Effect of Curing Time and CaSO₄ Whisker Content on Properties of Gypsum Board

Abstract

In this thesis, proper amount of whiskers were added to building gypsum used as the basic materials. The gypsum board properties, such as densities and flexural strength etc., were influenced by various whisker content. The results showed that the flexural performance of gypsum board could be enhanced when adding calcium sulfate whisker from a range of 0.5~3 wt.%. The flexural strength reached 5.38 MPa when calcium sulfate whisker content was 1 wt.%. The flexural strength could be higher than that of gypsum board without calcium sulfate whisker by 37.6%.

Experimental Study on Flexural Fatigue Resistance of Recycled Fine Aggregate Concrete Incorporating Calcium Sulfate Whiskers

“…In addition, with an increase in CSW dosage, the fatigue life of RFAC under the same stress level presented a trend of increasing and then decreasing, consistent with the trend observed in the static loading test. This is because when the amount of CSW is too large, the excessive microfiber cannot be uniformly distributed and may even cause agglomeration [43], leading to insufficient densification of the specimen and the formation of more pore spaces, thus decreasing the concrete's ability to withstand cyclic loading.…”

“…Therefore, when CSW is well-dispersed in the RFAC specimen, the increase in CSW per unit volume allows more whiskers to participate in the crack arresting effect. However, when the dosage of CSW is too high, due to the increased interactions between whiskers, the resistance of whiskers in the dispersion process increases [34,43], resulting in insufficient dispersion of whiskers and the whisker aggregation phenomenon occurring inside the test block. This loose accumulation of whiskers leads to a decrease in the densification of concrete, accelerating the expansion of the cracks under the action of cyclic loading and negatively affecting the fatigue performance of the CSWRF.…”

Preparation and Application in HDPE of Nano-CaSO4 from Phosphogypsum

“…As reinforcement materials, CaSO 4 ·0.5H 2 O whiskers with high length/diameter ratios, the synthesis of which has attracted much attention, have high strength and high application value in fields such as plastics. To obtain CaSO 4 ·0.5H 2 O whiskers with high aspect ratios, many researchers have conducted exploratory experiments on factors such as temperature, reaction time, and the organic or inorganic components added for the precipitation and dissolution of CaSO 4 ·0.5H 2 O whiskers. However, the loss of water from CaSO 4 ·2H 2 O and CaSO 4 ·0.5H 2 O results in a decrease in the whisker aspect ratio from a microscale perspective, the result of which is that a very fine powder, which cannot enhance or toughen the matrix material, is formed on the macro level .…”

Facile Synthesis of Phosphogypsum-Based Whiskers by Low Temperature Hydrothermal Route with CTAB Addition

“…In recent years, the synthesis of CaSO 4 •0.5H 2 O whiskers with high aspect ratios has drawn much attention since they have the greater intensity and the higher use value used as the reinforcing materials in many fields such as plastics, lightweight building materials, ceramics and paper making, etc [1]. To obtain high aspect ratios CaSO 4 •0.5H 2 O whiskers, many researchers have studied the factors that govern the precipitation and dissolution of the CaSO 4 •0.5H 2 O such as temperature [2], reaction time [3], organic [4]or inorganic additives [5,6].…”