The performance of soundless cracking agents for …

2019-5-30 · Aiming at the problems with hard rock roof of coal seams, such as their large strength and difficulty in caving, traditional high-pressure water injection, and deep-hole blasting methods for roof weakening are mainly used to change mechanical characteristics and conditions of roof strata. However, these methods are not free from problems, such as inconvenience operation, strict sealing ...

Effects of Expansive Agents on the Early Hydration ...

2019-6-13 · The 14-day expansion rates of cementitious binders containing ZY-type™ expansive agent are in the range of 2.0 × 10-4 to 3.5 × 10-4, which could meet the basic requirements of anti-cracking performances in technical use according to Chinese industry standard JGJ/T 178-2009.

Effects of MgO Expansive Agent and Steel Fiber on Crack ...

To prevent cracks caused by shrinkage of the deck of the Xiaoqing River Bridge, MgO concrete (MC) and steel fiber reinforced MgO concrete (SMC) were used. The deformation and strength of the deck were measured in the field, the resistance to chloride penetration of the concrete was measured in the laboratory, and the pore structure of the concrete was analyzed by a mercury intrusion ...

Effect of Expansive Agent and Temperature on the Quality ...

2016-10-12 · Pre-cast concrete products are sometimes manufactured in two cycles per day production with one mold for the purpose of productivity improvement. In such cases, to secure the early strength, which is required at demolding, it is necessary to increase the steam-curing temperature. However, when this is done, the issue of temperature-related cracking becomes a concern. In addition, self ...

Investigation of the mechanical, microstructural and ...

2017-8-1 · This paper, therefore, was aimed at investigating mechanical, microstructural and mineralogical alterations taking place in SCDA during its hydration process, which are vital components that must be understood prior to modifying SCDAs for improved performance. 2. The soundless cracking demolition agent (SCDA)

Magnetic force wave Cracking Unit

2011-12-29 · Crushing using a special magnetic process. Different wastes materials can be processed at the same time. Only the maintance cost. No fuel, no electricity, and no engine teguired. Low temperature crushing 350 or lower. With a minimum supply of oxygen, the emission of dioxin and CO2 is suppressed. Crushing wastes before loaded improves the ...

Effect of Fibers and Expansive Agent on Shrinkage of Self ...

Adding the proper amount of expansive agent (EA) to concrete is an effective way to control shrinkage cracking. Fiber can be treated as a secondary reinforcement for controlling shrinkage and improving the crack resistance and mechanical properties of the concrete.

Strain Capacity and Cracking Resistance Improvement in ...

Despite the decrease in mechanical strength and the increase of free shrinkage length change, these composites exhibited a considerable improvement of strain capacity and cracking resistance. The plastic aggregates delay shrinkage cracking and cause multiple cracking with smaller crack widths.

Full strength and toughness recovery after repeated ...

2020-11-4 · Recovery of mechanical properties by repeated cracking and healing ... a R-curve behaviour 6,40,41,42 with a crack length expansion ... bacteria as self-healing agent for the development of ...

Mechanical Weathering: Definition, Process, Types ...

Mechanical weathering is the physical breakdown of rock by environmental factors. This process is always at work, and there are a number of different types of mechanical weathering.

Expansive Rock Breaking Non-Explosive Demolition Agent ...

Expanding Grout is a non-explosive demolition agent used for breaking rock and concrete. Also known as Expansive Demolition Grout, it is designed to provide job sites with non-explosive solutions for the demolition of rock and concrete in environmentally sensitive areas. Using a non-explosive product for rock and concrete breaking completely ...

Effects of Different Expansive Agents on the Properties of ...

Cracking happens in the case of restricted volumetric shrinking in cementitious materials which has a negative influence on the mechanical characteristics and longevity of concrete materials and ...

Effects of MgO Expansive Agent and Steel Fiber on Crack ...

The results showed that the expansion caused by the hydration of MgO could suppress the shrinkage of the bridge deck, and the deformation of the deck changed from -88.3 × 10 -6 to 24.9 × 10 -6, effectively preventing shrinkage cracks. At the same time, due to the restriction of the expansion of MgO by the steel bars, the expansion of the ...

Expansion of Cement Mortar Mixing Expansive Agent under ...

The expansion of cement mortar mixing expansive agent under standard curing and membrane curing conditions and compressive strength in constrained conditions are studied in this paper. Results show that the early expansion effect of calcium sulphoaluminate hydrate-calcium hydroxide expansive agent is obvious, mid-to late effect of magnesia expansive agent increase clearly.

A Rock Fracturing Method Using High-Pressure Gas Expansion ...

2021-5-6 · The use of explosives in cities is under strict control due to the risks associated with blasting. It is difficult to perform nonexplosive continuous excavation on hard rock connecting passage in crowded cities with dense high buildings and populations safely and rapidly. Therefore, a new method of rock fracturing through high-pressure gas expansion is proposed.

Silent cracking and expansive expansion agent for large ...

2020-6-28 · The scope of products 1. Exploitation of precious rock blocks and stone cutting. 2. Common rock breaking and loosening, large-size shaft, anti-slide pile, hole pile excavation, trench sinking …

Graphene production by cracking | Philosophical ...

2021-6-21 · 1. Introduction. Ever since it was separated from bulk graphite for the first time in 2004 [], graphene has come under the spotlight of scientific research.Graphene is defined as a single-atom flat monolayer made of sp 2-hybridized ''honeycomb'' carbon lattice [1–3].During the past two decades, scientists have discovered numerous unique properties of graphene such as high optical ...

Deformation, Cracking and Fracture Behavior of Dynamically ...

2019-11-13 · Abstract This study investigates the cracking behavior of oxide layers formed on molten metals and alloys including pure zinc, Zn–4 wt%Al (ZAMAK3) and Al–(0.5–2) wt%Ca in dynamic oxidation condition by injecting gas bubbles into the molten metal during the pouring process. The crack characteristics of the oxide layers were studied using a field emission scanning electron microscope. …

China CSA Expansive Agent (Shrinkage reducing)

China CSA Expansive Agent (Shrinkage reducing), Find details about China Csa Expansive Agent, Csa Expansive Additive from CSA Expansive Agent (Shrinkage reducing) - Tangshan Polar Bear Building Materials Co., Ltd.

Concrete Cracking

Concrete cracking is a result of the combined effects of mechanical loading and environmental conditions. 29 Concentrated chloride exposure is one of the most severe and aggressive among all possible forms of environmental exposure for concrete structures. 30 Serious concrete deterioration is generally initiated by concrete cracking under restrained shrinkage or stress concentration, which ...

Non-explosive demolition agent POWER BRISTAR | Taiheiyo ...

A low-pollution type crushing agent that uses the expansion pressure due to the reaction with water. Highly safe and environmentally friendly crushing method. It is easy to handle without being subject to legal restrictions during construction. The crushing efficiency is good, and the vibration and noise associated with the secondary crushing work can be reduced.

Impact of agricultural waste on the shrink–swell behavior ...

2019-4-26 · The swelling characteristics and cracking of expansive clayey soils usually lead to their low yield, and as a result, large areas of expansive soils remain uncultivated and unproductive. There is a need for the development of simple, low-cost …

A Continuum Coupled Thermo-Hygro Mechanical Time-Dependent ...

2015-9-17 · The mechanical component of the model simulates the dependence of the strength and stiffness properties of the model on the degree of hydration. Furthermore, the plastic-damage-contact model of Jefferson and Mihai; which simulates cracking, crushing and crack closure; has been extended to include hydration dependent behaviour.

A coupled thermomechanical nonordinary state‐based ...

2019-11-28 · A novel coupled thermo-mechanical nonordinary state-based peridynamics is proposed to study thermally induced damage in rocks. The thermal expansion characteristics of solid material are introduced into the coupled thermomechanical model to consider the influence of temperature.

Seismic cracking mechanism and control for pre-stressed ...

2021-6-2 · The box girder of the Miaoziping Bridge, a three-span prestressed concrete continuous rigid-frame bridge, suffered a serious crack in its box section''s web near the 1/6 to 1/2 length of the side span and the middle-span length of 1/4 to 3/4, as a result …

Mechanical Recovery of Cracked Fiber-Reinforced Mortar ...

This research is sought to characterize the stimulated autogenous healing of fiber-reinforced mortars that incorporate healing agents such as crystalline admixtures, expansive agents, and geomaterials. The effects of the healing materials on mechanical performance and water permeability were evaluated experimentally. Furthermore, microscopic and microstructural observations were conducted to ...

Controlled Concrete Demolition Using Expansive Cracking Agents

SCDA also known as soundless cracking agents, expansive demolition agents, expansive concrete, non-explosive demolition agents [34][35] [36] [37][38][39][40], are such alternative rock ...

Effect of rock mechanical properties on electromagnetic ...

2021-8-1 · The cracking agent was first mixed with a water-cement ratio of 1:3 and filled into the pre-drilled hole. The hole was then covered with steel gasket and the jack was adjusted to touch the top plate of the fixture, so that the cracking agent can expand and press against the hole wall.

(PDF) Expansive fracture agent behaviour for concrete cracking

Joseph F. Labuz. A study was conducted to determine the efficiency of a highly expansive cement (called Bristar) used to fracture rock and concrete. The 48-hour expansive pressure of the cement ...

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