Study On The Comparison Of The Modification Effect Of Gypsum-based Materials On Acidic Adobe And Alkaline Adobe

The raw material of adobe is soil.Due to the vast territory of China,the soil types are diverse.Therefore,the physical and chemical properties of adobe are also different from each other.Gypsum-based materials composed of gypsum and a small amount of fly ash.Using gypsum-based materials to modify acidic adobe and alkaline adobe can improve the performance of adobe.This also helps to understand the adaptability of gypsum-based materials to different types of adobe.This is of great significance to unify the standard of modification of adobe,expand the application range of modified adobe,and reduce the cost of modified adobe.Two different sources of adobe are selected in this paper,one is acidic and the other is alkaline.By adjusting the amount of gypsum,the modification effect of gypsum-based materials on the two types of adobe was studied.The result shows that whether it is acidic adobe or alkaline adobe,after being modified with gypsum-based materials,the strength,water resistance and resistance to dry and wet cycling damage are all improved with the increase of gypsum content.For the modified acidic adobe,the 28 d compressive strength increased by 2.3 times,while that of alkaline adobe increased by 7 times.The modified alkaline adobe also has better water resistance and resistance to dry and wet cycling.The acidic adobe and alkaline adobe still have certain ecological properties after modification.It can be considered that gypsum-based materials are suitable for the modification of acidic adobe and alkaline adobe.However,for the modification of acidic adobe,it is necessary to increase the amount of gypsum to achieve a better effect.In order to further understand the adaptability of the gypsum-based materials to the acid-causing or alkali-causing factors in the adobe,aluminum sulfate and calcium hydroxide were selected as acidic and alkaline p H modifiers and incorporated into the reference adobe.In this way,it can avoid differences in modification effects caused by other physical and chemical properties of adobe.The result shows,gypsum-based materials have better adaptability to alkali-causing factors in adobe.The alkalinity factor can make the modified adobe have better working performance.Affected by the same factor,the amount of gypsum increases,the water-solid ratio(same fluidity)of the modified adobe increases,and the setting time shortens.The compressive strength of the modified adobe can increase continuously with age when the alkalinity factor exists.The7 d compressive strength of the modified adobe with different p H values decreased first and then increased as the p H value increased,and the 28 d compressive strength increased as the p H value increased.When the same amount of gypsum is added,the alkalinizing factor is more conducive to the improvement of the strength of the modified adobe.The alkalinity factor can make the modified adobe resistant to water and not collapse when the amount of gypsum is less.It can also make the modified adobe maintain a higher softening coefficient.But the compressive strength of the modified adobe decreases with the extension of the immersion time.Alkalinity factors are beneficial for gypsum-based materials to inhibit the drying shrinkage of adobe.When the amount of gypsum is 30%,the drying shrinkage rate of the modified adobe with the alkaline modifier can be controlled at 0.25%.Under the same conditions,the increase in the amount of gypsum is beneficial to the improvement of the mechanical properties,water resistance and volume stability of the modified adobe.Gypsum-based materials can also neutralize the acidcausing and alkali-causing factors in the adobe,which is conducive to maintaining the ecological properties of the modified adobe.