scholarly journals Evaluación de elementos premoldeados de hormigón utilizados en instalaciones de crianza de ganado porcino en ambiente agresivo. Recomendaciones de fabricación

2013 ◽  
Vol 3 (2) ◽  
pp. 140-148
Author(s):  
M. Positieri ◽  
C. Baronetto ◽  
B. Raggiotti
Keyword(s):  
Ultrasonic Wave ◽  
Precast Concrete ◽  
Capillary Absorption ◽  
Aggressive Environment ◽  
Compression Speed ◽  
Intensive Rearing ◽  
Service Conditions ◽  
Precast Elements ◽  
Concrete Elements

RESUMENLas modernas instalaciones destinadas a la crianza intensiva de ganado porcino se construyen con elementos premoldeados de hormigón ensamblados in situ en grandes superficies techadas; están sujetas a un ambiente agresivo por los excrementos y vapores que el ganado porcino produce, produciéndose un recambio prematuro de piezas por la escasa durabilidad de las mismas. El trabajo presenta los resultados del estudio realizado sobre elementos premoldeados de hormigón (sin uso) que conforman la estructura, con el objetivo de verificar su comportamiento en las condiciones de servicio y realizar recomendaciones para asegurar su correcto desempeño. Se extrajeron testigos de las piezas y se midieron la resistencia a compresión, velocidad de pasaje de onda ultrasónica, absorción capilar, absorción y permeabilidad al aire. Los resultados obtenidos permiten calificar al hormigón entre regular y bueno y se presentan las recomendaciones que deberían considerarse al fabricar los elementos premoldeados para asegurar su durabilidad.Palabras Clave: hormigón; premoldeados; durabilidad; calidad; testigos.ABSTRACTThe modern installations for the intensive rearing of pigs are constructed based on precast concrete elements that are assembled on site in large areas covered and which are subject to an aggressive environment and in the feces they produce vapors, causing a premature replacement of parts by the low durability of the same. The paper presents the results of a study on precast concrete (unworn) that make up the structure in order to verify its performance in service conditions and make recommendations to assure its correct performance. Witnesses were extracted from the parts and measured the resistance to compression, speed of passage of the ultrasonic wave, capillary absorption, absorption and permeability to air. The results obtained allow us to qualify to the concrete between regular and good and presents the recommendations should be considered when manufacturing the precast elements to ensure their durability.Keywords: concrete; precast; durability; quality; witnesses.

Real Case: Assessing Sulfate Resistance of Coastal Protection Precast Elements

2016 ◽  
Vol 711 ◽  
pp. 327-334
Author(s):  
Francisco Aracil ◽  
Gaetan Dufour ◽  
Peter Wauters ◽  
Geert de Schutter ◽  
Roberto Torrent
Keyword(s):  
Precast Concrete ◽  
Initial Period ◽  
Field Investigation ◽  
Air Permeability ◽  
Coastal Protection ◽  
High Quality ◽  
Sulfate Resistance ◽  
Precast Elements ◽  
Concrete Elements

As part of a new harbor development, a new offshore breakwater will be constructed, for which the use of coastal protection plain precast concrete elements (AccropodesTM II) is required. The applicable exposure class is S1 (ACI 318). Over 4'000 elements have been produced. The owner required guarantees on the sulfate resistance of the elements before accepting them for usage in the project. For this, a revision of the documentation available was conducted, complemented by a thorough field investigation, measuring the coefficient of air-permeability kT (Swiss Standard SIA 262/1) of preselected elements (damaged during transportation) and elements representing the 28 weeks of production. The site NDTs confirmed a high quality of the majority of elements that were judged fit for the purpose. However, the NDTs confirmed the questionable quality of those cast during the initial period, requiring further evaluation before acceptance.The paper presents the results of: water aggressiveness, cement chemistry, strength quality control and air-permeability kT, and the criterion used to assess sulfate resistance of the elements.

scholarly journals Recycled Aggregates from Construction and Demolition Waste in the Manufacture of Urban Pavements

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6605
Author(s):  
Manuel Contreras-Llanes ◽  
Maximina Romero ◽  
Manuel Jesús Gázquez ◽  
Juan Pedro Bolívar
Keyword(s):  
Precast Concrete ◽  
Breaking Load ◽  
Construction And Demolition Waste ◽  
Recycled Aggregates ◽  
Waste Streams ◽  
Demolition Waste ◽  
Class 1 ◽  
Natural Aggregates ◽  
Precast Elements ◽  
Concrete Elements

Construction and Demolition Waste (CDW) is among the largest waste streams in the world. Therefore, within the Circular Economy concept, there is a growing interest in its reuse. The purpose of this work was to study the use of recycled aggregates (RAs) obtained by a specific separation method from CDW, replacing natural aggregates (NAs) in the manufacture of precast concrete elements, such as kerbstones and paver blocks. The physical and technological properties of precast products formulated with RAs were analysed in accordance with current regulations, comparing them with those of commercial products manufactured with NAs. The results indicated that partial or total substitution of NAs by RAs increased the water absorption and apparent porosity values of the precast elements while reducing the bulk density and compressive strength. However, all units manufactured with RAs showed breaking load values higher than the minimum required by EN 1338 and, in some cases, slightly higher average tensile strength values than the reference material. In addition, some of the compositions including RAs gave rise to pieces that, according to their flexural strength, were classified as class 1 and marked S in accordance with EN 1340. According to abrasion resistance, in most cases, the precast elements are classified as Class 4 and I (≤20 mm). Finally, precast concrete produced from RAs satisfies the tolerance requirements for classification as class 3 (≤1.5 kg m−2). Therefore, it could be suitable for use in high pedestrian or traffic areas.

scholarly journals Industrial Low-Clinker Precast Elements Using Recycled Aggregates

2020 ◽  
Vol 10 (19) ◽  
pp. 6655
Author(s):  
Carlos Thomas ◽  
Ana I. Cimentada ◽  
Blas Cantero ◽  
Isabel F. Sáez del Bosque ◽  
Juan A. Polanco
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Precast Concrete ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Slight Reduction ◽  
Construction And Demolition Wastes ◽  
Precast Elements ◽  
The Impact ◽  
Concrete Elements

Increasing amounts of sustainable concretes are being used as society becomes more aware of the environment. This paper attempts to evaluate the properties of precast concrete elements formed with recycled coarse aggregate and low clinker content cement using recycled additions. To this end, six different mix proportions were characterized: a reference concrete; 2 concretes with 25%wt. and 50%wt. substitution of coarse aggregate made using mixed construction and demolition wastes; and others with recycled cement with low clinker content. The compressive strength, the elastic modulus, and the durability indicator decrease with the proportions of recycled aggregate replacing aggregate, and it is accentuated with the incorporation of recycled cement. However, all the precast elements tested show good performance with slight reduction in the mechanical properties. To confirm the appropriate behaviour of New Jersey precast barriers, a test that simulated the impact of a vehicle was carried out.

scholarly journals Degradation of architectural precast concrete elements on the facade of St. Michael the Archangel church in Warsaw

2019 ◽  
Vol 284 ◽  
pp. 07001
Author(s):  
Grzegorz Adamczewski ◽  
Piotr Woyciechowski
Keyword(s):  
Ground Penetrating Radar ◽  
Precast Concrete ◽  
Radar Method ◽  
Precast Elements ◽  
Ground Penetrating ◽  
Concrete Elements

The paper presents the case study of the degradation of architectural precast concrete elements on the facade of St. Michael the Archangel church in Warsaw. The background of the contemporary precast non-standard prefabrication was presented with the examples of polish recent applications. The GPR (ground penetrating radar) method was used in determining the location of reinforcement in the precast elements in the degraded façade. The conceptions of repair were analyzed and the reasons of the destructions of the precast elements.

scholarly journals A STUDY ABOUT TERRESTRIAL LASER SCANNING FOR RECONSTRUCTION OF PRECAST CONCRETE TO SUPPORT QLASSIC ASSESSMENT

2016 ◽  
Vol XLII-4/W1 ◽  
pp. 135-140 ◽  
Author(s):  
M. A. Aziz ◽  
K. M. Idris ◽  
Z. Majid ◽  
M. F. M. Ariff ◽  
A. R. Yusoff ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Precast Concrete ◽  
Terrestrial Laser Scanning ◽  
Assessment System ◽  
Construction Productivity ◽  
Measuring Tape ◽  
Real Time Applications ◽  
White Target ◽  
Precast Elements

Nowadays, terrestrial laser scanning shows the potential to improve construction productivity by measuring the objects changes using real-time applications. This paper presents the process of implementation of an efficient framework for precast concrete using terrestrial laser scanning that enables contractors to acquire accurate data and support Quality Assessment System in Construction (QLASSIC). Leica Scanstation C10, black/white target, Autodesk Revit and Cyclone software were used in this study. The results were compared with the dimensional of based model precast concrete given by the company as a reference with the AutoDesk Revit model from the terrestrial laser scanning data and conventional method (measuring tape). To support QLASSIC, the tolerance dimensions of cast in-situ & precast elements is +10mm / -5mm. The results showed that the root mean square error for a Revit model is 2.972mm while using measuring tape is 13.687mm. The accuracy showed that terrestrial laser scanning has an advantage in construction jobs to support QLASSIC.

Investigation of Grouted Coupler Connection Details for Accelerated Bridge Construction

2021 ◽  
pp. 036119812199939
Author(s):  
Brent Phares ◽  
Yoon-Si Lee ◽  
Travis K. Hosteng ◽  
Jim Nelson
Keyword(s):  
Crack Width ◽  
High Performance ◽  
Static Load ◽  
High Performance Concrete ◽  
Precast Concrete ◽  
Chloride Penetration ◽  
Load Testing ◽  
Test And Evaluation ◽  
Load Tests ◽  
Precast Elements

This paper presents a laboratory investigation on the performance of grouted rebar couplers with the connection details similar to those utilized on the precast concrete elements of the Keg Creek Bridge on US 6 in Iowa. The testing program consisted of a series of static load tests, a fatigue test, and evaluation of the chloride penetration resistance of laboratory specimens. The goal of this testing was to evaluate the ability of the grouted rebar couplers to develop flexural capacity at the joint between the precast elements as well as the durability of the connection. For structural load testing, seven full-scale specimens, each with #14 epoxy-coated rebars spliced by epoxy-coated grouted couplers, were fabricated and tested in three different loading cases: four-point bending, axial tension plus bending, and a cyclic test of the system in bending. The static load testing demonstrated that the applied axial load had a minimal effect on the formation of cracks and overall performance of the connection. When ultra-high performance concrete was used as a bedding grout, the initiation of crack was slightly delayed but no considerable improvement was observed in the magnitude of the crack width during loading or the crack closure on unloading. The results of the seventh specimen, tested in fatigue to 1 million cycles, showed little global displacement and crack width throughout the test, neither of which expanded measurably. No evidence of moisture or chloride penetration was detected at the grouted joint during the 6-month monitoring.

Chromate and amine contact allergies in workers manufacturing precast concrete elements

2016 ◽  
Vol 75 (6) ◽  
pp. 363-369 ◽  
Author(s):  
Martin Mowitz ◽  
Erik Zimerson ◽  
Inese Hauksson ◽  
Ann Pontén
Keyword(s):  
Precast Concrete ◽  
Concrete Elements

scholarly journals Modified mortar pad behavior in the transfer of compressive stresses

2016 ◽  
Vol 9 (3) ◽  
pp. 414-434
Author(s):  
J. D. Ditz ◽  
M. K. EL Debs ◽  
G. H. Siqueira
Keyword(s):  
Precast Concrete ◽  
Concrete Strength ◽  
Compressive Load ◽  
Stress Transfer ◽  
Compressive Stresses ◽  
Bonded Phase ◽  
Concrete Blocks ◽  
Load Tests ◽  
Styrene Butadiene ◽  
Concrete Elements

ABSTRACT This research aims to analyze the compressive stress transfer between precast concrete elements using cement mortar pads modified with polypropylene fibers, styrene-butadiene latex and heat-expanded vermiculite. The stress transfer analyses are performed interleaving a cementbearing pad between two concrete blocks, subjecting the entire specimen to different compressive load tests. The parameters analyzed in the tests are: surface roughness (using bosses on the bonded phase of different thicknesses), compressive strength with monotonic and cyclic loadings. The main results obtained in this study are: a) the presence of pad increased the strength in 24% for thicknesses of imperfections of 0.5 mm and approximately 12% for smooth faces blocks; b) gain of effectiveness of the bearing pad when the concrete strength was reduced; c) for cyclic loading, the bearing pad increased in 48% the connections strength.

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