Effets des cendres volantes sur le développement des résistances mécaniques des bétons préfabriqués

1996 ◽  
Vol 23 (4) ◽  
pp. 940-949
Author(s):  
Y. Maltais ◽  
J. Marchand ◽  
R. Gagné ◽  
A. Tagnit-Hamou
Keyword(s):  
Compressive Strength ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Initial Increase ◽  
Thermal Curing ◽  
Portland Cement Concrete ◽  
Concrete Compressive Strength ◽  
Fly Ashes ◽  
Steam Curing ◽  
Curing Regime

The results of an investigation of the influence of fly ashes on the development of mechanical properties of concretes subjected to 24-h thermal curing are presented in this paper. In addition to the curing temperature (23 and 60 °C), the variables studied in this investigation were the type of cement (types 10 and 30) and the source of fly ashes (four different North-American class F fly ashes). Overall, 10 different concrete mixtures were tested. Test results indicate that thermal curing tends to increase significantly the concrete compressive strength in the first 24 h. Data also demonstrate that the thermal curing regime does not have any detrimental effect on the long-term compressive strength of ordinary portland cement concrete. Compressive strength of fly ash concretes was significantly reduced by thermal curing in the 1- to 28-day period, despite an initial increase. The influence of thermal curing on the development of concrete compressive strength is discussed. Key words: compressive strength, steam curing, fly ashes, precast concrete.

scholarly journals Comparative Study Involving Effect of Curing Regime on Elastic Modulus of Geopolymer Concrete

Buildings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 101 ◽  
Author(s):  
Peiman Azarsa ◽  
Rishi Gupta
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Resonant Frequency ◽  
Construction Material ◽  
Bottom Ash ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Steam Curing ◽  
Curing Regime

Geopolymer Concrete (GPC) as a cement-less construction material has attracted worldwide attention due to its lower carbon footprint. There are numerous studies reported on GPC made using different by-products including fly-ash. However, since the use of bottom-ash is comparatively limited, making potassium-based GPC using this waste can be an alternative to Portland Cement Concrete (PCC). In this study, two methods of accelerated curing were used to determine the influence of elevated temperature on the compressive strength of GPC, composed of 50% bottom-ash and 50% fly-ash. GPC specimens were cured using various temperatures including ambient, 30 °C, 45 °C, 60 °C, and 80 °C for 24 h, all followed by 28 days of ambient curing. The highest compressive strength was obtained with steam curing at a temperature of 80 °C for a duration of 24 h. It is of great significance to evaluate elastic modulus of the concrete mixture so that the short-term rigidity of structures subjected to elongation, bending, or compression can be predicted. In this study, a longitudinal Resonant Frequency Test (RFT) as a non-destructive test (NDT) was used to calculate the elastic modulus of both GPC and a comparative PCC mix. Based on the results, PCC had higher resonant frequency (by about 1000 Hz) compared to GPC. A review of empirical models for predicting GPC’s elastic modulus showed that all of the predicted elastic modulus values were lower than experimental values.

Variasi Penambahan Sika Cim Dan Fiber Kawat Pada Beton Mutu Fc’ 30 Mpa

2018 ◽  
Vol 9 (2) ◽  
pp. 67-73
Author(s):  
M Zainul Arifin
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Curing Temperature ◽  
Test Results ◽  
Concrete Compressive Strength ◽  
Normal Concrete ◽  
Astm Method ◽  
Additive Type ◽  
Composition Variation ◽  
Compressive Strength Of Concrete

This research was conducted to determine the value of the highest compressive strength from the ratio of normal concrete to normal concrete plus additive types of Sika Cim with a composition variation of 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1 , 50% and 1.75% of the weight of cement besides that in this study also aims to find the highest tensile strength from the ratio of normal concrete to normal concrete in the mixture of sika cim composition at the highest compressive strength above and after that added fiber wire with a size diameter of 1 mm in length 100 mm with a ratio of 1% of material weight. The concrete mix plan was calculated using the ASTM method, the matrial composition of the normal concrete mixture as follows, 314 kg / m3 cement, 789 kg / m3 sand, 1125 kg / m3 gravel and 189 liters / m3 of water at 10 cm slump, then normal concrete added variations of the composition of sika cim 0.25%, 0.50%, 0.75%, 1.00%, 1.25%, 1.5%, 1.75% by weight of cement and fiber, the tests carried out were compressive strength of concrete and tensile strength of concrete, normal maintenance is soaked in fresh water for 28 days at 30oC. From the test results it was found that the normal concrete compressive strength at the age of 28 days was fc1 30 Mpa, the variation in the addition of the sika cim additive type mineral was achieved in composition 0.75% of the cement weight of fc1 40.2 Mpa 30C. Besides that the tensile strength test results were 28 days old with the addition of 1% fiber wire mineral to the weight of the material at a curing temperature of 30oC of 7.5%.

scholarly journals Machine Learning Approaches for Prediction of the Compressive Strength of Alkali Activated Termite Mound Soil

2021 ◽  
Vol 11 (11) ◽  
pp. 4754
Author(s):  
Assia Aboubakar Mahamat ◽  
Moussa Mahamat Boukar ◽  
Nurudeen Mahmud Ibrahim ◽  
Tido Tiwa Stanislas ◽  
Numfor Linda Bih ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Construction Materials ◽  
Curing Temperature ◽  
Sustainable Construction ◽  
Support Vector ◽  
Learning Approaches ◽  
Artificial Neural Network Ann ◽  
Curing Regime ◽  
Alkali Activated

Earth-based materials have shown promise in the development of ecofriendly and sustainable construction materials. However, their unconventional usage in the construction field makes the estimation of their properties difficult and inaccurate. Often, the determination of their properties is conducted based on a conventional materials procedure. Hence, there is inaccuracy in understanding the properties of the unconventional materials. To obtain more accurate properties, a support vector machine (SVM), artificial neural network (ANN) and linear regression (LR) were used to predict the compressive strength of the alkali-activated termite soil. In this study, factors such as activator concentration, Si/Al, initial curing temperature, water absorption, weight and curing regime were used as input parameters due to their significant effect in the compressive strength. The experimental results depict that SVM outperforms ANN and LR in terms of R2 score and root mean square error (RMSE).

Effect of Type of Cement and Expansive Agent on the Hardening of Steam-Cured Concrete

2017 ◽  
Vol 744 ◽  
pp. 105-113 ◽  
Author(s):  
Takayoshi Maruyama ◽  
Hideaki Karasawa ◽  
Shigeyuki Date
Keyword(s):  
Early Stage ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Steam Curing ◽  
Slag Powder ◽  
Expansive Agent ◽  
Cast Concrete ◽  
Increase Productivity ◽  
Early Strength ◽  
Furnace Slag

Pre-cast concrete products are sometimes manufactured in two cycles daily. It is ensured that they have the required strength at an early stage of demolding by increasing the steam curing temperature to reduce cost or increase productivity. However, the reduction in durability because of cracking due to thermal stress is a topic of concern. On the other hand, it has been known that fine blast-furnace-slag powder and expansive agents show high temperature dependence. Although they are used even in precast concrete products, the effect of steam curing on these materials is not known. Thus, in this study, the expression of compressive strength and expansion that are critical in improving the quality and productivity of precast concrete products was investigated, using high early-strength cement and two types of expansive agents, namely, ettringite-based and lime-based agents. Consequently, the strength expression was accelerated by the addition of expansive agent to ordinary cement and high early-strength cement. The extent of restrained expansion is greater for the lime-based expansive agent than for the ettringite-based expansive agent, and when an expansive agent is added to high early-strength cement, the extent of restrained expansion falls to a level lower than that in the case of ordinary cement.

scholarly journals Application of the High Early Strength Type Expansive Agent to the Blast Furnace Slag Combination Concrete with GGBFS under Steam Curing

2019 ◽  
Vol 278 ◽  
pp. 01005
Author(s):  
Erica Enzaki ◽  
Takashi Sakuma ◽  
Eizou Takeshita ◽  
Shigeyuki Date
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Early Stage ◽  
Precast Concrete ◽  
Curing Temperature ◽  
Strength Development ◽  
Steam Curing ◽  
Expansive Agent ◽  
Early Strength ◽  
Furnace Slag

In recent years, the use of blast furnace slag material is being focused as environmental loading reduction and sustainable construction. However, in general, autogeneours shrinkage of the concrete using much amount of GGBFS is large in compared to normal concrete, therefore risk of cracking should be cared. On the other hand, strength development speed of concrete at early stage will be decreasing as the dosage of GGBFS increases, even under steam curing condition. It can be considered these points will be significant disadvantage in both productivity and quality of precast concrete. So in this study, early strength type expansive agent and setting accelerator were used in combination. As a result, it was confirmed that compressive strength at early stage is obviously increased. And steam curing temperature can be reduced about 10 degrees, and also, 600×10-6 of restraint expansion was obtained.

scholarly journals Effect of NaOH concentration and curing regime on geopolymer

2017 ◽  
Vol 10 (6) ◽  
pp. 1174-1181 ◽  
Author(s):  
C. N. LIVI ◽  
W. L. REPETTE
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Curing Temperature ◽  
Lower Amount ◽  
Alkali Concentration ◽  
X Ray Diffraction ◽  
Highest Weight ◽  
Thermogravimetric Data ◽  
Naoh Solution ◽  
Curing Regime

Abstract The effect of alkali concentration and curing temperature regime on fly ash-based geopolymer pastes was investigated in this study by using NaOH solutions. Prismatic specimens were molded, cured at 65 °C and 85 °C and submitted to flexural and compressive strength tests. Unreacted fly ash and geopolymers were characterized by X-ray diffraction and thermogravimetric analysis. In general, the mechanical strength was enhanced by increasing the molar concentration and the curing temperature. This trend was confirmed by thermogravimetric data. However, for a lower amount of NaOH there were no significant differences between the strength results. The mixture with the highest strength was obtained with the 16 M NaOH solution and curing temperature of 85 °C, which resulted in flexural strength of 4.20 MPa, compressive strength of 21.35 MPa and also the highest weight loss of 9.89%.

Effect of Gypsum on Strength Development of Steam-Cured Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1085-1088
Author(s):  
Zhi Min He ◽  
Xiao Ju Shen ◽  
Jun Zhe Liu
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Strength Development ◽  
Early Age ◽  
Strength Gain ◽  
Fly Ashes ◽  
Steam Curing ◽  
Gain Rate ◽  
Early Strength ◽  
Chemical Activator

The use of fly ashes for cement-replacement purposes, especially in high volumes, decreases rate of early strength development of the steam curing concrete. To resolve it, this paper developed a new steam-cured concrete incorporating fly ash and a chemical activator (gypsum). Experiments were conducted to investigate the mechanical properties at early and later ages of steam and standard curing concretes. The corresponding mechanism was also discussed by testing the microstructure of concretes. Results indicate that the demoulding compressive strength of steam curing concrete with 4% gypsum dosage can meet production requirements, and compressive strength of this concrete at later ages increase well. Compared with that of ordinary pure cement steam-cured concrete, concrete with 4% gypsum has a higher compressive strength gain rate. At an early age, addition of the gypsum can distinctly accelerate the extent of hydration of the steam curing fly ash cement systems, and thus the microstructure of concrete becomes denser. However, in standard curing condtion, the effect of gypsum is not distinct.

Flood Mud as Geopolymer Precursor Materials: Effect of Curing Regime on Compressive Strength

2015 ◽  
Vol 815 ◽  
pp. 177-181 ◽  
Author(s):  
Mohd Mustafa Al Bakri Abdullah ◽  
Mukridz Md Mohtar ◽  
Liew Yun Ming ◽  
Muhammad Faheem Mohd Tahir ◽  
Kamarudin Husin ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Strength Properties ◽  
Sem Analysis ◽  
Raw Material ◽  
Curing Temperature ◽  
Strength Tests ◽  
Maximum Compressive Strength ◽  
Curing Regime

This paper studies the effect of curing temperature and curing duration to the flood mud based geopolymer on compressive strength properties. Flood mud was used as a raw material for geopolymer and geopolymer samples were synthesized by using sodium silicate and sodium hydroxide 14M solution. These samples were cured at different temperature (100°C, 150°C, 200°C and 250°) for different curing duration (6h, 12h and 24h) respectively. Compressive strength tests were carried out at after 28 days. The compressive strength and SEM analysis of geopolymer products were evaluated. Result showed that the maximum compressive strength was 24 MPa at temperature of 150°C for 24 hours. With increasing ageing day, densification of geopolymer gel was observed.

Influences of Limestone Aggregates on Concrete Strength in Pipe Piles Production

2014 ◽  
Vol 584-586 ◽  
pp. 1370-1374
Author(s):  
Yuan Hai Jiang
Keyword(s):  
Compressive Strength ◽  
Coarse Aggregate ◽  
Concrete Strength ◽  
Normal Pressure ◽  
Concrete Compressive Strength ◽  
Steam Curing ◽  
Coarse Aggregates ◽  
Siliceous Rocks ◽  
Pressure Steam ◽  
Autoclave Curing

Taking the limestone and siliceous rocks as coarse aggregates to mix concrete,through normal pressure steam curing and autoclave curing,the concrete compressive strength after demould and compressive strength after autoclave curing are tested.The results indicate that the concrete compressive strength increases obviously after normal pressure steam curing when taking the limestone and granite as coarse aggregates,and the strength increasing laws are basically in accordance.However,the concrete compressive strength is great different after autoclave curing when taking the limestone and granite as coarse aggregates,the concrete strength increases lower with limestone as coarse aggregate,but the concrete strength increases higher with siliceous rocks as coarse aggregate.

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