scholarly journals Determination of Initial and Final Set of Ternary Mortars and Compressive Strength with Regard to Temperature Variation

2019 ◽  
Vol 8 (1) ◽  
pp. 8-12
Author(s):  
Alan Richardson ◽  
Susan Dawson ◽  
Giovanni Pesce
Keyword(s):  
Compressive Strength ◽  
Strength Development ◽  
Additional Time ◽  
Cement Replacement ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Ambient Room Temperature ◽  
Two Factors ◽  
The Difference ◽  
Time Required

The research examined herein classifies initial and final set times, for samples of ternary mortars composed of CEM 1 (52.5) and Ground Granulated Blast Furnace Slag (GGBS). The samples  tested comprised of different CEM 1 and GGBS proportions. The mixes used, ranged from 100% CEM1 where this component was replaced at 10% increments by mass terminating at a 20% CEM1 content.  With a reduction in cement content, the balance of the total required binder was being made up with GGBS. The ternary mortar cubes were tested for initial and final set times at average ambient room temperature (19.7 – 22.2 °C) and temperatures of 5 and 40 degrees Celsius. The findings highlighted the additional time required for initial and final set times at reduced temperatures and it also highlighted the further additional time for initial and final set times when GGBS is used as a cement replacement in progressively increasing quantities. Initial and final set times at 40 degrees Celsius were faster than ambient and 5 degrees Celsius, however the difference between initial and final set times was much reduced at 40 degrees Celsius. Both temperature and cement replacement affected the compressive strength at a curing period of 28 days, however GGBS is known to take longer than CEM1 to achieve a given strength development of say 90% of the final or ultimate strength. The two factors of temperature and cement replacement have a significant impact on setting times.

Effect of Ground Granulated Blast Furnace Slag on Compressive Strength of POFA Blended Concrete

2015 ◽  
Vol 802 ◽  
pp. 142-148
Author(s):  
M.N. Noor Azline ◽  
Farah Nora Aznieta Abd Aziz ◽  
Arafa Suleiman Juma
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Strength Development ◽  
Replacement Level ◽  
Concrete Compressive Strength ◽  
Cement Replacement ◽  
Granulated Blast Furnace Slag ◽  
Strength Tests ◽  
Furnace Slag

The article reports a laboratory experimental programme that investigated effect of ground granulated blast furnace (GGBS) on compressive strength of POFA ternary concrete. Compressive strength tests were performed at a range of cements combinations, including 100%PC, two POFA levels for binary concrete, 35% and 45%, and 15%GGBS inclusion for POFA ternary concrete. The compressive strength results were examined in comparison to PC only and equivalent POFA binary concretes for up to 28 days. Results show that the reduction in compressive strength is greater with the higher cement replacement level for all concretes particularly for POFA binary concretes. However, 15%GGBS in POFA blended concrete has a comparable compressive strength compared to PC concrete at both, 35% and 45%, cement replacement levels except for ternary concrete at 0.65 w/c. In addition, the compressive strength of ternary concrete is slightly higher compared to binary concrete for all concrete combinations. Although there is no significant noticeable influence on strength development, the presence of GGBS did not adverse the strength development of POFA blended concrete. Thus, it can be concluded that GGBS compensates the adverse effect of POFA at early strength development.

scholarly journals Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

2021 ◽  
Author(s):  
Jean Noël Yankwa Djobo ◽  
Dietmar Stephan
Keyword(s):  
Blast Furnace ◽  
Boric Acid ◽  
Blast Furnace Slag ◽  
Volcanic Ash ◽  
Strength Development ◽  
Main Process ◽  
Reaction Products ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

AbstractThis work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

A Chronometric Study of Some Relations between Sentences

1964 ◽  
Vol 16 (4) ◽  
pp. 297-308 ◽  
Author(s):  
George A. Miller ◽  
Kathryn Ojemann McKean
Keyword(s):  
Detailed Data ◽  
Paper Test ◽  
Additional Time ◽  
Verb Constructions ◽  
Additive Relation ◽  
The Difference ◽  
Pencil And Paper ◽  
Time Required ◽  
Syntactic Relations ◽  
Negative Difference

An attempt was made to study how people handle syntactic relations among English sentences by measuring the time required to convert one type of sentence into another. Preliminary results based on rate of work in a pencil-and-paper test are briefly summarized. More detailed data are given for an experiment in which subjects controlled the duration of presentation of the sentence they transformed. Presentation times were measured and compared with the presentation times when no transformation was required; the difference between these times was taken as a measure of the additional time required to perform the transformation. In such tasks, an active-passive difference requires more additional time than does an affirmative-negative difference; when both are involved the additional time required is approximately the sum for the two separately. Differences in verb constructions, however, all require about the same amount of time, and no additive relation is apparent. The relation of these results to the distinction between rules of formation and rules of transformation in descriptive linguistics is discussed.

scholarly journals Acoustic Properties of Lightweight Foamed Concrete with Eggshell Waste as Partial Cement Replacement Material

2021 ◽  
Vol 50 (2) ◽  
pp. 537-547
Author(s):  
Siong Kang Lim ◽  
Kar Poh Foo ◽  
Foo Wei Lee ◽  
Hock Yong Tiong ◽  
Yee Ling Lee ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Industrial Revolution ◽  
Acoustic Properties ◽  
Sound Insulation ◽  
Strength Development ◽  
Cement Replacement ◽  
Foamed Concrete ◽  
Partial Cement Replacement ◽  
Strength Result ◽  
Eggshell Waste

Nowadays, almost every industry needs to undergo green and sustainable industrial revolution due to pollutions like waste dumping and noise that deteriorating the environment. Therefore, feasibility study on application of eggshell waste as partial cement replacement in lightweight foamed concrete was conducted by aiming to solve environmental and acoustical issues, i.e. reduce eggshell waste and improve acoustic properties. In this study, compressive strength and acoustic properties of 1300 kg m-3 lightweight foamed concrete with and without 5% eggshell powder as partial cement replacement material were tested. Optimal water to cement ratio of 0.6 was obtained for acoustic properties test by comparing compressive strength result. The result shows that application eggshell powder has generally reduced 7 days compressive strength but improved 28 days compressive strength, and either improve or maintain acoustics properties, in which lightweight foamed concrete that containing eggshell powder has improved noise reduction coefficient at testing ages of 7, 28, and 90 days and improved sound transmission class at testing age of 56 and 90 days. Based on these results, 5% of eggshell powder is feasible to be incorporated into lightweight foamed concrete as partial cement replacement material for sound insulation and strength development purposes.

scholarly journals Evaluation of Strength Development in Concrete with Ground Granulated Blast Furnace Slag Using Apparent Activation Energy

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 442 ◽  
Author(s):  
Hyun-Min Yang ◽  
Seung-Jun Kwon ◽  
Nosang Vincent Myung ◽  
Jitendra Kumar Singh ◽  
Han-Seung Lee ◽  
...  
Keyword(s):  
Activation Energy ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Apparent Activation Energy ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
Strength Development ◽  
Replacement Ratio ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Ground granulated blast furnace slag (GGBFS) conventionally has been incorporated with ordinary Portland cement (OPC) owing to reduce the environmental load and enhance the engineering performance. Concrete with GGBFS shows different strength development of normal concrete, but sensitive, to exterior condition. Thus, a precise strength evaluation technique based on a quantitative model like full maturity model is required. Many studies have been performed on strength development of the concrete using equivalent age which is based on the apparent activation energy. In this process, it considers the effect of time and temperature simultaneously. However, the previous models on the apparent activation energy of concrete with mineral admixtures have limitation, and they have not considered the effect of temperature on strength development. In this paper, the apparent activation energy with GGBFS replacement ratio was calculated through several experiments and used to predict the compressive strength of GGBFS concrete. Concrete and mortar specimens with 0.6 water/binder ratio, and 0 to 60% GGBFS replacement were prepared. The apparent activation energy (Ea) was experimentally derived considering three different curing temperatures. Thermodynamic reactivity of GGBFS mixed concrete at different curing temperature was applied to evaluate the compressive strength model, and the experimental results were in good agreement with the model. The results show that when GGBFS replacement ratio was increased, there was a delay in compressive strength.

scholarly journals Influence of Silica Modulus and Curing Temperature on the Strength of Alkali-Activated Volcanic Ash and Limestone Powder Mortar

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5204
Author(s):  
Adeshina Adewale Adewumi ◽  
Mohd Azreen Mohd Ariffin ◽  
Mohammed Maslehuddin ◽  
Moruf Olalekan Yusuf ◽  
Mohammad Ismail ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Low Temperatures ◽  
Room Temperature ◽  
Volcanic Ash ◽  
Curing Temperature ◽  
Limestone Powder ◽  
Strength Development ◽  
Mass Ratio ◽  
Ambient Room Temperature ◽  
Alkali Activated

This present study evaluates the effect of silica modulus (Ms) and curing temperature on strengths and the microstructures of binary blended alkali-activated volcanic ash and limestone powder mortar. Mortar samples were prepared using mass ratio of combined Na2SiO3(aq)/10 M NaOH(aq) of 0.5 to 1.5 at an interval of 0.25, corresponding to Ms of 0.52, 0.72, 0.89, 1.05 and 1.18, respectively, and sole 10 M NaOH(aq). Samples were then subjected to ambient room temperature, and the oven-cured temperature was maintained from 45 to 90 °C at an interval of 15 °C for 24 h. The maximum achievable 28-day strength was 27 MPa at Ms value of 0.89 cured at 75 °C. Samples synthesised with the sole 10 M NaOH(aq) activator resulted in a binder with a low 28-day compressive strength (15 MPa) compared to combined usage of Na2SiO3(aq)/10 M NaOH(aq) activators. Results further revealed that curing at low temperatures (25 °C to 45 °C) does not favour strength development, whereas higher curing temperature positively enhanced strength development. More than 70% of the 28-day compressive strength could be achieved within 12 h of curing with the usage of combined Na2SiO3(aq)/10 M NaOH(aq). XRD, FTIR and SEM + EDX characterisations revealed that activation with combined Na2SiO3(aq)/10 M NaOH(aq) leads to the formation of anorthite (CaAl2Si2O8), gehlenite (CaO.Al2O3.SiO2) and albite (NaAlSi3O8) that improve the amorphosity, homogeneity and microstructural density of the binder compared to that of samples synthesised with sole 10 M NaOH(aq).

scholarly journals Effect of Changing Cement Grade on the Properties of Structural Concrete

2020 ◽  
Vol 17 (3) ◽  
pp. 197-204
Author(s):  
C.A. Fapohunda ◽  
B.I. Famodimu ◽  
B.C. Adigo ◽  
A.S. Jeje
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Structural Member ◽  
Design Stage ◽  
Strength Development ◽  
Dead Load ◽  
Design Load ◽  
Setting Times ◽  
Portland Limestone Cement ◽  
Limestone Cement

Many research efforts have been carried out, in a quest to produce mix design information that will guide the concrete and construction industry on how to achieve different concrete strengths, using the different grades of cement available. This is with a view to arresting the rampant collapse of buildings in Nigeria. The work presented in this paper is the result of investigation carried out to determine effects of changing cement grade, while casting a structural member, on the strength behaviour of the concrete. Two types of cement grades: 32.5 R and 42. 5 R were used for this research. In this investigation, the chemical and physical properties of the cement were determined. Consistency and setting times of mortar specimens from the two cement grades were also determined. Concrete samples made from the two cement grades 32.5 R and 42.5 R were evaluated for workability, density, compressive and tensile strengths at water/cement ratios of 0.40, 0.50 and 0.60. The results showed that the cement grade 42.5 consistently developed higher densities at all the water/cement ratios considered. This may be as a result of unforeseen additional dead load at the design stage, which would now amount to underestimation of dead load and thus design load. The results also showed that at higher water/cement ratios, the cement grade 42.5 R has densities exceeding the 2400 kg/m3 recommended by BS 8110. Furthermore, the concretes produced with cement grades of 32.5 R and 42.5 R have different strength development pattern and developed different 28-day compressive strength. Thus, it can be concluded that the action of changing the cement grade during concreting, for the same structural member is not supported by the national code, and will not result in safe and durable concrete. Keywords: Cement grades, Compressive strength, Density, Portland limestone cement, Tensile strength, Workability

THE USE OF QUARRY DUST FOR PARTIAL REPLACEMENT OF CEMENT IN CEMENT-SAND MORTAR

2021 ◽  
Vol 4 (4) ◽  
pp. 432-437
Author(s):  
Muhammad Magana Aliyu ◽  
Muhammad Musa Nuruddeen ◽  
Yahaya Atika Nura
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Cement Paste ◽  
Dust Content ◽  
Experimental Results ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Cement Replacement ◽  
Setting Times ◽  
Quarry Dust

This research was carried out to investigate the effect of partially replacing cement with quarry dust in cement-sand mortar. Tests including setting times, water absorption, compressive strength and density test were carried out on mortar with cement partially replaced with 0%, 5%, 10%, 15%, 20%, 25% and 30% quarry dust and presented. Experimental results show that replacement of quarry dust as partial replacement of cement in cement-sand mortar decrease the initial and final setting times of cement paste and increase the water absorption of the mortar. The partial replacement shows an improvement of compressive strength at 5% quarry dust content after which there is a decrease with increase in quarry dust content at all the ages. The increase in compressive strength at 5% indicates possible pozzalanic activity at that level. Thus quarry dust can be utilized as cement replacement material at 5% dust content. Above this it can be utilized as fine aggregate replacement for use in low-strength mortar applications

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