Effects of mineral admixtures and additional gypsum on the expansion …
For different contents of mineral admixtures, both expansion rates decreased with the increasing content of GGBS or FA (Fig. 1 (a and b)), and the reason probably is the three as follows: (a) the partial substituted of mineral admixtures decreased the content of cement in system, in which the hydration of cement contains a mass of AFt; (b) due ...
Role of Gypsum in Cement and its Effects – …
Gypsum plays a very important role in controlling the rate of hardening of the cement, so its is generally termed as retarding agent of cement. It is mainly used for regulating the setting time of cement and is an indispensable component.
Use of recycled gypsum in the cement-based stabilization of very …
Indeed, these standards apply to the Portland cement-based pastes, mortars, and concretes, and its requirement for a low gypsum fraction is due to the consideration of the uniform and dense structure of these hardened cement products that hence can accommodate little or are prone to damage by aforementioned internal expansion and resulting ...
Properties and hydration mechanism of slow-setting and expansive cement
From Fig. 5 (d), it can be seen that with the increase of SF content, the expansion rate of the cement paste of the same age gradually decreases, and the corresponding linear expansion rate of the final linear expansion rate (10 −6) is categorized into 188, 117, 92 and 72. This suggests that SF can reduce the volume expansion of cement.
High-Performance Grouting Mortar Based on Mineral …
The results show that the best conditions for gypsum-bauxite grouting mortar are as follows: a water-to-binder ratio of 0.3, a mineral admixture content of similar to 15%, and a molar ratio K of 2.
Effects of mineral admixtures and additional gypsum on the expansion …
However, the effect of expansive agent and the amount of hydration of cement are very relevant, for the generation and growth of AFt significantly affected by the concentration of Ca 2+, SO 4 2− and OH − [6], [23], [24], [25]. After cement substituted by high volume mineral admixtures, because of the cement content reduced, the production of AFt in expansive agent …
Experimental Study on Physical and Mechanical Properties of Gypsum …
In order to study the physical and mechanical properties of gypsum rock samples in three states (natural, high-temperature dehydration and hydration time), natural gypsum rock was put into high-temperature condition of 220°C for dehydration treatment, and then the high-temperature dehydrated gypsum rock was treated with different hydration time, and the …
Effects of active mineral admixture on mechanical properties …
The mix ratio: 10% metakaolin, 15% ultra-fine fly ash, and 3% silica fume, achieves best activities of the three mineral admixtures all through the whole curing period of the concrete, realizing optimal mechanical properties of concrete. The mineral admixture concrete is quite resistive to single SO 4 2− corrosion.
Does gypsum formation during sulfate attack on concrete …
However, some scholars found that the formation of gypsum can also cause concrete expansion and cracking [14, 15]. As for the latter, the theories of solid volume increase, solid topological ...
Strength and Expansion of LHEC with Different Gypsum …
Low-heat expansive cement (LHEC) is an environmentally friendly and low-carbon cementitious material. Compared to ordinary Portland cement (OPC), LHEC reduces CO2 emissions from the cement production process; furthermore, it enhances the service life of the cement by overcoming the problem of OPC's strength inversion in hot and humid …
Recent advance of MgO expansive agent in cement and concrete
Li et al. [96] found that the application of Ca–Mg expansive agent (3% CaO + 3% MgO) in concrete-filled steel tube could produce enough expansion in core concrete to compensate autogenous and thermal shrinkage, with the concrete still in expansion state when the temperature finally stabilized, which could effectively restrain the separation ...
Deleterious Expansion of Gypsum-Containing Grout
cement. grouts with added gypsum have been available for decades and continue to be produced, marketed, and utilized today because demand exists. some commercially available grouts utilize only gypsum as a binder or overwhelmingly rely on gypsum as a binder relative to other binders. Distress from Grout expansion given adequate gypsum and portland
Variation in the sulfate attack resistance of iron rich
When sulfate ions penetrate into the interior of the cementitious matrix via the pores, they can react with the calcium hydroxide produced by cement hydration to form gypsum [7], [8]. Additionally, if the cement contains aluminate minerals, the above reaction would further generate AFt, causing a nearly doubled volume expansion [9 ...
Gypsum products | PPT
INTRODUCTION Gypsum (CaSO4•2H2O; calcium sulfate dihydrate) is a mineral mined in various parts of the world, ... HIGH EXPANSION (TYPE V) This gypsum product exhibits an even higher compressive strength than the Type IV dental stone by lowering the W/P ratio even further than that used for Type IV stone. In addition, ...
Hydration and mechanical properties of FGD gypsum-cement-mineral …
The compressive strength contours of the gypsum-cement-mineral powder ternary system for different ages is shown in Fig. 7. The optimal regions of the compressive strength were within 75–85% gypsum content, <10% cement content, and 10–23% mineral powder content. Moreover, the effect of each component on strength and the corresponding ...
Effects of different gypsum varieties on the hydration and …
Red mud (RM) is the major waste with strong alkaline discharge produced in alumina manufacturing. The main chemical compositions are Fe 2 O 3, Al 2 O 3, and SiO 2, which are similar to those of the raw materials for SAC.RM is a kind of waste with large output and serious pollution, and its effective disposal is the important problem facing the environment at …
Effects of Gypsum on Cementitious Systems with Different Mineral Mixtures
Portland cement CEM I is obtained from (95–97%) of clinker and (3–5%) of gypsum, according to EN 197-1 (2011) standard. Sulfur xide SO3 is the main component of gypsum (Calcium Sulfate ...
The Future of Gypsum
Gypsum cements possess considerably greater strength and hardness as compared to non-gypsum cement. Water required in gypsum based cement for the hydration process is less. The use of gypsum as an additive in …
Physicomechanical Properties of Gypsum with Mineral …
Gypsum, from either nature or industrial by-products, can be a lower-cost and cleaner alternative binder to Portland cement used in construction projects, such as affordable housing in developing countries. Although various building products have successfully used gypsum as the binder, some drawbacks of this material have still been claimed, for example, …
The Role of Gypsum in Cement and Its Effects
Gypsum helps regulate the expansion and shrinkage of cement during the curing process. It counteracts the tendency of some cement compounds to cause excessive expansion and cracking, promoting …
Executive Summary – FCI Aravali Gypsum And Minerals …
7. EXPANSION AND DIVERSIFICATION. Presently the company is dealing only in one mineral i.e. mining and marketing of mineral gypsum. Now the company has focused to diversify its activities into the field of manufacturing SSP, white cement and mining of other minerals like Dolomite and Rock Phosphate for which the company is making continuous ...
Effects of different gypsum varieties on the hydration and …
By controlling the mineral composition of clinker and adjusting the varieties and quantities of gypsum, this experiment provides a feasible method for solving the stacking …
(PDF) Simulation of expansion in cement based materials …
Day expansion for mortar without mineral admixture, experimental and simulate. ... made from a combination of Portland cement and gypsum. ... ASTM C452 Standard Test Method for Potential Expansion ...
(PDF) Effect of Gypsum Amount in Cement on …
Gypsum plays a crucial role in cement. Though it is used in a small quantity, in the range of 2.5-3.0 percent in terms of SO3, gypsum's role in cement is significant, more predominantly at early ages.
Gypsum, the speed breaker
While producing 53 grade of cement, generally cement plant prefers to use mineral gypsum. Today industry faces shortage of mineral gypsum, which is the purer form of gypsum and the gap is bridged by synthetic gypsum mainly coming from fertiliser industry. ... expansion in the global market. We have successfully acquired J.J. Jenkins Inc. a ...
Mechanical, expansion and rheological properties of …
The problem of over- expansion of f-CaO is summarized, which limits the scale application of CFBFA in ecological cement. Hence, the challenge for f-CaO in CFBFA to compensate for cement volume shrinkage is proposed, which is beneficial to the utilization of CFBFA in ecological cement, and the reduction of CO2 emissions from the cement industry.
Deleterious Expansion of Gypsum-Containing Grout
given adequate gypsum and portland cement content as well as exposure to moisture, internal volumetric expansion of post pocket grout can occur long after the grout's initial set. the …
Decoding Cement Composition: Ingredients & Properties
Minor Cement Chemical Components and Their Functions. The main ingredients form cement's core, but there are some other minor cement mineral compositions, which are: Gypsum (Calcium Sulfate): Gypsum is added to cement to slow down its setting, keeping it workable for a longer time. Gypsum reacts with tricalcium aluminate, slowing down the ...
Effect of Nano-Magnesium Oxide on the Expansion …
Many scholars are concerned about the effect of nano-MgO as an expansion agent on the performance of cement-based materials at an early age, but over a long period less attention is paid to expansion stability and mechanical properties. This article examines the influence of nano-MgO on the long-term consistency, fluidity, expansion stability, hydration, …
The effect of the source of cement SO3 on the expansion of mortars
In order to evaluate the risk of the source and quantity of cement SO 3 on the expansion properties of mortars, this paper studied the influence of Gypsum, Bassanite and clinker sulfate on the cement paste expansion and the formation of delayed ettringite. The investigation covers the mortar cured at 20 °C and 80 °C and stored in water.In contradiction …