5—consolidation of preplaced aggregate concrete

... shear strengths of RAC are generally lower than those of Natural Aggregate Concrete (NAC); the modulus of elasticity for RAC generally reduces as the content of Recycled Coarse Aggregate (RCA) ... capacity of recycled concrete aggregates, the recycled concrete aggregates used were presoaked by additional water before mixing The water amount used to presoak the recycled concrete aggregates ... ranged from 17.5MPa to 25MPa (a) Debris of concrete (b) Produced aggregate (c) Recycled coarse aggregate Figure 2 Plan of RAC production Recycled aggregates can be produced in plants similar

Ngày tải lên: 10/02/2020, 08:57

... Trang 6of the bulk density of HSC The compressive strength of the concrete cured in water for two days following by sealed with polyethylene sheet (curing type 1-C1) was higher than that of the concrete ... resulting in a reduction of autogenous shrinkage, an improvement of compressive and flexural strengths, a decrease in water absorption and volume of voids in concrete at the age of 28 days Trang 7LỜI ... research was the concrete with 100% FECA replacement This result can be explained that the effectiveness of internal curing exceeded the negative effect in terms of porous structure of FECA, resulting

Ngày tải lên: 03/03/2021, 19:56

... 1 2 Because of the salient (not round) structure of the rotor, the self inductance of the stator is afunction of the rotor position and the first term on the right hand side of the above torque ... relative position of the stator and rotorand is independent of the shape of the stator and rotor poles Model of Electromechanical Systems To illustrate the general principle for modeling of an electromechanical ... equation model of any electromechanical systems Exercises 1 An electromagnet in the form of a U shape has an air gap, between each pole and anarmature, of 0.05 cm The cross sectional area of the magnetic

Ngày tải lên: 11/07/2014, 05:20

... these elements ofthinking, the more you will get out of them Trang 14At the end of this book you will find an invitation to share your own stories of effective thinking atwww.elementsofthinking.com ... pedagogical principles to the general realm of practical affairs and the entirerange of academic endeavor Regardless of the reader’s background, The 5 Elements offers highlyapplicable and original lessons ... GPA, for leaders of society andmasters of the universe who care more about serving the public good than increasing their profitmargin, and for artists who constantly remind us of the human condition

Ngày tải lên: 20/07/2014, 20:24

... by colors. Trang 3Analysis of the sequence variabilityOur previous analyses of the sequence variability of the 5'UTR of HCV-1 found a small increase in the variability of cultured HCV compared ... able to generate PCR fragments for all of our sam-ples (Figure 2 and Table 2) Comparison of the 5'UTR of HCV from patients' sera and CIMM-HCV The first sample of HCV-3 analyzed was from patient ... macrophages A flow chart of our samples is shown in Figure 1 Determination of best primer sets for analyses For the purposes of this report, we first made degenerate versions of the primers that were

Ngày tải lên: 12/08/2014, 04:20

... Twelve of them regularly used a combination of β-sympathicomimetic drugs and inhalation steroids None of the children needed supplemental oxygen Two of the total population were fol-lowed because of ... of severe developmental delay or neuromotor disabilities were reported in some 20% of ECMO survivors [3,8,10,12] The range of morbidity widens with evaluation after age one, when assessment of ... questionnaires Results Seventeen of the 98 children included in the analysis (17%) were found to have neurological deficits Six of those 17 (6% of the total) showed major disability Two of those six children

Ngày tải lên: 13/08/2014, 03:20

... strength stress-of theconcrete An understanding of concrete behavior in compres-sion, thus, requires an understanding of both the behavior of ce-ment paste in compression and the interaction of cementpaste ... controlled 3.4.2 Influence of quantity and type of aggregate on shrinkage—Concrete shrinkage is due primarily to shrinkage of the hardened cement paste The presence of aggregate in con-crete reduces ... drying shrinkage of concrete (Hansen and Almudaiheem 1987). Fig 3.5—Typical effect of water content of concrete on drying shrinkage (USBR 1981). Table 3.1—Effect of aggregate type on concrete shrinkage

Ngày tải lên: 24/10/2014, 15:46

... therefore, part of the mixing water normal-2.3.8 Modulus of elasticity of lightweight aggregate particles—The modulus of elasticity of concrete is a function of the moduli of its constituents Concrete ... bymany factors, such as type of aggregate, type of cement,grading of aggregate, water content of the mixture, moisturecontent of aggregate at time of mixture, amount of entrained E c = w c1.533 ... the hydration of high cementitous content concrete with very low w/cm. 4.6—Modulus of elasticity The modulus of elasticity of concrete depends on the relative amounts of paste and aggregate and

Ngày tải lên: 24/10/2014, 15:47

... reflects the state of the art of corrosion of metals, and espe-cially reinforcing steel, in concrete Separate chapters are devoted to the mechanisms of the corrosion of metals in concrete, protective ... of concrete’s inherent protective attributes, corrosion of reinforcing steel does not occur in the majority of concrete elements or struc-tures Corrosion of steel, however, can occur if the concrete ... crack-ing in the concrete cover 2.2.4.1 Corrosion initiation by chlorides—The most common cause of initiation of corrosion of steel in concrete is the presence of chloride ions The source of chlorides

Ngày tải lên: 24/10/2014, 16:04

... production of shrinkage-compensating concrete The state of knowledge report outlined the theory and results of studies into the general behavior of such con-cretes, including the effects of concrete ... The physical characteristics of the cured shrinkage-compensating concrete are usuallysimilar to other types of concrete The durability of shrink-age-compensating concrete should be judged on ... the cement Levels of expansion will be differentwhen job materials are used in the concrete mix ce-2.2—Aggregates Concrete aggregates that are satisfactory for portland ment concretes can also

Ngày tải lên: 24/10/2014, 16:04

... modulus of elasticity of concrete E c = age-adjusted modulus of elasticity of concrete at time t E s = modulus of elasticity of nonprestressed reinforcing steel EI = flexural stiffness of a compression ... compressive strength of concrete f ct , f t′ = splitting tensile strength of concrete f r = modulus of rupture of concrete f s = stress in nonprestressed steel f y = specified yield strength of nonprestressed ... thickness of a member I = moment of inertia of the transformed section I cr = moment of inertia of the cracked section trans-formed to concrete I e = effective moment of inertia for computation of

Ngày tải lên: 24/10/2014, 17:25

... a reinforcement-of-choice for polymer concrete In spite of earlier research on the use of FRP reinforcement in concrete, commercial application of this product in con-ventional concrete was not ... parameters: 1) bond strength of FRP reinforcing bar2) splitting tensile strength of concrete3) area of concrete cross section in tension4) number of reinforcing bars in tension5) size of reinforcing bar ... strength 5.1.3 Bond and development of reinforcement—The eval-uation of bond characteristics of FRP reinforcements is of prime importance in the design of FRP reinforced concrete members Due to variations

Ngày tải lên: 24/10/2014, 17:25

... and forces E c = modulus of elasticity of concrete under short-term load, psi E ci = modulus of elasticity of concrete at age t i, psi E s = modulus of elasticity of reinforcement, assumed ... specified compressive strength of concrete, psi. f ’ ci = specified compressive strength of concrete at time of prestressing, psi. f ci = the initial stress in the concrete at time t i, immediately ... r = inside radius of tank, ft r d = inside radius of dome, ft r i = averaged maximum radius of curvature over a dome imperfection area with a diameter of , ft. t = age of concrete at time long

Ngày tải lên: 24/10/2014, 17:26

... stiffness of the aggregate, the more effective vol-it is in reducing the shrinkage of the concrete (i.e., the shrinkage of concrete containing sandstone aggregatemay be more than twice that of concrete ... amount of creep Theamount of drying shrinkage is influenced mainly by theamount and type of aggregate and the water content ofthe mix The greater the amount of aggregate, thesmaller the amount of ... capacity, concrete will crack The effects of temperature differentials due to different rates of heat dissipation of the heat of hydration of cement are normally associated with mass concrete

Ngày tải lên: 24/10/2014, 17:37

... showed minor concrete scaling ofthe concrete wall surfaces of Outlets 1 and 2 One yearlater, in 1974, serious erosion had occurred at wallsurfaces of both outlets immediately downstream of thewall ... ofthe gate slots at small, part-gate operation; and 2) lack ofrounding and lack of offset of downstream edge of gateslot Trang 13REPAIR OF EROSION DAMAGED HYDRAULIC STRUCTURES 210.1R-13SOLUTION ... maximum depth of erosion was about % in The divers also dis-covered two pieces of steel plating that had been em-bedded in the concrete around the intake of one of the lower sluices Because of concern

Ngày tải lên: 24/10/2014, 17:40

... in concrete sea structures The control of concrete temperatures includes selection of cements which have low heat of hydration, reduced rates of placement, precooling of aggregates, the use of ... reinforcing bar f = mean tensile strength of concrete k = yield stress of reinforcing bars = 28-day strength of concrete (ACI 318) h = section thickness X = depth of compression zone YC = material factor ... The rise of temperature in concrete because of ce-ment heat of hydration requires strict control to prevent steep temperature stress gradients and possible thermal cracking of the concrete on

Ngày tải lên: 24/10/2014, 17:40

... (Reeves and Yates 1985) 2.3—Coarse aggregate The nominal maximum size aggregate (NMSA) normally affects the ease of compaction of RCC due to the tendency of large aggregate to segregate from the ... process of freshly mixed concrete or mortar In ACI 309R, consolidation is the pre-ferred term used for conventional concrete work For the pur-poses of this document on roller-compacted concrete, ... used for all types of RCC mixtures, because it more appropriately describes the method of densification 1.5—Importance of compaction The effect of compaction on the quality of RCC is signifi-cant

Ngày tải lên: 24/10/2014, 21:58

... of forms and placement of coarse aggregate, McArthur Bridge, Detroit, Michigan 4.2-Preparation of concrete surfaces Fig 12 -Concrete preparation of an arch rib before removal of deteriorated concrete, ... 1983, Preplaced Aggregate Concrete, ” Department of the Army Corps of Engineers, Office of the Chief of Engineers 12 Tirpak, Edward G., “ORNL-1739, Report on Design and Placement Techniques of Barite ... revolving wash screens 4.5.2 Aggregate placement-Coarse aggregate is PREPLACED AGGREGATE CONCRETE Fig 14-Flow of coarse aggregate through tremie pipe for embedment of draft tubes was controlled...

Ngày tải lên: 24/10/2014, 17:44

... Distribution profile of coarse aggregate mass for concrete with F5 aggregate in Series I and corresponding Mass Deviation Index (MI) 129 - vii - Table 6.2 – Distribution profile of coarse aggregate ... yield stress of concrete with F6.5 aggregate in Series I (The concretes had the same SP dosage) 92 Fig.4.13 – Effect of air entrainment on the plastic viscosity of concrete with F6.5 aggregate ... resistance of the concrete and is a measure of the force necessary to start the movement of the concrete The h-value is the relative viscosity and is a measure of the resistance of the concrete...

Ngày tải lên: 16/09/2015, 08:30

... penetrability of concrete for three different types of concretes: normal weight granite concrete (NWC), lightweight aggregate concrete (LWAC) and recycled aggregates concrete (RAC) The penetrability of concrete ... strength of recycled aggregate concrete 82 Table 4.3: Summary of recycled concrete aggregate penetrability properties 86 Table 4.4: Summary of R2 Values 87 Table 4.5: Summary of Penetrability of concrete ... ratio, size of lightweight aggregate, density of lightweight aggregate and volume of lightweight aggregate has reasonable effects on penetrability properties of lightweight aggregate concrete The...

Ngày tải lên: 13/10/2015, 15:55