Durability Properties Of Mortar Research Articles

Mechanical and durability performance of ternary blended calcined clay and pulverized granite mortar composites

ABSTRACT Partially replacing cement with pozzolans, apart from the enormous technical benefits, has been reported as an effective approach to reducing greenhouse gases emanating from cement production. Calcined clay and pulverised granite, in recent years, have been experimented individually for their use as filler or pozzolan in concrete to improve workability and compressive strength. This research includes study of the synergistic characteristics of these two mineral admixtures and their influence on the mechanical and durability properties of mortar. Cement was partially substituted with 5–20% by weight of the composite material to form a ternary blended cement composite. The compressive strengths of the ternary blended cements were evaluated at 3, 7, 28 and 90 days. Durability properties such as alkali silica reactivity (ASR), rapid chloride permeability test (RCPT) and performance of the blended cements in aggressive media have been discussed. Test results indicated that, blended cements containing 5% and 10% of the pozzolan recorded similar compressive strengths at 28 days and outperformed it by 2.4% and 0.6% respectively at 90 days. Beyond 10% replacement, compressive strengths declined. The ternary blended cements were found to be highly reactive, potentially causing ASR in concrete than the reference cement.

Hydration, Reactivity and Durability Performance of Low-Grade Calcined Clay-Silica Fume Hybrid Mortar

Low-grade calcined clay, due to its low cost, availability and low temperature calcination, has been gaining attention in recent times as a supplementary cementitious material (SCM) in the manufacture of revolutionary building materials to improve the fresh and hardened properties of concrete. Silica fume, on the other hand, has been used, over the years, to improve the performance of concrete due to its reduced porosity and improved transition zone quality. In spite of the individual contribution of these two pozzolans to the strength and durability of concrete, there is a knowledge gap in the properties of ternary blended mixes utilizing calcined clay and silica fume. In this study, the synergistic effect of calcined clay and silica fume on the fresh and hardened properties of cementitious mortar have been investigated. The two pozzolans were used to partially substitute Portland cement to form a ternary blended composite binder having, at a maximum, a replacement of 30% by weight and a varying content of calcined clay and silica fume. The influence of the binary and ternary blended mixes on hydration, pozzolanic reactivity and the mechanical and durability properties of mortar was studied. From the results, partial replacement of cement with 30% calcined clay and silica fume caused significant reductions in the portlandite content of the two hydrated pastes at all curing ages. Drying shrinkage was found to be less severe in the control mortar than the blended cement mixes. Compared to the blended cement specimens, the control suffered the most weight (13.3%) and strength (10%) losses, as indicated by the sulphate resistance test.

Activated sugarcane bagasse ash as efficient admixture in cement-based mortars: Mechanical and durability improvements

Biomass ashes can be used in cementitious materials as cement or sand substitution. Nevertheless, ashes resulted from the combustion of biomass in generation plants present drawbacks that can reduce their potential use if they are not previously treated. In this research, industrial sugarcane bagasse ash (SCBA) was mechanically activated by grinding and its effects evaluated when used as mineral admixture in cementitious materials. Four different substitution rates (0%, 10%, 20% and 30%) where used to investigate the influence of the amount of ashes replaced on the durability and mechanical performance of mortars and identify the optimal substitution rate. To get a thorough comprehension, results were also compared to mortars containing untreated ashes. The combination of a performance-based testing campaign (compressive and flexural strength, open porosity, apparent density, water capillary absorption, surface electrical resistivity, rapid chloride migration coefficient) and a set of analytical techniques (XRD, FT-IR, SEM and TGA-DTA) enabled to characterise the mechanical and durability properties of mortars and identify the mechanisms behind the results. The research concluded that, at 28 days, the incorporation of ground SCBA enhances the compressive strength of mortars up to 62%, decreases the porosity of samples by 35%, highly improves the resistance to the diffusion of chlorides by 10 times and improve the interfacial transition zone by narrowing and closing the gap between aggregates and pastes.

Enhancing the mechanical and durability properties of subzero-cured one-part alkali-activated blast furnace slag mortar by using submicron metallurgical residue as an additive

Cold weather (<0 °C) is known for its detrimental impacts on concrete, and thus expensive and energy-consuming heating and insulation systems are used in cold-weather concreting to prevent frost damage. Supplementary cementitious materials are not recommended for use in cold-weather concreting because they slow down the setting time of concrete. In this study, one-part alkali-activated slag (AAS) was presented as an alternative environment-friendly binder for winter construction. The impacts of iron-containing submicron metallurgical residue on the reactivity, hardened properties, and durability of subzero-cured one-part AAS pastes and mortars were comprehensively studied. The incorporation of submicron particles (SMPs) enhanced the reactivity of AAS pastes by increasing the amount of precipitated hydrate phases and developing supplemental hydration products like calcium ferrosilicate hydrate. The positive effects of SMPs were highlighted via the denser microstructure, higher ultrasonic pulse velocity, increased compressive strength, and better durability properties of the AAS mortars. These improvements were attributed to the nucleation and filling behaviors of the added SMPs. On the contrary, decreased subzero curing temperature hindered the reaction progress, which adversely affected the hardened and durability properties of the mortars and limited the SMPs efficiency. With additional above-zero curing, higher compressive strength and lower water absorption and permeable porosity were measured in the AAS mortar cured initially at −5 °C compared to that cured at +20 °C.

Effects of cyclic carbonation and chloride ingress on durability properties of mortars containing Trass and Pumice natural pozzolans

AbstractWith an increase in CO2 emission, corrosion of reinforcement as a result of carbonation has become more significant to researchers besides corrosion due to chloride ion ingress. Many structures are exposed to coupled effects of carbonation and chloride attack; therefore, investigating the effect of this combined attack on the durability of concrete is a vital subject. Also, the use of supplementary cementitious materials (SCMs) has become more common due to their contribution to concrete's properties. In this study, the combined effect of chloride attack and carbonation on the durability of mortars containing SCMs was studied. Two natural pozzolans (Pumice and Trass) were used as cement replacements in mortar mixtures with three w/b ratios of 0.485, 0.44, and 0.4. Four exposure conditions, namely normal (immersed in lime‐saturated water), chloride attack, carbonation, and cyclic carbonation and chloride attack were considered. Compressive strength, carbonation and chloride penetration depth, capillary water absorption, surface electrical resistivity, and chloride diffusion tests were performed. The results indicate that while carbonation depth is reduced in the combined attack environment, it imposed a more severe corrosive condition in comparison to pure immersion in saline water by increasing the diffusion coefficient up to 500%. Also, addition of pozzolans showed the potential to reduce the diffusion coefficient of the mortars as much as 76% pointing out that mortars without pozzolans were more vulnerable to this combined attack environment. Furthermore, cement replacement with Trass and reduction of w/b showed to be beneficial in reducing the destructive effects of the combined environment.

Influence of Granite Powder on Physico-Mechanical and Durability Properties of Mortar.

This study explored the pozzolanic reactivity of granite powder (GP) and its influence on the microstructure of cement paste. An analysis of the physical properties (water demand, setting time, heat of hydration and total shrinkage), compressive strength and durability indicators (water absorption, porosity, acid attack and chloride ions diffusion) was carried out on mortar containing 10%, 15% and 20% of GP as partial substitution to cement (CEM I 42.5 R) in the short and long term. The results showed that the GP does not exhibit pozzolanic reactivity and that it reduces the heat of hydration. Water demand and setting time were not affected by the GP. The compressive strength decreases with increasing the content of GP; but in the long term, the compressive strength was not affected for 10% GP substitution. The presence of granite powder in mortar induces an increase in porosity, which led to an increase in the diffusion properties of fluids (capillary water absorption and chloride ions diffusion).

Experimental study on effects of natural admixture on blended mortar

The present study deals with the incorporation of the Natural admixture Egg as an admixture to the mortar and also the Silica fume and Fly ash as partial replacement materials for cement. Construction industries are the paramount key to find alternatives for the industrial byproducts. Since they possess the pozzolanic property they are used in this study for the replacement of cement. The study aims at heat curing of mortar at specified temperature to compare the results that of normal mortar. The natural admixture with 3 different percentages respect to water to bind ratio are chosen and the respective results were found. The mechanical and durability properties of mortar were done to analyze the conclusion for this project. The mortar with 15% of partial replacement for cement with Silica fume and Fly ash were found to be optimum with 0.50% of Natural admixture Egg.

Silica fume-hydrated lime blended cements: contribution of pre-blending to strength development in mortars

ABSTRACT This paper presents an experimental study on the mechanical properties at 28 days of mortars comprising Condensed Silica Fume (CSF), Hydrated Lime (CH) or both, at various substitution rates and water-to-binder ratios (w/b). An evaluation of the mechanical properties has been carried out using Ultrasonic Pulse Velocity (UPV) tests and compressive/tensile strength tests, to assess CSF, CH and CSF-CH addition and substitution rate effect on strength development. A marked increase in the mechanical properties of the CSF, CSF-CH mortars is noted, with the best results obtained after CSF-CH pre-mixing, reaching 35.71% improvement vs control, highlighting the occurrence of considerable pozzolanic reactions. UPV tests have shown increased velocities for CSF and CSF-CH mixes, transcribing a densification of the matrix. The results of the study seem to indicate that CSF and CSF-CH addition could represent a suitable solution to significantly increase both the mechanical and durability properties of mortars.

Calcium sulfoaluminate and alkali-activated fly ash cements as alternative to Portland cement: study on chemical, physical-mechanical, and durability properties of mortars with the same strength class

There is an increasing interest towards the development of alternative binders for the manufacture of sustainable mortars and concretes. Ordinary Portland cement (OPC) is the most commonly used material in construction, even if its production process is highly polluting. Both calcium sulfoaluminate (CSA) and alkali-activated cements (AAC) are potential alternative binders to be used in both structural (R3 class, with Rc ≥ 25 MPa) and non-structural applications (R1 and R2 classes, with Rc ≥ 10 MPa and Rc ≥ 15 MPa, respectively) according to UNI EN 1504-3. This paper reports the hydration mechanisms and the evolution of porosity of OPC-, CSA- and AAC-based binders. The properties of fresh and hardened mortars, belonging to the above-mentioned mechanical strength classes, were evaluated and compared with particular emphasis on durability properties in terms of capillary water absorption, drying shrinkage, and resistance to sulfate attack. The results show that CSA-based mortars exhibit the lowest drying shrinkage due to their highest elasticity modulus. AAC mortars are characterized by the highest water vapor permeability and the lowest capillary water absorption for the highest presence of large pores (>3000 nm).

Effect of fly ash on mechanical and durability properties of mortar containing microfibers with different length

Cement was replaced by fly ash to improve the mechanical properties of the mortars, and microfiber was added to the mixtures to improve the durability properties of the mortars. This study also investigated the effect of microfibers on the durability index values of cement mortars with fly ash content. In the preparation of the samples, CEM I 42.5 R-type cement, standard sand and fly ash (FA) were used as raw materials. Three different sizes of polyamide micro-synthetic fiber were added to mixtures. 0.5% (by mass) fiber was added to mixtures. Physical properties were determined according to Archimedes' principle after 28 and 90 days of curing. Then, compressive and flexural strength tests were performed. In conclusion, strength increased with an increase in curing time, and ≥30% FA addition increased water absorption, resulting in a decrease in mechanical strength. FA addition up to 20% improved the 90-day specimens‘strength. The 28-day specimens no R1228 (46.4 MPa) and 90-day specimens no 2FA1290 (49.1 MPa) had the highest compressive strength. According to the durability index, FA replacement improved durability. Although the results varied according to fiber lengths, it was concluded that the use of 12 mm fiber was more suitable in terms of durability.

Study in the Durability of Silane-Based Mortar

Abstract This article investigates the durability properties of mortar containing three types of silanes as integral additives. Compared with the plain mortar, mortar samples with silanes exhibited better performance when subjected to freezing-thawing cycles and chemical and carbonation corrosion. The addition of silanes also results in the formation of chemical bonding across the interface, which is helpful for improving crack resistance. Additionally, mortar samples with γ-Glycidoxypropyl methyldimethoxysilane (GDMMS) show better freezing-thawing resistance and chemical corrosion resistance than do mortar samples with γ-aminopropytriethoxysilane and 3-(Trimethoxysilyl)propyl methacrylate, because of the more effective interface between the GDMMS and mortar. For mortar samples with silanes, the effect of the types and quantity of silanes on the crack resistance of mortar and carbonation corrosion is not obvious. Scanning electron microscopy images show that silanes perform the networking and “coupling” effect to hold mortar particles, resulting in the improvement of mortar durability.

A comparative study: Effects of different nanoparticles on the properties of gold mine tailings containing cement mortars

In this study, fresh and hardened features of gold mine tailings containing cement mortars prepared with various ratios of CuO, SiO2, and Al2O3 nanoparticles were investigated. The setting time, compressive and flexural strength, Differential thermal analysis (DTA)/Thermogravimetric analysis (TG), Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), Fourier Transformed Infra-Red (FT-IR), Scanning Electron Microscope (SEM) and water absorption tests were carried out to observe the mechanical, thermal and durability properties of mortars. According to analyses results, the highest increment in the compressive strength was obtained for 0.2 wt% SiO2 addition as 11.46%. BET results conformed to strength test results and lower ratios of nano-CuO and nano-SiO2 improved the microstructure of mortars when nano-Al2O3 did not show the same effects for all replacement ratios. On the other hand, 2.5 wt% nano-Al2O3 increased the water absorption resistance of mortar up to 45.22% of the reference sample.

Evaluating the Effects of Sugarcane-Bagasse Ash and Rice-Husk Ash on the Mechanical and Durability Properties of Mortar

AbstractThe influence of sugarcane-bagasse ash (SCBA) and rice-husk ash (RHA) as cement replacement materials on the mechanical and durability properties of mortars was investigated in this study. ...

Effects of Environment in the Microstructure and Properties of Sustainable Mortars with Fly Ash and Slag after a 5-Year Exposure Period

Nowadays, getting a more environmentally sustainable cement production is one of the main goals of the cement industry. In this regard, the use of active additions, like fly ash and ground granulated blast-furnace slag, has become very popular. The behaviour, in the short-term, of cement-based materials with those additions is well-known when their hardening is produced under optimum conditions. However, real structures are exposed to different environments during long periods, which could affect the development of microstructures and the service properties of cementitious materials. The objective of this work is to analyse the effects in the long-term (up to 5 years approximately) produced by the exposure to different non-optimum laboratory conditions in the microstructure, mechanical and durability properties of mortars made with slag and fly ash commercial cements. Their performance was compared to that observed for ordinary Portland cement (OPC) mortars. The microstructure has been analysed using mercury intrusion porosimetry. The effective porosity, the capillary suction coefficient, the chloride migration coefficient and mechanical strengths were analysed too. According to the results, mortars prepared using slag and fly ash sustainable commercial cements, exposed to non-optimum conditions, show a good performance after 5-years hardening period, similar or even better than OPC mortars.

Combined effect of isobutyltriethoxysilane and silica fume on the performance of natural hydraulic lime-based mortars

Natural hydraulic lime (NHL)-based mortars were prepared by introducing isobutyltriethoxysilane (SO) and silica fume (SF) as partial replacement of NHL by percentage of 20%. Main physical, mechanical and durability properties of mortars were evaluated. Compared with control mortars, apparent density, water absorption and shrinkage of modified mortars decreased, mechanical and durability properties were improved. Generally, SF was more effective than SO in improving main physical and mechanical properties of mortars. The reason was attributed to pozzolanic reaction between SF and Ca(OH)2, which generated more hydrate product and refined pore structure. SF modified mortars showed the highest compressive strength (CS). The combined use of SF and SO showed the largest improvement in mortars’ flexural strength (FS) and bond strength (BS), for that SO played a bridge coupling role between components in mortars. Durability properties of mortars were greatly improved by the presence of SO and it was related to water repellency of SO. Mortars prepared with SF and SO had the highest durability.

Evaluating the effects of sugar cane bagasse ash (SCBA) and nanosilica on the mechanical and durability properties of mortar

Influence of nanosilica and sugar cane bagasse ash (SCBA) on the mechanical and durability properties of mortar, is investigated in this study. Sixteen mortar mixtures were designed with a particular water to binder ratio of 0.485 and a sand to binder ratio of 2.75. Test specimens were prepared with 3% and 6% replacement of cement weight with nanosilica and a 10–30% replacement of cement weight with SCBA. A compressive strength test was applied to evaluate the mechanical performance of mortars containing nanosilica and SCBA. In addition, transport tests, chloride permeability, electrical resistivity and mercury intrusion porosimetry of single, binary, and ternary blended mortars were conducted to investigate the influence of replacement materials on durability properties of mortars. Nanosilica improved mechanical and durability properties of mortar, while SCBA did not have a substantial influence on mortar performance according to lower strength and durability at early ages. The addition of SCBA in mixtures containing nanosilica intensely decreased compressive strength at the ages of 3days and 7days. However, ternary mixture results showed the best performance in the long term.

Effects of treatments on biomass bottom ash applied to the manufacture of cement mortars

The use of biomass for power generation is increasingly common. However, one of the most important problems when using biomass is the amount of waste produced in the combustion process such as ash, which must be transported to landfills for deposition.Biomass bottom ash may contain a large amount of organic matter which is the most restrictive property for reusing this by-product. The potential reuse is determined by chemical and physical properties. The presence of light particles and organic matter confer to biomass bottom ash certain physical and chemical characteristics which significantly reduce the possibility of reuse. Previous studies have demonstrated the possibility of using biomass bottom ash in cement-treated materials, but its properties imply a decrease of compressive and flexural strength.Therefore, this paper reported the study of the mechanical and durability properties of mortars containing biomass bottom ash applying different processing methods. Cement was replaced with different rates of substitution of biomass bottom ash and several samples were treated applying different techniques, such as grinding, elimination of lightweight particles and combustion.The results showed significant improvements in the mechanical and durability properties of mortars in which some treatment were applied. Lightweight particle extraction and organic matter removal by burning considerably improved the mechanical behaviour of the manufactured mortars. Therefore, mortars with crushed biomass bottom ash without floating particles and without organic matter led to a 10% of compressive strength decrease with respect to the control mortar.Thus, this study displays a possibility of waste valorisation by means of to the reuse of this type of by-product in mortars and concretes manufacture.

The Influence of Metakaolin from Saaba (Burkina Faso) over Physico-Mechanical and Durability Properties of Mortars

The paper evaluates the feasibility of reducing clinker in the Portland Cement production using local metakaolin in Burkina Faso. Standardized testing methods have been used for this purpose, and experiments were performed on mortar prisms containing different amounts of metakaolin. Important results about the physical, mechanical and durability characterization of blended mortars were carried out in this study. The obtained results are discussed based on available literature data. These results have shown increased physical and durability properties for blended mortars. Although the mechanical strengths remained relatively low for higher MK incorporations, the latter grow to surpass these of PC mortars (the reference) at 28, 56 and 90 days of curing. The results in the paper, have confirmed the possibility of using metakaolin to partially substitute cement, a possibility to reduce the CO2 production by the cement industry in Burkina Faso.

An investigation on mechanical and durability properties of mortars containing nano and micro RHA

This study investigated the effects of nano rice husk ash (NRHA) and micro rice husk ash (MRHA) on chloride permeability, electrical resistivity, capillary absorption and compressive strength of mortars. It was found that the incorporation of NRHA and MRHA enhanced mortar performance in the long term, whereas NRHA contributed to considerable enhancements at both early and long-term ages. Results proved that the strength and durability properties of mortars containing NRHA up to 7.5% levels of replacement by weight of cement gradually enhanced in comparison with control mix. However, mortars incorporating 2.5% NRHA together with 12.5% MRHA demonstrated the best improvements for durability and strength development at the age of 90days.

RETRACTED: Microstructure and durability properties of cement mortars containing nano-TiO2 and rice husk ash

Abstract In the present study, Compressive strength, water absorption, electrical resistivity, Rapid Chloride Permeability Test (RCPT) and Ultrasonic Pulse Velocity (UPV) tests of the hardened composites incorporating two supplementary cementitious materials: agricultural waste ash namely as rice husk ash (RHA) and nano-TiO2 (NT) in cement mortars were investigated. The interfacial transition zone (ITZ) and the microstructure were studied by using Scanning Electron Microscope (SEM) and X-ray Diffraction (XRD) analysis, respectively. Compressive strength results showed a substantial improvement in samples containing NT and also a slight increase in mortar performance was observed by using up to 10 wt% of RHA as a replacement of cement. However, binary mixtures displayed the best results for strength development and durability. It is also seen that a combination of 15% RHA and 5% NT in mortar led to a positive contribution to durability properties. XRD analysis showed that intensity of Alite and Belite phases decreased and new peak of portlandite achieved with the addition of NT. The SEM micrographs illustrated the widespread distribution of mortars containing NT with packed pore structures which resulted in promoting of strength and durability of specimens. Consequently, the combined mixture of RHA and NT has led to the enhancement of strength and durability properties of mortars. In general, it seems that 15% RHA and 5% NT can be considered as a suitable replacement regarding to the economic efficiency and hardened properties.