydration of cement.
Description : The development of first 28 days strength is on account of the hydration of (a) Tricalcium silicate (b) Dicalcium silicate (c) Tricalcium aluminate (d) Tetra calcium alumina ferrite
Last Answer : (a) Tricalcium silicate
Description : Early attainment of strength in rapid hardening cement is mainly due to (A) Gypsum (B) Finer grinding (C) Tri-calcium silicate (D) Tri-calcium aluminate
Description : Mixture of aluminates and silicates of cal- cium is?
Last Answer : Cement
Description : Glass is made of the mixture of-------? A. Quartz and Mica B. Sand and Salt C. Sand and Silicates (Answer) D. None of these
Last Answer : C. Sand and Silicates (Answer)
Description : What igneous rock contains mostly plagioclase feldspar and about 30 percent dark silicates?
Last Answer : A Diorite.
Description : What are silicates made of?
Last Answer : Silica tetrahedra, made up of silicon and oxygen, form chains, sheets, and frameworks, and bond with other cations to form silicate minerals.
Description : What are soaps? (1) Salts of silicates (2) Ester of heavy fatty acids (3) Sodium or potassium salts of heavier fatty acids (4) Mixture of glycerol and alcohol
Last Answer : (3) Sodium or potassium salts of heavier fatty acids
Description : The heavier silicates named ‘Sima’ or silica + magnesium are most abundant in which layer?
Last Answer : Crust
Description : Agglomeration of individual particles into clusters (flocs) is called flocculation. To prevent flocculation, the most commonly used dispersing agents are (A) Carbonates (B) Sulphates (C) Silicates & phosphates (D) Bi-carbonates
Last Answer : (C) Silicates & phosphates