LIGHTWEIGHT MORTAR GEOPOLIMER BASED ON FLY ASH AND PALM ASH

This research discusses the use of alumunium powder in the manufacture of geopolymer mortar made from fly ash and palm ash, with the aim of knowing the optimal amount of alumunium powder mixture against the compressive strength of geopolymer mortar. The research method used experimental methods in the laboratory, to examine the compressive strength of different geopolymer mortar tests used in the form of cubes measuring 5 x 5 x 5 cm with a mixture composition of NaOH: Na2SiO3 = 1: 2.5, Activator: Precursor = 1: 1, Fine Aggregate: Precursor = 1.5: 1 Concentration of NaOH = 12 M for the ratio of fly ash use: palm ash = 75: 25% using alumunium powder as much as 0, 0.5, 0.75 and 1%. Mortar strength testing was carried out after 3, 7, 14, 21 and 28 days of maintenance The compressive strength results obtained in each composition of the geopolymer mortar mixture are for geopolymer mortar without a mixture of alumunium powder as large as Mpa, for geopolymer mortar with a mixture of alumunium powder as much as 0.5%, 0.75% and 1% have a compressive strength of 20.9 Mpa, 15.2 Mpa, 12.7 Mpa Dan 9,7 Mpa

The Study of Kenaf Powder Performance in Mortar

As cement is essential in producing mortar, reforms and innovations are needed to reduce the adverse effects of CO2 in the future. The objectives of this study were to determine the optimal amount of kenaf powder in mortar strength and to examine the mechanical and flexural properties of kenaf powder in the mortar. Thirty-six mortar cubes of 50 mm x 50 mm x 50 mm and 12 number of mortar prism were cast using mix ratio of 1:3 with two different water-cement ratios. The replacement of kenaf powder ranging from 10% to 20% to the cement matrix were tested to investigate the mechanical parameters such as workability, density, compressive strength, and water absorption capabilities. Furthermore flexural strength was assessed using a similar mix proportion. The mortar containing 10% of kenaf powder and superplasticizer additives had demonstrated the best performance in workability and improved the compressive strength and flexural strength.

Mechanism on Activation of Coal Gangue Admixture

Coal gangue, an industrial waste, is rich in silicon and aluminum phase and may be used as a mineral admixture in concrete after moderately stimulating activity, allowing for efficient solid waste utilization. This study used a mortar strength and activity evaluation method to investigate single or compound activation methods to find the optimum activation method of coal gangue. FLIR, XRD, and SEM were used to investigate the activation mechanism of different modes, providing a theoretical foundation for the study of coal gangue as a concrete admixture. Results showed that mechanical ball milling, microwave, and chemical activator could activate coal gangue, and the composite activation effect was the best. The fineness of the coal gangue powder was more than 300 mesh, according to the optimal compounding method. Accordingly, the particle surface was smooth, the internal defects were reduced, and the microwave irradiation temperature was 700°C–800°C, causing the coal gangue particles to form a bonding surface and gradually agglutinate and densify. Meanwhile, the layered structure of kaolin minerals was destroyed, and a significant amount of glassy active SiO2 and Al2O3 was produced, enhancing the gel ability and activity of coal gangue. Finally, 8% Ca(OH)2 was added in the production of mortar specimens, which increased the alkalinity of the slurry, stimulated the rapid cracking and secondary hydration of the coal gangue, and enhanced the strength of mortar. At this time, the activity rate of coal gangue powder reached the highest, which was 90.5%.

Verification of the Use of a Kučera Drill for Testing of Wood Properties

In common practice, we encounter cases where it is not possible to test the wood quality by destructive methods and it is, therefore, necessary to use non-destructive or semi-destructive methods, especially when the wood is already used in construction. The article deals with the methodology of non-destructive and semi-destructive testing of wooden structures using the methodology commonly used for the diagnosis of masonry structures, where mortar strength is tested using a so-called Kučera drill, and with verification of the applicability of this method in the testing of wood properties. Kučera drill was specially modified for the purpose of the experiment and its functionality was tested. The depth of penetration of the drill into the test specimen was tested. The article describes the principle of measurement and the design of the initial experiment, but also the pitfalls, which had to be faced.

The Effect of Fine-Ground Glass on the Hydration Process and Properties of Alumina-Cement-Based Composites

This paper discusses studies regarding the impact of fine-ground glass additives on the hydration and properties of alumina cement pastes and mortars. Fine-ground glass was added to pastes and mortars instead of high-alumina cement and calcium aluminate cement in quantities of 5% and 10%. The findings are inconclusive as to the impact of glass on the properties of tested alumina cement types. The effect produced via the addition of glass instead of cement depends on the type of alumina cement used. Adding fine-ground glass to high-alumina cement enhances the paste’s density while improving paste and mortar strength. Using the same additive for calcium aluminate cement reduces its density and strength. The addition of glass to high-alumina cement adversely affects its strength at higher temperatures.

The Influence of Water/Binder Ratio on the Mechanical Properties of Lime-Based Mortars with White Portland Cement

Protecting the built cultural heritage is one of the most important tasks in architectural practice. The process of repair is time-consuming, weather-dependent, and sensitive to materials applied. Introducing new materials in historic building repair in order to decrease the time needed for repair, brings some risk in the preservation process. The most common material for masonry repair is lime mortar. Adding cement to lime mortar can improve the mechanical properties of mortar and speed up the repair process. The high amount of cement may increase the strength, but decrease ductility and permeability of mortar, causing damages to protected buildings. An increase in strength with the smallest amounts of cement demands optimization of water content in the mixture. Tests were performed to investigate the influence of the water/binder (w/b = water/(lime + cement) ratio on mortar strength and water permeability. An air-entraining agent (AEG) was introduced to improve permeability. Results confirmed that adding small amounts of cement to lime (20% by weight) and decreasing of w/b ratio, improves the strength, with almost negligible influence on water permeability. The addition of very small amounts of AEG did not decrease the strength, nor the permeability.

Local Buckling Behavior of Buckling-Restrained Braces with Longitudinally Profiled Steel Core

One of the most important requirements for a well-designed buckling restrained brace (BRB) under severe earthquake loading is to ensure its stability until the brace achieves sufficient elasto-plastic deformation. This study presents the finite element analysis results of the proposed buckling restrained brace with a longitudinally profiled steel core (LPBRB). The objective of the analyses is to conduct a performance evaluation of the proposed LPBRBs, and to perform a parameter study with different clearance, width:thickness ratio, mortar strength, and friction coefficient for investigating the local buckling behavior of the LPBRBs. Numerical analyses results demonstrate that the LPBRBs exhibited good ductile performance and stable hysteretic behavior. The local buckling failure can be predicted by the demand:capacity ratio formula. The friction coefficient has little influence on the hysteretic behavior of LPBRBs. The local stability can be improved by adopting the mortar with higher compression strength or the LP core with lower width:thickness ratio. The proposed LPBRBs have a similar hysteretic response to the conventional BRBs.

Effects of mortar compressive strength on out of plane response of unreinforced masonry walls

In this study, the out-of-plane response of infill walls that are widely used in Turkey and the surrounding regions were experimentally investigated. Several out-of-plane wall tests were performed in the laboratory, with the walls specimens produced with lateral hollow clay bricks (LHCB) and different mortar qualities. The walls were tested in their out-of-plane (OOP) direction under static load conditions and evaluated based on the load-bearing and energy dissipation capacities, crack propagations, mortar strengths, and initial stiffnesses. These walls are experimentally investigated to understand the effects of the mortar strength on the infill wall structural behaviors and to assess the effectiveness of the out-of-plane strength formulations. It was found that when the mortar strength is low, the first major crack occurs at the mortar, however, because of the arch mechanism efficiency in this situation the OOP load-carrying and energy dissipation capacities of unreinforced walls can be significantly increased. When the first major crack in the wall occurs in the brick itself, the arc mechanism is provided with delicate sections in the brick, which leads to strength decreasing in the walls. In this case, excessive deviations occur in the out-of-plane strength formulations estimates. This study shows that the arc mechanism, the damage start region and progress can change significantly unreinforced masonry (URM) infill walls behaviors.

Experimental Investigation of Traditional Clay Brick and Lime Mortar Intended for Restoration of Cultural Heritage Sites

To properly restore masonry cultural heritage sites, the materials used for retrofitting can have a critical effect, and this requires standards for traditional Korean brick and lime mortar to be examined. This study experimentally investigated the material characteristics of Korean traditional bricks and two types of lime mortar (quicklime lumps and powdered hydrated lime) and the strength of masonry specimens made from those materials. Four different mixing ratios of lime, sand and white cement were considered as material parameters in this study. The experiment included uniaxial compressive testing and flexural testing to examine the mortars’ mechanical properties, and compression tests, triplet shear tests and diagonal compression tests for the masonry specimens. The results found that the strength of the masonry specimens was not necessarily associated with the mortar’s strength, but rather the cohesion between brick and mortar. In the material test, adding white cement had no noticeable effect on mortar strength. Meanwhile, in the masonry specimen, the effect of the added white cement was significant in terms of compressive and shear strength. This suggests that the bonding ratio between mortar and brick, which is an important factor influencing the behavior of bricks, was stronger with the addition of white cement. Furthermore, it was found that quicklime lumps had a lower strength than powdered hydrated lime. The test specimen with white cement added to powdered hydrated lime exhibited the greatest strength.

STRENGTH OF CONCRETE MORTAR PREPARED BY PARTIAL SUBSTITUTION OF CEMENT WITH RECYCLED GLASS POWDER

This experiment was conducted to determine the utility of substituting cement with the recycled glass powder (RGP) in mortar mixtures. A total of 21 mortar mixtures were produced using various RGP (FG) ratios (CG), and fly ash (FA) powders. The mortar mixtures were used to prepare cubes which were tested for 7-and 28-day compressive strength. The substitution of cement with FG and CG in mortar resulted in reduced 7-and 28-day compressive strength values. However, the amount and type of RGP substituted for cement plays a crucial role in the determination of mortar strength. Above contraction in compressive strength was observed at an initial maturity than at the final maturity. Further, replacement of cement with Fly Ash showed increase in compressive strength up to certain content. More research and testing for the optimal percentage and size of waste glass powder that can be used is required in flowable fill.