Effective Fine Concrete Modified with a Highly Dispersed Wollastonite-Based Additive

An effective highly dispersed additive based on the wollastonite Miwoll 05-97 with an average particle diameter of 6.5 microns is obtained. A stable effect of interacting the additive components with Portland slag cement CEM II/A–Ш 42.5H is revealed; it results in improving the strength of fine-grained concrete produced with the raw materials mentioned above. It is established that using water suspension of wollastonite solid particles, highly water-reducing/superplasticizing modifier based on the polycarboxylate ether Master Glenium 430, as a stabilizer of the surface-active substance allows producing an additive with an evener distribution of solid particles in the liquid, and with stable functional properties. A highly dispersed wollastonite-based additive, obtained by ultrasonic dispersion for 10 minutes in the bath-type activator at the frequency of 35 kHz in the aquatic environment with a suspension stabilizer, enables producing the wollastonite-modified fine concrete with a compressive strength of more than 50 MPa, with the 10% additive being 2 times higher than that of the control.

Improving the Efficiency of Slag Portland Cement by Reducing Shrinkage Deformations

The influence of the artificial additive introduced at the joint grinding of granulated slag, Portland cement clinker and gypsum on the Portland slag cement hydration, its compression strength at an early stage and shrinkage deformation is investigated. It was found that in the presence of sulfoferrite clinker there is an amorphization of cement stone structure with formation of stone with high density and strength in early setting. The open porosity of the hardened paste is reduced by 13 – 15 % in comparison with plain Portland slag cement. The samples strength increases by 1.55 - 1.78 times at grade stage, by 15.5 - 19.4 % in bending and by 6.4 - 11.2 % in compression.

Performance and Micro Structural Analysis of Portland Slag Cement Mortar Induced with Pozzolanic Additives

Portland cement is a kind of cement used where the high strength and durability is needed. Also, this type of cement is essentially used to control the CO2 emission during the manufacturing process of the concrete. This cement is made up of slag with the activator such as alkalis in the form of sodium hydroxide or sodium silicate. However, this addition is increasing the overall cost of the production of concrete. In this research, a new attempt has been made to use the natural activators of Rice Husk Ash (RHA) and Natural Steatite Powder (NSP). This research aims to determine the effects of RHA and NSP with Portland slag cement by partial replacement with 5%, 10%, 15% and 20% of RHA and NSP. The influence of the RHA and NSP on the mechanical properties of the mortar was evaluated by measuring the compressive strength and the split tensile strength. The durability properties of the specimens were analyzed by water absorption, sorpitivity and acid attack tests. The analysis of the microstructure of the specimens was done by scanning electron microscope (SEM) and Fourier Transform Infrared Spectra analysis (FTIR). It was observed that the maximum compressive strength and split tensile strength was in 5% RHA and NSP blended mortar. The durability results showed that the 10% RHA and 10% NSP had lesser water absorption and sorpitivity values. From the results of micro structural analysis it was observed that replacing cement with 5% RHA and 5% NSP results in improvement of microstructure of cement mortar.

MINERAL COMPOSITION OF DUMP BLAST FURNACE SLAG

Industrial wastes, accumulating in a dumping ground, have useful technical properties in many cases, so they can be considered as secon dary resources. The investigation of slag properties and modifications in different conditions needs a complex approach that includes X-ray phase, electron microscopic and petrographic analyses. The research aim is to substantiate the resource value of Zaporozhstal PJSC dump blast furnace slag on the basis of chosen experimental methods. X-ray phase analysis allows us to discover the minerals of blast furnace slag that are crystalline: rankinite 3CaO·2SiO2 , quartz SiO2 , helenite 2CaO·Al2O3·SiO2 , bredigite α-2CaO∙SiO2 , okermanite 2CaO·MgO·2SiO2 and pseudowollastonite α-CaO·SiO2 . The minerals okermanite, bredigite and pseudowollastonite are technically useful to produce binders as they are hydraulically active. The mass fraction of a vitreous component, which composes half of blast furnace slag mass of Zaporozhstal PJSC, was computed. Amorphous phases testify on the higher sorption and chemical slag activation that are important in terms of the use of slag to produce binders. The mass contribution of amorphous substance state is slightly higher in large fraction slag. Microphotographs of the surfaces of blast furnace slag particles show high loosening degree and needle-shaped and lamellar crystallines that stipulate sorption properties of the slag. The dump blast furnace slag of Zaporozhstal PJSC can be recommended to produce binders – Portland cement and Portland slag cement – at totality of chemical parameters: high concentration of hydraulically active minerals and amorphous phase, highly developed surface of slag particles and surface sorption activation.

BEHAVIOR OF M 50 GRADE SELF-COMPACTING CONCRETE DEVELOPED USING PORTLAND SLAG CEMENT AND METAKAOLIN

Self-compacting concrete (SCC) is a revolutionary development in concrete construction. The addition of mineral admixtures like metakaolin, which is a highly reactive pozzolana to the SCC mixes, gives it superior strength and durability. The present work is an effort to study the behavior of M50 grade SCC by partial replacement of Portland Slag Cement (PSC) with metakaolin. Its strength and durability aspects are comparable with a controlled concrete (without replacement of cement). In the present work, a new mix design methodology based on the efficiency of metakaolin is adopted. The optimum percentage replacement of cement with metakaolin is obtained based on compressive strength test results. The influence of metakaolin on the workability, compressive strength, splitting tensile strength and flexural strength of SCC and its behavior when subjected to elevated temperature was investigated through evaluation against controlled concrete and non-destructive testing. From the test results, it was observed that incorporation of metakaolin at an optimum dosage satisfied all the fresh properties of SCC and improved both the strength and durability performance of SCC compared to controlled concrete.