Use of wet cellulose to cure shotcrete repairs on bridge soffits. Part 1: Field trial and observations

2006 ◽  
Vol 33 (7) ◽  
pp. 807-814 ◽  
Author(s):  
Medhat Shehata ◽  
Mike Navarra ◽  
Tom Klement ◽  
Mohamed Lachemi ◽  
Hannah Schell
Keyword(s):  
Relative Humidity ◽  
Field Trial ◽  
Cellulose Fibers ◽  
Heat Of Hydration ◽  
Polypropylene Fibers ◽  
Negative Effects ◽  
Surface Cracking ◽  
Curing Period ◽  
Curing Method ◽  
Curing Compound

This paper presents the results obtained from a research project that focused on investigating the feasibility of using cellulose fibers to cure bridge soffit repairs. The use of cellulose as a curing method involves spraying wet cellulose on the freshly applied shotcrete. By adhering to the shotcrete, the wet cellulose maintains the relative humidity within the shotcrete above the level required to sustain hydration of the cementing materials. Twelve 1000 mm × 1000 mm × 130 mm panels were prepared using two types of shotcrete materials and cured using either air curing, curing compound, misting and curing compound, or cellulose. The results showed that the cellulose could be applied to shotcrete in an overhead position and remained adhered to the shotcrete for 28 days. At the end of the curing period, the cellulose was easily removed from the shotcrete surface by means of a hand shovel. Cellulose-cured panels showed the least evidence of surface cracking. Also, the use of cellulose did not have any negative effects on the temperature of the shotcrete.Key words: bridge repair, shotcrete, silica fume, accelerator, polypropylene fibers, curing, cellulose, heat of hydration, adhesion.

scholarly journals Effects of Sources and Forms of Vitamin K3 on Its Storage Stability in Vitamin Premixes or Vitamin Trace Mineral Premixes

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1140
Author(s):  
Huakai Wang ◽  
Pan Yang ◽  
Longxian Li ◽  
Nan Zhang ◽  
Yongxi Ma ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Storage Time ◽  
Storage Stability ◽  
Choline Chloride ◽  
Crystal Form ◽  
Negative Effects ◽  
Trace Mineral ◽  
Vitamin K3 ◽  
Choline Group ◽  
Micro Sphere

Six types of vitamin K3 (VK3); two sources (menadione sodium bisulfite, MSB; menadione nicotinamide bisulfite, MNB), and three different forms (crystal, micro-capsule, and micro-sphere) were used to determine the retention of VK3 in vitamin premixes (Experiment 1) or vitamin trace mineral (VTM) premixes (Experiment 2) after 1, 2, 3, and 6 months of storage. The retention of VK3 in vitamin premixes was evaluated at 25 °C/60% relative humidity or 40 °C/75% relative humidity in an incubator in Experiment 1 and in VTM premixes (choline chloride: 0 vs. 16,000 mg/kg) stored at room temperature in Experiment 2. The VK3 retention in vitamin premix or VTM premix decreased significantly with the extension of storage time (p < 0.05). In Experiment 1, the VK3 retention was higher in the 25 °C/60% incubator (56%) than in the 40 °C/75% incubator (28%). The MNB retention (52%) was higher than MSB retention (32%). The retention of VK3 in micro-capsules (43%) or micro-spheres (48%) was higher than the crystal form (35%) after six months of storage. In Experiment 2, there was no difference between the retention of MSB (49%) or MNB (47%). The retention of VK3 of micro-capsule (51%) or micro-sphere (54%) was higher than that of crystal form (40%). The VK3 retention was higher in the choline-free group (51%) than in the choline group (47%) after six months of storage. Finally, the predicted equations of VK3 retention with storage time in vitamin premixes or VTM premixes were established. The R2 of the prediction equations was ≥0.9005, indicating that time is an important factor in predicting VK3 retention. In conclusion, the higher temperature-relative humidity, choline had negative effects on VK3 retention during premix storage. MNB retention was higher than MSB during storage of vitamin premix. The encapsulated forms of VK3, micro-capsules and micro-spheres, could improve VK3 storage stability in vitamin premix and VTM premix.

Influence of Sulphate on the Moisture Movement of Calcium Silicate Brick Masonry Wall

2010 ◽  
Vol 133-134 ◽  
pp. 201-204
Author(s):  
Ibrahim Mohamad H. Wan ◽  
B.H. Abu Bakar ◽  
M.A. Megat Johari ◽  
P.J. Ramadhansyah
Keyword(s):  
Relative Humidity ◽  
Calcium Silicate ◽  
Masonry Wall ◽  
Sodium Sulphate ◽  
Brick Masonry ◽  
Masonry Walls ◽  
Moisture Movement ◽  
Moisture Expansion ◽  
Curing Period ◽  
Wet Condition

This paper presents the behaviour of moisture movement of calcium silicate brick masonry walls exposed to sodium sulphate environment. The walls were exposed to three sodium sulphate conditions with sulphate concentrations of5%, 10% and 15%. For comparison, some walls were also exposed to dry and wet condition which acts as a control conditions. All specimens were prepared and cured under polythene sheet for 14 days in a controlled environmental room and maintained at relative humidity and temperature of 80 ± 5% and 25 ± 2°C, respectively. After the curing period, the specimens were exposed to sodium sulphate as well as drying and water exposures, during which moisture movement was measured and monitored for a period of up to 7 months. As a result, the moisture expansion was observed and recorded for all masonry wall specimens after exposed to the sulphate condition.

scholarly journals Systems of aerial spraying for soybean rust control

2011 ◽  
Vol 31 (4) ◽  
pp. 695-703 ◽  
Author(s):  
Ulisses R. Antuniassi ◽  
Edivaldo D. Velini ◽  
Rone B. de Oliveira ◽  
Maria A. Peres-Oliveira ◽  
Zulema N. Figueiredo
Keyword(s):  
Relative Humidity ◽  
Confidence Interval ◽  
Field Trial ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Aerial Application ◽  
Fungicide Application ◽  
Set Up ◽  
Cotton Oil ◽  
Electrostatic System

The soybean rust caused by Phakopsora pachyrhizi is considered the main soybean disease and consequently the appropriate selection and the use of spraying equipment are vital for its control. The aim of this study was to evaluate the performance of aerial application equipment for soybean rust control. It was used: Micronair AU 5000 at 10 L ha-1 (with oil) and at 20 L ha-1 (without oil); Stol ARD atomizer at 10 and 20 L ha-1 (both with oil) and Spectrum (electrostatic) at 10 L ha-1 (without oil). The adjuvant was cotton oil (1.0 L ha-1) with emulsifier (BR 455) at 0.025 L ha-1. The field trial was set up at the 3rd fungicide application, when f four replications of each treatment. There were no statistical differences among treatments related to fungicide deposits by at a Confidence Interval of 95%. It was observed that the best results were obtained with Micronair (10 L ha-1 with oil), Stol (20 L ha-1 with oil) and electrostatic system at 10 L ha-1 with the lowest relative humidity (64%).

scholarly journals Effect of TiO2Nanoliquid on the Properties of Cement Mortar

2018 ◽  
Vol 7 (3.12) ◽  
pp. 223
Author(s):  
C Prabalini ◽  
Z Aysha Farsana ◽  
A Sumathi
Keyword(s):  
Outer Surface ◽  
Cement Mortar ◽  
Heat Of Hydration ◽  
New Methods ◽  
Curing Period ◽  
Lime Water ◽  
To Come ◽  
Strength And Durability

Mortar/Concrete is effectively used in the construction of buildings. In the view of developing the infrastructure, it is essential to come up with new methods. Generally, the mortar which is being used has numerous pores in it and thus the strength gets reduced and the absorption increases. To reduce the durability problems nano liquid is being added. Nano liquid has the advantages of anti microbial and anti UV action. This paper deals with the nano liquid on the properties of cement mortar with two curing medium (water and saturated lime water) for 3, 7 and 28 days and the results were compared with control mortar in terms of strength and durability. Nano liquid was added in terms of 2.5ml, 5ml, and 7.5ml per kg of cement. After the completion of curing period the nano liquid is uniformly sprayed on the outer surface of the mortar cube. Since the nano liquid emits heat, the curing is made with lime to reduce the heat of hydration.  

scholarly journals Hydration and Microwave Curing Temperature Interactions of Repair Mortars

2021 ◽  
Vol 03 (04) ◽  
pp. 1-1
Author(s):  
Pal S. Mangat ◽  
◽  
Shahriar Abubakri ◽  
Konstantinos Grigoriadis ◽  
Vincenzo Starinieri ◽  
...  
Keyword(s):  
Portland Cement ◽  
Heat Of Hydration ◽  
Curing Temperature ◽  
Early Age ◽  
Normal Density ◽  
Concrete Repair ◽  
Microwave Curing ◽  
Polymer Addition ◽  
Curing Period ◽  
Repair Materials

Microwave curing of repair patches provides an energy efficient technique for rapid concrete repair. It has serious economic potential due to time and energy saving especially for repairs in cold weather which can cause work stoppages. However, the high temperatures resulting from the combination of microwave exposure and accelerated hydration of cementitious repair materials need to be investigated to prevent potential durability problems in concrete patch repairs. This paper investigates the time and magnitude of the peak hydration temperature during microwave curing (MC) of six cement based concrete repair materials and a CEM II mortar. Repair material specimens were microwave cured to a surface temperature of 40-45 °C while their internal and surface temperatures were monitored. Their internal temperature was further monitored up to 24 hours in order to determine the effect of microwave curing on the heat of hydration. The results show that a short period of early age microwave curing increases the hydration temperature and brings forward the peak heat of hydration time relative to the control specimens which are continuously exposed to ambient conditions (20 °C, 60% RH). The peak heat of hydration of normal density, rapid hardening Portland cement based repair materials with either pfa or polymer addition almost merges with the end of microwave curing period. Similarly, lightweight polymer modified repair materials also develop heat of hydration rapidly which almost merges with the end of microwave curing period. The peak heat of hydration of normal density ordinary Portland cement based repair materials, with and without polymer addition, occurs during the post microwave curing period. The sum of the microwave curing and heat of hydration temperatures can easily exceed the limit of about 70 °C in some materials at very early age, which can cause durability problems.

Influence of steel and polypropylene fibers on cracking due to heat of hydration in mass concrete structures

2018 ◽  
Vol 20 (2) ◽  
pp. 808-822 ◽  
Author(s):  
Muneer K. Saeed ◽  
Muhammad K. Rahman ◽  
Mohammed H. Baluch
Keyword(s):  
Concrete Structures ◽  
Heat Of Hydration ◽  
Polypropylene Fibers ◽  
Mass Concrete

Evaluation of the expansion attained to date by concrete affected by alkali–silica reaction. Part II: Application to nonreinforced concrete specimens exposed outside

2004 ◽  
Vol 31 (6) ◽  
pp. 997-1011 ◽  
Author(s):  
Nizar Smaoui ◽  
Benoit Fournier ◽  
Marc-André Bérubé ◽  
Benoit Bissonnette ◽  
Benoit Durand
Keyword(s):  
Relative Humidity ◽  
Alkali Silica Reaction ◽  
Test Surface ◽  
Good Relationship ◽  
Surface Cracking ◽  
Reactive Aggregate ◽  
Concrete Blocks ◽  
Relationship Coefficient ◽  
Concrete Elements ◽  
Made In

In part I, relationships were obtained in the laboratory between the expansion due to alkali-silica reaction (ASR) and (i) the "stiffness damage test" (SDT), (ii) the "damage rating index" (DRI), and (iii) the surface cracking of the concrete. These tests were conducted on nonreinforced concrete blocks and cylinders made with various reactive aggregates and stored at 38 °C and >95% relative humidity. The objective of part II was to verify the validity of the relationships from part I for concrete elements made in the laboratory but exposed outside. On average for the 51 blocks and 14 slabs tested, the surface cracking increased with ASR expansion and approached the measured expansion in the case of the most severely exposed sections of the specimens tested. The ratio between the expansion estimated from the surface cracking and the measured expansion varied greatly from one specimen to another (between 0 and 4.3), however. Taking into account the type of reactive aggregate involved did not explain the situation. Despite a variety of reactive aggregates, a quite good relationship (coefficient of linear regression R2 = 0.89) was obtained between the DRI and the ASR expansion for the six blocks cored and tested for DRI and SDT. This relationship is significantly different from those obtained in the laboratory, however. Moreover, the exposed concretes clearly differ from the laboratory concretes regarding the most important defects observed in the DRI test. As in the laboratory, the results obtained from the SDT seem to depend on the type of reactive aggregate involved. Nevertheless, this test globally supplied results with the best agreement with the measured expansion.Key words: aggregates, alkali–silica reaction, concrete expansion, damage rating index, petrography, stiffness damage test, surface cracking.

Germination response to phytochrome depends on specific dormancy states in wild oat (Avena fatua)

1993 ◽  
Vol 71 (11) ◽  
pp. 1528-1532 ◽  
Author(s):  
J. Q. Hou ◽  
G. M. Simpson
Keyword(s):  
Relative Humidity ◽  
Gibberellic Acid ◽  
Red Light ◽  
Avena Fatua ◽  
Mechanical Injury ◽  
Wild Oat ◽  
Dormancy Breaking ◽  
Negative Effects ◽  
Germination Response ◽  
Genetic Origins

Effects of brief red and far-red light on germination of seeds from dormant lines of wild oat (Avena fatua L.) were studied in combination with mechanical injury to the seed coat, application of gibberellin A3, or changes in relative humidity during afterripening. Aberrant germination responses to phytochrome action were observed in the mechanically injured seeds in some of the lines, i.e., brief red light inhibited or delayed germination induced by injury, and immediately following far-red light cancelled the negative effects. Phytochrome action influenced germination of the gibberellin-treated seeds in a normal fashion, although effects of the gibberellic acid and brief red light on germination were not additive. Brief red light inhibited germination of seeds afterripened in zero relative humidity; the same light promoted germination of those in 30 and 60% relative humidity. Germination response to phytochrome in wild oat depends on specific seed dormancy states, illustrated by genetic origins, dormancy-breaking methods and afterripening conditions. Key words: Avena fatua, dormancy, mechanical injury, gibberellin A3, phytochrome, relative humidity.

Nonlinear and threshold of the association between meteorological factors and bacillary dysentery in Beijing, China

2015 ◽  
Vol 143 (16) ◽  
pp. 3510-3519 ◽  
Author(s):  
Z. J. LI ◽  
X. J. ZHANG ◽  
X. X. HOU ◽  
S. XU ◽  
J. S. ZHANG ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Bacillary Dysentery ◽  
Sunshine Duration ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Negative Effects ◽  
Response Curves ◽  
Linear Effect ◽  
Control Programmes ◽  
Effects Of Temperature

SUMMARYPrevious studies examining the weather–bacillary dysentery association were of a large time scale (monthly or weekly) and examined the linear relationship without checking the linearity assumption. We examined this association in Beijing at a daily scale based on the exposure-response curves using generalized additive models. Our analyses suggested that there were thresholds for effects of temperature and relative humidity, with an approximately linear effect for temperature >12·5 °C [excess risk (ER) for 1 °C increase: 1·06%, 95% confidence interval (CI) 0·63–1·49 on lag day 3] and for relative humidity >40% (ER for 1% increase: 0·18%, 95% CI 0·12–0·24 at lag day 4); and there were linear effects of rainfall (ER for 1-mm increase: 0·22%, 95% CI 0·12–0·32), negative effects for wind speed (ER: −2·91%, 95% CI −4·28 to −1·52 at lag day 3) and sunshine duration (ER: −0·25% 95% CI −0·43 to −0·07 at lag day 4). This study suggests that there are thresholds for the effects of temperature and relative humidity on bacillary dysentery, and these findings should be considered in its prevention and control programmes.

scholarly journals A study on the influence of curing on the strength of a standard grade concrete mix

2010 ◽  
Vol 8 (1) ◽  
pp. 23-34 ◽  
Author(s):  
Rao Krishna ◽  
Rathish Kumar ◽  
Azhar Khan
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Ordinary Portland Cement ◽  
Test Results ◽  
Accelerated Curing ◽  
Design Life ◽  
Curing Method ◽  
The One ◽  
Curing Compound ◽  
Portland Pozzolana Cement

Curing is essential if concrete is to perform the intended function over the design life of the structure while excessive curing time may lead to the escalation of the construction cost of the project and unnecessary delays. Where there is a scarcity of water and on sloping surfaces where curing with water is difficult and in cases where large areas like pavements have to be cured, the use of curing compound may be resorted to. The parameters of the study include the curing period [1, 3, 7, 14 and 28 day], curing method [conventional wet curing, membrane forming compound curing and accelerated curing] and the type of cement [Ordinary Portland Cement(OPC) 43 grade, Portland Pozzolana Cement(PPC) 43 grade and Ordinary Portland Cement(OPC) 43 grade +10% Silica Fume(SF) replacement for cement]. In all a total of 99 cube specimens were cast and cured under different conditions before testing. Test results indicate a drop in strength at all ages for concretes with PPC and the one in which 10% OPC is replaced by silica Fume(SF) in comparison with the concrete with OPC. Curing by membrane forming curing compound yielded nearly the same results as that of conventional wet curing for concrete with OPC and there was a marginal decrement in concrete with PPC. Predicted 28-day strength of concrete from the accelerated curing test was found to be on a conservative side compared to control concrete.

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