scholarly journals The transport properties of cement mortars subjected to freeze-thaw cycles

2018 ◽  
Vol 49 ◽  
pp. 00128
Author(s):  
Alicja Wieczorek ◽  
Marcin Koniorczyk ◽  
Dalia Bednarska ◽  
Kalina Grabowska
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Transport Properties ◽  
Positive Impact ◽  
Gas Permeability ◽  
Cement Matrix ◽  
Capillary Absorption ◽  
Water Absorption Coefficient ◽  
Freeze Thaw ◽  
Cement Mortars

The parameters characterizing the microstructure of cementbased materials, such as porosity or permeability, determine not only durability, but also risk of degradation of the cement matrix due to an aggressive environment. The report presents results of a research on transport properties of cement mortars subjected to cyclic water freezing. Mortars prepared on the basis of two different cements were the object of the research: Portland cement CEM I 42.5R and Portland blast-furnace slag cement CEM III/A 42.5N LH/HSR/NA, with two water-cement ratio (w/c=0.45 and 0.40). The experimental study was carried out in order to determine the relationship between intrinsic permeability and the water absorption coefficient in relation to the number of freeze-thaw cycles. The evolution of transport coefficients was determined using a capillary absorption test and the modified RILEM-Cembureau method. It was established that the degradation processes induced an increase of transport properties. Moreover, the microcracks had a more significant influence on permeability and lesser influence on the water absorption coefficient. The gas permeability of damaged mortar changed very significantly, an increase with several orders of magnitude could be noticed. Moreover, the positive impact of CEM III on ice-induced degradation was also visible.

scholarly journals The influence of type of cement on the degradation of microstructure and transport properties of cement mortars exposed to frost induced damage

2018 ◽  
Vol 174 ◽  
pp. 01014
Author(s):  
Alicja Wieczorek ◽  
Marcin Koniorczyk
Keyword(s):  
Absorption Coefficient ◽  
Pore Structure ◽  
Water Absorption ◽  
Transport Properties ◽  
Cement Mortar ◽  
Gas Permeability ◽  
Water Absorption Coefficient ◽  
Freeze Thaw ◽  
Cement Mortars ◽  
Small Pore

The purpose of the study is to understand how the cyclic water freezing (0, 25, 50, 75, 100 and 150 freeze-thaw cycles) impacts microstructure and transport properties of cement-based materials. Tests were conducted on cement mortars with different water/cement ratios (w/c=0.45 and 0.40) and on two types of cement (CEM I and CEM III) without air-entraining admixtures. The changes of pore size distribution and open porosity were investigated by means of mercury intrusion porosimetry. Additionally, the relationship between intrinsic permeability and the water absorption coefficient of cement mortar samples was analysed. The water absorption coefficient and gas permeability were determined using capillary absorption test and the modified RILEMCembureau method. The evolution of transport coefficients with growing number of freeze-thaw cycles were determined on the same sample. It was also established that change of pore structure (a decrease of small pore volume <100nm and increase of larger pores >100nm) induces an increase of water transport parameters such as permeability and water absorption coefficient. The higher gas permeability corresponds to the higher internal damage. In particular, it is associated with the change of cement mortar microstructure, which indicates damage of narrow channels in the pore structure of cement mortars.

scholarly journals Effects of Imposed Damage on the Capillary Water Absorption of Recycled Aggregate Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Qi Gao ◽  
Zhiming Ma ◽  
Jianzhuang Xiao ◽  
Fuan Li
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Capillary Absorption ◽  
Capillary Water ◽  
Aggregate Concrete ◽  
Capillary Water Absorption ◽  
Freeze Thaw ◽  
Loading Level

Capillary water absorption of concrete is closely related to its pore structure, permeability, and durability. This paper intensively investigates the effects of imposed damage, including freeze-thaw damage and loading damage, on the capillary water absorption of recycled aggregate concrete (RAC). Freeze-thaw cycle test, loading test, and the experiment of capillary water absorption were carried out, respectively. The results demonstrate that the addition of recycled coarse aggregate (RCA) results in the increase in the capillary absorption behavior of RAC without imposed damage, and there exists a linear correlation between the behaviors of capillary water absorption and chloride penetration of RAC. The imposed freeze-thaw damage or load damage of RAC boosts with the increase of RCA replacement percentages after suffering the same freeze-thaw cycles or loading level. The imposed freeze-thaw damage and load damage further lead to the increase in the capillary water absorption of RAC, and the capillary absorption coefficient of RAC increases linearly with the increased RCA replacement percentages, after suffering the same freeze-thaw cycles or loading level. Furthermore, capillary absorption coefficient increases linearly with the growth of imposed freeze-thaw damage or load damage degree, which can be used to estimate the capillary absorption behavior of RAC exposed to the extreme environment.

scholarly journals Improvement of Recycled Aggregates Properties by Means of CO2 Uptake

2021 ◽  
Vol 11 (14) ◽  
pp. 6571
Author(s):  
Marie Sereng ◽  
Assia Djerbi ◽  
Othman Omikrine Metalssi ◽  
Patrick Dangla ◽  
Jean-Michel Torrenti
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Co2 Storage ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Cement Matrix ◽  
Co2 Uptake ◽  
High Porosity ◽  
Accelerated Carbonation ◽  
Water Absorption Coefficient

Concrete from deconstruction can have a second life in the form of recycled concrete aggregates (RCAs). They unfortunately have poor properties (high porosity and water absorption coefficient (WAC)) with respect to natural aggregates. Accelerated carbonation was implemented to improve the RCA properties and to increase their use by storing carbon dioxide (CO2) in the cement matrix and thereby reduce their environmental impact. This paper aims to perform a parametric study of a process for accelerated carbonation of RCAs to store the largest possible amount of CO2 and improve their properties. This study highlights the fact that each of these parameters affects CO2 storage, with an optimum water content for the maximum CO2 uptake depending on the nature and the source of the RCAs. This optimum is related to the RCA water absorption coefficient by a linear relationship. The results show that accelerated carbonation reduces the water absorption coefficient by as much as 67%. Finally, carbonation also decreases porosity, as observed by mercury intrusion porosimetry, by filling the capillary pores.

scholarly journals Experimental investigation of frost induced damage of cement mortar

2019 ◽  
Vol 282 ◽  
pp. 02103
Author(s):  
Alicja Wieczorek ◽  
Marcin Koniorczyk ◽  
Kalina Grabowska
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cement Mortar ◽  
Cement Matrix ◽  
Capillary Absorption ◽  
Water Absorption Coefficient ◽  
Cement Mortars ◽  
Water Saturated ◽  
The Impact

Questions connected to influence of frost degradation on microstructure and physical properties of water saturated cement mortars and their resistance to cyclic water freezing are the objectives of research. The main aim of the investigation is to analyze the ice-induced deterioration of cement mortars with different water/cement ratios (w/c=0.50 and 0.40) in a accelerated durability tests. The changes of pore size distribution and water absorption coefficient are investigated by means of mercury intrusion porosimetry and capillary absorption test. Additionally, the analysis of the impact of drying temperature (40°C, 60°C, 80°C and 105°C) on the microstructure is introduced.The performed tests enabled to estimate that the destruction of the cement matrix and the range of observed changes depend on the initial pore size distribution and their volume in the cement matrix. It is also established that the increase of transport properties is correlated with the change of pore size distribution. The obtained results allow to conclude a decrease of content of small pores (up to 150nm) and increase of larger pores for mortar with w/c=0.50. Application of superplasticizer, which resulting in reduction of water to cement ratio up to 0.40, allows to obtained resistant to 150 frost cycles cement mortar.

scholarly journals Water Absorption Properties of Geopolymer Foam after Being Impregnated with Hydrophobic Agents

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4162
Author(s):  
Hiep Le Chi ◽  
Pavlína Hájková ◽  
Su Le Van ◽  
Petr Louda ◽  
Lukáš Voleský
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Positive Impact ◽  
High Sensitivity ◽  
Acoustic Properties ◽  
Total Water ◽  
Absorption Properties ◽  
Major Barrier ◽  
Water Absorption Coefficient ◽  
Hydrophobic Agent

Geopolymer foam is classified as a lightweight material with high porous in its matrix which has great offer for applications requiring fire-resistant, thermal, and acoustic properties. However, the high sensitivity to humid environments can be a major barrier of geopolymer foam that limits the variety of applications of this material. Based on this drawback, two types of hydrophobic agent (Lukosil M130 and Lukofob ELX) were used as an impregnator to treat the surface of geopolymer foam samples. This paper presented the results of water absorption properties of the untreated and treated geopolymer foam composites. The obtained properties were flexural strength, compressive strength, density, total water absorption, the rate of water absorption, and water absorption coefficient. The results showed that the samples after being impregnated with hydrophobic agents improved significantly their waterproof property especially using Lukosil M130. Moreover, the samples treated with Lukosil M130 had positive impact on their mechanical strength.

scholarly journals Durability of Structural Lightweight Concrete with Sintered Fly Ash Aggregate

Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4565 ◽  
Author(s):  
Lucyna Domagała
Keyword(s):  
Fly Ash ◽  
Moisture Content ◽  
Water Absorption ◽  
Water Permeability ◽  
Lightweight Concrete ◽  
Concrete Strength ◽  
Initial Moisture Content ◽  
Cement Matrix ◽  
Secondary Importance ◽  
Freeze Thaw

The aim of this study was to present the problem of durability of structural lightweight concrete made of a sintered fly ash aggregate. The issue of durability was researched for 12 concrete series in terms of their water absorption, water permeability, and freeze-thaw resistance. Additionally, the microstructure of several concretes was analyzed with a scanning electron microscope (SEM). In the durability research, the influences of the following parameters were taken into consideration: The initial moisture content of sintered fly ash (mc = 0, 17–18, and 24–25%); the aggregate grading (4/8 and 6/12 mm); and the water-cement ratio (w/c = 0.55 and 0.37). As a result of various compositions, the concretes revealed different properties. The density ranged from 1470 to 1920 kg/m3, and the corresponding strength ranged from 25.0 to 83.5 MPa. The durability research results of tested lightweight concretes showed that, despite considerably higher water absorption, a comparable water permeability and comparable or better freeze-thaw resistance in relation to normal-weight concrete may be present. Nevertheless, the fundamental requirement of lightweight concrete to achieve good durability requires the aggregate’s initial moisture content to be limited and a sufficiently tight cement matrix to be selected. The volume share of the cement matrix and aggregate, the cement content, and even the concrete strength are of secondary importance.

Ermittlung der Kapillartransportkoeffizienten mineralischer Baustoffe aus dem w-Wert / Estimating the capillary transport coefficients of mineral building materials from the water absorption coefficient

1997 ◽  
Vol 3 (3) ◽  
pp. 219-234
Author(s):  
M. Krus ◽  
A. Holm ◽  
Th. Schmidt
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Building Materials ◽  
Transport Coefficients ◽  
Capillary Transport ◽  
Water Absorption Coefficient ◽  
Standard Material ◽  
Moisture Balance ◽  
Computer Calculations ◽  
Building Components

Abstract Computer calculations are of increasing importance for the assessment of moisture balance in building components, since modern calculation methods achieve good agreement with measurements. A broader application of these methods is hampered, however, by the laborious measurements needed to determine the capillary transport coefficients essential for the calculations. A new method is therefore presented which allows to estimate the coefficients from wellknown standard material properties (free capillary saturation, practical moisture content and water absorption coefficient). These coefficients are sufficient for estimative assessment of the moisture balance of many materials, as is demonstrated by comparison of suction profiles calculated in this way and measured profiles.

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