【摘要】：隨著我國道路交通量和交通荷載的日益增加，部分早期高速公路和城市道路的改擴建工程不斷增，建設中所存在的占地拆遷、軟土地基處理、凍土破壞以及管涵外保溫施工等問題對道路基層和面層的質量和耐久性有著重要的影響，不少關鍵技術沒有得到有效解決。泡沫混凝土作為一種自立性好、保溫抗凍、來源廣泛且價格低廉的新型道路基層材料，近些年在道路建設中取得了一定的應用和發(fā)展，但也出現(xiàn)了諸如泡沫不穩(wěn)定、強度較低、吸水率過大等問題。本文參照《公路路面基層施工技術規(guī)范》（JTJ034-2000）中對基層材料強度的要求，進行高穩(wěn)定發(fā)泡劑和泡沫混凝土的制備與配比優(yōu)化設計，系統(tǒng)地探討了影響發(fā)泡劑、泡沫混凝土及其內部孔結構的因素、改善措施和機理。主要內容包括： （1）通過對比研究不同陰離子表面活性劑的泡沫性能，以及不同穩(wěn)泡劑摻量對發(fā)泡倍數(shù)和泡沫穩(wěn)定性的影響，制備出兩種性能優(yōu)越的泡沫混凝土發(fā)泡劑，即GL-1和GL-2型。研究表明：GL-1型發(fā)泡劑制備的泡沫在空氣中表現(xiàn)出較高的穩(wěn)定性，但性能受外界溫度變化的影響較大。GL-2型發(fā)泡劑在溫度5~45℃的條件下，仍然保持其較高的穩(wěn)定性，對道路施工條件的適應性較強，且泡沫細膩均勻，有光澤，發(fā)泡倍數(shù)為42.2倍，，1h泌水量和沉降距分別為16.3ml和1.3mm； （2）以抗壓強度、吸水率、導熱系數(shù)和干縮值為性能指標，系統(tǒng)研究不同水灰比、粉煤灰、砂和纖維摻量對不同干密度等級下的泡沫混凝土性能的影響。研究表明：在水膠比為0.44，粉煤灰替代水泥用量30%時，制備的600級泡沫混凝土性能最優(yōu)，28d抗壓強度為4.14MPa。水料比為0.42，膠砂比為1:1.8，減水劑摻量為1.2%時，制備的1000級泡沫混凝土28d抗壓強度達到最高為4.54MPa，其中砂摻量對強度的影響最大。水料比0.58，纖維摻量0.10%時制備的400級泡沫混凝土，7d和28d抗壓強度分別為0.76MPa和1.32MPa，吸水率為17.5%，導熱系數(shù)為0.072W/(m·K)，干縮為0.98mm/m，制備的不同干密度下的泡沫混凝土強度指標可滿足不同等級公路對基層和底基層的要求。 （3）利用顯微鏡對不同干密度、水灰比以及膠砂比下的泡沫混凝土內部氣孔結構進行觀察，推導并計算出不同干密度和水灰比下的泡沫混凝土孔隙率，并利用Image J圖像分析軟件對其平均孔徑進行測量，研究表明：隨著干密度等級的增大，氣孔直徑和孔隙率逐漸減小，砂摻量越大，對孔結構的破壞越明顯。 （4）結合泡沫混凝土28d抗壓強度、孔隙率和孔徑的數(shù)據(jù)，以Griffith斷裂力學和復合材料理論為基礎，對泡沫混凝土強度和孔結構之間的關系進行定量分析與修正，并建立相應的數(shù)學模型，揭示泡沫混凝土強度與其孔隙率和孔徑大小之間的關系。
[Abstract]:With the increasing traffic volume and traffic load in our country, the reconstruction and extension projects of some early freeways and urban roads have been increasing, the construction of the existing land removal, soft soil foundation treatment, The damage of frozen soil and the construction of pipe and culvert external insulation have important influence on the quality and durability of road base and surface layer, and many key technologies have not been solved effectively. As a new type of road base material with good independence, good insulation and cold resistance, wide sources and low price, foam concrete has been applied and developed in road construction in recent years, but it has also appeared such as foam instability and low strength. Excessive water absorption and other problems. In this paper, according to the requirement of material strength in JTJ034-2000, the preparation and proportion optimization design of high stability foaming agent and foamed concrete are carried out, and the influence of foaming agent on foaming agent is discussed systematically. Foam concrete and its internal pore structure factors, improvement measures and mechanisms. The main contents are as follows: (1) the foam properties of different anionic surfactants and the effects of different amount of foam stabilizers on foaming ratio and foam stability are studied. Two foaming agents of foamed concrete, GL-1 and GL-2, were prepared. The results showed that the foams prepared with the foaming agent of 1: GL-1 exhibited high stability in air, but the properties of the foaming agent were greatly influenced by the outside temperature. GL-2 type foaming agent maintained its high stability at the temperature of 545 鈩

本文編號：2206558