Presence Of Deicing Salts Research Articles

Freeze–thaw field exposure and testing the reliability of performance test temperature cycle for concrete scaling in presence of de-icing salts

Freeze–thaw field exposure and testing the reliability of performance test temperature cycle for concrete scaling in presence of de-icing salts

Lightweight Reactive Powder Concrete Containing Expanded Perlite.

This paper presents the test results of the lightweight concrete properties obtained by adding expanded perlite (EP) to an RPC mix in quantities from 30% to 60% by volume of the concrete mix. It has been shown that in these cases it is possible to obtain concrete containing 30% by volume with density of approximately 1900 kg/m3 and the compressive strength > 70 MPa, with a very low water absorption value (3.3%), equal to the water absorption value of RPC without lightweight aggregate (3.3%). However, with the increased quantity of perlite (from 45% to 60%), the concrete density reduction is not observed, as the expanded perlite demonstrates very low resistance to crushing. With the increased amount of perlite, the longer periods of mixing time for all the mix components are required to obtain the homogeneous and fluid concrete mix, what causes grounding down EP. Therefore, using larger quantities of this aggregate in RPC is not recommended. The lightweight RPC shows very good freeze-thaw resistance in the presence of de-icing salt (the scaling mass is lower than 0.1 kg/m2). The above is explained by the compact microstructure of this concrete and the RPC mix location in open pores on the perlite aggregate surface, which consequently affects the strengthening of the aggregate-matrix contact without an interfacial transition zone (ITZ) visible. It has been demonstrated that pozzolanic activity of expanded perlite is much lower than the activity of silica fume and quartz powder, and its impact on increasing the RPC strength is minimal.

Effect of freeze-thaw cycles on the response of roller compacted concrete pavement reinforced by recycled polypropylene fibre under monotonic and cyclic loadings

The present research focused on the effect of freeze-thaw cycles on behaviour of roller-compacted concrete pavement (RCCP) reinforced with recycled polypropylene fibres. RCCP specimens were designed with dry aggregates, four water to cement ratios of 0.3, 0.4, 0.5 and 0.6 and four fibre dosages of 0, 1, 3 and 5 kg/m3. Experiments were performed before and after exposure to freeze-thaw cycles in the presence of de-icing salt. The main experiments included the workability test by measuring the Vebe time, the ultrasonic pulse velocity (UPV), the modulus of rupture and the fatigue resistance with three-point bending method. Based on the results of the UPV test, which was performed before freeze-thaw cycles, and every 60 cycles up to 300 cycles, the specimens designed with water to cement ratios of 0.4 and 0.5 and reinforced with 1 kg/m3 fibre had better performance than other reinforced RCCPs. Modulus of rupture and fatigue tests were conducted after 0, 150 and 300 freeze-thaw cycles. The results of the modulus of rupture tests were largely similar to the UPV test. In contrast, given to the fatigue test results, the specimens containing 1 and 3 kg/m3 fibre exhibited similar behaviour after being exposed to freeze-thaw conditions and had a higher fatigue life than unreinforced specimens and those reinforced with 5 kg/m3 fibre. According to the results of monotonic and cyclic loadings, RCCPs with water to cement ratios of 0.4 and 0.5 and fibre contents of 1 and 3 kg/m3 are recommended to be used in real practice.

Valorization of fly ash from a thermal power plant for producing high-performance self-compacting concrete

This study analyzes the feasibility of valorizing industrial by-product, fly ash from a thermal power plant as a partial replacement of mineral filler-limestone for the production of self-compacting concrete (SCC). Three types of SCC mixtures with different portions of fly ash and the reference mixture with limestone were designed. The synthesized SCCs in the fresh state were examined for density, entrained air content, flowability (Slump flow, Slump flow time (t500), V-funnel time (tv)), passing ability (L-box), and segregation resistance, while hardened state testing included: density, compressive and flexural strength, static modulus of elasticity, water permeability, resistance against freezing in the presence of de-icing salt, and SEM analysis. Taking into account the obtained results it can be concluded that the addition of fly ash has a positive impact on the concrete properties and that the optimal content of fly ash is 20 % with respect to the total filler mass.

Durable photocatalytic thin coatings for road applications

Abstract In this study, 6 different coatings have been developed as photocatalytic coatings based on TiO2, which can be applied to concrete for road applications. The goal of these coatings is to degrade pollutants such as nitrogen oxides and volatile organic compounds emitted by road transport. The coatings are synthesized by sol-gel process in organic or water solvent or by a functionalization technique with hydroxybenzoic acid on commercial TiO2 nanoparticles (P25). These suspensions are deposited by dip-coating or spray-coating on three different concrete substrates: pavement blocks, brushed or exposed aggregates road concrete. For each process, particular attention has been paid to the development of TiO2 synthesis that will be easily produced on a larger scale. The samples are characterized with photocatalytic test on NOx degradation, mechanical resistance test and resistance to freeze-thaw cycles in presence of de-icing salts. Except from the samples resulting from the sol-gel organic route, all other samples show a NOx degradation between 10 and 45%. From resistance point of view, the best coating is the TiO2 P25/E coating synthesized by functionalization of P25 nanoparticles. Results highlight that anatase TiO2 is well present at the surface of the sample and an optimal TiO2 loading exists for this coating. The TiO2 P25/E coating shows promising properties for road applications.

Abrasion and impact resistance of concrete before and after exposure to freezing and thawing cycles

Abstract This study evaluated the abrasion and impact resistance of a number of self-consolidating and vibrated concretes before and after exposure to freezing and thawing cycles in the presence of de-icing salts (salt scaling). The study investigated the effects of supplementary cementing materials (fly ash (FA), slag (SL), silica fume (SF), and metakaolin (MK)), binder contents (250 kg/m3 and 500 kg/m3), coarse aggregate size (10 mm and 20 mm), and coarse-to-fine (C/F) aggregate ratio (0.7 and 2). Around 32.5% extra average scaling damage was observed in the specimens that were exposed to abrasion before freezing and thawing compared to non-abraded specimens exposed to freezing and thawing. In addition, the pre-exposure to freezing and thawing cycles significantly reduced the impact and abrasion resistance, especially in concrete with low binder content and concrete with high C/F aggregate ratio. Concretes with SF and/or MK showed the highest resistance to abrasion and impact loading (before and after the exposure to salt scaling) while concrete with FA showed the lowest resistance. The results also indicated that using higher C/F aggregate ratio decreased the resistance of concrete to freezing and thawing and impact loading while no significant effect was observed when the coarse aggregate size was changed.

Evaluation of the Causes of Concrete Kerbs Fast Damage

The paper presents the results of testing double-layered concrete kerbs with surface damage occurred after 3 years of construction. The testing was conducted to determine the causes of the fast destruction. The testing featured a visual inspection of the kerbs’ damage at the location of their construction and then sampling of 7 kerbs with various degrees of damage, which were transported to the laboratory. It was founded that in some kerbs the surface layer was damaged, whereas the concrete’s structural layer in all kerbs was in very good condition, without any damage. The testing program featured determination of properties, such as compressive strength, water absorption, capillary absorption and freeze-thaw durability – resistance to internal cracking and surface scaling. It was founded that the results of structural concrete testing: compressive strength, water absorption, freeze-thaw durability (resistance to internal cracking) and capillary absorption tests were not too useful in determining the kerb surfaces’ resistance to damage. Tests conducted using an optical microscope indicated that the concrete’s texture layer is insufficiently compacted. The test results indicate that the concrete’s water absorption (samples with the thickness of 50 mm, cut out from the kerb’s top surface) is best correlated with the test results the concrete kerb’s surface scaling in the presence of de-icing salts.

Durability properties of non-air entrained roller compacted concrete pavement containing coal waste ash in presence of de-icing salts

The aim of this study was to evaluate the durability properties of non-air entrained roller compacted concrete pavement (RCCP) containing coal waste ash (CWA) as partial replacement of cement in presence of de-icing salts. Four different mix combinations were used to prepare RCCP specimens. In control mix with no CWA, the cement content was fixed to 14% by mass of dry aggregates. In other mixes, cement was replaced with 2, 3 and 4% CWA (by mass of dry aggregates) named as C2, C3 and C4, respectively. Durability characteristics such as permeable void content, chloride ion penetration, de-icing salt surface scaling resistance and freeze-thaw resistance exposed to salt solution were evaluated. According to results, all studied RCCPs showed acceptable chloride ion penetration. By increasing CWA content up to 3%, surface scaling exposed to salt solution delayed approximately 5cycles. In presence of salt solution, up to 180freeze-thawcycles, ultrasonic pulse velocity in control mix was slightly more than C2 and C3 mixes while at higher cycles than 180 the reverse was true. C4 mix revealed excellent resistance during initial 180freeze-thawcycles while its resistance drastically reduced in continue and showed critical behavior up to 300cycles. Relative dynamic modulus of elasticity during 300freeze-thawcycles was almost the same for the control, C2 and C3 mixes. Conversely, C4 mix experienced more than 40% dynamic modulus reduction at the end of freeze-thaw test. The durability factor at the end of freeze-thaw test was satisfactory for the control, C2 and C3 mixes. Based on the results of durability tests, the optimum CWA content was determined as equal to 3%.

Immobilization of Trace Metals in Contaminated Urban Soil Amended with Compost and Biochar

Urban soil amendment with organic matter can increase the steady state concentration of trace metals in urban soil. Different types of organic matter have different abilities to sorb and retain trace metals. The potential of urban soil amended with compost derived from mixed green and table waste and with maple-wood-derived biochar to retain trace metals (Cu, Zn, Cd, Pb) in the presence of de-icing salt (Na) was studied in a leaching test. Soil amended with compost retained significantly higher concentrations of Zn and Pb, as compared to soil amended with biochar, possibly due to the high cation exchange capacity of compost and its positive effect on soil pH. Indicating high ability for retaining trace metals, compost can bind contaminants originating from urban runoff water percolating through urban soil and provide a healthier medium for street tree growth.

The evaluation of the influence of mineral additives on the durability of self-compacting concretes

The physical, mechanical and rheological properties of self-compacting concretes enable their application in the construction of bridges which are structures particularly vulnerable to the processes of carbonation and cyclic freezing and thawing. The technology of self-compacting concrete requires an increase in high powder content in the concrete mix, which is obtained by the application of mineral additives. The paper presents test results of the physical and mechanical properties of self-compacting concrete with cement with mineral additives and of the microstructure of its surface layer. The objective of the tests was to evaluate the influence of mineral additives (limestone powder, siliceous fly ash and blast-furnace slag) on the durability of the surface layer of self-compacting concrete subjected to accelerated carbonation and the freeze-thaw process in the presence of de-icing salts. The microstructure of the surface layer of the carbonated concrete was less compact, which was confirmed by the increased surface water absorption and water penetration in the layer in comparison with the non-carbonated concrete. Moreover, carbonated concrete exhibited more significant surface scaling when compared to non-carbonated concrete.

Multi-disciplinary characterization and monitoring of sandstone (Kandla Grey) under different external conditions

Nowadays there is an increase of imported natural building stones, often used as replacement of local, more traditional building stones. The durability of these traditional stones is generally well known; however, when new imported materials are used, it is essential to study their behaviour under the current and local climatological conditions to predict their weathering resistance. In addition to water exposure, these building materials have to be resistant to significant mechanical stress created by the imbibition of de-icing salt solutions, frequently used during winter in Western Europe, with temperature periodically changing from freeze to thaw conditions. Porous network modifications related to the materials’ chemical composition are very complex when different forces are acting on the stone itself. Therefore it is crucial to determine the internal structure of the building stone under changing external conditions with and without the presence of de-icing salts, to understand the influence of these additional salts. In this paper, particular attention was paid to the multi-characterization of compact Kandla Grey laminated sandstone, a building stone frequently imported from India to Belgium recently. Traditional as well as highly advanced research techniques were used for the characterization and monitoring of changes under different external conditions. This study demonstrates that the structural characteristics of the laminations have an effect on the frost resistance of the stone and its response to salt weathering. From the experiments carried out, it can be concluded that Kandla Grey can be sensitive to frost and salt weathering under the current climatic conditions in Western Europe.

Ecotoxicological Assessment of an In-Lake Remediation Method

Abstract Eutrophication and contaminated sediments are preoccupying issues in aquatic ecosystems and water resources protection. Saint-Augustin Lake (Quebec, Canada) is affected by both problems (eutrophication and contaminated sediment) and the presence of de-icing salts. According to sustainable management principles, Galvez and collaborators are developing an in-lake remediation method to restore eutrophicated lakes which consists of (a) the precipitation of the phosphorus present in the water column by the addition of alum in association with (b) the deposit of an active capping layer (calcite+sand) to isolate P, Al, and the contaminated sediments. The objective of this study is to assess the ecotoxicological impact of this restoration method for the Saint-Augustin Lake. Two ecotoxicological approaches will be used to assess this impact: (a) single-species bioassays using algal (Pseudokirchneriella subcapitata; growth), duckweed (Lemna minor; growth), daphnid (Daphnia magna; survival and reproduction), amphipod (Hyalella azteca; survival and reproduction), and invertebrate (Chironomus riparius; survival, growth, and emergence); and (b) a 2-L microcosm assay using the same organisms for purpose of comparisons. Alum toxicity, calcite impact, and organisms’ recolonization ability will be studied separately: first in artificial conditions, by using formulated sediments and artificial water and by considering de-icing salts impact, and secondly by using the sediments and overlying water of the Saint-Augustin lake. Preliminary results are available and presented here. No effect was measured for salt (NaCl) toxicity on algae, daphnids, chironomids, and amphipods. Alum inhibited algal growth strongly, had no impact on D. magna mobility and survival, but a clear dose-effect response was observed for daphnid reproduction. The global remediation method had almost the same effect as alum on P. subcapitata but stimulated daphnid reproduction at 10 mg/L alum, while it was reduced with 20 mg/L, and completely inhibited with 30 mg/L.

De-icing salt scaling resistance of mechanically loaded engineered cementitious composites

This paper reports the durability performance of non-air-entrained Engineered Cementitious Composites (ECC) with different fly ash content when subjected to mechanical loading and freezing and thawing cycles in the presence of de-icing salt. ECC is a newly developed high performance fiber reinforced cementitious composite with substantial benefit in both high ductility in excess of 3% under uniaxial tensile loading and improved durability due to intrinsically tight crack width. After 50 freezing and thawing cycles in the presence of de-icing salt, the surface condition visual rating and total mass of the scaling residue of ECC, even those with high volume fly ash content, remain within acceptable limits according to the ASTM C 672. This level of durability holds true even for specimens pre-loaded to cracking at high deformation level. Non-air-entrained mortar specimens with and without fly ash were also used as reference specimens. As expected, these mortar prisms under identical testing conditions deteriorated severely. Pre-loaded and virgin (no pre-loading) ECC coupon specimens were also exposed to freezing and thawing cycles in the presence of de-icing salts for 25 and 50 cycles to determine their residual tensile behavior. The reloaded specimens showed negligible loss of ductility, but retained the multiple micro-cracking behavior and tensile strain capacity of more than 3%. It is also discovered that multiple micro-cracks due to mechanical loading will heal sufficiently under freezing and thawing cycles in the presence of salt solutions to restore nearly the original stiffness. These results confirmed that ECC, both virgin and micro-cracked, remain durable despite exposure to freezing and thawing cycles in the presence of de-icing salts.