Papers by Keyword: Mortar

Abstract: Chloride ions penetrated reinforced concrete structures. Corrosion of reinforcing bars occurs because of cracks due to corrosion expansion, which is a problem of chloride damage deteriorating structures' performance. Blast furnace slag (from now on referred to as "BFS") is the inevitable by-product of steel product manufacturing as sustainable materials. BFS is more effective in preventing corrosion of reinforcing bars in concrete due to the denser cured and its high ability to immobilize chloride ions. Thus, the influence of BFS on the durability of mortar using BFS powder with different basicity was studied by using "Standard on Test Methods for Chloride Ion Diffusion Coefficients in Concrete" by electrophoresis (Draft) (JSCE-G571-2003)" and the total chloride ion amount was measured following JIS R 5202. The result confirmed that the immobilization performance could be greatly improved by increasing the basicity. It was remarkable in the case of air curing, a curing method for available precast products.

Abstract: Polycarboxylic acid-based superplasticizers are used for all types of concrete, but it is not well known that their fundamental performance changes with heating. Previous research confirmed that the superplasticizer storage environment changes its physical properties, which in turn changes the fluidity and workability of concrete or mortar. Therefore, this study confirmed the thermal stimulation effect on polycarboxylic acid-based and other superplasticizers and also confirmed the mechanism of polymer “entanglement” using superplasticizers that were centrifuged to simulate long-term storage. Based on the results, it was confirmed that the change in physical properties due to the change in environmental temperature is specific to polycarboxylic acid-based superplasticizers. It was also confirmed that centrifugal treatment of the superplasticizer slightly decreased its performance but increased the effect of thermal stimulation.

Abstract: The harmful impact of Portland cement manufacture on a global scale has prompted an extensive search for clinker replacement materials and alternative low CO₂ cements. This paper investigated prospects and application of Calcined Clay Pozzolan with Hydraulic Lime in built industry. Limestone and Raw clay from Ewekoro and Owode-Ketu areas in Ogun State were sourced for the production after being calcined in kiln at temperatures of 950°C and 700°C for 2 hours respectively. Binders were produced by blending Calcined lime (L) and Calcined clay (C) together by mass in different variations (20%L:80%C; 40%L:60%C; 60%L:40%C; 80%L:20%C; 100%L:0%C). Consequently, these binders were mixed with fine aggregate to produce mortar cubes at a mix ratio and water cement ratio of 1:3 and 0.5 respectively. An average of 3 cubes were cast per mix to produce a total of 90, 100mm cubes and cured by water sprinkling for 3, 7, 14, 21, 28 and 90 days respectively. These cubes were subjected to bulk density and compressive strength tests in order to ascertain their durability. Owode-Ketu calcined clay was found to be a class N Pozzolana according to ASTM C618-08. The densities and compressive strengths of the various cubes ranged between 1785 – 1870 kg/m³ and 0.15 – 1.09 MPa respectively for all the curing periods. The binder 60%L:40%C was found to be the best of all the binders owing to its compressive strength (0.89 MPa) after 28 days curing period. All binders except 100%L:0%C could be used in any masonry, rendering, plastering and pointing application because they exhibited compressive strengths in the range of 0.4 to 2.5 MPa after 28 days curing period.

Abstract: This study aims to explore the inclusion of microfibre in fine recycled aggregate (FRA) mortars under dynamic impact load. A 12-mm-diameter Split Hopkinson Pressure Bar (SHPB) was employed to test the impact of a recycled mortar with a single and hybrid fibre system and to determine potential improvements in its dynamic mechanical properties. In recycled mortar production, two microfibres with different sizes and types, namely, polypropylene and nylon, were added whilst keeping the amount of microfibres at a volumetrical fraction of 0.6%. An impact loading test was conducted by using the striking bar of SHPB at impact speeds of 2, 4 and 6 m/s. The effects of fibre on failure mode, tensile curve, compressive strength and dynamic increase factor (DIF) were then analysed. Experimental findings show that the improved mortar fibre mix has superior quasi-static and dynamic compression power compared with the reference mortar mix. Meanwhile, compared with the single fibre mix, the hybrid fibre mix is more effective in enhancing the dynamic compressive ability of the recycled mortar. The recycled-hybrid-fibre-enhanced mortar showed lower DIF values compared with the reference mortar, and the inclusion of fibre reinforcement can reduce the fragmentation of the recycled mortar mix after being subjected to impact.

Abstract: Environmental degradation caused by deforestation activities for harvesting of limestone from the hills and its calcination process at cement factory along with disposal of cockle shell waste from fisheries industries is in need of resolution. In view of sustainable green environment, approach of utilizing cockle shell waste as partial cement replacement in cement production would reduce pollution caused by both industries. Thus, this research investigates the effect of cockle shell powder as partial cement replacement on setting time and compressive strength of mortar. A total of five types of mortar mixes consisting different percentage of cockle shell powder as partial cement replacement from 0%, 10%, 20%, 30%, and 40% by weight of cement were prepared. Setting time test were conducted on fresh paste. All specimens were subjected to water curing until the testing age. Compressive strength test were conducted on hardened mortar cubes at 3, 7 and 28 days. Finding shows that integration of cockle shell powder as partial cement replacement influences the setting time and compressive strength of mortar. Suitable combination of 10% cockle shell powder successfully enhances the compressive strength of mortar. Conclusively, success in transforming the cockle shell waste to be used as partial cement replacement in mortar production able to reduce cement consumption, save landfill usage for trash dumping and promote cleaner environment for healthier lifestyle of community nearby.

Abstract: Around 1000 million waste tyres are generated annually and over 5000 million more are estimated to be discarded by 2030. It is estimated that one waste tyre is discarded per person in developed areas, hence 1 billion waste tyres are disposed worldwide. Waste tyre is difficult to manage as it takes up space, is difficult to compress and combustion of tyre releases highly toxic substance into the air. Hence, most of them end up in the landfill, as past research data estimated that currently 4 billion waste tyres can be found in landfills. In this study, up to 30% tyre rubber with a fine grind size of 300nm to 500nm was used as partial sand replacement in type N cement mortar. The rubber was treated with 1M NaOH solution to enhance its ability to bond with the other constituent materials. Tests were conducted to determine the properties of rubberised mortar, including consistency, compressive strength, flexural strength, water absorption and acid attack. From the test result, tyre rubber reduced the consistency and strength of mortar. Mathematical regression model showed that reduction of strength occurred in a second-order polynomial function with percentage of rubber. It was concluded that at up to 20% replacement rubberised mortar has the best resistance against water absorption and acid attack while still achieving the target strength.

Abstract: In recent years, concrete structures have tended to be taller and larger than before. With that trend, concrete as a material has diversified, and various kinds have been developed to meet differing quality requirements. In particular, the need for high-strength concrete is increasing. In general, high-strength concrete has a low water-binder ratio, so its workability is inferior to general concrete. Including admixtures such as silica fume is one way to remedy this problem. Previous studies have discussed the quality and hardening characteristics achievable using silica fume. Nevertheless, expected increasing demand for high-strength concrete dictates the need to understand not only its properties when fresh, but also to have an accurate picture of its vibration compaction properties on construction sites. In this study, the effect of adding silica fume on the workability of mortar was investigated by evaluating its fresh properties, plastic viscosity, and vibration propagation characteristics. Changes to mortar’s fresh properties due to pressure were also investigated to clarify its behavior in pumping environments. The study confirmed that the addition of silica fume decreases plastic viscosity and increases vibration propagation characteristics, and that increased plastic viscosity due to pressurization can be reduced.

Abstract: In the present work, the properties of Polyethylene Waste cement mortar containing Polyethylene Waste treated by a reactive material are tested and compared with normal Polyethylene Waste and normal cement mortar. The Polyethylene, which is cured by a different reactive material such as: (cement, a fly ash and silica fume) is used as fine as aggregate a volumetric fractional replacing of the sand in a cement mortar. The percent of replacement was 10% by volume, density, compressive strength, modulus of rupture, and absorption are tested for all mixes at variable ages. The current results display that the cure of Polyethylene by cement were significantly improves the characteristics of Polyethylene cement mortar. Moreover, the results show that all treatment improved properties of cement mortar as a compared with Polyethylene without treatment.

Abstract: Ashes from sugar cane’s residues is quantitively the greatest mineral residue generated from sugar ethanol industries which represent high calorific value, being able to be employed in a variety of products. In this present paper, it is proposed as final objective to analyze the viability of the partial substitution of this residue in mortar, study the resistance to axial compression and determine the influence of the residue utilization as alternative source to construction materials. Based on these mechanical tests, the results reveal the substitution of up to 10% (T1) of the cbc results in the production of a mortar within the developed standards in the experiment, fitting in the P6 Class of resistance to compression mortar for settlement and lining and roofs in the Technical Norm NBR 13.281:2005, leading towards superior values higher than 8MPa.

Abstract: This work evaluates mortars using sewage sludge calcined at temperatures of 600°C and 700°C as a hydraulic binder replacing the cement. The percentages incorporated by mass to replace the Portland cement were 10%, 20% and 30%, using the 1:3:0,60 (cement: sand: factor a/c) trace. Sludge ash was characterized and tensile strength at flexion as well as tensile strength (pullout test) were evaluated. As a way of performing a comparison with conventional mortars, the same tests were carried out using reference mortar. The results of the flexural tensile strength tests indicated that results were higher than the reference traces of the mortars with the calcined sludge at a temperature of 700°C, a factor related to the increase of the calcination temperature and the incorporated percentage. With respect to the tests on the determination of tensile strength, it was observed that the specimens submitted to the test suffered rupture in the mortar, and that the calcination temperature of the sewage sludge was not influenced. The results obtained with the mortars using sewage sludge ash with partial replacement of the cement are shown within the normative standards and approximate to the results obtained with the tests executed with the reference mortar.