现浇磷石膏应力-应变曲线试验研究

采用自制加载装置，通过棱柱体试件单轴受压试验研究现浇磷石膏的本构关系，并测定材料弹性模量和泊松比。制作了9组不同材料配合比试件共38个，采集到33个试件的有效数据。试验结果表明：当试件应变接近峰值应变时，现浇磷石膏具有迅速破坏的脆性性质，破坏状态主要为劈裂破坏；残余应力与峰值应力之比约为0.5～0.8，极限应变与峰值应变之比约为1.1～1.6；缓凝剂对峰值应力影响较大，当其掺入量在0.3%左右时，峰值应力可取8.6MPa，极限应变可取2.54×10^-3，而当其掺入量远大于0.3%时，峰值应力可取2.8MPa，极限应变可取2.01×10^-3；残余应力可取峰值应力的0.7倍，极限应变可取峰值应变的1.45倍；提出了材料的三段式本构方程，可反映受压试验所表现的全部特征；现浇磷石膏强度较高时，弹性模量也较高，当缓凝剂掺入量在0.3%左右时，弹性模量可取5300MPa，缓凝剂掺入量远大于0.3%时，弹性模量可取2 000 MPa；材料泊松比可取0.19。

Experimental investigation of stress-strain curves of cast-in-situ phosphogypsum

Constitutive relationship of cast-in-situ phosphogysum was researched at prismatic specimen under uniaxial compression test using self-loading device，and the elastic modulus and Poisson’s ratio were determined． Totally 38 specimens were made and divided into nine groups for testing. Effective data of 33 specimens were collected．Experimental results show that：test specimens rapidly appear splitting failure when the strain is close to ultimate strain．The ratio of residual stress to peak stress approximately ranges from 0.5 to 0.8，while the ratio of ultimate strain to peak strain is roughly between 1.1 and 1.6．Retarders have enormous influence on peak stress. When its mixing proportion becomes close to 0.3%，the peak stress can adopt 8.6 MPa，and the ultimate strain is approximate 2.54×10^-3. When its mixing proportion significantly exceeds 0.3%，the peak stress is 2.8 MPa，and the ultimate strain is 2.01×10^-3．The ratio of residual stress to ultimate stress is 0.7，while ultimate strain is 1.45 times than peak strain．This paper presents the three-part constitutive equation of cast-in-situ phosphogysum which can reflect all the characteristics of compression test．The elastic modulus is higher when the strength of cast-in-situ phosphogysum is higher. The elastic modulus can take 5-300 MPa when the mixing proportion of retarders is close to 0.3%. When the retarder significantly exceeds 0.3%，the elastic modulus is approximate 2 000 MPa. And the Poisson’s ratio is 0.19．