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Air lime mortars with addition of two types of sesame cooking oil were synthesized and cured in two different conditions: laboratory and natural climatic conditions of the Pasargadae and Persepolis World Heritage Sites. For the mortars cured in the laboratory, addition of oils in the mortar induced hydrophobic effects, but it adversely affected on permeability values and carbonation rates. However, the air lime mortars cured in the site conditions demonstrated increment in their hydrophobicity and superficial durability without retarding their setting time and adverse effects on their calcium carbonate formation values, due to various climatic parameters existing in natural outdoor conditions. [ABSTRACT FROM AUTHOR]

Glass with different chemical compositions, deriving from separate collection, has been used as fine aggregate to formulate cementitious mortars, substituting natural sand. Glass coming from cathode-ray tube monitors, fluorescent lamps, and crystal glass (from production of home décor items) along with glass deriving from soda-lime glass containers, which has been taken as a reference, have been investigated. Glass solubility has been determined in alkaline environment similar to the one inside the cementitious composite. Alkali silica reaction has been tested on glass modified cement mortar in different accelerated conditions. Mortar samples containing glass with chemical composition different with respect to soda-lime glass are subjected to alkali silica reaction. This behaviour is largely dependent on the ratio among modifier and stabilizer oxides in the glass. The same ratio affects glass solubility and consequently composition of expanding gels when alkali silica reactions take place. [ABSTRACT FROM AUTHOR]

Abstract: Blended cements are largely used for concrete: they are usually considered cements with a low environmental impact, as they require less clinker than ordinary Portland cement (OPC). Different constituents can be used as supplementary clinker component usually leading to cement with high resistance to outdoor environment. Polishing residue (PR), coming from porcelain stoneware tiles production, can be successfully used as new constituent for blended cement, however its action for enhancing the durability of cement matrix must be assessed. With this purpose, electrochemical tests (half cell potential, impressed voltage and linear polarization techniques) have been carried out on steel reinforced mortar samples, prepared using a 25% PR based cement and 100% OPC as binder and exposed to a 3.5% NaCl solution. The corrosion resistance results and microstructure analysis highlight better durability performances for PR based cement than those exhibited by OPC, mainly for curing time >28days. [Copyright &y& Elsevier]

Alkali-activated fly ashes have been proposed for various applications where resistance against high temperatures is required, yet several details regarding the response of these materials to heat-exposure need to be clarified. In the present study, heat-induced cracking in fly ash-based alkali-activated pastes and lightweight mortars was analyzed by in-situ acoustic emission (AE) detection during complete heating-cooling cycles (up to ∼1100 °C), augmented by thermogravimetry and ex-situ SEM and XRD analyses. The applicability of the lightweight mortars as passive fire protection coatings was assessed by recording temperature-time curves of mortar-coated steel plates. Cracking during heating was limited and associated exclusively with the dehydration of the materials in the temperature range ∼90–360 °C. However, samples heated to temperatures above ∼600 °C exhibited intense cracking on cooling. This was attributed to differential deformations caused by local sintering and partial melting at the glass transition temperature, and subsequent quenching on cooling. [ABSTRACT FROM AUTHOR]

The suitability of new lime mortars for restorative rendering applications was investigated. Air-, formulated- and hydraulic-lime mortars were synthesized with inclusion of two different types of spent sunflower cooking oils and, when necessary, brick waste powder as pozzolanic addition. The results of spent cooking oils addition in the mortars exhibited promising hydrophobic effects, such as sorptivity reduction up to 60 times and improvement of superficial durability. Addition of high-oleic acid cooking oil in 13 wt% in the formulated and hydraulic lime mortars significantly increased their hydrophobicity without worsening their mechanical strengths. All the investigated mortars exhibited appropriate indexes as restorative materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reclaimed asphalt pavement (RAP) was tested as aggregate replacement for concrete. • Five types of RAP sourced by different Italian collection sites were characterized. • RAP shows irregular porous surface due to bitumen covering the natural aggregate. • RAP shows hydrophobic behavior. • RAP exhibits dimensional stability and frost resistance. A study about the performances of reclaimed asphalt pavement (RAP) sourced from 5 different Italian collection sites is presented to evaluate RAP as aggregate for concrete. Several RAP properties were investigated: physical properties (particles size distribution, water absorption, porosity, wettability), microstructure by microscopy, dimensional stability (drying shrinkage of mortar and concrete with 100% of RAP as aggregates) and durability assessment by freezing-thawing cycles. Several differences between RAP and natural aggregates used for concrete were highlighted. The use of RAP as recycled aggregate for concrete is a promising route, but a complete characterization is needed to ensure concrete performance and durability. [ABSTRACT FROM AUTHOR]

Abstract: Old reinforced concrete (RC) structures often exhibit unsatisfactory performances in terms of both residual serviceability and seismic behavior. The durability requirements were not considered at all at the age of design and construction, exposing such structures to severe decay in aggressive urban and/or industrial environment; in the meantime, the use of plain steel bars (with poor bond strength) was common at the age of construction and this jeopardizes the RC performance under cyclic load reversals like those induced by earthquakes. In this paper, the deep impregnation of cement-based mortars and concrete with a solution of ethyl silicate and with electrochemical treatments by means of a solution of sodium carbonate was investigated, with a twofold aim: (1) increasing the bond strength of the embedded plain steel bars in existing structures without any need for demolition and (2) increasing the durability and safety of the reinforced concrete elements. Both the treatments are already exploited in other fields: ethyl silicate solutions are widely used for stone consolidation (and only recently proposed for concrete surface protection), while migration of sodium carbonate under DC voltage is used for RC realkalization. In the present study these treatments are expected to penetrate inside mortar and concrete and to modify their microstructure, hence improving their properties. The effects of the treatments are investigated by comparing the characteristics of treated and untreated mortar and concrete samples reinforced with plain bars, in terms of penetration inside the samples, pull-out strength, water absorption, pore size distribution, carbonation resistance and corrosion resistance. [Copyright &y& Elsevier]

• The fracture properties of three alkali-activated mortars are studied. • Low values of fracture energy might be associated with the presence of unreacted FA. • The fracture energy depends on the type of aggregate used. • Digital image correlation can be used to estimate the size of the FPZ. Results of three-point bending tests on notched beams cast with three alkali-activated mortars that differ by the type and size of the aggregates are presented. Digital image correlation is used to estimate the size of the fracture process zone. The fracture energy is computed by means of the work-of-fracture method and found to be strongly dependent on the type of aggregate used and does not differ whether the LDVT or DIC load-deflection curves are used. Finally, low values of the fracture energy in alkali-activated mortars might be associated with the presence of unreacted fly ash. [ABSTRACT FROM AUTHOR]