Papers by Keyword: Compressive Strength

Abstract: Cost-efficient 3D-printing can create a lot of new opportunities in engineering as it enables rapid prototyping of models and functional parts. In the present study, Polylactic acid (PLA) cubic specimens with different types of infill patterns (IPs), rectilinear, grid and cuboid, were additively manufactured by Fused Filament Fabrication 3D-printing. The PLA cubes are fabricated with one perimeter and different IPs density (10, 20, and 30%). Subsequently, the compressive strengths of the PLA materials were measured in two loading directions, i.e., the layers building direction is parallel (PD) to the loading axis and perpendicular (ND) to the loading direction. An optical microscope was used to examine the deformed IPs in both loading directions. The compressive flow stress curves of the PLA cubes infilled with rectilinear and grid patterns exhibited strong fluctuations with lower compressive strengths in the loading direction along ND. The PLA with 30% grid IP revealed a superior strength of ~12 kN in the loading direction along PD. On the contrary, the same material exhibited a worst compressive strength 3 kN along ND.

Abstract: This investigation was carried out to identify the engineering properties of compressed interlock earth blocks manufactured from locally available lateritic soil and introduce to use the manufactured soil blocks to minimize the material and finishing cost for the low cost housing projects. The soil samples used in this study were well-graded lateritic sandy soil which has the composition of 1.9% gravel, 94% sand and 4.1% silt / clay. These soil samples were passed through the 100-mesh sieve and mixed with ordinary Portland cement to prepare the admixture. While compressing through a hydraulics jack by varying the compositions and the volume of soil-cement admixtures, compaction soil blocks were manufactured in a locally fabricated 250 mm x125 mm x100 mm standard steel mould. The manufactured soil blocks allowed to cure while spraying small quantity of water and covering with polythene for 28 days. Average compressive strengths of soil blocks made with 5% cement with 1.6:1 and 1.8:1 volume compactions were 1.3 Mpa and 1.9 Mpa, respectively. However, both compressive strength values were less than the standard limits of 2.8 MPa stated in SLS 1382:2009, local standards for soil blocks used for construction industry. However, soil blocks made with 10% cement under same compaction ratios attained compressive strengths of 3.0 MPa and 3.6 MPa respectively and it is above the required standards limits. However, 15% and 20% cement containing earth blocks have much higher compressive strengths but increase the cost of production. Regression analysis results confirmed the strong correlation between cement content and the compressive strength of the soil bricks. The soil bricks manufactured with more than 12.06% cement soil mix by maintaining compaction ratio into 1.6:1 or Soil bricks manufactured with more than 5.16% cement mix by maintaining compaction ratio into 1.8:1 will produce standards soil bricks for construction industry and these results further confirmed that wet and dry compressive strength of soil bricks will increase with increasing the compaction ratio and the cement content. However, when considering the compressive strength, water absorption level and cost effectiveness, soil bricks manufactured by maintaining compaction ratio into 1.8:1 with more than 5.16% cement mix will produce required standards cost effective soil bricks for construction industry.

Abstract: As the world population continues to increase, so does the demand for raw materials to produce basic needs of the human race. One of the areas where this pressing demand for means of production is evident is in the production of concrete materials for building construction and infrastructure. The source of constitutive materials for concrete production, such as cement and aggregates are fast shrinking across the nations of the earth, and there is an urgent need for substitutes that will guarantee the availability of this essential material to the built environment sector of the economy. One of the trending approaches is the adoption of waste materials as a replacement for some of the constitutive materials of concrete. This research reviews past works on the use of recycled plastic waste and periwinkle shells for the production of lightweight aggregate concrete. The results of this review showed that the adoption of a reduced percentage of waste plastic in concrete leads to acceptable strengths for lightweight concrete, economy, efficient energy and excellent crack resistance. The use of periwinkle shell is beneficial for satisfactory strengths for normal aggregate concrete and for lightweight aggregate concrete, excellent resistance to heat and economy. This approach is sustainable as a means of recycling and will facilitate the actualization of the sustainable development goal “Responsible Production and Consumption”, (SDGs 12). There is a perspective that combining these two waste materials will lead to improvement towards achieving sustainable concrete.

Abstract: There are many reasons neededfor continuous evolution in concrete technology; one of them concern on the greenhouse gas emission and depletion of natural resource as a results of high production of Portland cement. Many solutions are used to solve these problems; one of them is using cement replacement materials in concrete like metakaolin (in micro or Nano scale) which offered positive effect on the properties of cement concrete. Therefore, the main aim of this study is to evaluate and compare the effects of metakaolin (MK) and Nano-metakaolin (NMK) on some physical and mechanical properties of cement mortar. For this purpose, mortar mixes are prepared by substituting cement (by weight) with (10%) metakaolin or (1, 3, 5, and 7%) Nano - metakaolin. The amount of binder for mortar mixtures is 700 kg/m with a constant water / binder ratio of 0.33. Workability, apparent density, water absorption, compressive strength, and flexural strength of all mortar mixes are determined and compared with reference mix without any mineral admixture (0% MK or NMK). The results indicated that the performance of mortar mixes can be enhanced by metakaoline replacement. Furthermore, Nano-metakaolin has significantly positive impacts on the properties of mortar mixes which have found to be improved with increasing the Nano-metakaolin replacement, due to better pore refinement, micro filling action, and higher pozzolanic reaction. The optimum Nano-metakaolin substitution ratio (7%) causes increase in compressive and flexural strength reach to (82.6% and 59.5%), respectively compared with the reference mix, at age of 28 days.

Abstract: Pistachio shells (PS) are one of the agricultural wastes, that are considered as economic and wide available material. It has some features that encourage using it to produce lightweight concrete and cement mortar. The essential objective of the current investigation is to evaluate the possibility of incorporating PS as a fibre in the cement mortar and the effect on its properties. Four different fibre percentages (0%, 0.5%, 1% and 1.5% by volume of cement) were examined. After curing the samples for 7 and 28 days, the fundamental properties of the cement mortars, including splitting tensile and compressive strengths I addition to the density, were determined and compared. The results revealed that the optimum content of the pistachio shells fibre lies between 0.5% and 1% where the splitting tensile and compressive strengths increased and the mortar’s density reduced at age of 28 days.

Abstract: Non-Destructive methods have greater advantage in assessing the homogeneity, compressive strength, corrosion of rebars in concrete etc. of damaged structures. The aim of the present study is to assess the existing building, which is 41 year old, in the Technical Institute of Amara affiliated with the Southern Technical University, Maysan, Iraq. The research focus on the assessment of the concrete strength and the inspection of the damages in the building. Besides the visual inspection, the ultrasonic pulse velocity and schmidt hammer were used as a non-destructive test method for testing of 30 columns and 15 beams for a building consisting of three floors. The concrete compressive strength was estimated by using SonReb method. The equations proposed by Gasparik, 1984, Di Leo & Pascale, 1994, Arioglu et al., 1996, Cristofaro et al. (EXP), 2020 and Cristofaro et al (PW), 2020 were used for assessment the compressive strength of oncrete. The non-destructive test results indicated that the average strength of the structural elements greater than the design compressive strength of the tested elements. Therefore, the building can be considered structurally is safe.

Abstract: Copper slag can be considered as waste product which could have a favorable future in construction industry as a substitution to fine aggregates in concrete. Concrete is a very brittle material and in due course of time it tends to crack .These cracks, expands and corrodes the steel reinforcement which intensify the cost of maintenance and decreases the structural stability over periods of time. To avoid crack formation in concrete microorganism can be directly added to concrete during the mixing stage which is called as bacteria impregnated concrete. Bio concrete makes use of calcium carbonate precipitation in the presence of the suitable media results in microbial induced calcite crystals. This work reports an experimental procedure to investigate the effect of using copper slag in concrete when it is remedied by microorganism. Five series of concrete mixtures were prepared with different proportions of copper slag ranging from 0%, 25%, 50%, 75% and 100% to fine aggregate. Copper slag concrete mixtures were treated with 1% and 2% microorganisms by the weight of cement. All Specimens were cured for 7, 14 and 28 days before testing. Mechanical properties such as Compressive strength and Flexural Strength of Bacterial copper slag concrete were found and compared with the conventional concrete. The highest Compressive strength obtained was 45.6 Mpa at 75% substitution of copper slag with 2% microorganism and the corresponding strength for control mix was 26.8Mpa. The highest flexural strength obtained was 10.3Mpa and the corresponding strength for control mix was 4.5Mpa.It has been observed that 75% replacement of copper slag can be effectively used as a replacement for fine aggregate when it is treated by Microorganisms.

Abstract: This paper deals with impact of M-sand utilization rather than ordinary fine total (N-Sand) and iron shavings as far as volume of cement to improve the elastic nature of the matrix material. Basically, concrete is a composite material invented in ancient period for construction purpose. Out of the total volume of concrete 30% of volume filled with fine aggregate which is brought from digging of rivers, lakes, and canals, which causes serious tread to environment by land sliding. Now this research is carried out to identify the suitability of alternative material instead of natural sand. In this context manufactured sand produced from crushing of basalt stone is being replaced in various percentages as 0%, 20%, 40%, 60%, 80% and 100% in the place of natural sand for M25 Grade concrete. Also Iron shavings was added at 0%, 2%, 4%, 6%, 8% and 10% for total volume of concrete.

Abstract: The article is devoted to determining the patterns of improving the performance of concrete using hydro-remote ash-slag mix and polypropylene fiber. For this, a four-step methodology was developed for producing purified aluminosilicates from ash-slag mix. A set of experimental studies included the study of both raw materials and developed composites. The compressive strength, flexural strength, and freeze-thaw resistance were chosen as the target characteristics. The mechanism of the effect of purified aluminosilicates on the compaction of the composite structure was determined. At the same time, polypropylene fiber effectively inhibits the formation of cracks and they growth. The optimal composition is the replacement of cement with an ash-slag mix in an amount of 50% and in the presence of fiber. In this case, the compressive strength was increased by 19%, and the flexural strength by 122% compared with the reference composition. Thus, it was proved that both hydro-remote ash-slag mix and polypropylene fiber, and especially from combined use, make it possible to create effective fiber-reinforced concrete with excellent mechanical and durability characteristics.

Abstract: Introduction of finely disperse mineral additives of natural and man-made origin to Portland cement in order to improve the indicators of its physical-mechanical properties and partially replace clinker is one of the urgent directions for solving the resource and energy saving problems, as well as environmental protection problems in the production and application of building materials. The expansion of the raw material base of mineral additives can be achieved by using calcined polymineral clays, which are common in many regions of the Russian Federation, including the Republic of Mordovia. The article presents the results of research on the effects of calcination temperature and time of thermally activated polymineral clays of the Republic of Mordovia on their physical-chemical efficiency in cement systems. According to the study results of dehydration processes of clay minerals using the synchronous thermal analysis, it is established that the optimum calcination temperature for clays of Nikitsky and Staroshaigovsky deposits located in the area of 500–800 °C. This temperature range corresponds to the processes of the initial crystal structure restructuring of clay minerals of the kaolinite and illite groups, associated with their dehydroxylation, which contributes to the transition of these phases to the active form. The optimization of calcination parameters of polymineral clays based on the study results of influence of their additives on the mixed cement binder activity confirmed the thermal analysis data. It was found that the production of mineral additives with the highest values of the activity index is facilitated by 2-hour heat treatment of clays at 700 °C. At the specified calcination parameters, the replacement of 10% of Portland cement with the additive of thermally activated Nikitsky clay allows achieving the mixed binder activity that exceeds by 3 % the same indicator of mixed binder based on Portland cement and high-quality metakaolin.