Solutions in cement. Holcim Ultra Durable

Transcription

1 Confidence that builds. Solutions in cement. Holcim Ultra Durable Data sheet Holcim Ultra Durable Holcim Ultra Durable HS Type cement is developed under the NTE INEN 2380 standard, equivalent to the ASTM C1157 standard. This product has equal performance in resistance to GU type cement, but also meets the requirements of high resistance to attack from sulfates (HS). Description and features Traditionally, cements used and recommended to resist attack from sulfates have been OPC cements (Ordinary Portland Cement) - pure cements - they are identified by the standard ASTM C150 as type II cements when they are required to provide moderate sulfate resistance and cement type V for high resistance to sulfate attack. However, the regulations with greater preponderance today, as the ASTM C1157, which categorize cements by their performance, tend to favor replacement and use of cements that fulfill the same objectives of resisting attack from sulfates, and cause minimal pollution to the environment, such as Holcim Ultra Durable HS Type. It should be considered that 1 ton of produced clinker may emit into the environment almost 1 ton of CO2 and the added cements, like Holcim Ultra Durable HS Type can reduce up to 20% of this gas emission into the atmosphere. As for the sulfate resistance, these may be sulfates of sodium, potassium, calcium or magnesium, which occur naturally in the soil, dissolved in water, or present in aggregates. Sulfate can be present in effluent and industrial waste such as the industries associated with the manufacture of chemicals, batteries, aluminum and mining. The water used in cooling towers may also contain sulfates due to the gradual accumulation of sulfates from evaporation. Unasur, Quito 2017 Holcim Ecuador S.A. 1

2 Data sheet Holcim Ultra Durable Likewise, the sulfates present in the soil or dissolved in the water reacts with the calcium hydroxide (Ca(OH)2) generated during the hydration of cement, forming calcium sulfate, which reacts with the aluminate hydrated calcium forming sulpho aluminate of calcium (etringita1). These reactions cause expansion and can produce the decomposition of concrete. Usually, the specifications of the cements limit content of aluminate tricalcium phosphate (C3A) as a criterion for the resistance of sulfates. The Salts Particularly active are of magnesium sulfate and sodium sulfate.the attack of sulfates accelerates in important way if it is accompanied with wetting and drying interspersed. According to the ASTM C1157, for a cement to qualify as high resistance to the sulfates (HS), the expansion must not exceed 0.05% at 6 months or 0.10% at 365 days of age. It is of particular importance the use of cement Holcim Ultra Durable HS Type when the concrete is exposed to solutions of sulfates since it is going to be attacked and could be damaged to a degree that depends on the constituents of the concrete, the quality of the concrete prepared on location, as well as the type and concentration of the sulfate. As with any chemical reaction, the speed of the reaction increases with the temperature. It is necessary to be aware of the characteristics of the concrete resistant to sulfates so that they can be given the appropriate steps to minimize the deterioration of concrete exposed to solutions of sulfates. It is briefly reviewed in this brochure the factors that affect the resistance to sulfates of concrete, seeking to put in perspective its influence and thus allowing to take practical and effective measures to make concrete resistant to sulfates, which may be present in effluents and industrial wastes, related to industries in the manufacturing of chemicals, batteries, and aluminum, as well as the mining industry. Technical specifications of Holcim Ultra Durable. Factors affecting concrete and its resistance to sulfates Concrete sulfate attack occurs when the sulfate solution penetrates into the concrete and chemically reacts with its constituents, mainly with the cement matrix. Thus the factors affecting the resistance to sulfates in concrete are not only those that influence the chemical reaction with the cement matrix, but also those who influence the permeability and the overall quality of the concrete. Cements Holcim Ultra Durable HS Type cement is classified and evaluated as a cement of high resistance to sulfates. Studies have shown that cements that have potentially less calcium hydroxide (Ca(OH)2) in hydration behave well in exposure of sulfates. The use of Holcim Ultra Durable cement helps in the production of a concrete resistant to sulfates. In addition, there are other factors which must be considered, because its effect can be more important than the resistance to sulfates of the cement in the concrete Holcim Ecuador S.A. 2

3 Pozzolana The effect of the pozzolana used in the manufacture of Holcim Ultra Durable HS Type is double in mitigating the attack of sulfates: first it reacts with the calcium hydroxide (Ca(OH)2) so that it is no longer available to react with the sulfates and second, compared with using only Portland Cements, the same content of cement mixed by m³ of concrete results in less calcium hydroxide (Ca(OH)2). Cement content of concrete The use of cement Holcim Ultra Durable HS Type of high resistance to sulfates must be combined with the use of a minimum amount of cement. Relationship water-cement The permeability of the concrete is a significant factor that influences its resistance to the attack of sulfates. When good-quality materials are used, satisfactory provisions are taken and a good practice is applied, the permeability of concrete is a direct function of its relationship to watercement and curing time. In other words, being all factors equal, resistance to sulfates of concrete increases with the reduction of water-cement relationship; for example, the use of concrete with a low water-cement ratio produces concrete less permeable and more durable especially when exposed to humid environments such as foundations, reservoirs or treatment plants. Additives There are many types of additives available for concrete, to improve certain properties, to economize, or both. Generally, the affect of additives in the properties of concrete not only depend on its formula and its interaction with the cement, but also with the variations or adjustments that create the proportions in the mixture of the concrete. In this way, additives which cause a reduction in the relationship water-cement and/or increase working effectiveness, produce a concrete less permeable and more resistant to sulfates, on condition that they are not used to reduce its content of cement. Avoid the use of additives that are water reducers that contain calcium chloride because they decrease resistance of concrete to sulfates. Construction Practices The placement, compaction and curing of the concrete is important factors for producing low permeability concrete. Adding more water to the site during concrete placement to reset slump or help with the finish, will hurt the resistance of concrete to sulfate. It is required adequate compaction and curing to produce dense concrete with discontinuous capillaries (low permeability). Giving a finish to concrete that provides a dense surface, free from holes and defects, can improve resistance to sulfates. For more information, check the curing section and protection of reinforced concrete, the NEC is HM. Design and details Structures and appropriately designed and detailed elements should provide an appropriate reinforcement and be correctly located to minimize cracking Holcim Ecuador S.A. 3

4 Concrete resistant to sulfates The strength of concrete to sulfates can be significantly improved by producing an impermeable and dense concrete, made with a cement resistant to sulfates like Holcim Ultra Durable, a low water-cement ratio, sufficient amounts of cement and that is properly placed, compacted and cured. The ACI 201.2R and the NEC IS HM (Table # 1) have classified the aggressiveness of a number of categories and severeness. In function with this classification, the use of cement with high resistance to sulfates are to be used in extreme exposure and in combination with other requirements. I should be considered that magnesium sulfate is more aggressive than sodium sulfate. In the presence of large quantities of magnesium ions (> 1000 mg/lt) it is necessary to take additional security measures. Sulfate concentration expressed in (SO4)* Exposure Soluble sulfates (SO4) water in the soil, % mass Sulfate (SO4) dissolved in water, ppm Not Applicable < 0.1 < 150 Moderate 0.1 to to 1500 Severe 0.2 to 0.2 1,500 to 10,000 Very severe > 2.0 > 10,000 Table #1: Classification of the Severity of the environment of sulfates in accordance to NEC-is-HM The resistance of concrete to sulfate attack can be tested in the laboratory by the storage of specimens in a sodium or magnesium sulfate solution or a mixture of the two. Alternate wetting and drying accelerate the damage due to the crystallization of salts in the pores of the concrete. The affects of exposure can be estimated by the loss of resistance of the specimen, by changes in its dynamic modulus of elasticity, for its expansion, by its loss of mass, or can be assessed even visually. The method to test the C1012 ASTM standard "Standard Test Method for length Change of Hydraulic-Cement" employs hydrated mortar immersion in a solution of sulfates and considers the excessive expansion as a criterion of failure under attack by sulfates. According to expert analysis, both in our laboratories and external ones, such as the prestigious CTL Group ( and the Faculty of physical sciences and mathematics of the University of Chile ( our Holcim Ultra Durable HS Type cement meets the specified average 6-month expansions (< 0.05%) as a requirement to resistance of sulfate attack, in accordance with the ASTM C1157 cements HS Type (High Sulfate Resistance) standard Holcim Ecuador S.A. 4

5 Average values in the analysis of the sample of Holcim Ultra Durable HS type demonstrate expansions < 0.05% at 180 days. Disfigurement (%) Age (days) Expansion Limit NTE INEN 2380 We exceed the limits of the standards NTE INEN 2380 GU Type Comparative of strength Resistance in MPa Holcim Ultra Durable HS Type NTE INEN Holcim Ecuador S.A. 5

6 Benefits Provides broad resistance to the attack of chloride ions, minimizing the risk of corrosion of the reinforced steel. Provides a high level of performance to the concrete for sulfate aggressive environments and acidic environments. Applications of Holcim Ultra Durable To minimize the risk of chemical attacks by sulfates that can cause deterioration of the concrete and structural failures: High early and final strength On-site slaughtering, pig farms, feedlot and food processing plants Water treatment plants Mines and other environments with acidic soil Factories associated with the production of milk, forestry, fishing and other environments with structures susceptible to chemical attacks. Docks and marinas Walls exposed to marine environment, dams, reservoirs In-water pipes for sewerage and plants treatment. Bridges and other structures submerged in tidal areas and seawater splash. To minimize the risk of corrosion to reinforcement steel induced by chlorides and to guarantee long-term durability: Wharves and sports ports Walls exposed to marine ambiences, preys, reservoirs In-water tubes for sewerage and plants of treatment Bridges and other structures immersed in tidal areas and seawater splash Certifications Holcim Ultra Durable HS Type cement has been certified in accordance with the INEN seal of quality, which guarantee its excellence. In addition, all of our cement manufacturing processes, concrete and aggregates have international quality certifications ISO 9001:2008, environment ISO 14001:2004 and occupational health and safety OHSAS 18001: Holcim Ecuador S.A. 6

7 Rights of use The content (including images, logos and graphics) of this document is privately owned by Holcim Ecuador S.A., so no natural or legal person may use it without the express consent of Holcim Ecuador S.A. If Holcim Ecuador S.A. proves the unauthorized use of this document, it reserves the right to initiate the corresponding civil or criminal actions by violation of its intellectual property rights. Responsibility This brochure is for informative and educational use, non-profit, so Holcim Ecuador S.A. is and will not be liable for the improper use that third parties may give the information contained herein. In addition, Holcim Ecuador S.A., resulting from the use of this document, will not be liable neither civil nor criminally by the application of any improper practice during the process of construction or for any injury or damage to persons, property or the environment. Holcim Ecuador S.A. Ave. Barcelona and Jose Rodriguez Bonin Guayaquil Ecuador Phone Box Holcim (465246) info.holcim-ecu@holcim.com Holcim Ecuador S.A. 7