The Effect of Hydrophobization on the Properties of Mortar Mixtures

IOP Conference Series: Materials Science and Engineering PAPER • OPEN ACCESS The effect of hydrophobization on the properties of mortar mixtures To cite this article: V Novak and J Zach 2018 IOP Conf. Ser.: Mater. Sci. Eng. 385 012040 View the article online for updates and enhancements. Related content The influence of the addition of gypsum on some selected properties of limemetakaolin mortars J Majerova and R Drochytka - The Influence of Moisture on the Storage Phenomenon in As2Se3 Evaporated Films Nobutaka Utsumi and Masanobu Wada - Comparing the Environmental Impacts of Alkali Activated Mortar and Traditional Portland Cement Mortar using Life Cycle Assessment P S Matheu, K Ellis and B Varela - This content was downloaded from IP address 147.229.6.155 on 07/12/2018 at 08:48 1 Content from this work may be used under the terms of theCreativeCommonsAttribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd 1234567890‘’“” Construmat 2018 IOP Publishing IOP Conf. Series: Materials Science and Engineering 385 (2018) 012040 doi:10.1088/1757-899X/385/1/012040 The effect of hydrophobization on the properties of mortar mixtures V Novak and J Zach Brno University of Technology, Faculty of Civil Engineering, Institute of Technology of Building Materials and Components, Veveri 331/95, 602 00 Brno, Czech Republic Abstract. One of the possible methods to reduce degradation effects due to the influence of moisture on building structures and materials is the use of hydrophobic agents - hydrophobization. The article deals with the influence of the hydrophobic preparations use on the change of mortar mixtures properties, where not only the impact on capillary absorption, but also other key properties which can be influenced by the application of the hydrophobic agent, are monitored. By realizing a wide range of measurements, optimal concentrations were determined to achieve properties comparable with the rehabilitation materials without negative effect on other key properties of mortar mixtures, when is mainly a significant reduction of the capillary absorption factor of mortar mixtures only at tiny changing the thermal conductivity factor of the mortar mixtures and without proved changing the other monitored properties. 1. Introduction One of the main factors that can significantly reduce the durability of the building is the influence effect of moisture [1]. In particular, this is a liquid form of moisture, which is primarily getting in construction due to a direct exposure of the construction to the moisture. In this case, the moisture in the construction spreads through the capillary system of materials - capillary absorption [2-3]. The most effective protection against this exposure of moisture is to prevent contact of moisture in the liquid form with the construction or the use of special materials for this purpose - waterproofing. In case of failure of these protection methods, either due to inappropriate design and use of the building, unprofessional application or mechanical damage of waterproofing, to reduce the impact of moisture degradation it is possible to use reducing capillary absorption of building materials. One of the possible measures is the hydrophobization of building materials and mortar mixtures from which the structures are made [4-5]. 2. Tested materials For the experimental part, four basic mortar mixtures were chosen - masonry mortars and plasters. This is a basic masonry mortar for all masonry works, rough coating plaster and masonry mortar applicable to masonry and coating plastering. A detailed description is given in table 1. 2 1234567890‘’“” Construmat 2018 IOP Publishing IOP Conf. Series: Materials Science and Engineering 385 (2018) 012040 doi:10.1088/1757-899X/385/1/012040 Table 1. Overview and description of the tested mortar mixtures [6]. Description Application Baumit MM 50 Industrially manufactured dry mortar mixture for manual and machine processing. Masonry mortar for all types of common masonry elements, for supporting walls, partitions and chimney bodies. Baumit Manu 4 Industrially manufactured dry plaster mixture for manual processing in the exterior and interior. Rough coating plaster for manual plastering, usable both in exterior and interior. Baumit DuoDur Industrially manufactured dry mixture suitable as masonry mortar as a universal plaster for manual processing. Masonry mortar for all types of common masonry elements, for supporting walls and partitions. Coating plaster for manual plastering, usable both in exterior and interior. The selected mixtures were mixed with water according to the manufacturer's recommendations and the individual consistencies were monitored by spill on a jogging table according to European standard EN 1015-3 Testing methods for masonry mortars. Test specimens were prepared from individual mixtures, resp. from the pure reference mixture and subsequently with the addition of a hydrophobic agent. The hydrophobic agent was dosed to a total volume of mixture in an amount of 0.2 %, 0.6 % and 1.0 %. It was a silicone emulsion hydrophobic agent with a recommended dosage of 0.5 to 0.8 % of the finished mortar mixture volume. Silicone based hydrophobic agents work on principle of changing the physical-chemical properties of the material, in particular in a substantial increase of the wetting angle, which significantly reduces the absorption of moisture in the liquid form into the material. 3. Testing methodology Test specimens were produced from individual mortar mixtures, namely 40 mm x 40 mm x 160 mm beam for the density in fresh and matured state and the capillary water absorption determining. Slabs 300 mm x 300 mm x 50 mm were also produced to determine the thermal conductivity factor and circular samples to determine the diffusion resistance factor. 3.1. Bulk density The density in the fresh state was determined on 40 mm x 40 mm x 160 mm beams. By weighing the triple forms during production of the test specimens [7]. The density in the matured state was determined after 7 and 28 days of aging. 3.2. Adhesion The effect of the hydrophobic agent on the adhesion both on the reference surface - concrete and ceramic masonry blocks was tested in the recipes. In case of adhesion to the concrete surface, the individual mixtures were applied in a uniform 10 mm thick layer to pre-moistened concrete slabs. In the case of adhesion to ceramic masonry fittings, the individual mixtures were also applied at a thickness of 10 mm in width of the ceramic wall fittings. In both cases, after 28 days of sample maturation, steel targets with a diameter of 50 mm by using two-component Sikadur glue were glued on the specimens. After curing, the targets were cut with the angle grinder in accordance with the relevant standard, always through the tested mixture to the subbase, and subsequently the adhesion by the DYNA Z 16 device was determined [8]. 3 1234567890‘’“” Construmat 2018 IOP Publishing IOP Conf. Series: Materials Science and Engineering 385 (2018) 012040 doi:10.1088/1757-899X/385/1/012040 3.3. Capillary absorption Determination of capillary absorption was performed on the beams made for this purpose. All of the longer surfaces must first be provided with a waterproofing coating so that water could then flow through only the lower square surface. After the waterproofing coat was matured, the beams were broken transversely into two halves. Each beam was weighed and with broken side down was put into a plastic container on a grid. The beams were watered up to a height of 5 to 10 mm from the bottom surface. At specified times, the weight gain of the test specimens was monitored as a result of water absorption. After the last weighing, each beam was longitudinally broken by a hammer and a steel chisel. On the fracture area of the sample was measured the height of the water rising [9]. 3.4. Diffusion resistance The principle of determining the diffusion resistance of mixtures consists of accurately monitoring the amount of moisture passing through by the material defined surface and the thickness of the material at fixed boundary environmental conditions. Prior to the start of testing, individual specimens were covered with silicone throughout their height to ensure a defined area. The specimens thus prepared were fixed by silicone on special testing vessels filled with dried silica gel. The vessels were placed in climate chamber with a defined environment of +23 °C and 80 % relative humidity. Approximately every 12 hours, the vessels with test specimens were weighed and the diffusion resistance factor was determined from the weight gain due to moisture passing through the silica gel [10]. 3.5. Thermal conductivity The thermal conductivity factor was determined on plates 300 mm x 300 mm x 50 mm by a stationary plate method on a Holometrix Lambda 2300 device based on a stationary plate method. Prior to the measurement, the flatness of the surface of each slab was checked and the slab was grounded if necessary. The determination of the thermal conductivity factor was performed in a steady state at an average temperature of +10 °C and a temperature gradient of 10 K. The measurement was always made on three test specimens (on each specimen was realized the determination of the thermal conductivity factor in total at 5 consecutive intervals) which were dried at a temperature of +75 °C to a constant weight. The final result presented is the arithmetic mean of these three measurements [11-12]. 4. Influence of the hydrophobic agent on the properties of mortar mixtures For mortar mixtures, the effect of the hydrophobic agent on the density was monitored both in the fresh state and at the maturation period after 7 and 28 days (table 2). From referred values, it appears that by adding the hydrophobic agent to the mortar mixtures, in almost all of the specimens is density in the fresh state and during maturation reduced. There was no dependence between the size of the hydrophobic agent addition to the mixture and its density. In general, the addition of the hydrophobic agent to the mixtures does not have a significant effect on the density. Table 2. Summary overview of densities of hydrophobic mortar mixtures. Addition of hydrophobic agent [%] Baumit Manu 4 Baumit DuoDur Baumit MM 50 Density fresh state ρ [kg/m3] 0.0 1947 1950 2051 0.2 1878 1953 1653 0.6 1911 1924 1859 1.0 1855 1979 1784 Density 7 days ρ [kg/m3] 0.0 1721 1694 1854 0.2 1631 1720 1748 0.6 1656 1705 1643 1.0 1638 1654 1594 4 1234567890‘’“” Construmat 2018 IOP Publishing IOP Conf. Series: Materials Science and Engineering 385 (2018) 012040 doi:10.1088/1757-899X/385/1/012040 Density 28 days ρ [kg/m3] 0.0 1749 1724 1824 0.2 1575 1696 1711 0,6 1642 1688 1592 1.0 1620 1601 1581 After 28 days of maturation, the hydrophobic agent effect on the properties of the mortar mixtures was monitored (table 3). Capillary absorption, adhesion, diffusion properties and thermal insulating properties were monitored. Table 3. Summary overview of adhesions of hydrophobic mortar mixtures. Addition of hydrophobic agent [%] Baumit Manu 4 Baumit DuoDur Baumit MM 50 Adhesion strength on concrete ft [MPa] 0.0 0.12 0.10 0.54 0.2 0.14 0.11 0.10 0.6 0.11 0.21 0.54 1.0 0.13 0.11 0.34 Adhesion strength on brick ft [MPa] 0.0 0.03 0.05 0.03 0.2 0.06 0.03 0.12 0.6 0.07 0.07 0.05 1.0 0.03 0.05 0.12 From the resulting values, no effect of the hydrophobic agent on adhesion of mixtures to concrete or ceramic surfaces is apparent. Table 4. Summary overview of changes in properties of mortar mixtures. Addition of hydrophobic agent [%] Capillary absorption C [kg/m2] Thermal conductivity factor λ [W/(m.K)] Diffusion resistance factor µ [-] Baumit Manu 4 0.0 18.25 0.4651 4.26 0.2 17.30 0.5251 4.06 0.6 12.30 0.4313 4.49 1.0 2.85 0.4060 4.75 Baumit DuoDur 0.0 17.95 0.4668 3.81 0.2 16.05 0.5455 3.75 0.6 14.00 0.4895 4.10 1.0 2.55 0.4635 4.04 Baumit MM 50 0.0 14.45 0.6227 4.60 0.2 14.20 0.6759 4.95 0.6 5.75 0.6165 4.54 1.0 1.50 0.5340 4.41 From the values of the capillary absorptions listed in table 4 the positive effect of the hydrophobic agent addition to the mortar mixtures clearly evident. There was an indirect proportionality between the increasing dose of the hydrophobic agent and the capillary absorption coefficients; therefore, the capillary absorption coefficients are reduced by increasing the hydrophobic agent dosage in all test mixtures. With Manu 4, DuoDur and MM 50 mortar mixtures, the same effect of the addition of the hydrophobic agent on the thermal insulation properties is evident. Adding a small amount, namely 0.2 % will increase the thermal conductivity factor. On the contrary, with increasing amounts of added hydrophobic agent in plaster mixtures, the factor of thermal conductivity decreases, at a concentration of 1.0 % will be reached lower values than to plaster mixtures without the use of a hydrophobic agent. 5 1234567890‘’“” Construmat 2018 IOP Publishing IOP Conf. Series: Materials Science and Engineering 385 (2018) 012040 doi:10.1088/1757-899X/385/1/012040 No dependence of the diffusion resistance factor due to the addition of the hydrophobic agent to the mixture has been proved for the tested mortar mixtures. The addition of the hydrophobic agent has always had a different effect on the diffusion resistance factor. 5. Conclusion The results of the previous chapter clearly confirm the positive effect of the hydrophobic agent on mortar mixtures. This is mainly a significant reduction of the capillary absorption factor of mortar mixtures, when similar properties of capillary absorption as achieved by rehabilitation mixtures were achieved by adding 1.0% hydrophobic agent to the Baumit Manu 4, Baumit DuoDur and Baumit MM 50 tested mortar mixtures. The addition of hydrophobic agent in an amount of 1.0 % also seems optimal in terms of the change in thermal insulation properties, when by the addition is slightly reduced the thermal conductivity factor of the mortar mixtures. The effect of the hydrophobic agent has not been proved for the other monitored properties, which is also positive, especially in terms of adhesion, which did not show a significant decrease with the addition of 1.0% hydrophobic agent. In case it is desired to achieve capillary absorption values of mortar mixtures comparable to rehabilitation plaster values, without effect on changes in other properties of mortar mixtures, the optimal dosing of the hydrophobic agent was proved to be 1.0%. Acknowledgements This paper has been worked out under the project No. LO1408 "AdMaS UP - Advanced Materials, Structures and Technologies", supported by Ministry of Education, Youth and Sports under the „National Sustainability Programme I". References [1] Annila P J, Hellemaa M, Pakkala TA, Lahdensivu J, Suonketo J and Pentti M 2017 Case Studies in Construction Materials (Amsterdam: Elsevier) p 103-108 [2] Zhao J and Meissener F 2017 Energy Procedia (Amsterdam: Elsevier) p 261-266 [3] Hall Ch, Hoff W D, Viles H A and Eklund J A 2010 Proceedings of The Royal Society A (London: Royal Society Open Science) p 194-211 [4] CSN 73 0600: 2000 Waterproofing of buildings - Basic provisions [5] CSN 73 0610: 2000 Waterproofing of buildings - The rehabilitation of damp masonry and additional protection of buildings against ground moisture and against atmospheric water – Basic provision [6] Baumit https://www.baumit.cz/produkty (online) [7] EN 1015-6: 1998 Methods of test for mortar for masonry - Part 6: Determination of bulk density of fresh mortar [8] EN 1015-12: 2016 Methods of test for mortar for masonry - Part 12: Determination of adhesive strength of hardened rendering and plastering mortars on substrates [9] EN 1015-18: 2002 Methods of test for mortar for masonry - Part 18: Determination of water absorption coefficient due to capillarity action of hardened mortar [10] EN 1015-19: 1998 Methods of test for mortar for masonry - Part 19: Determination of water vapour permeability of hardened rendering and plastering mortars [11] EN 12667: 2001 Thermal performance of building materials and products - Determination of thermal resistance by means of guarded hot plate and heat flow meter methods - Products of high and medium thermal resistance [12] CSN 72 7012-1: 1994 Determination of Steady State Thermal Conductivity of Materials. Hot Plate Methods