Papers by Keyword: Lightweight Concrete

Abstract: As a country within the World Ring of Fire, Indonesia is a country prone to natural disasters such as earthquakes. As a result, casualties, damage to buildings and limited access to a number of isolated locations in remote areas. However, the handling of victims should not be slowed down. The development of civil engineering supports environmentally friendly behavior while creating building innovations from small mass materials that are able to reduce the weight of the building itself which has been a problem with the magnitude of the impact of earthquakes. The author conducted mechanical testing on lightweight concrete sandwich panel material as an initial study of the concept of earthquake-resistant houses. A number of tests were carried out, compressive strength on typical sandwich panels with wiremesh reinforcement, flexure tests, and shear tests on composite materials to develop the shear capacity of the panels in receiving the earthquake load distribution received by the building. For the purpose of maximizing the sliding capacity of wall panels, shear joint engineering has been obtained with the addition of glue and connectors. Respectively, the addition of 10 diameter threaded iron connectors is able to increase the load achievement by 10%, and then the addition of connectors and glue is able to increase the load capacity by 30%.

Abstract: This study investigated the use of Styrene Acrylic Emulsion (SAE) as a surface treatment for Oil Palm Shell (OPS) aggregates to enhance the mechanical properties of lightweight concrete. SAE, known for its superior adhesion, was applied to OPS to create a protective layer, addressing a gap in current research on OPS concrete. The research examined the impact of SAE-treated OPS under various curing conditions, assessing the compressive, flexural, and splitting tensile strengths. Results demonstrated that continuous water curing (NW) was the most effective for improving the compressive strength of treated specimens, particularly those with moderate SAE treatment (5%, 10%, and 15%). Specimens with 25% SAE treatment (ST25) exhibited reduced strength due to clumping and increased porosity. Flexural and splitting tensile strengths also improved with SAE treatment, with ST5 showing the highest flexural strength and ST10 performing best in splitting tensile strength tests. Alternating curing (AC) conditions showed moderate success, while external curing (EC) conditions negatively impacted strength due to rapid thermal cycling. Overall, the SAE treatment significantly enhanced the bond between the OPS particles and cement matrix, improving the mechanical performance of OPS lightweight concrete. These findings suggest that SAE-treated OPS could provide a sustainable and effective solution for concrete production.

Abstract: This study evaluates the impact of adding metalized plastic waste (MPW) fibers to lightweight concrete that is used as a filler material in building slopes and bridge ramps. The goal is to open up new opportunities for recycling plastic waste and promote a more sustainable and productive construction industry. This study examined the mechanical behavior of lightweight concrete (LC) at 3, 28, and 90 days, both with and without MPW fiber (1%, 2%, and 3%). Compression tests, 3-point bending tests, and pull-out tests were used to measure the fibers' compressive strength, flexural strength, and maximum load-bearing capacity, respectively. According to the results, the compressive strength (CS) and elasticity modulus (MOE) decreased with increasing fiber content when MPW fiber was added. In the long term, the CS and MOE decrease for the LC containing 3% MPW fiber was 8% and 7%, respectively, lower than for the control concrete. At 90 days, the flexural strength of the LC with 1% MPW fiber was marginally higher than that of the control concrete, rising by 2.40%. After this initial rise, however, the flexural strength declined as the fiber concentration increased, eventually reaching an 8% reduction for LC with 3% MPW fiber.The optimum method for determining maximal load-bearing and comprehending the deformation mechanism is hence the fiber pull-out test. The microstructure study of the LC examined how the pull-out test affected the quality of bonding at fiber-matrix interfaces. The tensile and flexural strength of lightweight concrete are enhanced by MPW fiber's ability to bear significant pulling stress.

Abstract: The purpose of this paper was to assess the effect of upcycling crushed lightweight bricks and plastic waste on the hardened properties of structural lightweight high-strength concrete before and after exposure to elevated temperatures. The lightweight concrete under study was prepared with sand, lightweight crushed bricks as fine aggregate, dolomite, coarse plastic waste, crushed lightweight bricks as coarse aggregate, Portland cement, silica fume (SF), and high-range water-reducing admixtures (HRWR). Besides the slump test, dry density, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity were investigated on the produced lightweight concrete. At the age of 28 days, the prepared samples were exposed to high temperatures of 100-800 °C in a preheated test furnace to evaluate the residual mechanical properties of the concrete. The experimental results showed that by increasing the aggregate replacement ratio, the workability slightly increased, and the mechanical properties of lightweight concrete decreased. It is also indicated that crushed lightweight bricks can be recycled as a replacement for natural aggregates to obtain high-strength lightweight concrete with appropriate properties. It has also been proven that crushed lightweight bricks and plastic waste can be used as fine and coarse aggregates to conserve natural resources without significantly deteriorating the properties of concrete. The incorporation of crushed lightweight bricks and coarse plastic waste into high-strength lightweight concrete showed better strength under elevated temperatures.

Abstract: The civil construction area is one of the activities with the highest consumption of raw materials, presenting a large generation of waste. The use of EPS polymer (expanded polystyrene), in addition to being technological, has a low environmental impact by reducing the use of traditional concrete inputs, in addition to being 100% recyclable, cost-effective. The study enabled the elaboration of the composite based on concrete with different contents of recycled expanded polystyrene (EPS) added (0.20; 0.10 and 0.05%, in % weight/weight). The use of this material allowed the partial replacement of standard sand in the composite aggregate, obtaining an environmentally sustainable material, with low specific mass, thermal resistance with insulating, hydrophobic properties that allow low water absorption, with a low impact manufacturing process. This addition of EPS to the fresh concrete mixture showed a reduction in water penetration, making the construction material more hydrophobic, minimizing infiltration problems, reducing the physical process of absorption. The specimens for the concentration of 0.10% (weight/weight) showed better axial mechanical performance, with an average of 11.4 kgf, 52% in gain of reinforcement effect, in relation to the concentration of 0.20% (weight/weight). For this concentration of 0.20 (weight/weight), the EPS beads obtained greater homogeneity in the dispersion in the cementitious matrix, promoting better impact absorption during mechanical efforts. The absorption test was carried out for 10 and 20 minutes, and with that the percentage of water absorbed for each composite was verified. The specimens prepared with higher contents of styrofoam (0.20% and 0.10%), with 0.98 and 1.29%, respectively, of absorbed water, showed a more hydrophobic character due to the higher percentage of presence of pearls. EPS, making the material less permeable to water. The absorption results were quite satisfactory, showing values ​​below 20%, as recommended in the NBR 8491 standard.

Abstract: Towards the sustainable development goals in the built environment, the use of waste and recycled sources has been attaining great interest among researchers and policy-makers, especially in concrete as the most used construction material. Excess use of natural aggregates, as one of the main components of concrete, causes the depletion of natural resources and the associated environmental problems, thus, the use of artificial and recycled aggregates is of great importance. In this regard, the production of lightweight artificial aggregates from industrial and hazardous wastes may be a promising solution that not only mitigates the depletion of natural resources but also stabilize those kinds of wastes. This study aimed to investigate the production of concrete with recycled aggregates from industrial wastes, mainly municipal solid waste incineration fly ash (MSWI-FA). To this end, different kinds of mix designs to manufacture the aggregates were developed based on MSWI-FA, ground granulated blast furnace slag (GGBFS), marble sludge (MS), and cement. The concrete samples containing different artificial aggregates, as well as recycled polyethylene terephthalate (PET) in the sand form, were produced and the properties, including compressive strength and thermal insulation, were evaluated. The obtained results of the lightweight concrete demonstrated enhanced thermal property (up to 30%), but at least 30% lower resistance with respect to the normal concrete produced from the natural aggregate.

Abstract: This work investigates the influence of date palm and sisal fibers on the mechanical and physical behavior of lightweight concrete based on expanded clay aggregates. The choice of these fibers types is aimed at the recovery of agricultural waste in Tunisia. Their exploitation serves to improve the mechanical and physical properties of a new material dedicated to filling and insulation in buildings. In this context, series of tests were carried out using untreated short fibers in lightweight concrete. The evaluation of the mechanical and physical behavior of the material was obtained by determining the compressive strength, bending strength and thermal conductivity. The results obtained showed the influence of the fibers volume fraction. For mechanical behavior, the optimum of fibers volume fraction was estimated at 1% for lightweight concrete with date palm and sisal fibers. The thermal conductivity is inversely proportional to the fibers volume fraction, which justifies the use of this composite as a filling and insulation material.

Abstract: The production of lightweight concrete is mainly carried out in the traditional way using lightweight ceramic aggregates. The aim of the pilot research was to verify the possibility of producing lightweight concrete based on artificial aggregate in the form of agglomerated aggregate from high temperature fly ash. A representative of such aggregate is the artificial aggregate referred to as aploporite. This aggregate is characterised by comparable grain strength to ceramic aggregates but, on the other hand, has a relatively high absorption rate of up to 30 %. Concrete formulations with up to 50% replacement of natural aggregate by aploporite have been proposed in order to achieve the volumetric weights characteristic of lightweight concrete. The results obtained confirmed that it is possible to produce lightweight concrete with this aggregate and to achieve strengths comparable to those of ordinary concrete.

Abstract: The two-way shear failure of concrete elements is sudden; thus, reliable design codes are a must. In this current study, three reliability methods were implemented, namely: the Mean Value First Order Second Moment (MVFOSM), the First-Order Second Moment Method (FOSM), and the Rackwitez-Fiessler procedure (RFHL-FOSM) on the two-way shear provisions of the European design code for lightweight concrete. A brief state-of-the-art review of existing reliability methods is presented and compared. An extensive experimental database of lightweight concrete slabs testing under two-way shear loading was gathered. The reliability index was calculated for the design code. This index was compared with the target values set by international standards. For two-way shear of lightweight concrete, the European design code was found to achieve the target of reliability. The MVFOSM was found to provide a better reliability index than using the FOSM.

Abstract: The use of the periwinkle shell in the production of lightweight concrete has been studied and accepted to be used for concrete works. Hard water containing detergent-like chemicals has been observed to be used in mixing locally produced concrete. This exploratory study is on the effect of water mixed with detergent in a concrete prepared with the periwinkle shell as a coarse aggregate. A total of 27 concrete cubes of size 150mmx150mmx150mm were prepared in the laboratory with a mix ratio of 1:2:4. A water-cement ratio of 0.4 was used with the addition of detergent at varying percentages (0%, 0.3% and 0.6). The cubes were cured in water and tested at 7days, 14days and 28days respectively. Laboratory tests, which includes bulk density, specific gravity, grain size analysis, slump and the compressive strength test was carried out on the aggregates and concrete. The periwinkle shell had a bulk density of 1440kg/m³and a specific gravity of 2.50. The workability tested revealed that the slump values increased with increase in the percentages of detergent. The compressive strength at 28days and at 0.3% and 0.6% were 12.58N/mm² and 14.06N/mm² respectively. It was observed that the compressive strength decreased with the addition of detergent because of the tiny air bubbles introduced into the concrete by the detergent. From the results of the study, it can safely be concluded that the use of detergent contaminated water in concrete production will reduce its compressive strength and increase its workability.