scholarly journals Nano-TiO2 in Hydraulic Lime–Metakaolin Mortars for Restoration Projects: Physicochemical and Mechanical Assessment

Buildings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 236
Author(s):  
Kali Kapetanaki ◽  
Chrysi Kapridaki ◽  
Pagona-Noni Maravelaki
Keyword(s):  
Mechanical Properties ◽  
Setting Time ◽  
Hydrated Lime ◽  
Pozzolanic Reaction ◽  
Plastic Behavior ◽  
Hydraulic Lime ◽  
Three Point Bending ◽  
Natural Pozzolans ◽  
Fine Aggregates ◽  
Lime Mortars

In recent years, lime mortars mixed with artificial or natural pozzolans are commonly used in restoration applications. The aim of this work is the assessment of carbonation, pozzolanic reaction, setting time, and mechanical properties of metakaolin–lime mortars mixed with crystalline nano-titania (nT) as additive. The studied mortars consist of hydrated lime and metakaolin in 60/40 ratio (wt%) and fine aggregates of either carbonate or silicate sand. The concentration of the nano-titania is equal to 6 (wt%) of the binder. For comparison purposes, three types of mortars and pastes are designed: Without the addition of nano-titania, with nT activated or not under UV irradiation. The evaluation of the carbonation and pozzolanic reaction over a 1.5-year curing period is carried out through thermal analysis (DTA/TG), infrared spectroscopy (FTIR) and X-ray diffraction analysis (XRD). The uniaxial compression and the three-point bending tests at 28 days, 3 months, and 6 months were carried out to evaluate mechanical properties. The addition of activated nano-titania, due to an increased photocatalytic activity, accelerated the setting of the mortars, improving at the same time the mechanical properties. The plastic behavior of the lime–metakaolin mortars with activated nT was attributed to the evolution of carbonation and pozzolanic reaction.

scholarly journals Utilization of Solid Waste from Brick Industry and Hydrated Lime in Self-Compacting Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1109
Author(s):  
Mati Ullah Shah ◽  
Muhammad Usman ◽  
Muhammad Usman Hanif ◽  
Iqra Naseem ◽  
Sara Farooq
Keyword(s):  
Mechanical Properties ◽  
Solid Waste ◽  
Manufacturing Industry ◽  
Setting Time ◽  
Hydrated Lime ◽  
Pozzolanic Reaction ◽  
Early Age ◽  
Cement Pastes ◽  
Brick Powder ◽  
High Degree

The huge amount of solid waste from the brick manufacturing industry can be used as a cement replacement. However, replacement exceeding 10% causes a reduction in strength due to the slowing of the pozzolanic reaction. Therefore, in this study, the pozzolanic potential of brick waste is enhanced using ultrafine brick powder with hydrated lime (HL). A total of six self-compacting paste mixes were studied. HL 2.5% by weight of binder was added in two formulations: 10% and 20% of waste burnt brick powder (WBBP), to activate the pozzolanic reaction. An increase in the water demand and setting time was observed by increasing the replacement percentage of WBBP. It was found that the mechanical properties of mixes containing 5% and 10% WBBP performed better than the control mix, while the mechanical properties of the mixes containing 20% WBBP were found to be almost equal to the control mix at 90 days. The addition of HL enhanced the early-age strength. Furthermore, WBBP formulations endorsed improvements in both durability and rheological properties, complemented by reduced early-age shrinkage. Overall, it was found that brick waste in ultrafine size has a very high degree of pozzolanic potential and can be effectively utilized as a supplementary cementitious material.

scholarly journals Lime based Dry Mixes with Carbonate Aggregates

2019 ◽  
Vol 8 (11) ◽  
pp. 3289-3292 ◽  
Keyword(s):  
Mechanical Properties ◽  
Quartz Sand ◽  
Carbonate Rocks ◽  
Physical And Mechanical Properties ◽  
Lime Mortar ◽  
Fine Aggregates ◽  
Lime Mortars ◽  
The Matrix ◽  
Optimal Values ◽  
Quarry Dust

The use of carbonate rocks as aggregates for cement concretes and mortars is limited due to their insufficient strength and the threat of corrosion. The use of quarry dust from crushing carbonate rocks are technically and economically feasible in building compositions based on air-hardening lime. The results of the study of the effect of replacing a part of quartz sand in lime mortar by limestone and dolomite fine aggregates on the basic physical and mechanical properties of lime mortars for restoration are presented in the paper. The matrix of planning experiments, which allows increasing the informativity of the research results in order to reduce the number of experiments in the search for optimal values, is proposed. The efficiency of replacement of the quartz sand with quarry dust of carbonate rocks in the production of dry mixes for restoration is shown.

scholarly journals CHARACTERIZATION OF LIGHTWEIGHT LIME MORTARS CONTAINING BRICK WASTE POWDER

2019 ◽  
Vol 22 ◽  
pp. 133-138
Author(s):  
Martin Vyšvařil ◽  
Tomáš Žižlavský ◽  
Patrik Bayer ◽  
Pavla Rovnaníková
Keyword(s):  
Mechanical Properties ◽  
Quartz Sand ◽  
Pozzolanic Reaction ◽  
Expanded Perlite ◽  
Pore System ◽  
Lime Mortars ◽  
Hardened Properties ◽  
Good Contact ◽  
Powder Content

This work deals with the effects of an expanded perlite (EP) on the hardened properties of air lime mortars with a 50% brick waste powder content. The influence of different substitution of quartz sand by EP is also monitored here. A relationship between EP content and physical-mechanical properties of mortar (flexural and compressive strength, pore system) and mortar frost resistance has been found. Very good contact between the binder matrix and EP surface was observed in microstructural images of mortars that conclusively exhibits the formation of products by pozzolanic reaction on the surface of EP. This work could be helpful for the establishment of the essential proportions of EP and quartz sand to be used in air lime mortars designed for restoration works.

Influence of the Variability of Limestone and Fly Ash on the Setting and Mechanical Properties of a Moroccan Composite Cement

2022 ◽  
Author(s):  
Nisrine El Fami ◽  
Hind Agourrame ◽  
Nacer Khachani ◽  
Ali Boukhari ◽  
Adeljebbar Diouri
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Setting Time ◽  
Physical And Mechanical Properties ◽  
High Energy ◽  
Pozzolanic Reaction ◽  
Cement Industry ◽  
Chemical Compositions ◽  
Significant Prolongation ◽  
Cement Manufacturing

The Moroccan cement industry is looking for new processes to effectively minimize the high energy costs associated to cement manufacturing. This work presents the effect of three types of limestone with different chemical compositions and different CaCO3 contents on the physical and mechanical properties of resulting composite cements by the addition of fly ash in the proportions by weight of: 5 % and 10 %. The samples are studied in order to evaluate the interaction between different types of limestone and fly ash. Ternary cements based on fly ash-limestone-clinker induce a significant prolongation of the setting time compared to binary cements based on limestone-clinker. The substitution of clinker by limestone induces an improvement in mechanical strength compared to ternary cements in the first days; at 28 days, cements prepared with fly ashes reach significant strength due to their pozzolanic reaction.

Effect of Admixture Dosage and Specimens Age on Mechanical Fracture Parameters of Lime Mortars Enhanced by Burnt Clays

2014 ◽  
Vol 1000 ◽  
pp. 356-359
Author(s):  
Hana Šimonová ◽  
Ivana Havlíková ◽  
Eva Navrátilová ◽  
Pavel Schmid ◽  
Pavla Rovnaníková ◽  
...  
Keyword(s):  
Hydrated Lime ◽  
Mechanical Fracture ◽  
Lime Mortar ◽  
Three Point Bending ◽  
Historical Materials ◽  
Brick Powder ◽  
Lime Mortars ◽  
Fracture Tests ◽  
Bending Fracture ◽  
Reference Mixture

In the restoration of historic buildings with priorities of historic preservation there exists an effort to modify the mortars by admixtures which are in compliance with historical materials and techniques. Therefore the specimens were made from lime mortar modified by brick powder or metakaolin. The reference mixture used only hydrated lime while the other mixtures were enhanced by brick powder or metakaolin in the amounts of 25, 50 and 100 % of the weight of hydrated lime. This paper presents the results of three-point bending fracture tests obtained by using double-K fracture model. The specimen’s age was 90 and 150 days.

Tensile Behaviour and Durability of Mortar-Based Strengthening Systems with Glass-Aramid Textiles

2014 ◽  
Vol 624 ◽  
pp. 346-353 ◽  
Author(s):  
Stefano de Santis ◽  
Gianmarco de Felice
Keyword(s):  
Mechanical Properties ◽  
Design Parameters ◽  
Tensile Behaviour ◽  
Masonry Structures ◽  
Hydraulic Lime ◽  
Experimental Campaign ◽  
Cement Mortars ◽  
Lime Mortars ◽  
The Matrix ◽  
Strength And Stiffness

Mortar-based composite materials are currently receiving great attention for strengthening masonry structures, especially when specific preservation criteria need to be fulfilled. Their mechanical properties and durability, however, still need to be fully investigated. An experimental campaign has been carried out to characterize the tensile behaviour of composite strengthening systems comprising glass-aramid textiles. First, textile specimens comprising either E-glass or AR-glass have been aged in alkaline environment, for different durations up to 1000 hours, and tested under tension to investigate their durability. Then, composite specimens have been manufactured with the AR-glass-aramid mesh and four different mortar matrices, ranging from strong mineral and cement mortars, to weak hydraulic lime mortars. Strength and stiffness, failure mode and response stages under tension have been identified and compared to those of the dry textiles to investigate the contribution provided by the matrix and derive design parameters for various field applications.

scholarly journals Assessment of the Impact of Inaccuracy and Variability of Material and Selected Technological Factors on Physical and Mechanical Properties of Fresh Masonry Mortars and Plasters

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1382
Author(s):  
Małgorzata Gołaszewska ◽  
Jacek Gołaszewski ◽  
Grzegorz Cygan ◽  
Jerzy Bochen
Keyword(s):  
Mechanical Properties ◽  
Physical And Mechanical Properties ◽  
Hydrated Lime ◽  
Strength Properties ◽  
Technological Factors ◽  
Air Content ◽  
Lime Mortars ◽  
Mixing Intensity ◽  
The Impact ◽  
Plasticizing Admixture

The article presented the analysis of the impact that various kinds of technological inaccuracies have on the properties of fresh masonry mortars and plasters. Analyzed were the inaccuracies in dosing of mortar components, namely, water, lime, and air-entraining plasticizing admixture (APA) (±10% of mass), and the effect of variable technological conditions, namely, different mixing intensity (fast, slow, normal) and temperature (5 °C, 20 °C, and 35 °C) during first 72 h after mixing. The impact of differences in the properties of cement and aerial (hydrated) lime originating from different manufacturers was also analyzed. The impact of these factors was determined for consistency, density, air content, compressive, and flexural strength. The sensitivity to changes in the analyzed properties was determined by the coefficient of variation. Changes in the dosing of constituents, mixing speed, and temperature adversely affected strength properties. For mortars with APA, these changes exceeded 20% and reached 40%. The greatest impact was evident in the consistency, especially with an excess of APA, where changes ranged from 6% to 80%. The results showed greater resistance of cement-lime mortars to changing selected technological conditions and errors in measuring the amount of ingredients than mortars with air-entraining plasticizing admixture (APA).

An overview on the activation of reactivity of natural pozzolans

2001 ◽  
Vol 28 (5) ◽  
pp. 778-786 ◽  
Author(s):  
Caijun Shi
Keyword(s):  
Chemical Activation ◽  
Setting Time ◽  
Construction Materials ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Natural Pozzolan ◽  
Natural Pozzolans ◽  
Early Strength

Natural pozzolan is one of the oldest construction materials. Lime-pozzolan cements have been used for several thousands of years and have an excellent reputation for their durability. Pozzolans are being widely used as a cement replacement in Portland cement concrete. The use of pozzolans has the advantage of lower costs and better durability, but the disadvantage of a longer setting time and a slower early strength development. Different techniques have been tried to increase the reactivity of natural pozzolans to overcome these disadvantages. This paper has reviewed various methods used to activate the pozzolanic activity of natural pozzolans. All activation methods can be classified into three catalogues: thermal, mechanical, and chemical activation. A comparison based on strength–cost relationship indicates that the chemical activation method is the most effective and cheapest one.Key words: activation, reactivity, natural pozzolans, pozzolanic reaction, calcination, elevated temperature curing, chemical activators, strength, cost.

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