scholarly journals CHARACTERIZATION OF THE INTERFACE BETWEEN FRESH CONCRETE AND FORMWORK

2015 ◽  
Vol 22 (1) ◽  
pp. 26-37 ◽  
Author(s):  
Samir BOUHAROUN
Keyword(s):  
Surface Quality ◽  
Pore Solution ◽  
Fresh Concrete ◽  
Concrete Surface ◽  
Chemical Interactions ◽  
Construction Sites ◽  
Release Agent ◽  
Physicochemical Investigation

Concrete surface quality is generally linked to the development conditions of concrete close to the formwork. This work aims to study the influence of the nature of release agent and the quantity of fine elements on the chemical interactions at the concrete/oil/formwork interface. Five concretes were prepared at 28, 30, 32, 34, and 36% of paste to study the influence of paste volume on the friction between formwork and fresh concrete. The friction tests were performed using an apparatus which can reproduce the same conditions of construction sites. In addition, a physicochemical investigation was achieved to identify the effect of fine elements on the ability to form the interstitial mediums at the interface. The formation of soap in the vicinity of the formwork surfaces was also studied as a function of the content and the nature of oils. The results showed that the friction between fresh concrete and formwork depends on the pore solution content present at the interface.

Concrete Surface Quality Improvement Technique Using Highly Water Repellent Sealing Method

2016 ◽  
Vol 54 (11) ◽  
pp. 1105-1110
Author(s):  
K. Watanabe ◽  
G. Sakai ◽  
N. Sakata ◽  
T. Ishida
Keyword(s):  
Quality Improvement ◽  
Surface Quality ◽  
Concrete Surface ◽  
Water Repellent

Use of Wavelet Packet Transform in Characterization of Surface Quality

2007 ◽  
Vol 46 (15) ◽  
pp. 5152-5158 ◽  
Author(s):  
J. Jay Liu ◽  
Daeyoun Kim ◽  
Chonghun Han
Keyword(s):  
Surface Quality ◽  
Wavelet Packet ◽  
Wavelet Packet Transform

Surface quality characterization of textile-reinforced thermoplastics

2000 ◽  
Vol 21 (4) ◽  
pp. 630-635 ◽  
Author(s):  
M. Neitzel ◽  
M. Blinzler ◽  
K. Edelmann ◽  
F. Hoecker
Keyword(s):  
Surface Quality ◽  
Reinforced Thermoplastics

Effect of retardant admixtures type and their using method on the behavior of concrete

2021 ◽  
Vol 12 (3) ◽  
pp. 104
Author(s):  
Tamer Ibrahim Ahmed ◽  
Mohamed Roshdy Afify
Keyword(s):  
Compressive Strength ◽  
Fresh Concrete ◽  
Setting Time ◽  
Casting Process ◽  
Additional Dose ◽  
Construction Sites ◽  
Effective Option ◽  
Initial Setting ◽  
Crisis Conditions ◽  
Ready Mix Concrete

Construction sites may be exposed to crisis conditions during the casting process, resulting in delays of several hours and causing destruction of ready-mix concrete. This study suggests an experimental analysis of the possibility of using a specific additional dose of retardant admixtures, which may be used to ready-mix concrete before the initial setting of the concrete occurs. The effect of this additional dose on concrete characteristics in terms of workability, setting time, and compressive strength is also being studied. To conduct this investigation, three types of retardant admixtures from three branded companies were used. In addition, a penetration resistance experiment was conducted on the concrete to determine its setting time. The setting time of concrete was measured at different period intervals depending on when the additional dose of the retardant admixtures was added from the start of the concrete mixing. The results showed that concrete maintained proper workability for a period of more than 5 hours after using the additional dose of retarding admixtures. The additional dose of retarding admixtures not only delayed the concrete setting but also improved the compressive strength of the concrete. This implies that the use of an additional dose of retardant admixtures specifically tailored for ready-mix concrete is an effective option to avoid the return of ready-mixed fresh concrete.

scholarly journals Characterization of Shear Strength of FRP Anchors

2018 ◽  
Vol 199 ◽  
pp. 09008
Author(s):  
Philipp Mahrenholtz ◽  
Jae-Yeol Cho ◽  
Ja-Min Park ◽  
Rolf Eligehausen
Keyword(s):  
Load Capacity ◽  
Concrete Surface ◽  
Shear Loading ◽  
Seismic Retrofitting ◽  
Static Tests ◽  
Cyclic Shear ◽  
Concrete Body ◽  
Seismic Tests ◽  
Frp Sheet

A critical performance aspect of FRP retrofitted concrete elements is the bonding of the FRP sheet to the concrete surface. In general, the performance is limited by the debonding of the loaded FRP sheets from the concrete surface. One method to delay debonding and enhance the capacity is the use of FRP anchors which interlock the FRP sheet to the concrete body. FRP anchors are made of rolled FRP fibres epoxied into in predrilled boreholes. There are a considerable number of studies on FRP strengthening methods available, and also FRP anchors attract more attention of the research community recently. However, to date FRP anchors were tested in a system together with the FRP sheet attached to the concrete, inhibiting the development of general design models. Moreover, the anchor behaviour was never tested for cyclic loads, though most applications are for seismic retrofitting schemes and cyclic shear loading generally results in reduced load capacity due to fatigue failure. To overcome the deficit in knowledge, shear tests on various FRP anchors were carried out. For these tests, FRP anchors were installed in concrete specimens on a separating steel section. The FRP anchor was then directly loaded to determine the capacity of the isolated component. This paper describes the testing approach and procedure. Details on the experimental results for static tests are presented and an outlook on seismic tests is given.

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