Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 26 for “"air entrained"”.
-
Durability of non air entrained concrete
Frost-þíðu skemmdir í steinsteypu eru að öllum líkindum sá þáttur sem hefur hvað mest áhrif á endingu bygginga á Íslandi. Utanhússteypa á Íslandi þarf að standast kröfur um að flögnun sé ekki meiri en 1 kg/m2 samkvæmt stöðluðu sænsku frostþols prófi, SS 137244. Til að uppfylla þessar kröfur er …
-
Scour under air entrained jets below dams and flip buckets
… It was. surmised by the writer that plunge pool air entrainment could also be a relevant parameter and apparatus was built to examine this assumption. Two dimensional testing without air indicated scour to be independent of head drop (H) and directly proportional to flow (q), such that x=1.0 and …
-
Freeze-Thaw Resistance and Microstructural Characteristics of Concretes Containing Pozzolans
… a study undertaken to determine the effect of air entrainment on workability and air content of fresh concrete incorporating silica fume (SF), metakaolin (MK), fly ash (FA) and blends of FA and MK and to assess the effects of such pozzolans on freeze-thaw durability, air void system and …
-
Evaluating CEN/TS 12390-9 To Assess Concrete for UK Freeze-Thaw Exposure Conditions
… and CEM II/A-L (limestone) cements, both non-air and air entrained, with different target strengths (20-60 MPa for non-air entrained and 20-50 MPa for air entrained) and a target air content of 4.5%, in accordance with BS 8500. BS EN 197-1 outlines the maximum addition contents that can be …
-
Freeze-thaw durability of high strength silica fume concrete
… fume) ratio of 0.25 to 0.32, with and without entrained air, were tested for freeze-thaw durability in accordance with ASTM C666, procedure A (freezing and thawing in water). In addition, another set of similar specimens were moist cured for 28 days instead of 14 days and tested in accordance …
-
Characterization and deterioration detection of portland cement concrete using ultrasonic waves
… water to cement (w/c) ratio, aggregate type, and air entrainn1ent on measured ultrasonic wave velocity and signal energy. Three w/c ratios (0.35, 0.45, and 0.55) were evaluated. Two aggregate types, quartzite and limestone, were included in the PCC mixes separately. Mixes were prepared as non-air …
-
Development of a short test for the identification of aggregates causing poor concrete performance when frozen
… incorporation in concrete. Freeze-thaw teats of air-entrained concrete specimens, teats on curing period of air-entrained concrete specimens exposed to freeze-thaw cycles, and mercury-intrusion porosimeter tests of individual aggregate particles were conducted. Several parameters have been …
-
Evaluation of different treatments to improve the durability of concrete having deleterious chert particles as its coarse aggregate
On the basis of freezing and thawing tests of air-entrained concretes having poor quality cherts as course aggregates subjected to three different treatments for improving durability, the following conclusions have been derived: 1. Removal of cherts lighter than the BSSD specific gravity of 2.5 by …
-
Super Absorbent Polymers (SAPs) as physical air entrainment in cement mortars
… for using SAPs as a mechanism for physical air entrainment. Mixtures were produced using various quantities of either dry or pre-saturated SAP to replace conventional air entrainment agents (AEAs) along with a conventionally air-entrained control. One additional mixture used lightweight fine …
-
Agricultural spray droplet dispersion in turbulent windflow
… following the above approach, indicating that air entrained into the liquid spray stabilizes the spray to the cross flow action. Measurements within an agricultural spray in still air show that small droplets are passively transported within the entrained air field, whose characteristic …
-
Admixture compatibility and freeze-thaw resistance of concrete prepared using commercially produced limestone calcined clay cements
… available high range water reducers (HRWRs) and air entraining agents (AEAs) by studying the impact on flow diameters and initial setting time of mortars. Polyethylene-based HRWR was the least suited, whereas vinsol-based AEA was the most suited for use with LC3 cements. The high fineness of LC3 …
-
A numerical model study about the impacts of dry air on tropical cyclone formation
The impacts of dry air on tropical cyclone formation are examined in the numerical model simulations of ex-Gaston (2010) and pre-Fay (2008). The former can be regarded as a non-developing system as it failed to redevelop after being downgraded into a remnant low, and the latter developed into a …
-
Nonlinear dynamic model and simulation of a high pressure monotube shock absorber using the bond graph method
… as fluid inertia effects, laminar orifice flow, air entrained in the hydraulic fluid, and cavitation. Simulation results demonstrate good model accuracy when compared t.o test data for similar hydraulic dampers. Parametric studies involving various elements of the system including gas …
-
Environmental durability of FRP bond to concrete subjected to freeze-thaw action
… substrate were used: regular high strength and air-entrained concrete. The specimens were freeze-thaw cycled for three different numbers of cycles using two different freeze-thaw procedures. First freeze-thaw procedure used chloride solution (3% NaCI) as its medium; the second procedure utilized …
-
Microstructure characterization of foamed cement and concrete
… is a major durability issue in cold climates. Air-entraining admixtures are used to create a network of fine bubbles that enhance frost resistance. Experience has shown that fresh air content alone cannot predict the effectiveness of the entrained air system. Instead, parameters such as bubble …
-
Effect of freezing and thawing on unconfined compressive strength of clay-lime mixture with and without air entraining agent
… To investigate the effect of the addition of an air entraining agent on the freezing and thawing durability of lime-soil mixtures. For the first part, twelve specimens were prepared for each of 0, 5, 10, 15 and 20 percent combination of lime-clay mixture, giving a total of 60 specimens. For the …
-
The effect of high volumes of ungraded fly ash on the properties of foamed concrete
… slurry thus entrapping numerous small bubbles of air in the cement paste or mortar. The density of foamed concrete is a function of the volume of foam added to the slurry and the strength decreases with decreasing density. In this study the effect on the properties of foamed concrete, of replacing …
-
Quantifying entrainment and dilution in numerical simulations of developing thunderstorms
… by which turbulent clouds draw environmental air inward, and this process has long been understood to dilute the cloud, i.e., reduce the cloud liquid water content, buoyancy, and updraft velocity. In cumuli, entrainment results from overturning thermal circulations near cloud top. Past …
-
The behaviour of Siphon Spillways, with particular reference to air entrainment and model scale effects
This work is a broad study of the mechanisms of air entrainment and air regulation in self-priming, air-controlled siphon spillways. The early chapters of the work provide the reader with the history and general design principles of siphon spillways as well as a comprehensive review of the research …
-
The olfactory basis for attraction of the Bollworm helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) to host-plant flowers
… benzyl alcohol. Increases in upwind flight to air entrained extracts of floral odours indicated that these cues caused attraction when presented to female H. armigera. A synthetic T. erecta blend comprising benzaldehyde, (f)- linalool, phenylacetaldehyde and (+)-limonene gave significant …
Page 1 of 2