Formwork pressure induced by highly flowable concretes – material investigations and large‐scale tests

Abstract

This paper documents the results of a joint research project dealing with the loading of formwork systems used with highly flowable concretes. First calculation approaches concerning the pressure of fresh concrete on vertical formwork were developed on the basis of the investigations conducted on the material behaviour of highly flowable concretes. In doing so, construction management questions regarding, for instance, process design and quality assurance in the application of highly flowable concretes were also investigated. Different scientists from German research institutes collaborated in a research group to pool their knowledge in the field of the pressure of fresh concrete. Because of the extent and complexity of the tasks to be tackled, the joint research project was divided into five subprojects (A to E), which were performed by the research institutes according to their individual respective capacities.

Experimentelle Untersuchungen und numerische Verifizierung zum Frischbetondruck bei geneigten Schalungssystemen

“…Aus Versuchsergebnissen [13,14] mit einer sogenannten Kombinierten Versuchseinrichtung (KVA) [15] an Betonen der Konsistenzklasse F5 und F6 wurden Funktionen des Seitendruckbeiwerts als Mittelwerte in Abhängigkeit von der Zeit λ i,MW (t/t E,eff ) für eine nachgiebige Schalung abgeleitet (vgl. Gln.…”

Lateral Formwork Pressure for Self-Compacting Concrete—A Review of Prediction Models and Monitoring Technologies

“…Steel formwork generated a higher pressure than plywood and watering the surface increased the pressure as well, [ 59 ]. The formwork pressure tended to decrease more slowly for steel and PVC surfaces but faster for polyester and plywood [ 64 ].…”

“…The decrease in pore water content was assumed to be related to the thixotropic build-up and hydration process. Initially, Graubner et al [ 64 , 73 ] used the following formula to calculate the maximum horizontal pressure, Equation (8). where is the normalized maximum pressure corresponding to the maximum horizontal pressure σ h,max divided by the hydrostatic pressure σ h , E , hydro where is the casing rate, t E is the setting time measured using the Vicat penetration test, γc = ρc ∗ g , with concrete density ρc and gravity constant g and is calculated for SCC using Equation (10): where h E is the height measured from the level of the hardened concrete to the location of the concrete pump.…”

Analysis of casting rate for the validation of models developed to predict the maximum lateral pressure exerted by self-compacting concrete on vertical formwork

“…The German guidelines DIN 18218-10 [23], from 2010, are based on the investigation of Proske and Graubner Group [6,15,[24][25][26] who propose a bilinear distribution of the lateral pressure exerted by SCC against the formwork, with a hydrostatic distribution that is up to the maximum pressure and constant down to the bottom of the formwork. The maximum value of the lateral pressure is determined using Eq.…”

“…The literature classifies those factors into three categories: formwork characteristics, concrete characteristics and placing method. Several researchers have studied these variables [1][2][3][4][5][6]. Each category contains a large number of factors, which explain the complexity of the problem.…”