Effect of slag, silica fume, and finishing on the sorptivities of field concrete

2006 ◽  
Vol 33 (8) ◽  
pp. 1022-1026 ◽  
Author(s):  
Peter J Tumidajski

For Canadian Standards Association C-2 exposure conditions (i.e., nonstructurally reinforced concrete exposed to chlorides and freezing and thawing) after 1 year, the effect of cement binder and finishing techniques on the capillary suction sorptivities of commercially batched and field-placed, cured, and finished concrete is reported. It was found that the addition of 40% ground granulated blast furnace slag or 8% silica fume is very effective in reducing sorptivities of field concrete. Furthermore, finishing techniques that do not overwork the surface assist in reducing sorptivities of field concrete.Key words: capillary suction, saturation, sorptivity, silica fume, slag, finish.

Concrete is one of the most suitable materials in the world which are used for construction. It becomes more versatile because of his suitability in almost all situations. Reinforced structures are subject to corrosion by various means. Carbonation is one of these means that causes corrosion of reinforced concrete structures. The service life of the structures has been reduced due to the deterioration of the structures because of the corrosion of the reinforced concrete due to carbonation. This paper focuses on the effect of carbonation on the mechanical properties of concrete composed of mineral admixtures, such as ground granulated blast furnace slag and silica fume, by partial replacement of the cement. In this experiment, silica fume replaced cement in 5%, 10%, 15% and ground granulated blast furnace slag replaced the cement in 10%, 20%, 30%. Samples such as cubes, cylinders and prisms were casted and cured. Certain number of these specimens were also placed in carbonation chamber and tested for compressive strength, tensile strength and flexural strength. Normal concrete samples are also tested and the results are compared.


Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1593
Author(s):  
Monika Czop ◽  
Beata Łaźniewska-Piekarczyk

In Europe, the use of wastes in the cement and construction industry follows the assumptions of sustainability and the idea of circular economy. At present, it is observed that cement plants introduce wastes to the cement in the form of so-called mineral additives. The most often used mineral additives are: fly ash with silica fume, granulated blast furnace slag and silica fume. The use of mineral additives in the cement is related to the fact that the use of the most expensive component of cement—Portland cement clinker—is limited. The purpose of the article is a preliminary evaluation of the suitability of slag from the municipal solid waste incineration plant for its use as a replacement of cement. In this article, slag from the municipal solid waste incineration (MSWI) replaces cement in the quantity of 30%, and presents the content of oxides and elements of slag from the MSWI. The obtained results are compared to the requirements that the crushed and granulated blast furnace slag need to meet to be suitable for use as an additive of type II to the concrete. The conducted analyses confirmed that the tested slag meets the requirements for the granulated blast furnace slag as an additive to the concrete in the following parameters: CaO ≤ 18.0%, SO3 ≤ 2.5% and Cl ≤ 0.1%. At the same time, mechanical features were tested of the designed mortars which consisted of a mixture of Portland cement (CEM I) with 30% of slag admixture. The designed mortar after 28 days of maturing reached a compressive strength of 32.0 MPa, and bending strength of 4.0 MPa. When compared to the milled granulated blast furnace slag (GBFS), the obtained values are slightly lower. Furthermore, the hardened mortars were subject to a leachability test to check the impact on the environment. Test results showed that the aqueous extracts from mixtures with 30% of slag admixtures slightly exceed the limits and do not pose a sufficiant threat to the environment as to eliminate the MSWI slag from economical use.


2017 ◽  
Vol 12 (3) ◽  
pp. 456-469 ◽  
Author(s):  
Toshiki Ayano ◽  
◽  
Takashi Fujii ◽  
Kyoji Niitani ◽  
Katsunori Takahashi ◽  
...  

Concrete deck slabs of bridges are often deteriorated by heavy traffic and freezing and thawing actions. Spraying salt during the winter further promotes the deterioration of concrete. Some reports estimate that the length of highway roads requiring the renewal of deteriorated concrete slabs exceeds 230 km. In order to extend the lifespan of damaged bridge girders, the load for these girders must not be increased. This means that prestressed concrete (hereafter, PC) members are desirable to sustain bridge life, because they can be thinner than reinforced concrete (hereafter, RC) members. In addition, to shorten the period of traffic regulation during renewal construction, precast members should be applied. One problem in manufacturing durable precast concrete is steam curing. When the temperature, period, or both of the steam curing process are inadequate, the effect of air-entraining (hereafter, AE) agents is lost because the warmed air trapped by the AE agent expands and escapes from the concrete. Another problem is concrete fatigue. It is well known that the fatigue lives of concrete slabs in wet conditions are much shorter than those in dry conditions. Concrete slabs are waterproofed immediately after construction, but the waterproofing can be fractured soon after opening bridges, and water can reach the concrete surface. The lifespan of concrete slabs in contact with water often depends on the fatigue of the concrete. Granulated blast furnace slag sand (hereafter, BFS) can enhance the resistance to freezing and thawing actions without using AE agents. Therefore, the resistance to freezing and thawing of concrete mixed with BFS is not damaged by steam curing. The fatigue of concrete in water is also improved by the addition of BFS. Furthermore, BFS can reduce the drying shrinkage of concrete. It is advantageous to restrict the loss of prestress in PC. This study shows that precast PC members with high durability can be manufactured when granulated blast furnace slag is used as a fine aggregate in the concrete. BFS reacts with cement hydrates. It is well known that the carbonation of concrete with ground granulated blast furnace slag (hereafter, GGBF) is much greater than that with ordinary binder. However, BFS does not accelerate the carbonation of concrete. When using granulated blast furnace slag as a fine aggregate, no disadvantage in the concrete properties is detected.


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