木质素基超塑化剂的制备及其在砂浆中的应用

来源于木材、麦草、竹子和蔗渣的木质素磺酸钠与三聚氰胺、甲醛和焦亚硫酸钠合成出磺化木质素三聚氰胺甲醛超塑化剂(LSMF).系统研究了LSMF对砂浆减水率、抗压强度、抗折强度和加速碳化深度等应用性能的影响.结果表明,使用麦草基木质素磺酸钠合成出磺化度3.663mmol/g,特性黏度7.24mL/g的LSMF对砂浆的减水增强性能最好.当LSMF掺量为0.7%时,砂浆减水率为21.1%.硬化砂浆28d加速碳化深度为13mm,空白砂浆为34.5mm.掺加LSMF后,硬化砂浆28d抗压强度和抗折强度分别比空白砂浆提高37%和18%.LSMF超塑化剂为木质素高效利用提供了一种新的思路.

Preparation of Lignin-based Superplasticizer and Its Application in Mortar

Lignosulfonate-modified sulfonated melamine formaldehyde resin (LSMF) has been synthesized as a superplasticizer used in mortar, and its effects on the performance of mortar have been systematically investigated. To obtain a new superplasticizer LSMF, lignosulfonates originated from wood, straw, bamboo and bagasse were selected to react with sulfonated melamine formaldehyde through a four-step reaction. The effects of LSMF on the performances of the superplasticized mortar were studied through measuring water-reducing ratio, compressive strength, flexural strength, and accelerated carbonation depth. The result shows that straw-based LSMF with sulfonic group content of 3.663mmol/g and intrinsic viscosity of 7.24mL/g has the best water-reducing and reinforcement effects. When LSMF is used in dosage of 0.7% by weight of cement, water-reducing ratio reaches 21.1 %. Compared with that of the control mortar, compressive strength and flexural strength of the superplasticized mortar increase 37% and 18% at 28d, respectively. The minimum carbonation depth of superplasticized mortar at 28d is 13mm, while that of the control mortar is 34.5mm. This understanding can lead to push forward the utilization of lignin with high efficiency.