植石水泥混凝土路面成型工艺试验

Experimental on molding process for chip-sprinkling cement concrete pavement

为了研究植石水泥混凝土表面纹理与碎石压入效果的关系,针对压入时间、压入深度与压入荷载等碎石压入效果关键成型工艺控制参数,采用路面材料强度试验仪模拟植石水泥混凝土室内成型工艺,分析不同因素对成型工艺参数的影响。首先选取水泥混凝土、水泥砂浆、水泥净浆3种拌合物,分别测试不同压入条件下的压入荷载,分析拌合物材料组成对成型工艺参数的影响。然后根据不同稠度水泥混凝土拌合物的初凝时间,推荐了碎石的最迟压入时间,并在不同的压入深度条件下分析混凝土稠度、碎石粒径、碎石撒布面积、压入时间等因素对压入荷载的影响,并推荐植石水泥混凝土适宜的成型工艺参数。同时通过计算压入荷载的极差,分析不同因素对成型工艺参数影响程度的差异。试验结果表明:植石水泥混凝土碎石压入荷载主要来自于水泥混凝土拌合物中粗集料的阻碍作用,此外细集料影响了碎石与水泥混凝土拌合物接触界面的摩擦特性,也对其产生一定的影响;水泥混凝土拌合物流动性越好,碎石越易压入,但是流动性过大时碎石易被完全压入,推荐采用稠度为塑性水泥混凝土作为植石技术的嵌入层材料;碎石宜采用单粒径,其压入荷载与碎石撒布面积成正相关关系,碎石撒布面积过小无法形成丰富的表面纹理,碎石撒布面积过大则易脱落,撒布面积宜为60%~70%;压入时间过迟,水泥混凝土早期强度逐渐形成,碎石压入可能会造成水泥混凝土塑性破坏,压入时间不宜超过75℃·h;混凝土稠度对植石水泥混凝土碎石压入荷载的影响最为突出,碎石粒径与压入时间次之,碎石撒布面积影响最小。

Aimed at the relationship between the surface texture of chip-sprinkling cement concrete and the pressing-in effect of crushed aggregates, the key molding process parameters, including the pressing-in time, pressing-in depth, and pressing-in load, which control the pressing-in effect of crushed aggregates, were studied. The road material strength tester was used to simulate a laboratory molding process of chip-sprinkling cement concrete, and the effects of different factors on the molding process parameters were analyzed. Three kinds of mixes, including cement concrete, cement mortar, and cement paste, were chosen. Moreover, pressingin loads were measured, respectively, under different pressing-in conditions. The latest pressingin time of the crushed aggregates was recommended on the basis of the initial setting times of the cement concrete mix with different consistencies, and the effects of certain factors, such as concrete consistencies, aggregate particle sizes, aggregate spreading areas, and pressing-in time, on pressing-in loads, were analyzed under different pressing-in depths. The appropriate molding process parameters of chip-sprinkling cement concrete were recommended. The effect differences of different factors on the molding process parameters were analyzed by calculating appropriate ranges. The results show that the impeding effects of coarse aggregate in the cement concrete play a major role in pressing-in load sources. Fine aggregate affects the friction characteristics of the contact interface between the crushed aggregate and cement concrete, and the friction resistance has a certain effect on pressing-in load. The better the workability of cement concrete, the more easily implanted it is for crushed aggregates; however, crushed aggregates are easily entirely implanted if the workability is too large. The cement concrete with a plasticity consistency is recommended as the implanted layer material for chip-sprinkling technology. The crushed aggregates of chip-sprinkling technology should be single particle size. The pressing-in loads positively correlate with the spreading area of the crushed aggregates. A spreading area that is too small could result in bad surface texture, and a spreading area that is too large could result in crushed aggregates falling off. The spreading area should be distributed within a range of 60% to 70%. A pressing-in time that is too late could result in the plastic failure of the cement concrete, due to the gradual forming of early strength. The pressing-in time should not exceed 75 ℃ · h. Cement concrete consistency is the most prominent influence on molding process parameters for chip-sprinkling cement concrete, followed by the effects of the crushed aggregate particle size and the pressing time. The crushed aggregate spreading area has a minimal impact on molding process parameters. 4 tabs, 9 figs, 27 refs.