一、水泥穩(wěn)定碎石作用原理及強度機理

　　1、 Principle and strength mechanism of cement stabilized crushed stone

　　1、作用原理?

　　1. Working principle?

　　水泥穩(wěn)定碎石是以級配碎石為骨料， 輔以膠凝材料和水泥漿體按照嵌擠原理進行攤鋪壓實，該種工藝的初期強度高， 強度隨齡期延長而增加， 其抗?jié)B性能較高， 該工藝的水泥用量為混合料的3%～6%， 施工后7d無側限抗壓強度可達2MPa～4MPa， 其施工質(zhì)量優(yōu)劣將直接影響路面的使用性能和壽命。?

　　Cement stabilized crushed stone is made of graded crushed stone as aggregate, supplemented with cementitious materials and cement slurry, and spread and compacted according to the principle of interlocking. This process has high initial strength, which increases with age and has high impermeability. The cement dosage of this process is 3% to 6% of the mixture, and the unconfined compressive strength can reach 2MPa to 4MPa after 7 days of construction. The quality of its construction will directly affect the performance and service life of the road surface.?

　　2、 強度機理?

　　2. Strength mechanism?

　?。?）嵌擠作用?

　　(1) Squeezing effect?

　　該工藝采用的骨料是由顆粒組成， 施工后小粒徑顆粒可填充大粒徑顆?？障?， 應按照一級填補一級的原則進行， 攤鋪后在外力作用下， 大小顆?？删o密的嵌鎖在一起， 顆粒間的嵌擠和摩阻作用而形成內(nèi)模阻力可提高其強度和穩(wěn)定性。?

　　The aggregate used in this process is composed of particles. After construction, small particles can fill the gaps between large particles, and the principle of filling one level at a time should be followed. After paving, under external force, the large and small particles can be tightly interlocked, and the internal mold resistance formed by the interlocking and friction between particles can improve its strength and stability.?

　　（2）水泥硬化?

　　(2) Cement hardening?

　　施工后水泥內(nèi)礦物質(zhì)和水將發(fā)生水解和水化反應， 最終產(chǎn)物為Ca（OH）2和其他水化物， 部分水化物可自行硬化生成水泥石骨架， 部分則與碎石內(nèi)的其他礦物質(zhì)發(fā)生硬凝反應和碳酸化作用，該類產(chǎn)物可增加水泥穩(wěn)定碎石基層強度。?

　　After construction, minerals and water in the cement will undergo hydrolysis and hydration reactions, and the final products are Ca (OH) 2 and other hydrates. Some hydrates can self harden to form a cement stone skeleton, while others undergo hardening and carbonation reactions with other minerals in the crushed stone. These products can increase the strength of cement stabilized crushed stone base.?

　　二、水泥穩(wěn)定碎石在公路工程中的應用

　　2、 Application of cement stabilized crushed stone in highway engineering

　　二、水泥穩(wěn)定碎石在公路工程中的應用　　1、原材料控制?

　　2、 Application of cement stabilized crushed stone in highway engineering 1. Raw material control?

　　水泥碎石穩(wěn)定基層結構屬于半剛性結構，對原材料要求比較嚴，嚴把材料質(zhì)量關是保證工程質(zhì)量的基礎和重要環(huán)節(jié)。水泥穩(wěn)定碎石路面基層的原材料主要有水泥、粗集料、細集料、礦粉。?

　　The cement crushed stone stabilized base structure belongs to a semi-rigid structure, which has strict requirements for raw materials. Strictly controlling the quality of materials is the foundation and important link to ensure the quality of the project. The raw materials for the cement stabilized crushed stone pavement base mainly include cement, coarse aggregate, fine aggregate, and mineral powder.?

　?。?）水泥?

　　(1) Cement?

　　水泥作為穩(wěn)定劑，是控制水泥碎石穩(wěn)定基層質(zhì)量的關鍵所在。水泥選用初凝時間3h 以上和終凝時間較長的低標號水泥，各項技術指標必須滿足技術規(guī)范的要求，同時水泥初終凝時間是確定水泥穩(wěn)定碎石的施工控制時間的重要依據(jù)。在施工過程中，為了保證水泥的質(zhì)量，我們對進場水泥每批次都進行水泥強度、初凝時間、終凝時間、安定性和細度指標的檢驗。?

　　Cement, as a stabilizer, is the key to controlling the quality of cement stabilized crushed stone base. Low grade cement with an initial setting time of more than 3 hours and a longer final setting time must be selected for cement. All technical indicators must meet the requirements of technical specifications. At the same time, the initial and final setting time of cement is an important basis for determining the construction control time of cement stabilized crushed stone. During the construction process, in order to ensure the quality of cement, we conduct inspections on cement strength, initial setting time, final setting time, stability, and fineness indicators for each batch of cement that enters the site.?

　?。?）集料?

　　(2) Aggregate?

　　粗集料的質(zhì)量控制指標主要是根據(jù)結構層性能確定出碎石的強度和級配。細集料主要是控制好石屑的顆粒組成和摻加量，保證級配連續(xù)。為了把好原材料質(zhì)量關，工地試驗室加強對各類原材料的料源進行提前確定和檢查，在使用過程中按規(guī)定頻率抽樣檢驗，不合格的材料不能用于工程中。?

　　The quality control indicators of coarse aggregate mainly determine the strength and gradation of crushed stone based on the performance of the structural layer. Fine aggregate mainly controls the particle composition and dosage of stone chips to ensure continuous gradation. In order to ensure the quality of raw materials, the on-site laboratory strengthens the pre determination and inspection of various raw material sources, and conducts sampling inspections at the prescribed frequency during use. Unqualified materials cannot be used in the project.?

　　2、混合料組成及配合比設計?

　　2. Composition and mix design of the mixture?

　　級配選擇。各種不同粒徑的集料，按照一定比例搭配起來，才能達到較高的密實度和較大的摩擦力。因此，要求碎石集料有一定的級配。但施工時所用碎石集料顆粒不均勻，所以，原材料選定后，要對集料進行級配設計和級配調(diào)整，使其合成級配盡量滿足設計級配的要求。?

　　Grading selection. Various aggregates of different particle sizes can only be combined in a certain proportion to achieve higher density and greater friction. Therefore, it is required that the crushed stone aggregate has a certain grading. However, the crushed stone aggregate particles used during construction are uneven. Therefore, after selecting the raw materials, it is necessary to design and adjust the gradation of the aggregate to ensure that its composite gradation meets the requirements of the design gradation as much as possible.?

　　其他路用性能檢驗。初步擬定配合比后，綜合考慮混合料的抗拉性、剛度、耐久性、抗疲勞性、抗裂性等路用性能，得出最佳水泥摻量，從而確定最佳配合比。?

　　Other road performance tests. After preliminary formulation of the mix proportion, the optimal cement dosage is determined by comprehensively considering the road performance such as tensile strength, stiffness, durability, fatigue resistance, and crack resistance of the mixture.?

　　最佳級配確定。在確定最佳水泥劑量后，變化集料級配，通過混合料路用性能驗證，分析規(guī)范中三種典型級配對混合料路用性能的影響，得出最佳級配。?

　　Determine the optimal grading. After determining the optimal cement dosage, changing the aggregate gradation, verifying the road performance of the mixture, analyzing the influence of three typical gradation pairs in the specifications on the road performance of the mixture, and obtaining the optimal gradation.?

　　3、混合料的拌和?

　　3. Mixing of mixtures?

　　攤鋪用料攪拌前, 應檢查場內(nèi)各處集料的含水量, 計算當天的配合比, 外加水與天然含水量的總和要比最佳含水量略高。實際的水泥劑量可以大于混合料組成設計時確定的水泥劑量約0.5%, 但是實際采用的水泥劑量和現(xiàn)場抽檢的水泥劑量應小于5.5%。同時在充分估計施工富余強度時要從縮小施工偏差入手, 不得以提高水泥用量的方式提高路面基層強度; 每天開始攪拌之后, 出料時要在拌和機投料運輸帶上取樣檢查是否符合設計的配合比, 進行正式生產(chǎn)之后, 每1 h～2 h 檢查一次拌和情況, 檢驗其配比、集料級配、含水量是否變化。高溫作業(yè)時, 早晚與中午的含水量要有區(qū)別, 要按溫度變化及時調(diào)整; 拌和機出料不允許采取自由跌落式的落地成堆、裝載機裝料運輸?shù)霓k法。一定要配備帶活門漏斗的料倉, 由漏斗出料直接裝車運輸, 裝料時運輸車輛必須前后移動, 最少分3 次裝料, 避免混合料離析。?

　　Before mixing the paving materials, the moisture content of the aggregates in each part of the site should be checked, and the mix ratio for the day should be calculated. The total moisture content of the external water and natural water should be slightly higher than the optimal moisture content. The actual cement dosage can be about 0.5% higher than the cement dosage determined during the design of the mixture composition, but the actual cement dosage used and the cement dosage sampled on site should be less than 5.5%. At the same time, when fully estimating the surplus strength of construction, we should start with reducing construction deviations and not increase the strength of the pavement base by increasing the amount of cement used; After starting mixing every day, samples should be taken from the feeding conveyor belt of the mixer to check if they meet the designed mix ratio. After formal production, the mixing situation should be checked every 1-2 hours to check if the mix ratio, aggregate gradation, and moisture content have changed. When working in high temperatures, there should be a difference in moisture content between morning, evening, and noon, and adjustments should be made in a timely manner according to temperature changes; The discharge of the mixer is not allowed to adopt the method of free falling and stacking on the ground, or loading and transporting by the loader. It is necessary to equip a silo with a valve funnel, and the material should be directly loaded and transported from the funnel. When loading, the transport vehicle must move forward and backward, and the material should be loaded at least three times to avoid segregation of the mixture.?

　　4、 混合料的攤鋪?

　　4. Spread the mixture?

　　為了控制好水泥穩(wěn)定碎石基層的高程與平整度，采用自動找平攤鋪機攤鋪。將水泥穩(wěn)定碎石混合料通過自卸汽車直接卸入攤鋪機料斗內(nèi)，由攤鋪機均勻攤鋪，攤鋪均勻的料應立即碾壓，在攤鋪過程中要注意集料的離析。在攤鋪機后設專人消除粗細集料離析現(xiàn)象，特別應該鏟除局部粗集料帶，并用新拌混合料填補。使用攤鋪機鋪筑水泥穩(wěn)定土混合料時，必須嚴格遵守操作技術規(guī)程，才能達到較好的平整度。一次鋪筑的厚度不超過25cm，分層攤鋪時，上層厚度取10cm；工程計劃應盡量減少橫向接縫；做好橫向接縫，應立即用直尺檢驗；經(jīng)常檢驗控高鋼絲和傳感器；經(jīng)常用直尺檢驗表面；保持攤鋪機在良好的工作狀態(tài)。?

　　In order to control the elevation and flatness of the cement stabilized crushed stone base, an automatic leveling and paving machine is used for paving. The cement stabilized crushed stone mixture is directly unloaded into the hopper of the paver by a dump truck, and evenly spread by the paver. The evenly spread material should be immediately compacted, and attention should be paid to the segregation of aggregates during the paving process. After the paver, a dedicated person should be assigned to eliminate the segregation of coarse and fine aggregates, especially to remove the local coarse aggregate belt and fill it with fresh mixed material. When using a paver to lay cement stabilized soil mixture, it is necessary to strictly follow the operating technical regulations in order to achieve good flatness. The thickness of a single paving shall not exceed 25cm. When paving in layers, the thickness of the upper layer shall be taken as 10cm; The engineering plan should minimize horizontal joints as much as possible; Horizontal joints should be inspected immediately with a ruler; Regularly inspect the height control steel wire and sensors; Regularly inspect the surface with a ruler; Keep the paver in good working condition.?

　　5、壓實?

　　5. Compaction?

　　混合料經(jīng)攤鋪機攤鋪成型后，即可用壓路機碾壓，碾壓長度需根據(jù)施工現(xiàn)場的實際情況確定，如果實測混合料的含水量高于最佳含水量，且氣溫較低時可適當延長碾壓長度，如果混合料已接近最佳含水量且溫度較高蒸發(fā)快時，應縮短碾壓長度，確保在最佳含水量時進行碾壓。?

　　After the mixture is spread and formed by the paver, it can be rolled by a roller. The rolling length should be determined according to the actual situation of the construction site. If the measured moisture content of the mixture is higher than the optimal moisture content and the temperature is low, the rolling length can be appropriately extended. If the mixture is close to the optimal moisture content and evaporates quickly at high temperatures, the rolling length should be shortened to ensure that rolling is carried out at the optimal moisture content.?

　　從開始加水拌和到完成壓實的延遲時間，對水穩(wěn)的密實度和強度有很大影響。間隔時間過長，水泥會部分結硬，一方面影響水穩(wěn)的壓實度，而壓實度對強度的影響很大；另一方面將破壞已結硬水泥的膠凝作用，使水穩(wěn)的強度下降。?

　　The delay time from the start of water mixing to the completion of compaction has a significant impact on the compactness and strength of water stability. If the interval time is too long, the cement will partially harden, which on the one hand affects the compaction degree of water stability, and the compaction degree has a significant impact on strength; On the other hand, it will destroy the cementing effect of already hardened cement, causing a decrease in the strength of water stability.?

　　碾壓過程中的質(zhì)量控制∶試驗人員在現(xiàn)場檢測混合料含水量及配合比，發(fā)現(xiàn)問題，反饋信息，及時糾正。現(xiàn)場技術人員在壓實過程中，跟蹤檢測松鋪厚度、攤鋪寬度等各項指標，確保成型后的基層各項幾何尺寸符合要求。?

　　Quality control during rolling process: Testing personnel inspect the moisture content and mix proportion of the mixture on site, identify problems, provide feedback, and promptly correct them. On site technicians track and detect various indicators such as loose paving thickness and paving width during the compaction process to ensure that the geometric dimensions of the formed base meet the requirements.?

　　每次攤鋪結束后，暫留30～40m路段，將攤鋪機駛離混合料末端（注意應將攤鋪機內(nèi)存料清理干凈），然后人工將末端混合料弄整齊，使之與路中心線垂直，再進行碾壓。待攤鋪新的混合料之前，將末端不符合要求的混合料鏟除，末端切齊，使之與路中心線垂直并成垂直向下的斷面，然后再攤新鋪的混合料。?

　　After each paving is completed, leave a section of 30-40m for the paver to drive away from the end of the mixture (note that the material stored in the paver should be cleaned up), and then manually tidy the end of the mixture to be perpendicular to the centerline of the road before rolling it. Before laying the new mixture, remove the mixture that does not meet the requirements at the end, cut the end evenly, make it perpendicular to the centerline of the road and form a vertical downward section, and then lay the new mixture.?

　　6、養(yǎng)生?

　　6. Health preservation?

　　在下基層碾壓成型并經(jīng)壓實度檢驗合格后, 即采用復合材料養(yǎng)生膜覆蓋進行保濕養(yǎng)生。上基層碾壓結束表面稍干隨即灑布透層瀝青和攤鋪稀漿封層進行養(yǎng)生。薄膜覆蓋養(yǎng)生可以保證有充足的水分讓水泥充分水化, 并且可以防止因失水過多而引起干縮裂縫。養(yǎng)生期間, 應封閉交通。如不能封閉交通, 應禁止重車通行, 其他車輛的車速不得超過30 km/ h, 并避免在主車道上集中行駛。上基層采用透層油和稀漿封層養(yǎng)生時, 透層油采用慢裂、滲透性好的灑布型乳化瀝青, 稀漿封層采用慢裂快凝的拌和型乳化瀝青。氣溫低于10°或大風、即將降雨時, 不得噴灑透層油。?

　　After the lower base layer is compacted and passes the compaction degree inspection, composite material curing film is used to cover it for moisturizing and curing. After the compaction of the upper base layer is completed, the surface should be slightly dry, and then a prime coat of asphalt and a slurry seal layer should be sprayed for curing. Thin film coverage for health preservation can ensure sufficient moisture to fully hydrate cement and prevent shrinkage cracks caused by excessive water loss. During the period of health preservation, traffic should be closed off. If traffic cannot be closed, heavy vehicles should be prohibited from passing, and the speed of other vehicles should not exceed 30 km/h, and concentrated driving on the main lane should be avoided. When using permeable oil and slurry seal for curing the upper base layer, the permeable oil should be a slow cracking and permeable spray type emulsified asphalt, and the slurry seal layer should be a slow cracking and fast setting mixed emulsified asphalt. When the temperature is below 10 ° C or there is strong wind or imminent rainfall, it is not allowed to spray the penetrating oil.?

　　總之，影響水泥穩(wěn)定碎石基層質(zhì)量的因素很多, 在施工中, 不僅要嚴格執(zhí)行有關規(guī)范, 還應結合具體情況進行相應的調(diào)節(jié)、控制。實踐證明, 在施工中只要加強對混合料含水量、材料組成比例的控制, 有效防止混合料離析, 選擇合適的壓實機械, 采取適當?shù)膲簩嵐に嚥⒆⒁饣旌狭橡B(yǎng)生, 就能夠提高工程質(zhì)量。?

　　In summary, there are many factors that affect the quality of cement stabilized crushed stone base. During construction, it is not only necessary to strictly comply with relevant regulations, but also to make corresponding adjustments and controls based on specific circumstances. Practice has proven that in construction, as long as the control of the moisture content and material composition ratio of the mixture is strengthened, the segregation of the mixture is effectively prevented, suitable compaction machinery is selected, appropriate compaction processes are adopted, and attention is paid to the curing of the mixture, the quality of the project can be improved.?

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