Cement Mortar Mixes Research Articles

An Investigation on Effect of Oil Palm Shell Ash on Flexural Strength and Compressive Strength of Cement Mortar

One of waste agriculture materials is oil palm shell ash. It has been producing in high quantity in palm oil mill, and for storage of that an investment requires. In this paper, an attempt has been made to analysis effect of oil palm shell ash on compressive and flexural strength of cement mortar. The compressive strength and flexural strength of cement mortar has been measured. To improve accuracy of work 50% cement and 50% fine sand has been proposed in cement mortar mix design. The results have been indicated that the effect of OPS ash on flexural and compressive strength of cement mortar is not same. The deflection, load sustainability and time to failure for compressive strength have independent fluctuation of flexural strength. The positive and negative effect of OPS ash on mechanical properties of cement mortar has been observed. The morphology of crack failure has not been investigated. The work can be continued with many waste agriculture materials. Keywords: waste agriculture, deflection, load sustainability, time to failure.

Oil Palm Shell Ash: Cement Mortar Mixture and Modification of Mechanical Properties

The waste agriculture materials cause environment pollution, recycle of these materials help sustainable development. This study focused on the impact of used oil palm shell ash on the compressive and flexural strengths of cement mortar. Two different cement mortar mixes have been designed to investigate the impact of oil palm shell ash on strengths of cement mortar. Quantity of 4% oil palm shell ash has been replaced in cement mortar. The main objective of this paper is, to modify mechanical properties of cement mortar by replacement of oil palm ash in it at early age of 7 days. The results have been revealed optimum quantity of oil palm ash for replacement in cement mortar. The deflection, load to failure, time to failure of compressive strength and flexural strength of all specimens have significantly been improved. The stress-strain behavior has been indicated ability of modified cement mortar in control stress path and strain. The micro property of cement paste has not been investigated.

Mechanical performance and durability of treated palm fiber reinforced mortars

The performance of cement mortar reinforced with varying percentages of treated bundled date palm fibers is investigated to appraise their feasibility for structural and non-structural applications. The study first entailed the evaluation of two different alkali pre-treatments at varying concentrations by subjecting treated and untreated bundled fibers to tensile testing. The suitable pre-treatment was then adopted while casting cement mortar mixes. The physical properties of fresh mortar was studied through setting times and, for mortar mixes cured up to 28 days, through parameters such as drying shrinkage and water absorption. The unconfined compressive strengths, split tensile strengths as well as the flexural strengths of the cured mortar mixes at two different ages were undertaken to assess their mechanical properties; while the durability was gauged based on their sulfate resistance for up to a period of four months. Observed stress–strain behavior under tension led to the choice of 0.173% Ca(OH)2 as the preferred pre-treatment for the bundled fibers used in the mortar mixes. This was further supported by the microstructural examination on the hardened mortars which, revealed that the integrity of treated fibers remained intact within the cement matrix without hindering the hydration processes. Results also indicated that inclusion of fibers improves the flexural strengths as well as the sulfate resistance of the mortar mixes. However, the cylinder and cube compressive strengths decreased with the increase in treated fiber inclusion. Although, the work reported in this paper was carried out on cement mortars, conclusions are expected to be relevant to fiber reinforced concrete employing treated natural fibers.

Laboratory study on the properties of plastering mortar modified by feather fibers

AbstractThis laboratory study explores the development of plastering mortar modified by feather fibers, so as to lay the groundwork for utilizing poultry feathers in thermal-insulation materials and removing them from waste streams. The laboratory testing measured the consistency value, porosity, compressive strength and thermal conductivity of various cement mortar mixes as a function of feather fiber dosage. The experimental data were used to determine the appropriate weight fraction of feather fibers in the mortars for thermal insulation. The results indicate that the incorporation of feather fibers decreased the consistency value of fresh mortar and increased the surface roughness and porosity of hardened mortar. Under the investigated conditions, as the content of admixed fiber increased, both the compressive strength and thermal conductivity of hardened mortar decreased remarkably before leveling off. The desirable dosage of feather fibers falls in the range of 0.2–0.7% by mass of dry mixture.

The engineering properties of high performance concrete with HCWA–DSF supplementary binder

High calcium wood ash (HCWA) and densified silica fume (DSF) exhibit good cementitious properties and has a great potential as supplementary binder material for the concrete production industry. The experimental investigation was conducted to study the properties of HCWADSF cement and the mechanical behaviour of HCWA–DSF high performance mortar. A total of twelve different blended cement pastes and mortar mixes were fabricated with the use of HCWA at various cement replacement levels of 0% to 20% in combination with 7.5% densified silica fume (DSF) by total binder weight and subjected to rheological and mechanical strength tests. The rheological properties of blended cement paste studied are standard consistency, initial setting time and final setting time. The mechanical strength parameters of mortar covered in the study are compressive strength, flexural strength, static modulus of elasticity and dynamic modulus of elasticity. Experimental results indicated that the inclusion of HCWA at the content of 2–20% by binder weight does not have significant influence on the standard consistency of HCWA–DSF blended cement but significantly prolonged the setting times of the blended cement paste. The combined use of HCWA (2–6% by binder weight) and DSF (7.5% by binder weight) as supplementary binder material produced mortar mixes which exhibited compressive and flexure strengths which are 2.4–31.2% higher than equivalent ordinary Portland cement (OPC) mortar. Besides, the use of HCWA at cement replacement levels between 2% and 12% with 7.5% DSF by weight of binder was found to enhance the static and dynamic modulus of Portland cement mortar by 1.9–24.7%. The observed improvement in the mechanical properties is due to a significant densification in the microstructure of cement paste matrix in the presence of HCWA and DSF hybrid supplementary binder as observed from micrographs obtained in the study.

Effects of particle size of treated CRT funnel glass on properties of cement mortar

Over the last decade, new types of display technologies have increasingly replaced cathode ray tube (CRT) displays leading to an increase in the disposal of discarded old CRT monitors and TV sets. The present study is a further development of our previous work to explore the effects of using different size fractions of crushed CRT glass as 100 % substitution of sand in cement mortar. A range of cement mortar mixes were prepared and the tests conducted included table flow (fluidity), mechanical strength, drying shrinkage, alkali–silica reaction (ASR) expansion and toxicity characteristic leaching procedures. Generally, the results obtained for the CRT glass-based cement mortars were comparable to those of the beverage glass mortars except the hardened density due to the presence of lead in the CRT glass. Decreasing the particle size of the CRT glass led to a decrease in fluidity, compressive strength and water absorption. However, the use of finer glass particles slightly improved the flexural strength and reduced the risk of expansion due to ASR due to its pozzolanic reaction. The experimental results indicated that treated CRT glass can be utilized as 100 % replacement of sand in cement mortar regardless of its particle size.

Research on Polymer Latex Modify Comprehensive Properties of Cement Mortar

Aimed for current situation that most scholars concerned with mechanics, deformation, flow performance of modified cement mortar, the paper selected carboxyl styrene-butadiene latex as the modified material, researched on cement mortar’ water reducing effect, wear resistance, corrosion resistance-mechanical properties, drying shrinkage before modifing and after modifing. Compared cement fine mortar’s properties with cement mechine-made mortar’s properties before and after modification. Research results showed that the addition of carboxyl SB latex, the overall performance of cement mortar is greatly improved, and with the increase of polymer cement ratio, this improvement trend is more obvious, those changes especially are suitable for extra-fine cement mortar. The results clarify the properties variation law of cement mortar before and after modification, this provides scientific guidance for polymer latex modified cement mortar mix design.

COMPOSITE REINFORCEMENT FOR REINFORCED SOIL APPLICATIONS

Composite reinforcements achieve the desired performance with a synergetic action from two components. In this paper, development of a composite reinforcement system, made of high tensile steel wire, encased in a cement mortar as a viable system for soil reinforcement applications is proposed. The high tensile steel wire takes care of the tensile strength requirement, whereas the interfacial friction between the backfill and the cement mortar takes care of adequate frictional capacity requirement. Both requirements can be independently controlled, enabling an optimum design of the composite reinforcement from both the considerations for a given situation. The paper presents the development of the technique, behavior and analysis of failure mechanisms of composite reinforcement from pullout test results. The results demonstrate that pullout failure of the composite reinforcement, tensile failure of the steel wire and bond failure arising from the proportioning of cement mortar mix needs to be considered in the analysis.

Corrosion of reinforcement steel embedded in high water-cement ratio concrete contaminated with chloride

The aim of this investigation was to examine the role of internal chloride on the corrosion behaviour of steel in ordinary Portland cement (OPC), and sulphate resistant Portland cement (SRPC) mortar mixes of higher water-cement (w/c) ratios. For this purpose, the steel electrodes embedded in mortar specimens were subjected to short-term electrochemical monitoring. On completion of electrochemical monitoring, pore solution was extracted from the specimens for analysis. For the purpose of comparison, pore solution was also extracted from separate OPC and SRPC cylindrical mortar specimens hydrated in an environment isolated from the atmosphere. Results from microanalysis using scanning electron microscope (SEM) are also reported. The results demonstrated that mortars prepared with a cement of high tricalcium aluminate (C 3A) content, even when the w/c ratio of the mix was maintained at 0.70, still passivated the steel embedded in it even in the presence of chloride as high as 1% by weight of cement. Under a similar condition, the steel embedded in mortar prepared with a cement of low C 3A content was unable to passivate the steel electrode. The special protection mechanism by the lime-rich layer as proposed by Page for low w/c ratio concretes is also valid for the steel embedded in high w/c ratio mortar. The type of exposure condition (e.g. exposure to atmosphere) during the hydration period strongly influences the hydroxide ion concentration in the pore solution, while this has no effect on the freechloride concentration in the pore solution. This study reconfirms the significance of the C 3A phase of cement in respect to chloride-binding processes.

The structural properties and optimum mix proportions of palmnut fibre-reinforced mortar composite

Thirty six cement mortar mixes of widely differing water cement ratios were used to prepare fibre-mortar mixes with fibre volume fraction ranging from 0.5 to 4%. Relevant mechanical properties—compressive, tensile and flexural strengths of the composite were determined in order to study the effect of mix proportions on these properties. These properties were compared with those of corresponding plain mortar mixes. The results show that while palmnut fibre reduced the compressive and tensile strengths of mortar, the flexural strength of the composite is improved by up to 33%. A sand cement ratio of 2.0, water cement ratio of 0.60 and fibre volume fraction of 2.0% were found to be the optimum mix proportions.

Cement-based materials containing shredded scrap truck tyre rubber

Cement paste, mortar, and concrete (containing opc or opc and pfa) mixes were prepared using various proportions of either rubber crumb or low-grade rubber obtained from shredding scrap tyres. Properties examined for the 32 mixes prepared included density, compressive strength, impact and fire resistances, and nailability. Results showed that density and compressive strength of various mixes were reduced by the addition of rubber. (Rubber type had only marginal effect.) Density varied between about 1300 and 2300 kg/m 3. Compressive strength reduced by 70% when the proportion of rubber to total solid content by mass of concrete reached about 13%.

The mechanical and drying shrinkage properties of cement mortars containing carbide lime waste

The present study investigates the possibility of utilizing carbide lime waste, obtained from the generation of acetylene from calcium carbide, as a mineral filler material in various cement mortar mixes. The physical and chemical analysis of the waste were studied. Five mortar mixes containing various contents of carbide lime waste were prepared, tested, and compared with one control mix, to investigate the influence of the waste material on both fresh and hardened properties of mortars. The properties discussed were density, compressive strength, splitting tensile strength, flexural strength, and drying shrinkage. The strength and drying shrinkage values were determined at 3, 7 and 28 d, respectively. The results revealed that addition of carbide lime waste generally caused a reduction in both strength properties and density when compared with the control mix, in spite of the small influence on the drying shrinkage of some of the mortar mixes. However, the results obtained satisfy the minimum requirements of strength specified by British Standards, and hence it can be concluded that the material can readily be used for masonry mortar cement.

The effect of chloride ion source on the free chloride ion percentages in OPC mortars

The effect of incorporating varying percentages of sodium chloride (NaCl) and calcium chloride (CaCl 2) in ordinary Portland cement (OPC) mortar mixes on the free chloride ion content was investigated. After curing for 28 days with different levels of chloride ions, mixes were tested to assess the percentages of chlorides that remain in the pore solutions and those that are chemically bound by the cement hydration products. It was found that a considerable amount of chloride remains in a free form and that NaCl produces higher percentages of free chloride ions than CaCl 2 at all concentrations up to 2% (Cl − ion by mass of cement). NaCl was also found to produce lower pH than CaCl 2. Thus NaCl will present a greater threat in terms of corrosion of reinforcement than CaCl 2.

Pore structure of hardened cement paste and mortar

The paper describes an experimental investigation into the pore structure of hardened cement paste and mortar. The pore structure was studied using mercury porosimeter. Ordinary portland cement and natural river sand were used. Pore structure determination was carried out for both the cement paste and mortar mixes over four hydration periods and five water-cement ratios. The threshold radius which was found to be prominent in the hardened cement paste, flattens out as the fine aggregate content increased.