Investigation on Recycled Cement Based on Waste Concrete

2012 ◽  
Vol 509 ◽  
pp. 40-44 ◽  
Author(s):  
Zong Shou Lin ◽  
Yan Chong
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Raw Materials ◽  
Hydration Product ◽  
Sem Analysis ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Mix Proportion ◽  
Furnace Slag

Adding part of granulated blast furnace slag(GBFS), steel salg(SS) , Desulfurization gypsum(DG), we can use Waste Cencrete（WC）as the main raw materials to directly produce uncalcined cement by grinding.With mix proportion 40%~50% of WC and curing in water, the 3d compressive strength of the cement can reach 10MPa.,the 28d compressive strength of the cement can reach 20~40MPa. XRD and SEM analysis show that, the hydration products of the cement are ettringite and C-S-H gel. Parts of WC involves in the hydration reaction, residual WC is wrapped by the hydration product as aggregate filler.

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

scholarly journals Compressive Strength and Durability of FGD Gypsum-Based Mortars Blended with Ground Granulated Blast Furnace Slag

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3383
Author(s):  
Min Pang ◽  
Zhenping Sun ◽  
Huihao Huang
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Raw Materials ◽  
Steam Curing ◽  
Curing Conditions ◽  
Fgd Gypsum ◽  
Granulated Blast Furnace Slag ◽  
Mix Proportion ◽  
Furnace Slag

One new flue gas desulfurization (FGD) gypsum-based binder is attempted in this article, which is made up of FGD gypsum, ground granulated blast furnace slag (GGBS) and ordinary Portland cement (OPC). Influences of raw materials, chemical activators, and curing conditions on the compressive strength of this new binder-based mortar, as well as its durability performances and microscopic characteristics, are investigated in consideration of utilizing FGD gypsum as much as possible. Results show that the compressive strength of this new binder-based mortar under normal curing conditions could increase along with GGBS dosages from three days to 90 days. The compressive strength of one selected mix proportion (FG-4550), which contains the highest dosage of FGD gypsum (45 wt.%), is much the same as those containing the highest dosage of GGBS. A better compressive strength of FG-4550 under normal curing conditions could be gained if the fineness of GGBS is improved. The activated effect of CaCl2 on the compressive strength of FG-4550 is superior to that of Ca(OH)2 under steam curing conditions. FG-4550 shows a good capacity for resistance to water, a low shrinkage ratio, but poor compressive strength after 30 freeze-thaw cycles. Based on the mineralogy of X-ray diffraction, the morphology of scanning electron microscopy and the pore diameter distributions of 1H nuclear magnetic resonance, the compressive strength of this FGD gypsum-based mortar mainly depends on clusters of ettringite.

scholarly journals Influence of Molarity and Chemical Composition on the Development of Compressive Strength in POFA Based Geopolymer Mortar

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
S. M. Alamgir Kabir ◽  
U. Johnson Alengaram ◽  
Mohd Zamin Jumaat ◽  
Afia Sharmin ◽  
Azizul Islam
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Palm Oil Fuel Ash ◽  
Manufactured Sand ◽  
Granulated Blast Furnace Slag ◽  
Mix Proportion ◽  
Geopolymer Matrix ◽  
Fuel Ash ◽  
Oil Fuel ◽  
Furnace Slag

The investigation concerns the use of the optimum mix proportion of two locally available pozzolanic waste materials, namely, ground granulated blast furnace slag (GGBS) and palm oil fuel ash (POFA), together with metakaolin (MK) as binders. In addition, another local waste material, manufactured sand (M-sand), was used as a replacement for conventional sand in the development of green geopolymer mortar. Twenty-four mortar mixtures were designed with varying binder contents and alkaline activators. The oven dry curing was also kept consistent for all the mix proportions at a temperature of 65°C for 24 hours. The highest 28-day compressive strength of about 48 MPa was obtained for the mortar containing 20% of MK, 35% of GGBS, and 45% of POFA. The increment of MK beyond 20% leads to reduction of the compressive strength. The GGBS replacement beyond 35% also reduced the compressive strength. The entire specimen achieved average 80% of the 28-day strength at the age of 3 days. The density decreased with the increase of POFA percentage. The finding of this research by using the combination of MK, GGBS, and POFA as binders to wholly replace conventional ordinary Portland cement would lead to alternate eco-friendly geopolymer matrix.

Experimental Study on Compound Binding Material of Alkali Activated Metakaolin and Ground Granulated Blast Furnace Slag

2011 ◽  
Vol 287-290 ◽  
pp. 1275-1279
Author(s):  
Yong Jia He ◽  
Lin Nu Lu ◽  
Shu Guang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Hydration Product ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Binding Material ◽  
Measurement Results ◽  
Furnace Slag ◽  
Alkali Activated

Compound binding material was prepared by the alkali activation of metakaolin and ground granulated blast furnace slag. Hydration product components, microstructure and mechanical properties of the hardened paste were investigated by IR, XRD, SEM, MIP, and compressive strength measurement. Results indicated that hydration products included C-S-H and geopolymer, and both of them were amorphous although there were differences in their structure and morphology. When the dosage of slag was less than 50%, the compressive strength of hardened paste increased as the dosage increased, which was mainly because C-S-H produced by the reaction of GGBFS and alkali filled void in geopolymer phase, and part of unreacted slag particles acting as microaggregate to prevent from extension of microcrack in the hardened paste, so the porosity of hardened paste decreased and compressive strength increased.

Influence of the Slag Replacement Percentage on the Compressive Strength and Products of Slag Based Geopolymers

2010 ◽  
Vol 177 ◽  
pp. 489-492
Author(s):  
Li Rong Yang ◽  
Man Zhen Duan
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Amorphous Materials ◽  
Great Increase ◽  
Reaction Products ◽  
Granulated Blast Furnace Slag ◽  
Mix Proportion ◽  
Soluble Glass ◽  
Amorphous Aluminosilicate ◽  
Furnace Slag

The slag based geopolymers materials are synthesized at ambient temperature by using fly ash (FA) and ground granulated blast furnace slag (GGBFS) as the main starting materials, and NaOH and soluble glass together as activators. The influence of the mix proportion between GGBFS and FA on the strength and reaction products was investigated. The products obtained were characterized by means of XRD, FTIR spectroscopy and FE-SEM coupled with EDX. The results show that a great increase in compressive strength appears when the replacement percentage of GGBFS exceeds 30wt. %, the resultant products are mainly amorphous materials (amorphous aluminosilicate and/or C-S-H gel) and much more compact, homogeneous, and uniform when the amorphous aluminosilicate is increasingly turned into C-S-H gel with the increasing replacement percentage of GGBFS.

The Influence of the Properties of the Material Used for Obtaining Geopolymers on Their Structure and Compressive Strength

2017 ◽  
Vol 68 (6) ◽  
pp. 1182-1187
Author(s):  
Ilenuta Severin ◽  
Maria Vlad
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Wheat Straw ◽  
Red Mud ◽  
Blast Furnace Slag ◽  
Complex Structure ◽  
Point Of View ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Straw Ash

This article presents the influence of the properties of the materials in the geopolymeric mixture, ground granulated blast furnace slag (GGBFS) + wheat straw ash (WSA) + uncalcined red mud (RMu), and ground granulated blast furnace slag + wheat straw ash + calcined red mud (RMc), over the microstructure and mechanical properties of the synthesised geopolymers. The activation solutions used were a NaOH solution with 8M concentration, and a solution realised from 50%wt NaOH and 50%wt Na2SiO3. The samples were analysed: from the microstructural point of view through SEM microscopy; the chemical composition was determined through EDX analysis; and the compressive strength tests was done for samples tested at 7 and 28 days, respectively. The SEM micrographies of the geopolymers have highlighted a complex structure and an variable compressive strength. Compressive strength varied from 24 MPa in the case of the same recipe obtained from 70% of GGBFS + 25% WSA +5% RMu, alkaline activated with NaOH 8M (7 days testing) to 85 MPa in the case of the recipe but replacing RMu with RMc with calcined red mud, alkaline activated with the 50%wt NaOH and 50%wt Na2SiO3 solution (28 days testing). This variation in the sense of the rise in compressive strength can be attributed to the difference in reactivity of the materials used in the recipes, the curing period, the geopolymers structure, and the presence of a lower or higher rate of pores, as well as the alkalinity and the nature of the activation solutions used.

scholarly journals Synergistic Excitation Mechanism of CaO-SiO2-Al2O3-SO3 Quaternary Active Cementitious System

2021 ◽  
Vol 8 ◽  
Author(s):  
Fusheng Niu ◽  
Yukun An ◽  
Jinxia Zhang ◽  
Wen Chen ◽  
Shengtao He
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Test Block ◽  
Hydration Reaction ◽  
Alkaline Environment ◽  
Granulated Blast Furnace Slag ◽  
Cementitious System ◽  
Furnace Slag

In this study, the influence of steel slag (SS) content on the strength of the cementitious materials was investigated. The quaternary active cementitious material (CaO-SiO2-Al2O3-SO3) was prepared using various proportions of steel slag (SS), granulated blast furnace slag (BFS), and desulfurized gypsum (DG). The mechanism of synergistic excitation hydration of the cementitious materials was examined using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The strength of the mortar test block was initially increased and decreased later with the increase of the SS content. Mortar test block with 20% steel slag, 65% granulated blast furnace slag, and 15% desulfurized gypsum with 0.35 water-binder ratio showed the highest compressive strength of 57.3 MPa on 28 days. The free calcium oxide (f-CaO) in the SS reacted with water and produced calcium hydroxide (Ca(OH)2) which created an alkaline environment. Under the alkaline environment, the alkali-activated reaction occurred with BFS. In the early stage of hydration reaction, calcium silicate hydrate (C-S-H) gel and fibrous hydration product ettringite (AFt) crystals were formed, which provided early strength to the cementitious materials. As the hydration reaction progressed, the interlocked growth of C-S-H gel and AFt crystals continued and promoted the increase of the strength of the cementitious system.

scholarly journals Effect of fine recycled aggregates on the properties of non-cement blended materials

2020 ◽  
Vol 323 ◽  
pp. 01018
Author(s):  
Wei-Ting Lin ◽  
Lukáš Fiala ◽  
An Cheng ◽  
Michaela Petříková
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Interface Structure ◽  
Strength Test ◽  
Recycled Aggregates ◽  
Test Results ◽  
Granulated Blast Furnace Slag ◽  
Fine Aggregates ◽  
Compressive Strength Test ◽  
Furnace Slag

In this study, the different proportions of co-fired fly ash and ground granulated blast-furnace slag were used to fully replace the cement as non-cement blended materials in a fixed water-cement ratio. The recycled fine aggregates were replaced with natural fine aggregates as 10%, 20%, 30%, 40% and 50%. The flowability, compressive strength, water absorption and scanning electron microscope observations were used as the engineered indices by adding different proportions of recycled fine aggregates. The test results indicated that the fluidity cannot be measured normally due to the increase in the proportion of recycled fine aggregates due to its higher absorbability. In the compressive strength test, the compressive strength decreased accordingly as the recycled fine aggregates increased due to the interface structure and the performance of recycled aggregates. The fine aggregates and other blended materials had poor cementation properties, resulting in a tendency for their compressive strength to decrease. However, the compressive strength can be controlled above 35 MPa of the green non-cement blended materials containing 20% recycled aggregates.

scholarly journals Effect of Na2SiO3/Naoh on the Compressive Strength of Inorganic Polymer Concrete Mixed with Ground Granulated Blast Furnace Slag (GGBS) At Ambient Condition

2019 ◽  
Vol 9 (2) ◽  
pp. 1222-1228
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Ambient Condition ◽  
Polymer Concrete ◽  
Geopolymer Concrete ◽  
Split Tensile Strength ◽  
Standard Size ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

This paper aims to investigate the influence of alkaline activators solution i.e, Na2SiO3 / NaOH on compressive strength of geopolymer concrete mixed with Ground Granulated Blast furnace slag (GGBS) for constant molarity 8 M. The ratio of alkali to binder ratio is taken as 0.5 and the ratio of Na2SiO3 / NaOH is 2.5. The geopolymer mix is based on pervious sutdies. As per Indian standard size moulds for the cube, cylinder and prism are cast, cured and tested.The specimens were tested for fresh concrete properties such as slump cone test and hardened properties such as compressive strength for cubes, split tensile strength for cylinders and flexural strength for prism different days of curing under ambient temperature. Also, a microstructural study is done by using Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) for the tested sample. It is found from the test results that, with the aid of alumino-silicate solution, early strength is achieved by geopolymer concrete within 7 days under ambient condition due to the presence of ground granulated slag.

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