ZHANG Zhouqi， LIN Mingqiang， YU Yan， CHEN Wenwen
School of Civil Engineering and Architecture， University of Jinan， Jinan 250022， China
Abstract
Objective The physical foaming method is commonly used for preparing foam concrete in construction，but it often leads to issues such as delamination and collapse.Most existing studies focus on non-aggregate or lightweight aggregate foam concrete，with little clarity on the instability mechanism of fine aggregate foam concrete.To address its delamination instability in practical engineering，the study aims to further explore the instability mechanism of fine aggregate foam concrete and determine effective foam stabilization measures.
Methods In this paper，foam instability was theoretically studied， involving the mechanical analysis of foam collapse， stratification mechanism，and stabilization measures. It analyzed the micro-instability of foam and proposed stabilization measures using powder materials.Prepare foam pastes with different content of HPMC. Through the analysis of 1h bleeding rate and final defoaming time， evaluate the quality of foam，and determine the content of HPMC with the best foam stabilizing effect.Foam concrete of different densities（800，1 0000，1 200 kg/m3）and different hydroxypropyl methyl cellulose（HPMC）contents（0，0.05%，0.10%，0.15%，0.20%）was prepared and modified. Microscopic analysis and mechanical property tests were conducted on these samples.The influence degree of HPMC content on the pore morphology of foam concrete was determined by microscopic analysis，and the change degree of compressive strength was determined by mechanical property test. By evaluating the modification effects of varying densities and HPMC contents on foam stability， fluidity，dry density， and compressive strength，the optimal content for foam stabilizer was identified.Based on the test results，the causes of foam concrete delamination and the formation mechanism of pore wall structure are analyzed，and the action mechanism of HPMC is further studied.
Results and Discussion The study revealed that foam instability was caused by foam seepage， liquid film rupture， and gas diffusion.The maximum foam radius determined whether foam could remain stable.Uneven foam distribution led to delamination，with lower density of foam concrete being more prone to severe delamination.HPMC improved the pore structure in cement mortar by changing the properties of foam liquid film.The appropriate amount of HPMC could enhancefoam stability，improve slurry consistency， reduce foam pore size，limit gas diffusion，and produce a more uniform foam distribution. Microscopic analysis showed thickened pore walls，reduced pore diameters，improved uniformity， and fewer connecting pores.The existing research did not consider economic factors，which must be factored into large-scale constructions to determine the optimal mix ratio.When the HPMC content range was 0~0. 15%，foam stability，slurry consistency，pore size， gas diffusion， and foam distribution were all enhanced. For A08， A10， and A12 foam concrete，the optimal HPMC contents were 0.15%，0.15%，and 0.10%，respectively.The dry density decreased by 14%，7%，and 5%，respectively，and the compressive strength increased by 39.2%，38.8%，and 32.3%，respectively.While increasing HPMC content reduced foam fluidity and increased viscosity，excessive HPMC inhibited hydration reaction，resulting in an increase in dry density in later stages.The optimal HPMC dosage was density-dependent，with higher density foam concrete requiring less HPMC.For A08 and A10 foam concrete，the optimal content was 0.15%，and for A12，it was 0.10%.
Conclusion The research results determine the optimal content of foam concrete HPMC with different densities，and analyze the mechanism of HPMC improving the stability of foam concrete by improving the pore structure of foam concrete.By tailoring the optimal HPMC content to specific density，layer instability is effectively mitigated，and the performance of foam concrete is significantly enhanced in all aspects.This specifically includes reducing the pore size of foam，improving the uniformity and reducing the defoaming rate.And the dry density of foam concrete decreased，and the compressive strength increased significantly.It can be seen that the incorporation of HPMC plays an important role in the future practical application of foam concrete.
Keywords： foam concrete；hydroxypropyl methyl cellulose；stratified instability；mechanical property
Get Citation:ZHANG Zhouqi，LIN Mingqiang，YU Yan，et al.Study on properties of hydroxypropyl methyl cellulose modified foam concrete［J］.China Powder Science and Technology，2025，31（3）：1−13.
Received：2024-07-12.Revised:2024-08-23,Online:2025-03-03.
Funding Project：国家自然科学基金项目，编号：52308504。
First Author:张洲齐（1999—），男，硕士生，研究方向为结构工程。E-mail：zhangzhouqi2022@163.com。
Corresponding Author:：林明强（1979—），男，副教授，博士，硕士生导师，研究方向为建筑固废再生利用。E-mail：cea_linmq@ujn.edu.cn。
DOI：10.13732/j.issn.1008-5548.2025.03.013
CLC No:TU528； TB4 Type Code:A
Serial No:1008-5548（2025）03-0001-13
