Test Methods for Working, Initial Setting, and Service Strength Setting Times of Chemical-Resistant Resin Mortars

This study investigated the hardening process of alkali-activated material (AAM) mortar using calcium sulfoalumiante (CSA) expansive additive (CSA EA), which accelerates the initial reactivity of AAMs, and subsequent changes in ultrasonic pulse velocity (UPV). After the AAM mortar was mixed with three different contents of CSA EA, the setting and modulus of elasticity of the mortar at one day of age, which represent curing steps, were measured. In addition, UPV was used to analyze each curing step. The initial and final setting times of the AAM mortar could be predicted by analyzing the UPV results measured for 14 h. In addition, the dynamic modulus of elasticity calculated using the UPV results for 24 h showed a tendency similar to that of the static modulus of elasticity. The test results showed that the use of CSA EA accelerated the setting of the AAM mortar and increased the modulus of elasticity, and these results could be inferred using UPV. The proposed measurement method can be effective in evaluating the properties of a material that accelerates the initial reactivity.

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Influence of Colloidal Silica on Final Properties of no Cement Castables

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.321.125 ◽

2021 ◽

Vol 321 ◽

pp. 125-130

Author(s):

David Zemánek ◽

Lenka Nevřivová

Keyword(s):

Particle Size ◽

Compressive Strength ◽

Bulk Density ◽

Colloidal Silica ◽

Sol Gel ◽

Setting Times ◽

Sol Gel Process ◽

Initial Setting ◽

Basic Parameters ◽

Silica Sols

This paper deals with sol-gel process and application in no cement castables based on andalusite. The use of calcium free binder increases the refractory parameters of material and allows its faster drying. Six colloidal sols from CWK Bad Köstritz based on SiO2 were tested, which differed not only in concentration and particle size, but also in pH. The influence of silica sols on the consistency of fresh castable, initial setting and final setting times were investigated. Furthermore, basic parameters after firing, such as bulk density, apparent porosity, flexural and compressive strength, were tested.

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Micro-Silica for High-End Application from Carbon Capture and Storage by Mineralisation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.517.737 ◽

2012 ◽

Vol 517 ◽

pp. 737-744 ◽

Cited By ~ 9

Author(s):

Aimaro Sanna ◽

Marco Dri ◽

Xiao Long Wang ◽

Matthew R. Hall ◽

Mercedes Maroto-Valer

Keyword(s):

Compressive Strength ◽

Carbon Capture ◽

Carbon Capture And Storage ◽

Magnesium Content ◽

Partial Replacement ◽

Setting Times ◽

Initial Setting ◽

Pozzolanic Properties ◽

Micro Silica ◽

And Storage

Waste silica remaining after the Carbon Capture and Storage by Mineral carbonation (CCSM) could represent a potential pozzolan material for partial replacement in concrete. The objective of this work was the production and testing of cement gel cubes with the residual-silica by-product obtained from the accelerated carbonation of Mg-silicate rocks. The silica produced was characterised in terms of its chemical composition, morphology and LOI. Also, the silica was used as an additive to the cement (CEM I class) in order to assess the effect on (28 days) compressive strength in comparison with a cement control specimen. The influence of different cement replacement percentages (5% and 10wt.% silica) were determined by measuring initial setting times and compressive strength. The compressive strength of the cement specimens with 5 and 10wt.% silica as pozzolan replacement of Portland cement were 3% and 8% higher than the control cubes indicating that the residual silica powder may have pozzolanic properties. However, high LOI and magnesium content might represent a limit in high-end applications and further work is required to identify optimised CCSM conditions able to reduce the impurities in the silica by-product and to establish their potential as a pozzolan.

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The Linear Setting Expansions of the Dental Stone and Whose Initial Setting Times

Dentistry ◽

10.4172/2161-1122.1000308 ◽

2015 ◽

Vol 05 (06) ◽

Author(s):

Saip Denizoglu Nuran Yanikoglu

Keyword(s):

Setting Times ◽

Initial Setting ◽

Linear Setting

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Investigation on the Compressive Strength and Time of Setting of Low-Calcium Fly Ash Geopolymer Paste Using Response Surface Methodology

Polymers ◽

10.3390/polym13203461 ◽

2021 ◽

Vol 13 (20) ◽

pp. 3461

Author(s):

Pauline Rose J. Quiatchon ◽

Ithan Jessemar Rebato Dollente ◽

Anabel Balderama Abulencia ◽

Roneh Glenn De Guzman Libre ◽

Ma. Beatrice Diño Villoria ◽

...

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Unconfined Compressive Strength ◽

Setting Time ◽

Initial Setting Time ◽

Alkali Activator ◽

Setting Times ◽

Confirmatory Tests ◽

Initial Setting

Approximately 2.78 Mt of coal fly ash is produced in the Philippines, with a low utilization rate. Using fly ash-based geopolymer for construction will lessen the load sent to landfills and will result in lower GHG emissions compared to OPC. It is necessary to characterize the fly ash and optimize the geopolymer components to determine if it can replace OPC for in situ applications. The activator-to-precursor ratio, the water-to-solids ratio, and the sodium hydroxide-to-sodium silicate ratio were optimized using a randomized I-optimal design from the experimental results of 21 runs with five replicates, for a total of 105 specimens of 50 mm × 50 mm × 50 mm paste cubes. The engineering properties chosen as the optimization responses were the unconfined compressive strength (UCS), the initial setting time, and the final setting time. The samples were also ambient-cured with the outdoor temperature ranging from 30 °C to 35 °C and relative humidity of 50% ± 10% to simulate the on-site environment. Runs with high unconfined compressive strength (UCS) and short setting times were observed to have a low water-to-solids (W/S) ratio. All runs with a UCS greater than 20 MPa had a W/S ratio of 0.2, and the runs with the lowest UCS had a W/S of 0.4. The initial setting time for design mixes with a W/S ratio of 0.2 ranged from 8 to 105 min. Meanwhile, five out of seven design mixes with a W/S ratio of 0.4 took longer than 1440 min to set. Specimens with an alkali activator ratio (NaOH/WG) of 0.5 (1:2) and 0.4 (1:2.5) also had significantly lower setting times than those with an alkali activator ratio of 1. The RSM model was verified through confirmatory tests. The results of the confirmatory tests are agreeable, with deviations from the expected UCS ranging from 0 to 38.12%. The generated model is a reliable reference to estimate the UCS and setting time of low-calcium FA geopolymer paste for in situ applications.

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