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Effects of citric acid on setting times of building gypsum. Fig. 1 (a) and (b) show that all eight kinds of retarders play different degree on setting times for building …
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Slows the set time of gypsum and gypsum-containing materials; It is a high-strength retarder that is effective at low dosages; Purified material with no offensive odors; Dose-response is linear, making the determination of effective dosage easy; Can be used in cement-gypsum blends; Effective over wide range of pH; Efficacy does not diminish ...
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as a function of time. Two European standards deal with setting time: EN-196-3 and EN 480-2. EN 196-3 is used to determine the setting time of cement paste of standard consistency. Semi-adiabatic calorimetry (SAC) can be a suitable method for determining the setting time of cementitious materials and concretes of non-standard consistency.
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fewer nuclei will be per unit volume; consequently, the setting time will be prolonged. B. Mixing time and rate: the longer and the more rapidly the gypsum is mixed, the shorter is the setting time. As mixing begins, more particles will be exposed to water and thus form more crystals at the same time
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The test procedure for the determination of setting time involves the following series of steps: I. Initial Setting Time Test ~ About 400 grams of the cement is taken and a well-mixed cement paste is prepared.
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While the conventional reference gypsum set in normal times, ... Determination of water-to-gypsum ratio: ASTM C230/NTC 111 [7,8] Purity: Chemical analysis ... Compressive strength: Compressive strength: ASTM C472/NA : Setting time: Setting time: ASTM C472/NTC 490 : Density : Density : ASTM C188/NTC 221 [13,14] …
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The initial setting time of the cement tested by the Vicat apparatus in this paper was 282 min or 4 h and 42 min (4.70 h). The final setting time was 450 min or 7 h and 30 min (7.5 h). Download: Download high-res image (376KB) Download: Download full-size image; Fig. 9. Vicat apparatus testing: (a) initial setting and (b) final setting.
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Initial setting time: Initial setting time can be defined as the time when the cement paste starts losing its plasticity. ... Standard test method for the determination of the initial and final setting time of the hydraulic cement is measured by Vicat needle apparatus. ... The existing specifications correspond to that of construction gypsum ...
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The calcination process of gypsum binder was carried out at four different temperatures ranging from 170 to 190 °C. The specimens for testing were prepared on the basis of the obtained raw material with a …
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Fig. 2 Setting of gypsum obtained with various water-to-gypsum ratios (w/g = 0.6–0.74). Weight fraction of HEMC is equal to 0.5%. t s example of setting time measurements, t i induction time of setting 40 30 20 10 0 15 20 25 30 35 40 Height of the needle imersion/mm Time/min HEMC content[%] 0.25 0.5 0.75 1 1.5 without admixtures
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Regulation of crystal growth by polymers can widely improve gypsum performances, among which, protein retarders can prolong the setting time of gypsum …
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Cement paste setting time is affected by a number of items including: cement fineness, water-cement ratio, chemical content (especially …
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The effect o f adding gypsum on setting time can be seen in Figure 3. SNI 15-7064-2004 requires that the initial s etting time for PCC is ≥ 90 minutes, and the final .
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The setting time with FGD gypsum showed about 1 h delay compared with natural gypsum and its effect on compressive strength depend on composition of the …
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Determination of start time of gypsum setting by cutting method ......................................................... 7. (procedure according to standard PN-EN 13279 …
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Equipment for automatic execution of test for determination of setting time and consistency of cement tests by Vicat method. ... Setting times in gypsum as per EN 13279-2. Setting times in additives for concretes, mortars and pastes, as per EN 480-2. And, practically, any other standard or testing procedure, by means of built-in editor of ...
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APLUS ® gypsum has an average initial setting time of 10 minutes and 39 seconds, with a final setting time of 15 minutes and 97 seconds. This shows that the construction gypsum (APLUS ®) setting time meets ADA #25 standard specifications …
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The setting process of gypsum plasters has been followed using strength testing, acoustic techniques and scanning electron microscopy. Gypsum plasters were found to set in three stages: formation of the calcium sulphate dihydrate crystal matrix followed by relief of internal stress, and finally evaporation of excess water. The α …
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Keywords : Gypsum, Setting time, Portland Composite Cement. ... It was found further that the method with diantipyrylmethane was superior for the determination of titanium in these samples to the ...
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Gypsum quantitative determination in cements may be done from their thermogravimetric analysis (TG) data, which uses the mass of the water released from its gypsum dehydration during cement analysis, to determinate its content stoichiometrically. ... which act as retardants to control the setting time during cement hydration . The …
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The results reveal that control gypsum with 4% of gypsum has the highest strength as compared to 0% of gypsum and 8% of gypsum. The setting time of cement paste are discussed with respect to their influence on the strength of mortar. ... Methods of testing cement – Part 3: Determination of setting times and soundness, Department of …
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Determination of setting time. The setting time for phosphorous construction gypsum was ascertained in accordance with the operational requirements for setting time testing, as outlined in the national standard "Determination of Physical Properties of Building Gypsum Paste" (GB/T17669.4–1999). Initially, a layer of mineral …
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Initial setting time is the time when the paste starts losing its plasticity. The test is important for transportation, placing and compaction of cement concrete. Initial setting time duration is also required to delay the …
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TS-3a T 131-3 AASHTO 6.3. Glass Graduates, 200- or 250-mL capacity, and conforming to the requirements of ASTM C 1005. 6.4. Plane non-adsorptive plate, 100 ± 5 mm square of similar planeness, corrosivity, and absorptivity to that of glass (see Annex A1.1, Figure A1.1, H). 6.5. Flat trowel, having a sharpened straight-edged steel blade 100 to 150 mm …
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1.1 These test methods determine the time of setting of hydraulic cement by means of the Vicat needle. Two test methods are given; Test Method A is the Reference Test Method using the manually operated standard Vicat apparatus, while Test Method B permits the use of an automatic Vicat machine that has, in accordance with the …
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During initial setting time determination, the cement pastes' workable state ends and the hardening of the paste starts, with penetration depth at 6 ± 2 mm, according to the standard. The final setting time is recorded when the paste is fully hardened and the measured depth is 39.5 mm from the bottom of the mould (corresponding to a 0.5 mm ...
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The hardening of the conglomerates' materials is characterized by the change in the state of the paste, from a fluid state -after mixing- to its solid-state. At present, the well-known Vicat Needle Method is used to determine the hardening times, following the UNE-EN 13279-2 and UNE-EN 196-3 standards, depending on whether they are gypsum, plaster or …
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