EFFECT OF PARTIAL REPLACEMENT OF SAND BY MSWI-BA ON THE PROPERTIES OF MORTAR

Disposal of municipal solid wastes (MSW) has recently become a major problem in Lebanon as finding appropriate landfill is becoming more challenging than ever. Incineration is a technique currently used to reduce the volume of MSW generated. The output of this treatment is a residue well known as Municipal Solid Waste Incineration bottom and fly ash. This study is focused on the mortar containing Municipal Solid Waste Incineration Bottom Ash (MSWI-BA) as partial replacement of sand. For this purpose, mortar specimens were prepared with 25, 50 and 100% (by weight) MSWI-BA to replace the sand. Specimens were cured in water for 2, 7, 14, 28 and 56 days. Testing included; compressive strength, ultrasonic pulse velocity (UPV), density, capillary water absorption (CWA) and total water absorption (TWA). Results indicate that 25% of sand can be replaced with MSWI-BA without significant alterations in mortar properties. Above 25% replacement levels, there is drastic decrease in compressive strength and UPV. The absorption by total immersion and capillary rise was found to increase as the replacement levels of sand by MSWIBA go up from 25% to 100% but significantly diminish as the curing duration increases beyond 7 days

THE EFFECT OF WALNUT SHELL ASH ON THE PROPERTIES OF CEMENT PASTE AND MORTAR: A STUDY ON PARTIAL REPLACEMENT OF CEMENT

In the pursuit of a more sustainable future, the utilization of agricultural waste in cementitious products has emerged as a popular and effective solution. The current study explores the feasibility of incorporating ash derived from walnut nutshells, considered agro residues, into eco-friendly blended cement paste and mortars to examine its impact on their properties. A range of blended cement mixtures was formulated by incorporating walnut shell ash (WSA) in three varying proportions of 5%, 10%, and 15% relative to the weight of the cement. Tests were conducted to investigate the properties of the blended cement paste and mortar incorporating WSA, covering consistency, setting time, compressive strength, ultrasonic pulse velocity (UPV), water absorption, and drying shrinkage. The addition of 5%, 10%, and 15% of WSA led to an increase in water demand by 33.6%, 37%, and 39%, respectively, compared to the control mix, which is 30%. Additionally, as the WSA content increased, the initial and final setting times decreased. For 15% WSA, the initial and final setting times reduced by 91.28% and 70.76%, respectively, compared to the control mix. WSA-blended mortars showed lower UPV values compared to the control mix at all ages. The addition of WSA to the mortar resulted in a reduction of compressive strength at all ages. At 28 days, mortar with 5%, 10%, and 15% of WSA showed a reduction in compressive strength by 11%, 22.6%, and 53.2%, respectively. WSA-blended mortar demonstrated greater drying shrinkage compared to the control mix at all ages, with 10% WSA exhibiting the highest shrinkage after 90 days. Mortar containing 10% WSA showed the highest water absorption after 28 days of curing, at 13.15%, which is 33.8% higher than the control mix

METHODS AND SURFACE MATERIALS REPAIR FOR CONCRETE STRUCTURES – A REVIEW

Concrete is a very critical material that may require maintenance and possible repair periodically, especially in important structure such as bridges. In general, concrete in structures (e.g. reinforced concrete) may be subjected to cracks due to a variety of reasons. These include, design and external environments such as the ingress of harmful ions into the concrete, unexpected extra loads including earthquakes. These cracks can affect not only the appearance of the structure but more importantly the structural performance of concrete and the integrity of the concrete structure. Therefore, when cracks occur a proper repair method should be selected, based on the intended performance of the structure and economy. This should be taken into consideration while choosing the repair method in order to end up with a structure that can serve for the intended service life. The type of crack, its location, dimensions, and many other factors shall be taken into account while selecting the suitable repair method. This paper is a review of the various types of cracks and repair techniques used in each case

A REVIEW ON THE USE OF VEGETABLE OIL AND ITS WASTE IN CONSTRUCTION APPLICATIONS

The generation of waste materials is causing an impact on the environment due to many reasons including the effect on human health and decrease in landfill space. Of these waste materials is the waste cooking oil. There are large amounts of waste vegetable oil generated in the world and most of it is disposed of in the sewer system which can cause problems when treating wastewater. This paper is a review of literature on the use of vegetable oil (VO) and waste vegetable oil (WVO) as chemical admixtures in construction materials. The construction materials include mainly concrete and pavement. The properties examined were fresh, mechanical and durability properties. Fresh properties included slump test while the mechanical properties comprised compressive and flexural strength as well as shrinkage. The durability and durability related properties consisted of water absorption both by total immersion and capillary action, carbonation and efflorescence. This review suggests that virgin vegetable oil and its waste has the potential to be used as chemical admixtures in construction materials to improve their workability water resistance

MECHANICAL AND DURABILITY PROPERTIES OF FLY ASH GEOPOLYMER CONCRETE – A REVIEW

Geopolymers have emerged as a promising alternative for Ordinary portland cement (OPC) in construction industry, due to their potential to minimize the emissions of carbon dioxide (CO2) and improve the efficiency of waste recycling. This paper aims to study the fresh and hardened properties of fly ash geopolymer concrete (GPC), as well as to review the raw materials used in the production of geopolymers. Several factors impact the mechanical and durability properties of fly ash GPC, including the specific type of fly ash utilized, the curing temperature, the alkaline activator (AA) concentration, and the type of AA used. As a substitute for OPC concrete, fly ash GPC provides better mechanical and durability properties, as well as reducing CO2 emissions

EFFECT OF HOT WEATHER CONCRETING ON THE MECHANICAL AND DURABILITY PROPERTIES OF CONCRETE-A REVIEW

Nowadays, hot weather is an essential motivator that leads concrete to lose its special characteristics. The high loss of moisture by evaporation and rapid hardening encourage the cracking potential and placement operations. The fresh mixed and hardened concrete tend to be damaged due to several conditions such as: high concrete temperature, High ambient temperature, low relative humidity, and high wind speed. These circumstances accelerate the rate of moisture loss and cement hydration. This article briefly reviews hot weather concreting problems precautions, and curing methods and also discusses the role of incorporation SCMs in reducing the temperature of concrete and enhancing its mechanical and durability performance

ASSESSING THE INFLUENCE OF OVERWEIGHT AXLES ON RUTTING LIVES IN FLEXIBLE PAVEMENTS USING PARAMETRIC SURVIVAL ANALYSIS

The existence of rutting or permanent deformation on flexible pavement layers has always been a concern that negatively affects the performance of roads by reducing the lifespan of pavement structure and by posing a safety risk for vehicles over the road. Traffic overloading is one of the primary factors that accelerates the deterioration of flexible pavement. This study aims to determine the time to failure of the flexible pavement structures associated with rutting, to indicate the most significant factors affecting rutting, and to assess the influence of overweight axles on pavement rutting life using parametric survival analysis. The data used in this study are extracted from the LTPP program. The outcomes provide researchers and agencies with a good knowledge of the relations between several predictors including overweight axles and pavement performance and hence increase the ability of pavement to continue functioning properly over the design lifetime. The results indicated the factors that have a significant effect on pavement rutting life. Also, the results revealed that a 1% increase in the percentage of overweight axles can be related to a 16.24% increase in the hazard rate of rutting failure. Moreover, the survival time of rutting life can be reduced by up to 63% with the increase of the percentage of overloaded axles from 0% to 20%

A NOVEL PROBABILISTIC FRAMEWORK OF RC CORRODED STRUCTURES UNDER DYNAMIC LOADING

Steel corrosion in reinforced concrete structures can lead to severe deterioration damage under static and seismic loads. In practice, it is essential to mitigate failure risk by quantifying the extent of damage and simulating the structural response of damaged structures. However, numerical modeling of the dynamic behavior of corroded structure is challenging due to high nonlinearity of the problem and its multidisciplinary nature. In addition, corrosion damage exhibits various sources of uncertainty that impede accurate deterministic modeling of the dynamic response of RC structures. Therefore, this study presents a simplified framework, to simulate the non-linear response of corroded structures under seismic excitation, in a statistical setting. The presented scheme employs set of state-of-art experiments and numerical investigations of corrosion effect and response to capture the generic non-linear response. The presented scheme is utilized to conduct reliability analysis for corroded structures under earthquake loads by incorporating different sources of uncertainties associated with the used mathematical models and model parameters. The power of the suggested probabilistic scheme is illustrated on two simulated structures, where two different statistical properties are considered; the initial statistical parameters and a real-time monitored statistic for the rate of corrosion

NEW TYPE OF LIGHTWEIGHT AGGREGATE FOR USE IN STRUCTURAL CONCRETE

This research studied the utilization of municipal solid waste incineration bottom ash (MSWI-BA) in lightweight coarse aggregate (LWC) production. A special method was followed to prepare the new aggregate to fully replace the normal aggregates (NWA) in concrete. The mechanical properties such as compressive strength, tensile strength, and elasticity modulus were investigated for the LWC concrete. Then, two beams were prepared; one from LWC and the other from NWC. The structural performance of beams made up of lightweight aggregates compared to normal aggregates was investigated. The results showed that this type of aggregates led to a 20% reduction in concrete density. There was a decrease in compressive strength, tensile strength, and elasticity modulus when using lightweight aggregates. In addition, there was a reduction in the structural performance of the NWC beam was better than the LWC bea

THE INFLUENCE OF BIO-INHIBITOR ON THE CORROSION RESISTANCE OF REINFORCED CONCRETE BEAMS CONTAINING MSWI-BA AS A PARTIAL SAND REPLACEMENT

In this paper, the corrosion behavior of reinforced concrete beams containing municipal solid waste incineration bottom ash (MSWI-BA) as a partial sand replacement and Ceratonia siliqua extract as a green corrosion inhibitor was investigated. Four mixes were prepared: (0 and 20% replacement of sand by MSWI-BA with and without Ceratonia siliqua extract). Tests conducted were UPV, compressive strength, split tensile strength, and elastic modulus. RC beams were prepared for determining the flexural performance. Eight beams were casted. Four beams were exposed to accelerated corrosion test and four beams were kept at room temperature. It was found that the compressive strength, tensile strength, and elastic modulus decreased when 20% of fine aggregate was substituted by MSWI-BA and when adding Ceratonia siliqua extract. In addition, the deflection and strain of beams increased. However, the presence of corrosion also affected the deflection and strain and led to increase their values