La méthode du mortier de béton équivalent (MBE)—Un nouvel outil d’aide à la formulation des bétons adjuvantés

Abstract

R 15 S U M I~ A B S T R A C TUarticle pr&ente une nouvelle m&hode d'aide 5 la formulation des b&ons adjuvant&. Elle consiste 5 concevoir, ~ partir d'une composition de b&on, un mortier, dit mortier de b&on 6quivalent (MBE), dont les pro-pri&& rhdologiques sont corr61ables 5 celles du b&on. Le but est de diminuer le nombre de gfich6es de b&on. La d6marche de mise au point de la m&hode, son champ d'application et ses limites sont pr&ent&. Le mode op6ratoire ainsi que le mat&iel n&essaire sont d&aill&. Un exemple de corr61ation entre les propri&& rh6ologiques mesur&s sur MBE et celles mesur&s sur le b&on associ6 est pr&ent& Parall~lement aux suivis rh6ologiques, des suivis thermiques sur MBE peuvent &re effectu&. Ils permettent d'anticiper les effets de diff&ents adjuvants sur le temps de prise du b&on. On montre que les d&alages observ& par suivi thermique traduisent bien les &arts de r&istances aux tr~s courtes &h&nces. En associant suivis rh6ologiques et suivis thermiques, la m&hode MBE permet de s61ectionner rapidement parmi diff&ents adjuvants celui qui r@ond le mieux aux exigences d'efficacitd (rapport dosage/cofit), de maintien rh6ologique et de d6lai de d&offrage.This paper deals with a new method to design concrete containing admixture. Its principle is to design a mortar, deduced fiom the concrete composition and called concrete equivalent mortar (CEM), for which the rheological properties display correlation with those of concrete. The aim is to reduce the amount of concrete batches. This article pwsents the scientific approach which has led to this method, its field application and limits. The test procedure and the apparatus are detailed. An example of correlation between the theological properties measured on CEM and on the corresponding concrete is presented. After monitoringfluidity versus time relationship, thermal measurements on GEM were carried out. These measurements allow to anticipate the effects of different admixtures on the setting time. One shows that the setting delays obtained on CEM are in good agreement with the difference of compressive strengths measured at early age. With rheological and thermal results, the CEM method permits to select between numerous admixtures, which is the most likely to fit in with the specifications of effectiveness (proportion/cost ratio), capacity of keeping the rheological properties over time and delay of formwork removal.

Study of the rheology of self-compacting concrete with fine recycled concrete aggregates

“…This is probably due to the specific characteristics of the superplasticizer used that has a retarded effect. Other superplasticizers lead to a continuous decrease of the spread over time [18,32].…”

“…Schwartzentruber and Catherine [18] proposed the use of the concrete equivalent mortar (CEM) concept to study the rheology of fresh concrete with the assumption that the rheological properties of CEM should be correlated with those of the corresponding concrete. For CEM design it is considered that all friction phenomena take place at the cement paste/aggregate interface.…”

Influence of fine recycled concrete aggregates on the properties of mortars

“…After mixing, the slump of mortar was measured with the mini MBE cone (''Mortiers de Béton Equivalent'' that can be translated as ''Equivalent Mortars to Concrete'' with respect to the surface of solids relative to the fluid that is the cement paste in mortar and the mortar in concrete) [34] which is shown in Fig. 2.…”

Best Practices Guide for High-Volume Fly Ash Concretes : Assuring Properties and Performance

“…Approaches to mixture proportioning continue to be developed and promulgated, such as the method of concrete equivalent mortar that utilizes mortar mixtures to proportion a concrete with a reduction in the number of required concrete batches [24]. Another more recent example would be the International Center for Aggregate Research (ICAR) 'aggregate suspension' proportioning method for self-consolidating and other concretes, developed by Fowler and Koehler [25].…”