M. BEDDAR Miloud

The self-compacting concretes are distinguished by an extreme fluidity, allowing their placement without vibration. mineral additions and admixture are two essential components for the formulation of self-placing concretes (SCC). They are introduced into the concrete to improve their rheological behavior in the fresh state, but also to participate in enhancing the mechanical properties and durability of concretes, especially in the case of active additives.

In this study, a test program was performed on self-placing concretes composed of cement and silica fume and lime filler as mineral addition. The rheological parameters (viscosity and yield stress) were measured using the rheometer at the fresh state. Mechanical characterization was performed using the direct (compressive) and non-destructive testing methods (NDT), ultrasonic velocity, and rebound hammer for the assessment of the mechanical responses in the hardened state.

The results obtained showed an advantageous effect of these combined additions with an optimal dosage of 10% (5 % Silica fume + 5 % Limestone), about the improvement of the rheological and physico-mechanical properties of the self-compacting concrete mixtures studied.

Summary :

Over the last few years, the civil engineering and public works sector has seen a major surge in demolition and construction (C&D) waste, due to accidental causes such as earthquakes or ageing structures. As a direct consequence, thousands of tonnes of demolition and construction waste are generated.
The aim of this study is to contribute to the reuse of construction waste, essentially aggregates recovered from old concrete combined with marble powders from marble factories, in the manufacture of concrete. The characterization and formulation of an alternative environmental concrete (EC) based on locally recovered materials. The expected objectives are grouped below;
- Eliminate waste by recycling, thereby protecting the environment.
- To help solve certain problems linked to the lack of aggregates, and in particular to the use of alluvial aggregates.
- Reduce dust and gas emissions into the atmosphere by saving clinker through partial substitution of Portland cement by mineral additives (marble powders) . Thus, a contribution benefits of such climate change mitigation is to be implemented in regards to the utilization of solid wastes recoveriy.
Keywords; Construction & demolition waste, recovered aggregates, environmental concrete, recycling, environmental protection.

RESUME
Les additions minérales sont des composants indispensables lors de la formulation d’un
béton autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les
paramètres les plus influents sur le comportement rhéologique des BAP et par
conséquent sur la stabilité. L’objectif principale de notre étude est de caractériser
expérimentalement l’effet de la finesse et du dosage du laitier granule de haut fourneau
sur la stabilité dynamique et statique du béton autoplaçant. La caractérisation de
différents mélanges de BAP confectionnés avec 5 et 10 % du laitier selon les différentes
finesses (2000, 3000 et 4000 cm2

/g), a été fait a l’état frais par l’essai l’essai de la boite
en L (statbilité dynamique) ainsi que l’essai de la stabilité au tamis (stabilité statique).
Les résultats obtenus montrent clairement que la variation du dosage et de la finesse ont
un effet significatif sur la stabilité du béton autoplaçant.

RESUME
Les additions minérales sont des composants indispensables lors de la formulation d’un
béton autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les
paramètres les plus influents sur le comportement rhéologique des BAP et par
conséquent sur le comportement mécanique. L’objective principale de notre étude est de
caractériser expérimentalement l’effet de la finesse et du dosage du calcaire sur le
comportement mécanique du béton autoplaçant. La caractérisation de différents
mélanges de BAP confectionnés avec 10 et 20 % de calcaire selon les différentes
finesses (2000, 3000 et 4000 cm2

/g), a été faite à l’état durci par un essai destructif
(essai de compression et de flexion) et un essai non-destructif (vitesse ultrasonique). Les
résultats obtenus montrent clairement que la variation du dosage et de la finesse ont un
effet significatif sur les caractéristiques mécaniques du béton autoplaçant.

Résumé : Les additions minérales sont des composants indispensables lors de la formulation d’un béton
autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les paramètres
les plus influents sur le comportement rhéologique des BAP et par conséquent sur la stabilité.
L’objectif principale de notre étude est de caractériser expérimentalement l’effet de la finesse
et du dosage du laitier granulé de haut fourneau sur la stabilité dynamique et statique du béton
autoplaçant. La caractérisation de différents mélanges de BAP confectionnés avec 5 et 10 %
du laitier selon les différentes finesses (2000, 3000 et 4000 cm2/g), a été fait à l’état frais par
l’essai de la boite en L (stabilité dynamique) ainsi que l’essai de la stabilité au tamis (stabilité
statique). Les résultats obtenus montrent clairement que la variation du dosage et de la finesse
ont un effet significatif sur la stabilité du béton autoplaçant.
Mots-clés : Stabilité dynamique, stabilité statique, additions minérales, finesse, béton autoplaçants

Résumé. Les additions minerals sont des composants indispensables lors de la formulation d’un béton autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les paramètres les plus influents sur le comportement rhéologique des BAP et par consequent sur la stabilité. L’objectif principale de notre étude est de caractériser expérimentalement l’effet de la finesse et du dosage du calcaire sur la stabilité dynamique et statique du béton autoplaçant.
La caractérisation de différents mélanges de BAP confectionnés avec 10 et 20 % de calcaireselon les différentes finesses (2000, 3000 et 4000 cm2/g), a été fait a l’état frais par l’essail’essai de la boite en L (statbilité dynamique) ainsi que l’essai de la stabilité au tamis (stabilité statique).
Les resultants obtenus montrent clairement que la variation du dosage et de la finesse ont un effet significatif sur la stabilitédu béton autoplaçant.
Mots clés: Stabilité dynamique, Stabilité statique, Additions minérales, finesse, béton autoplaçants.

Résumé
Les additions minérales sont des composants indispensables lors de la formulation d’un béton autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les paramètres les plus influents sur le comportement rhéologique des BAP et par conséquent sur le comportement mécanique. L’objective principale de notre étude est de caractériser expérimentalement l’effet de la finesse et du dosage du calcaire sur le comportement mécanique du béton autoplaçant. La caractérisation de différents mélanges de BAP confectionnés avec 10 et 20 % de calcaire selon les différentes finesses (2000, 3000 et 4000 cm2/g), a été faite à l’état durci par un essai destructif (essai de compression et de flexion) et un essai non destructif (vitesse ultrasonique). Les résultats obtenus montrent clairement que la variation du dosage et de la finesse ont un effet significatif sur les caractéristiques mécaniques du béton autoplaçant.
Mots clés : Comportement mécanique, Additions minérales, finesse, béton autoplaçants, Essai destructif, Essai non destructif.

Résumé : Les additions minérales sont des composants indispensables lors de la formulation d’un béton
autoplaçant. La finesse et le dosage de ces ajouts en addition au ciment sont les paramètres
les plus influents sur le comportement rhéologique des BAP et par conséquent sur la stabilité.
L’objectif principale de notre étude est de caractériser expérimentalement l’effet de la finesse
et du dosage du laitier granulé de haut fourneau sur la stabilité dynamique et statique du béton
autoplaçant. La caractérisation de différents mélanges de BAP confectionnés avec 5 et 10 %
du laitier selon les différentes finesses (2000, 3000 et 4000 cm2

/g), a été fait à l’état frais par
l’essai de la boite en L (stabilité dynamique) ainsi que l’essai de la stabilité au tamis (stabilité
statique). Les résultats obtenus montrent clairement que la variation du dosage et de la finesse
ont un effet significatif sur la stabilité du béton autoplaçant.
Mots-clés : Stabilité dynamique, stabilité statique, additions minérales, finesse, béton autoplaçants.

Abstract
Recently, studies are oriented to introduce sustainable materials in construction. This study aims to investigate the efects
of sisal fbers on the thermophysical and mechanical properties of compressed earth blocks (CEB) made of local materials
by mixing red clayey soil taken from the M’sila region in Algeria and brick waste (BW). First, the maximum percentage of
BW is fxed at 20% while respecting the plasticity criteria. Then, the efects of fbers and cement addition on the engineering
properties of CEB are analyzed and compared according to fber and cement contents. Sisal fbers are added with diferent
percentages varying from 0 to 0.5%, while cement content is used with four percentages: 0, 5, 7, and 9% (by wt% of the
newly modifed soil). Many tests are performed including, capillary absorption rate, thermal conductivity, compressive/
tensile strengths, and abrasion resistance. The results showed that the inclusion of sisal fbers improves the thermal insulation of cement-stabilized blocks by up to 21% and strength by 150%. However, it is observed that the hydrophilic character
of sisal fbers increases the capillary absorption by 81%, and the abrasion coefcient increases with the increase in fber
content. Furthermore, the investigation revealed that the use of fbers alone is insufcient to ensure the stability of the blocks
in moist conditions since the material fully loses its resistance, which requires the total protection of material against any
type of infltration and/or the use of cement as stabilizing agents. As a result, the research showed that sisal fbers may be
used in CEB reinforcement, further an environmentally alternative solution was proposed for managing BW by their use in
CEB manufacturing as this contributed to sustainability and circular economy strategies.
Keywords Compressed earth block · Thermal insulation · Sisal fbers · Recycling · Strength

Nowadays, researchers are oriented to the usage of earth materials in construction as they possessed a lower thermal conductivity and thereby preserved the environment by reducing greenhouse emissions in buildings. One of these materials is the compressed earth block (CEB). Even though its attractive thermal and environmentally advantageous, CEB material present certain limitations related to its poorly strength in moist conditions, which limits its use at a high rate. The purpose of this article is to study the feasibility to improve the engineering properties of CEB produced from a red clay taken from M’sila region (Algeria) by the addition of sisal fibers, further cement is used to stabilize the composite. The fibers were added in different percentages 0; 0.1; 0.2; 0.3; 0.4 and 0.5 by total dry mass of the block. The obtained results show that the combined effect of fibers and cement improved the mechanical and physical properties of CEB material.

The formulation of an innovative concrete that meets the requirements of a self-compacting concrete (SCC), with acceptable performance in terms of rheology in the fresh state; good fluidity, ease of placing, without segregation as well as good mechanical strength and durability at hardened state has become of great research interest for the last decades. Numerous studies have shown the favorable effects of limestone fillers on the SCC properties. This study aims at investigating the effect of inert mineral addition of limestone fillers with dosages of 10% and 20% grinded to different fine nesses 2000, 3000 and 4000 cm2/g on the physico-mechanical properties of a fresh self-placing concrete using slump, the L-box and the sieve stability tests. Also, the means of destructive and non-destructive tests (NDT) methods to the assessment of the mechanical performances of SCC at hardened state were used. The use of experiment factorial design method allows us to have behavior laws to predict the mechanical strength response when combined with (NDT) according to a numerical model in such study. Hence, a numerical modeling of mechanical response could be derived by such statistical analysis in regards to the effects of factors and their interaction. The results obtained showed that the incorporation of limestone filler in the composition of the SCC improves the fluidity with limited segregation, as well as the good mechanical performances (resistance to compression and flexion). The numerical modeling of the predicted compressive strength response, in particular at the age of 28 days, is judged to be with an acceptable determined coefficient R2 equal to 0.994.

The self-compacting concretes are distinguished by an extreme fluidity, allowing their placement
without vibration.mineral additions and admixture are two essential components for the
formulation of self-placing concretes (SCC). They are introduced into the concrete to improve
their rheological behavior in the fresh state, but also to participate in enhancing the mechanical
properties and durability of concretes, especially in the case of active additives.
In this study, a test program was performed on self-placing concretes composed of cement and
silica fume and lime filler as mineral addition. The rheological parameters (viscosity and yield
strees) were measured using the rheometer at the fresh state. Mechanical characterization was
performed by means of the direct (compressive) and non-destructive testing methods (NDT),
ultrasonic velocity and rebound hammer for the assessment of the mechanical responses in the
hardened state.
The results obtained showed an advantageous effect of these combined additions with an optimal
dosage of 10% (5 % Silica fume + 5 % Limestone), with regard to the improvement of the
rheological and physico-mechanical properties of the self-compacting concrete mixtures studied.

Le béton autoplaçant est un béton innovant; qui se différencie d’autre type de bétons par sa forte fluidité qui le permet de prendre son place sans aucune vibration ainsi il présente une stabilité satisfaisante. Ce type de béton nécessite une formulation spécifique qui contient deux composants de plus q’un béton ordinaire, les adjuvants et les additions minérales ; ces composants servent à améliorer la rhéologie, les propriétés mécaniques et la durabilité du béton.
Dans cette démarche d’étude, un programme d’essais a été effectué sur des bétons autoplaçants formulés à base de ciment et d’ajouts minéraux, la fumée de silice et filler de calcaire. La série d’essais comprend des essais d’ouvrabilité (boite en L et essais de stabilité aux tamis) pour déterminer les paramètres rhéologiques principalement la fluidité, des essais mécaniques (essai de compression et de traction) ainsi que des essais de durabilité (Absorption d’eau).
Les résultats obtenus montrent un effet avantageux de ces additions combinées à un dosage optimal de 10%, quant à l’amélioration de la stabilité au tamis, la résistance mécanique et la durabilité des bétons autoplaçants étudiés.

Résumé :
Cette étude a été menée pour répondre à deux préoccupations principales, la possibilité de
formuler des BAP à base des matériaux locaux (granulats recyclés) et l’influence du dosage
d’une addition de fumée de silice et fillers calcaire sur le comportement rhéologique et
mécanique des bétons autoplaçants. L’objectif de ce travail, est d’optimiser la formulation du
BAP, par le choix du type et la proportion de l’ajout afin d’améliorer les propriétés mécaniques
du béton autoplaçants (essais destructifs et essais non-destructifs), en même temps de garder
les bonnes propriétés rhéologiques du BAP (capacités de remplissage, de passage et la
résistance à la ségrégation). Les résultats obtenus montrent que l’utilisation de la fumée de
silice seul ou combiné avec du calcaire à un taux limité améliore la performance d’une façon
remarquable des BAP recyclés à base de ces ajouts par rapport à un béton recyclé témoin (sans
fillers).

Cet article a pour objet de déterminer les propriétés mécaniques des blocs de terre comprimée (BTC) produits à base d’un sol peu plastique prélevé de la ville de M’sila.
Ces blocs ont été renforcés par des fibres végétales localement commercialisées (fibres de sisal). Ces fibres ont été ajoutées en différents pourcentages 0 ; 0,2 ; 0,3 ; 0,4 et 0,5 par rapport à la masse totale du bloc. En plus du renforcement mécanique, par fibres, les blocs ont été stabilisés par un liant hydraulique. L’objectif principal de ce travail de recherche consiste en l’étude de l’effet de ce traitement combiné (chimique et mécanique) sur les propriétés physico-mécaniques du produit final

An experimental program was conducted to studying the effect hardening the initial steam by solar energy on the compressive strength of concrete containing the limestone fillers. We set the same criterion of workability to all concretes made order to lead a rational study. In the first instance we started with evaluate the influence of the addition of limestone fillers at the cement on the compressive strength of concretes with age a function of the content of cement the limestone fillers. Thereafter, we studied the hardening effect the initial steam by solar energy on the compressive strength of concretes containing the limestone fillers. The introduction of the addition of the limestone fillers in the cement production enables, in addition to the ecological and economic gain, an improvement in the compressive strength of concretes, also the results obtained show that the use of hardening the initial steam by the solar energy improves the compressive strength of concretes compared with the curing with water, during the first seven days of hardening.

experimental program was conducted to studying the effect hardening the initial steam by solar
energy on the compressive strength of concrete containing the limestone fillers (LF). We set the
same criterion of workability to all concretes made order to lead a rational study. In the first instance
we started with evaluate the influence of the addition of LF at the cement on the compressive
strength of concretes with age a function of the content of cement the LF. Thereafter, we studied the hardening
effect the initial steam by solar energy on the compressive strength of concretes containing the LF.
The introduction of the addition of the LF in the cement production enables, in addition to the ecological and
economic gain, an improvement in the compressive strength of concretes. This improvement results primarily
from three effects: a physical effect, a physical-chemical effect and a chemical effect. These effects act
simultaneously and in a complementary manner. The results proved that up to 20% LF to replace cement could
be used with a fineness of 5000 cm²/g without affecting adversely the compressive strength, with an optimum
effect for a percentage of the order of 10%.
The results obtained show that the use of hardening the initial steam by the solar energy improves the
compressive strength of concretes compared with the curing with water, during the first seven days of hardening.
Concerning the influence of the LF under steam curing at 35°C, it can be observed that after 7 days, the
compressive strength of concretes (C10 and C20) is superior than the reference concrete (CO).
Saves time to reach the compressive strength at 28 days at water after steam curing for a day prolonged than
3 days of curing in water for concretes (C10 and C20); and prolonged by 7 days at the curing in water for
concrete (CO). For concretes (C10 and C20): 1 day steam curing at 35°C and 7 days at the curing in water, the
acquired resistance is higher than that obtained from curing in water at 28 days. Based on the results obtained it
was confirmed the contribution of the steam curing at the initial steam by solar energy to improve the
compressive strength of concretes containing the LF.
These results well justify interest that present the hardening technique to the initial steam by the solar energy
for allows rapid formwork removal a short-term resulting in an accelerated gain of compression strength and a
great economy of electrical energy, accelerating the cement hydration reactions (a rapid initial hydration),
acceleration cadences by reducing the setting time, so a faster progress of chantiers and accelerated rotation
especially in precast plants, as well as cold weather concreting.
Keywords: Concrete ; Hardening the initial steam ; Solar energy ; Limestone fillers; Compressive strength.
A

Cette étude vise à valoriser les déchets de béton sous forme de granulats dans les
mélanges de béton compacté au rouleau (BCR). Les particules de granulat recyclé ont été
ajoutées aux mélanges en remplacement partiel du volume total de graviers à différents
pourcentages (25%, 50%, 75%, et 100%). La démarche expérimentale entreprise dans ce
travail de mémoire consiste à étudier l’influence du granulat recyclé sur les propriétés du
BCR, aussi bien à l'état frais qu’à l'état durci.
En présence du granulat recyclé, le BCR est devenu moins dense, plus ségrégé, et
plus absorbant à l’eau. Le principal inconvénient lié à l’incorporation du granulat recyclé dans
le BCR est la chute des propriétés mécaniques. Pour remédier à ce problème, nous avons
procédé au traitement des granulats recyclés en les lavant et également à l’addition du produit
de cure (MEDACURE) et le laitier. Les résultats obtenus montrent qu’il est possible
d’améliorer la performance du BCR à base des granulats recyclés par modification de la
rugosité de surface du granulat recyclé. En effet, une grande partie de la chute de résistance
induite par le granulat recyclé a été corrigée.
Mots clés :
BCR, granulat recyclé, valorisation, résistance, amélioration, Laitier.

The aim of this paper is to investigate the effect of hot climate on the performance of roller-compacted concrete which is used for pavement. Mixes were placed in different environments in order to simulate the local climate conditions. Large-scale test has been carried out to assess the mechanical strength development in function of curing mode, temperature treatment and silica fume addition. Compressive strength, splitting tensile strength, shrinkage and capillary absorption of water were evaluated according to the program tests. The main results showed that an increase in temperature (over 40°) affects negatively the physical and mechanical properties due to malformation of hydration products, while cure methods showed a higher efficiency of the improvement in such properties. However, it should be noted that the wet cure method gave the best results as it provides appropriate and effective conditions to the hydration process. Regarding the effect of silica fume addition, even an improvement in the compressive strength was confirmed; however, it has a negative impact on the shrinkage.

Les bétons autoplaçants se distinguent par une forte fluidité, permettant leur mise en place sans vibration. Les additions minérales et les adjuvants sont deux composants indispensables pour la formulation des bétons autoplaçants (BAP) ; ces deux constituants régissent le comportement rhéologique de ces bétons spéciaux. L’incorporation de ces additives dans la squelette des bétons vise à améliorer leur comportement rhéologique à l’état frais, mais aussi pour participer favorablement au profit des propriétés mécaniques et la durabilité des bétons, notamment dans le cas d’ajouts actifs utilisés.
Dans cette étude, un programme d’essais a été effectué sur des bétons autoplaçants formulés à base de ciment et d’ajouts minéraux, la fumée de silice et filler de calcaire. La série d’essais comprend des essais d’ouvrabilité (étalement, boite en L et essais de stabilité aux tamis) pour déterminer les paramètres rhéologiques principalement la fluidité, ainsi que le seuil de cisaillement et la viscosité à l’aide du rhéomètre à l’état frais. Une caractérisation mécanique a eu lieu aux moyens des méthodes directes (écrasement) et essais non destructifs (ultrason, scléromètre) pour l’évaluation de la réponse mécanique à l’état durci.
Les résultats obtenus montrent un effet avantageux de ces additions combinées à un dosage optimal de 10%, quant à l’amélioration des propriétés rhéologique et physico-mécaniques des bétons autoplaçants étudiés.
Mots clés ; Bétons auto plaçant, la fluidité, rhéologie, additions minérales, viscosité, essais non destructifs (END).

The additions of supplementary cementitious materials are currently part of the latest developments in the production of cement, resulting in a significant improvement of the mechanical performances of cementitious materials. On addition to that, their use has as objective to reduce the clinker consumption so that to contribute in a simple and economic manner in solving the environmental problems. This experimental work consists to make a cement with mineral admixture while replacing a certain percentage of clinker by slag (0%, 6%, 10%, 20%, 25%, 30%, 35%, 40%, 50%, 65%, 70%, 80%, 85% and 90% ) in order to study its effect on the physico-chemical properties of cement manufactured with mineral addition and the mortar mechanical response. The physic-chemical properties of cement at anhydrous state and the hydrated state, as well as the characteristics of the mortars made at their bases, such as shrinkage, expansion, and the mechanical properties, have been studied. According to the experimental results obtained, it comes that the quantity of mineral additive (slag) and the chemical composition of cement manufactured are the principal parameters that influence on the variation of physico-chemical properties and the mechanical strengths (flexural and compressive) of the mortars tested.

Abstract. The use of fibers into cement–based materials has been studied extensively and as a
result of this research and development, a wide range of fibers is now available to be used in
cementitious materials. However, little work has been done on the addition of fibrous waste to
the cement, mortar and concretes to investigate this by-product fiber as reinforcing material
due the absence of industrialized fibers in many countries.
The main aim of this experimental study is to investigate the suitability of using fibrous waste
as a reinforcing material for cement-based materials. Presentation of such fibrous waste is
presented in this paper. The influence of type and content of fibrous waste is evaluated. The
results obtained, from series of trails, shown that some physical and mechanical properties of
the fibrous waste’s composite material are improved

The aim of the present work is to investigate the effect of marble waste fillers incorporation on the mechanical properties of
Recycled Aggregate Concrete (RAC). The RAC studied mixes were 0, 5, 8 and 10% (by weight of cement) of marble fillers
respectively. Direct tests of compressive and flexural strength and non-destructive testing (NDT) (rebound hammer, ultrasonic)
were performed. The optimal content of 5% marble fillers showed an improvement for both used test methods (compression,
flexion and NDT). The increase of RAC compressive strength was about 15%, whereas the flexural strength reached 10%
increase compared to control natural crushed aggregate concrete (CAC).
Key words: marble fillers, mechanical strength, natural aggregate, non-destructive testing (NDT), recycled aggregate concrete

A study of the effects of partial replacement of clinker by limestone in the cement manufacture

Blast furnace slag (BFS) and natural pozzolana (NP) have been widely used as a partial cement replacement in concrete
construction due to their advantages including cost reduction and improvement of the ultimate mechanical and durability
properties. Based on an ongoing experimental program, this research emphasizes on the effect of substituting cement with Blast
furnace slag and natural pozzolana up to 40 % on compressive strength and capillary water absorption of concrete. The
compressive strength was determined on prisms at the ages of 7, 28, and 90 days. Cylindrical specimens were employed for
capillary water absorption test after 28 days of curing. The results show that it is possible to obtain the same or better strength
grades by replacing cement with BFS up to 30% in concrete. However, the use of NP content reduced the compressive
strength. Lower capillary water absorption for BFS or NP substitution is observed.

During the last decades, the sector of construction has known a growing trend in construction and demolition (C&D) activities.
The management of the collected debris and waste causes real problems at the environmental level, which can be seen in the
decrease space in urban area and the agriculture land occupied by the waste of demolition. At the moment, researchers in civil
engineering domain are called to propose new solutions to find substitutions of the natural aggregate such as, the recycled
aggregates (RA) as an alternative for natural crushed aggregates (CA). This study here in focuses on the use the recycled
aggregates coming from old concrete tested specimens from construction sites. The aim of this research is the formulation of a
recycled aggregate concrete (RAC) within similar performances (resistance and durability) to conventional concrete (CAC).
The superplastizier as admixture at dosages 0 %, 0.5 %, 1 %, 1.5 % and 2 % was combined with a recycled aggregate at 100%
replacement. The physico-mechanical properties at fresh and hard state were investigated, mainly the density, absorption, air
content, elastic modulus and strengths. In addition the NDT test methods (ultrasonic and rebound hammer) were used to assess
the compressive strength of the due concrete. The correlation study of strength (Rc ) and the properties; such as elastic dynamic
modulus (Ed), ultrasonic velocity (V), rebound hammer number (Is), absorption (A) and the density (γ) to predict the
compressive strength in this particular case was considered.

The needs of the construction sector are still increasing for concrete. However the shortage of natural resources of aggregate could be a problem for the concrete industry. In addition, the negative impact on the environment is due to the construction demolition; where disposal wastes create a severe ecological and environmental hazard. In the last decade, a major interest has been developed for the reuse of recycled aggregates that present more than 70% of the concrete volume. The reused products should fulfill the requirements of lower cost and better quality, in order to establish its role in the concrete. The aim of this study is to assess the effect of the local admixtures on the mechanical behavior of recycled aggregate concrete (RAC). Physical and mechanical properties of RAC were investigated including density, compressive and flexural strength. The non-destructive test methods (NDT: pulse-velocity and rebound hammer) were used to determine the concrete strength. The results obtained were compared with crushed aggregate concrete (CAC) using the normal compressive testing machine test method. Thus, the convenience of indirect tests in the case of a recycled aggregate concrete were demonstrated.

Le sable de dune est largement disponible en Algérie, il est devenu un palliatif contre le déficit en sables que connaissent quelques régions. En effet, les sables de dune sont des matériaux très fins, monogranulaires et siliceux, leurs caractéristiques affectent les propriétés du béton à l’état frais et durci. La présente étude traite l’amélioration des propriétés du béton affectées par l’utilisation des sables de dunes, en incorporant un adjuvant superplastifiant, en ajoutant du sable concassé (sable correcteur) et en combinant les deux solutions. Les résultats obtenus montrent que la correction granulométrique du sable de dune améliore les propriétés mécaniques du béton.--------------------(November 6-7, 2012).

Experimental Study of Concrete Curing in Hot Climate

qsssssss

Admixtures effect on the properties of recycled concrete aggregate

« Influence de l’ajout de déchets fibreux sur le retrait d’un mortier »

Influence of fibrous waste addition on the shrinkage of mortars

Optimisation of fibres reinforced concrete mix design

Optimisation composition , béton en fibres