{"id":88311,"date":"2025-06-01T07:07:38","date_gmt":"2025-06-01T07:07:38","guid":{"rendered":"https:\/\/exam.pscnotes.com\/mcq\/?p=88311"},"modified":"2025-06-01T07:07:38","modified_gmt":"2025-06-01T07:07:38","slug":"the-setting-time-of-cement-is-lowered-by-adding","status":"publish","type":"post","link":"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/","title":{"rendered":"The setting time of cement is lowered by adding"},"content":{"rendered":"

The setting time of cement is lowered by adding<\/p>\n

[amp_mcq option1=”oxides of aluminium” option2=”gypsum” option3=”oxides of magnesium” option4=”silica” correct=”option1″]<\/p>\n

\n
\n
This question was previously asked in<\/div>\n
UPSC NDA-2 – 2016<\/div>\n<\/div>\n
Download PDF<\/a>Attempt Online<\/a><\/div>\n<\/div>\n
\nThe correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide).
\n<\/section>\n
\n– Setting time refers to the time required for cement paste to lose its plasticity.
\n– Additives are used to control setting time: accelerators decrease setting time, retarders increase it.
\n– Gypsum is a common retarder, preventing flash set by reacting with C\u2083A.
\n– Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. Certain forms of reactive alumina can act as accelerators.
\n<\/section>\n
\n– Calcium chloride (CaCl\u2082) is a very common and effective accelerator used in cement.
\n– Oxides of magnesium (MgO), if present in excess in portland cement, can cause delayed expansion and soundness issues, not primarily affecting initial setting time in a controlled manner.
\n– Silica (SiO\u2082) is a main component of cement (silicates C\u2083S and C\u2082S), which are responsible for strength development, but adding pure silica is not a method to control setting time.
\n– The phrasing “lowered by adding” implies acceleration. While gypsum is a crucial additive related to setting time, its effect is the opposite (increasing\/retarding). This points towards A as the intended answer, assuming a context where an aluminium oxide based additive is used for acceleration.
\n<\/section>\n","protected":false},"excerpt":{"rendered":"

The setting time of cement is lowered by adding [amp_mcq option1=”oxides of aluminium” option2=”gypsum” option3=”oxides of magnesium” option4=”silica” correct=”option1″] This question was previously asked in UPSC NDA-2 – 2016 Download PDFAttempt Online The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means … <\/p>\n

Detailed SolutionThe setting time of cement is lowered by adding<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1094],"tags":[1098,1096,1239],"class_list":["post-88311","post","type-post","status-publish","format-standard","hentry","category-upsc-nda-2","tag-1098","tag-chemistry","tag-inorganic-chemistry","no-featured-image-padding"],"yoast_head":"\nThe setting time of cement is lowered by adding<\/title>\n<meta name=\"description\" content=\"The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide). - Setting time refers to the time required for cement paste to lose its plasticity. - Additives are used to control setting time: accelerators decrease setting time, retarders increase it. - Gypsum is a common retarder, preventing flash set by reacting with C\u2083A. - Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. Certain forms of reactive alumina can act as accelerators.\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"The setting time of cement is lowered by adding\" \/>\n<meta property=\"og:description\" content=\"The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide). - Setting time refers to the time required for cement paste to lose its plasticity. - Additives are used to control setting time: accelerators decrease setting time, retarders increase it. - Gypsum is a common retarder, preventing flash set by reacting with C\u2083A. - Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. Certain forms of reactive alumina can act as accelerators.\" \/>\n<meta property=\"og:url\" content=\"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/\" \/>\n<meta property=\"og:site_name\" content=\"MCQ and Quiz for Exams\" \/>\n<meta property=\"article:published_time\" content=\"2025-06-01T07:07:38+00:00\" \/>\n<meta name=\"author\" content=\"rawan239\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"rawan239\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"The setting time of cement is lowered by adding","description":"The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide). - Setting time refers to the time required for cement paste to lose its plasticity. - Additives are used to control setting time: accelerators decrease setting time, retarders increase it. - Gypsum is a common retarder, preventing flash set by reacting with C\u2083A. - Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. Certain forms of reactive alumina can act as accelerators.","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/","og_locale":"en_US","og_type":"article","og_title":"The setting time of cement is lowered by adding","og_description":"The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide). - Setting time refers to the time required for cement paste to lose its plasticity. - Additives are used to control setting time: accelerators decrease setting time, retarders increase it. - Gypsum is a common retarder, preventing flash set by reacting with C\u2083A. - Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. Certain forms of reactive alumina can act as accelerators.","og_url":"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/","og_site_name":"MCQ and Quiz for Exams","article_published_time":"2025-06-01T07:07:38+00:00","author":"rawan239","twitter_card":"summary_large_image","twitter_misc":{"Written by":"rawan239","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"WebPage","@id":"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/","url":"https:\/\/exam.pscnotes.com\/mcq\/the-setting-time-of-cement-is-lowered-by-adding\/","name":"The setting time of cement is lowered by adding","isPartOf":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#website"},"datePublished":"2025-06-01T07:07:38+00:00","dateModified":"2025-06-01T07:07:38+00:00","author":{"@id":"https:\/\/exam.pscnotes.com\/mcq\/#\/schema\/person\/5807dafeb27d2ec82344d6cbd6c3d209"},"description":"The correct answer is A) oxides of aluminium. The question asks what is added to lower the setting time of cement, which means making it set faster. Gypsum (option B) is added to *increase* the setting time (retard setting). While standard accelerators are typically calcium chloride or alkali aluminates, reactive forms of aluminium oxides or phases rich in alumina like Calcium Aluminate Cements (CAC) or specific additives containing activated alumina can act as accelerators, causing rapid setting. Therefore, among the given options, oxides of aluminium (in a suitable form or context as present in cement phases like C\u2083A) are the most plausible candidates for contributing to or accelerating the setting process compared to the other options which are either retarders (gypsum) or primary components\/cause of expansion (magnesium oxide). - Setting time refers to the time required for cement paste to lose its plasticity. - Additives are used to control setting time: accelerators decrease setting time, retarders increase it. - Gypsum is a common retarder, preventing flash set by reacting with C\u2083A. - Oxides of aluminium are present in cement clinker primarily as tricalcium aluminate (C\u2083A), which hydrates rapidly and contributes to early setting. 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