These include freezing and thawing, alkaliaggregate reaction aar, sulfate attack, aggressive chemical attack, physical salt attack, corrosion of metals and other embedded materials, abrasion, or a combination of these. He is also a fellow of astm, and the engineering institute of canada. Thaumasite sulfate attack in cement mortars exposed to sulfate and chloride and implications to rebar corrosion a thesis submitted for the degree of doctor of philosophy in the faculty of engineering of the university of sheffield by. Fly ash increases resistance to sulphate attack august 95 strong water reducer and aids in reducing water cementitious ratio. Pozzolan concrete durability on sulphate attack pdf free. Sulfate attack of concrete request pdf researchgate. The mechanism of sulfate attack on portland cement concrete is not well understood. Class c ash ability to mitigate asr and sulfate attack class f first choice for mitigating asr pozzolanic consumes oh hydroxide central to asr some class c can also mitigate but much less effective need higher replacement levels cementitious slightly pozzolanic. Sulfate attack on concrete provides a comprehensive reference to this important subject. Examples include using sulfate rich aggregate, an excess of gypsum in the cement, or contamination.
Thaumasite sulfate attack in cement mortars exposed to. Test methods for resistance of concrete to sulfate attack. Sodium sulfate attack on portland cement structures. Sulfates can be found in some soils especially when arid conditions exist, in seawater, and in wastewater treatment plants. Shown are concrete beams exposed to highconcentration sulfate soilssolutions. Therefore, if sulfate attack chemical characteristic xa1 xa2 xa3 so 4 2 mgl 200 and 15 and jan 14, 2017 sulfate attack and sulfate content in concrete. Type v sulfate resistant cement should be used when the concrete will be exposed to severe sulfate attack. The concrete is weekend by a combination of expansive forces and a general loss of strength as the normal cement hydration products are decomposed to form sulfate salts. Sulfate attack occurs when sulfate salts dissolved in water penetrate the concrete and react with the cement hydration products. Types of sulphate attack in concrete influences and sources sulphate attack is the reaction between concrete constituents and sulphate ions in the pore solution of concrete that results in the production of new product with a fairly large molar volume.
C1 readymixed concrete 3 5 proprietaryconcrete this type of concrete allows concrete producers to supply concrete for specialist applications. Concrete technology sulphate attack on concrete process and control of sulphate attack sulphate attack on concrete process and control of sulphate attack sulphate attack on concrete is a chemical breakdown mechanism where sulphate ions attack. Sulfate attack is a test where sulfate ions attack the cement paste, due to this mechanical and durability properties of concrete are decreases. It was found that the rate of strength loss is noticed at ordinary concrete compared to sc concrete. In following the procedure described in astm e 632, the performance of concrete under sulfate attack needs to be divided into several phenomena and therefore several tests had to be developed. Structures in potentially aggressive environments must be designed to recognise the risk of sulphate attack, and specific precautions taken in the design process to manage that risk. The 5% mk concrete showed intermediate durability to sulfate attack reaching maximum sulfate expansion values of 0. The producer does not have to declare the composition of concrete, but is required to give an assurance that the concrete will meet particular requirements for major contracts. Types of sulphate attack in concrete influences and sources.
Ettringite formation and sulfate attack on concrete by m. The long term concrete properties need a more appropriate method. The sulfate attack in concrete by degradation of iron. Image analysis of sulfate attack on hardened cement paste.
Upon hydration, the main reaction products are a calcium silicate gels csh and calcium hydroxide caoh2 or ch in cement chemistry. Abstract sulfate attack and its effects are important from both scientific and industrial viewpoints. Sulphate attack might show itself in different forms depending upon the chemical form of the sulfate and the atmospheric environment which the concrete is exposed to. Effect of ggbs and nano silica on the durability properties. Compressive strength of concrete cube test pdf, procedure, results. Physical salt attack on concrete, part 2 aci spring 2012 convention march 18 21, dallas, tx r. Sulphate attack is a chemical break down mechanism where suphate ion attacks on components of cement paste. Many studies have attempted to better understand the underlying mechanisms in which the various modes of deterioration by sulfate attack manifest. External sulfate attack is not completely understood. Sulphate attack in concrete free download as pdf file. The durability analysis of concrete structures in contact to external sulfate solutions requires the definition of a proper diffusionreaction model, for the computation of the varying sulfate concentration and of the consequent. Deterioration of concrete due to sulfate attack is a complex process characterized by multiple damage manifestations including volumetric expansion, cracking.
Type i type i is a general purpose portland cement suitable for all uses where the special properties of other types are not required. It is perceived that cements containing pozzolan have better performance in sulfate solutions,since the pozzolanic reactions reduce the quantity of calcium hydroxide and increase calcium silicate hydrate. Sulphate attack on concrete process and control of. Sulphate attack on concrete has the potential to cause serious damage or structural failures. Sulfate attack can generally be classified as internal or external to the cementitious matrix, and the underlying.
The problem occurs when the fill material hardcore beneath the slab contains sulphates and these migrate into the concrete. Anderson award winner, and a member of numerous aci committees including c232 on fly ash and c201 on durability. Deterioration of concrete due to sulfate attack is a complex process characterized by multiple damage manifestations including volumetric expansion, cracking, spalling, softening, and in some cases mushiness. The confused world of sulfate attack on concrete sciencedirect.
Part i identifies the issues involved, pointing out disagreements, and distinguishes between the mere occurrence of chemical reactions of sulfates with hydrated cement paste and the damage or deterioration of concrete. Sulfate attack is the reaction between sulfate ions in the pore solution of concrete and constituents in the concrete that result in formation of new reaction products with a relatively large molar volume. Mar 26, 2015 sulphate attack on ground floor slabs is a very serious problem which can cause structural damage to the main walls of a building. Cement is composed of mainly two minerals tricalcium silicates and dicalcium silicates.
We define sulfate attack as destructive chemical action and damage. Effect of sulfates on cement and limestabilized soils. Internal sulfate attack occurs when a source of sulfate is incorporated in the concrete when mixing like excess gypsum in cement, sulfate in the aggregate, water or admixture, and contamination. Sulfate attack is one of several mechanisms of concrete deterioration. It is used where cement or concrete is not subject to specific exposures, such as sulfate attack from soil or water, or to an. The products of corrosion are greater in volume up to 600% than the. Sulphate attack in concrete concrete reinforced concrete scribd. Cements have long been known to undergo deterioration in sulfate rich service environments. To understand how the cement type may affect the sulfate attack process. The soluble salt content was very high in the samples.
Performance of geopolymer concrete under sulfate exposure. Lowering watercementitious ratio significantly can lead to more sulphate resisting concrete. Manual measurement of the depth of attack was performed using a needle. Sodium sulphate attacks calcium hydroxide and forms gypsum that becomes more than doubles the volume. Sulfate attack is a complex form of deterioration that has damaged concrete structures throughout the world. It transforms concrete into a noncohesive mass without any binding or load carrying capacity. For deleterious sulfate attack to occur in a ground floor slab, the concrete must be of. Cement is composed of mainly two minerals tricalcium silicates c3s and dicalcium silicates c2s. Aggressive substances can compromise the durability of concrete. Prediction of concrete compressive strength due to long term. Concrete mixes were prepared with portland slag cement, portland sulfate.
Field experience with concrete exposed to sulphates has often shown that concrete can suffer from surface scaling above the ground level caused by physical sulphate attack. Na 2 so 4, mgso 4, caso 4 and nh 4 2 so 4 are some detrimental sulphate sources that are primarily found in ground water contaminated with industrial effluents and agricultural products. Effects of substances on concrete and guide to protective. Flach savannah river national laboratory savannah river site, 77342a aiken, sc 29808 abstract saltstone is a cementitious waste form made by mixing salt solution originating from liquid waste. Introduction to concrete pavements ced engineering. It occurs when concrete comes in contact with water containing sulfates so 4. It has been shown that calcium chloride reduces sulfate resistance regardless of the type of cement used. Conclusion in addition to producing airentrained concrete with a moderate water content not more than 0. Sulfate attack is particularly complex because the source of sulfates can be external or internal delayed ettringite formation, and the distress can be chemical in nature, due to alteration of hydration of products, or physical in. Upon hydration, the main reaction products are a calcium silicate gels and calcium hydroxide caoh2 or ch in cement chemistry. Chemical sulfate attack sulfate ingress sulfate attack requires intimate contact between sulfate anions and the cement paste of the concrete. Sulphate attack on concrete process and control of sulphate attack. Sulfate damage to concrete floors on sulfatebearing hardcore.
Damage modelling in concrete subject to sulfate attack. Carbonation occurs when carbon dioxide in the environment penetrates into the concrete to react with calcium hydroxide to form calcium carbonate. The effect of recycled concrete aggregate rca on concrete performance against external sulfate attack esa is not yet fully known. The prediction of concrete structures service life needs an overview on the properties of concrete for a long time due to sulfate attack.
To ensure the most durable concrete possible, fly ash is an essential ingredient when the project will be. Pdf concrete resistance to aggressive sulfates is of paramount importance to concrete. High concentrations of sulfate, as was measured in the soil samples, can react with components in concrete to cause degradation and reduced strength in a mechanism known as sulfate attack. Asr gel and def crystals can also fill air voids, reducing. Fire resistance of concrete and cracking are not addressed. Durability of metakaolin concrete to sulfate attack pdf. The initial time to cracking was 240 and 200 days for concrete at wb. The deterioration of reinforced concrete by sulfate attack causes the. This book provides a comprehensive reference to this subject, covering. Damage in conjunction with ettringite formation in hardened concrete was first identified in heattreated, precast concrete elements which, during use, had been exposed to openair weathering with frequent wetting. In the worst cases the external walls bounding the floor slab can be pushed outwards, causing undersailing or oversailing at the dampproof course dpc andor disruption of. In this paper, we consider the mechanical effect of the sulfate attack on concrete. An aci technical publication american concrete institute. The sulphate concentration, compressive strength, and the mass change in the hpc specimens were determined for immersion in a na2so4.
This research project was undertaken to determine whether concrete used in the adot system is experiencing, or is potentially susceptible to, asr or sulfate. Evaluating the resistance of the sulfate attack we have considered weight loss as acceptable indicator and % reduction in strength. The use of fly ash is well documented as a sound and economical method of achieving sulphate resistance. Sulphate attack on concrete is a chemical process where sulphate ions attack components of cement paste. Sulfate solutions can also cause damage to porous cementitious materials through crystallization and recrystallization salt attack. Moisture makes this reaction happen and can cause serious structural damage to both wall slabs and walls in buildings. Projected impact of sulfate attack on the longterm performance of a concrete repository g. For conventional concrete, the above categories can all be used to predict the values of compressive strength, but for concrete exposed to sulfate attack as the number of input factor increases, the relationship between the input factors and the compressive strength becomes highly nonlinear and complex. So, the situation is that, in homes 10 ro 20 years old, no structural damage has occurred and no concrete needs to be replaced. Sulphate attack on concrete is a chemical breakdown mechanism. Sulfate attack comprises a series of chemical reactions between sulfate ions and the components of hardened concrete.
Their role in concrete durability march 99 once these ions reach the steel they depassivate the area surrounding the steel and in the presence of airwater, the steel commences to corrode. The potential for severe sulfate attack exists when the concrete is exposed to watersoluble sulfate in soil or water in excess of 0. Accelerated test for measuring sulfate resistance of. Sulfate attack and reinforcement corrosion in concrete with. Astm e 632, the performance of concrete under sulfate attack needs to be divided. Sulphate attack resistance of highperformance concrete under. Sulfate attack can be classified as internal or external to the cementitious matrix. Sulphate attack on concrete can appear in different forms depending on chemical form of the sulphate and atmospheric environment which the concrete is exposed to. Laboratory and field evaluations of external sulfate attack. Thaumasite sulfate attack tsa is a special form of sulfate attack typically occurring due to the availability of carbonatesbicarbonates in the cementitious matrix with abundance of moisture and a prevailing low temperature.
Sulphate attack in concrete, its effects, causes and. Pdf image analysis of sulfate attack on hardened cement. External sulfate attack can come from sulfates present in the soil or in the water. Sulfate attack on concrete modern concrete technology. In this paper, recycled aggregate concretes rac with 0. The sulfate attack in concrete by degradation of iron sulfides and the effect of the host rock servando chinchonpaya 1 izelman oliveira 2 antonio aguado 3 servando chinchon 4 abstract in this study we deal with the problems of durability of concrete made with reactive aggregates, and more particularly those containing oxidizable iron sulfides. Sulfate attack of concrete is perhaps the least understood of the major durability mechanisms plaguing reinforced concrete infrastructures. Internal sulfate attack occurs when a source of sulfate is incorporated into the concrete mix. Materials astm designation c 150 provides for eight types of portland cement.
Sulfate attack is a common form of concrete deterioration. Results are measured in terms of compressive strength, tensile strength, flexural strength and mass loss. External sulphate attack is when the source of sulphate ions is external to the concrete, such as when it is from ground water or seawater. Sulphate attack might show itself in different forms depending upon the chemical form of the sulfate and. Thus it seems prudent that the possibility of asr and sulfate attack in arizona be researched further. Sulfates in solution in contact with concrete can cause chemical changes to the cement, which can cause significant microstructural effects leading to the weakening of the cement binder chemical sulfate attack. This has limited confidence that can be placed in and hence the reliability of existing standard tests and models to predict performance and service life of concrete subjected to sulfate attack. An approach for predicting the compressive strength of cement. Test specimens were soaked in sodium sulfate solution and sulfuric acid solution for various periods of time, and the performance of geopolymer concrete is studied by evaluating the effect on the compressive strength, change in length and change in mass. Sulfate in the soil and concrete foundations concrete. The air voids provide microscopic expansion chambers for relief of the pressure that is built up in the concrete by the growth of the sulfate crystals. Sulfate resistance is improved when using selfcuring concrete.
Therefore, if sulfate attack chemical characteristic xa1 xa2 xa3 so 4 2 mgl 200 and 15 and sulfate damage to concrete floors. Yet the mechanism of attack has not been universally agreed and, arguably of even greater importance, test procedures to measure sulfate attack and specifications for sulfate resistant formulations are not agreed, or are disputed. Samples are immersed in sodium sulfate na 2 so 4 solution of 4% concentration. Effects of substances on concrete and guide to protective treatments concrete technology by beatrix kerkhoff fig. Sulphate attack on concrete ash development association of. The sulfate attack on the soilcement was more rapid than that on concrete, and cordon suggested that the speed of reaction might be associated with the fact that soilcement was less dense, so that diffusion of the sulfate solutions or water could occur more easily.
To prevent the sulphate attack on concrete, we must understand the factors which affect the sulphate attack. If sufficient new phases are formed, stresses can be induced in the concrete to such an extent that the concrete can undergo cracking. This report gives guidance on sulfateattack damage to houses from the past use of sulfatebearing hardcore and infill material. It also provides improved durability for concrete in most aggressive environments, reducing the risk of deterioration of the structure and structural failure. The assessment of concrete properties due to sulfate attack using experimental methods is limited to short time nearly 700 days. Sulfate resisting cement sulfate resisting cement is a blended cement designed to improve the performance of concrete where the risk of sulfate attack may be present. This course explores deterioration of concrete due to sulfate attack, a complex process characterized by multiple manifestations including volume expansion, cracking, spalling, softening of the cementitious matrix creating mushy concrete.
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