The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform

S Wild - One of the best experts on this subject based on the ideXlab platform.

  • strength and chemical resistance of mortars containing brick manufacturing clays subjected to different treatments
    Cement & Concrete Composites, 2006
    Co-Authors: Marie Ofarrell, S Wild
    Abstract:

    This paper presents the results of an investigation of the properties of mortar in which a calcined clay was employed as a pozzolan. Mortars were prepared using either heat treated clay or ground waste clay bricks (from the same clay subjected to 1000 °C calcining) as a pozzolanic partial replacement for cement at replacement levels of 10%, 20% and 30%. The compressive strengths of the mortars were monitored up to 90 days and the resistance to Sodium Sulphate Solution and synthetic seawater was monitored up to 300 days. The specimens were also monitored for weight changes. Partially replacing cement by ground brick or heat-treated brick clay gives early strengths that are lower than that of the control. At 90 days, however, the strengths are the same as or are greater than that of the control. Heat-treated clay is effective in reducing expansion during exposure of the mortar to Sulphate Solution and synthetic seawater. The rapidly cooled clay gives better performance, in terms of strength development and resistance to harmful Solutions, than the slow cooled clay.

  • resistance to chemical attack of ground brick pc mortar part i Sodium Sulphate Solution
    Cement and Concrete Research, 1999
    Co-Authors: M Ofarrell, S Wild, B B Sabir
    Abstract:

    Abstract The partial replacement of high C 3 A cement blended with ground brick (GB) is investigated in terms of resistance of GB mortar to Sodium Sulphate (Na 2 SO 4 ) Solution. The results indicate that the Sulphate resistance of mortar is generally increased as the replacement level of cement with GB increases up to at least 30% replacement. However, the GB types investigated exhibit varying resistance to Sulphate expansion when used as partial cement replacement and this is attributed to their chemical and phase composition. Sulphate content, glass content, and oxide chemistry are the principal factors that determine the effectiveness of GB in resisting Sulphate expansion. Small amounts of Sulphate in GB do not have any deleterious effects on GB mortars and can be beneficial. Bricks with high-calcium glass or a low proportion of glassy phase should not be used as pozzolans. Bricks with a high proportion of low-calcium glass make very effective pozzolans.

Miguel Gonzalez - One of the best experts on this subject based on the ideXlab platform.

  • thaumasite formation in limestone filler cements exposed to Sodium Sulphate Solution at 20 c
    Cement & Concrete Composites, 2005
    Co-Authors: Edgardo F Irassar, V L Bonavetti, M A Trezza, Miguel Gonzalez
    Abstract:

    Abstract This paper presents a microstructural analysis of mortars made with OPC (C3A=6%) and two SRPCs (C3A

  • Sulphate resistance of type v cements with limestone filler and natural pozzolana
    Cement & Concrete Composites, 2000
    Co-Authors: Edgardo F Irassar, Miguel Gonzalez, V Rahhal
    Abstract:

    Sulphate performance of concrete depends primarily on permeability. Under severe conditions of Sulphate exposure, low-permeability concrete is prescribed and it must also be made with high Sulphate resisting cement. For portland cement, the Sulphate resistance depends on the C3A content and the amount of CH produced at early stages of hydration. Some parameters that modify the quantity of early CH in the hardened cement paste are investigated in this paper. Two type V cements with quite different C3S content and blended cements containing natural pozzolana or limestone filler were used. Expansion, flexural and compressive strength of mortar, immersed until 1 yr in Sodium Sulphate Solution, with pH-controlled are presented. Results show that the Sulphate performance of portland cement with high C3S content is very poor compared with low C3S portland cement. Addition of natural pozzolana provides the maximum Sulphate resistance while the addition of 20% limestone filler declining Sulphate performance of low C3A cements. This behaviour can be attributed to the reaction between Sulphate ions with CH into the paste that produces an alteration of the predominant mechanism of Sulphate attack.

Edgardo F Irassar - One of the best experts on this subject based on the ideXlab platform.

  • thaumasite formation in limestone filler cements exposed to Sodium Sulphate Solution at 20 c
    Cement & Concrete Composites, 2005
    Co-Authors: Edgardo F Irassar, V L Bonavetti, M A Trezza, Miguel Gonzalez
    Abstract:

    Abstract This paper presents a microstructural analysis of mortars made with OPC (C3A=6%) and two SRPCs (C3A

  • Sulphate resistance of type v cements with limestone filler and natural pozzolana
    Cement & Concrete Composites, 2000
    Co-Authors: Edgardo F Irassar, Miguel Gonzalez, V Rahhal
    Abstract:

    Sulphate performance of concrete depends primarily on permeability. Under severe conditions of Sulphate exposure, low-permeability concrete is prescribed and it must also be made with high Sulphate resisting cement. For portland cement, the Sulphate resistance depends on the C3A content and the amount of CH produced at early stages of hydration. Some parameters that modify the quantity of early CH in the hardened cement paste are investigated in this paper. Two type V cements with quite different C3S content and blended cements containing natural pozzolana or limestone filler were used. Expansion, flexural and compressive strength of mortar, immersed until 1 yr in Sodium Sulphate Solution, with pH-controlled are presented. Results show that the Sulphate performance of portland cement with high C3S content is very poor compared with low C3S portland cement. Addition of natural pozzolana provides the maximum Sulphate resistance while the addition of 20% limestone filler declining Sulphate performance of low C3A cements. This behaviour can be attributed to the reaction between Sulphate ions with CH into the paste that produces an alteration of the predominant mechanism of Sulphate attack.

John M. Kinuthia - One of the best experts on this subject based on the ideXlab platform.

  • resistance of mortar containing unprocessed pulverised fuel ash pfa to Sulphate attack
    Cement & Concrete Composites, 2010
    Co-Authors: D G Snelson, John M. Kinuthia
    Abstract:

    Abstract An investigation was carried out to establish the physical, mechanical and chemical characteristics of an unprocessed pulverised fuel ash (PFA) from a former landfill site at the Power Station Hill near Church Village, South Wales, United Kingdom. This was aimed at establishing the suitability of the ash in road construction (embankment and pavement) and also in concrete to be used in the construction of a proposed highway. This paper reports on mortar blends made using the unprocessed PFA as cement replacement. The resistance of the mortar was tested by observing Sulphate attack during soaking in a standard BS Sodium Sulphate Solution, for soaking periods of up to 504 days. Mortar cylinders of various mix designs were subjected to splitting tensile strength tests, after curing in water for up to 28 days. Thermogravimetric and derivative thermogravimetric (TG/DTG) analyses were carried out on the unhydrated ingredients, in order to assess the degree of hydration and rate of, and portlandite formation in the cement paste after soaking in either water or Sodium Sulphate Solution environment. The binary PC–PFA mortar shows good Sulphate resistance under a sulphatic environment with the exception of one trial pit ash (Trail Pit No. 6). The tensile splitting strength decreases as the cement replacement increases.

Min Sun - One of the best experts on this subject based on the ideXlab platform.